US3317840A

US3317840A - Single sideband generator

Info

Publication number: US3317840A
Application number: US354526A
Authority: US
Inventors: Guttman Julius; Fourcher Kirk; Jonas M Shapiro
Original assignee: MANSON LAB Inc
Current assignee: MANSON LAB Inc; MANSON LABORATORIES Inc
Priority date: 1964-03-25
Filing date: 1964-03-25
Publication date: 1967-05-02
Anticipated expiration: 1984-05-02

Description

May 2, 1m

J. GUTTMAN ETAL SINGLE SIDEBAND GENERATOR I Filed March 25, 1964 8 Sheets-Sheet l '2 MODULA 7E0 RF our F To TRANSMITTER GENERA TOR :3 15 v sm/r/ms/z "-72 R F COUNTER L GENERA r02 14 cAue Ai'a/e a j 00 0N5 MC ktmemva 5002a ONE. N am: MEGA era: a, Y5 TA! 1;

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SINGLE SIDEBAND GENERATOR Filed March 25, 1964 8 Sheets-Sheet 2 May 2, J. GUTTMAN ETAL SINGLE SIDEBAND GENERATOR Filed March 25, 1964 8 Sheets-5heet 6 QTTQRNEY y 2, 1967 J. GUTTMAN ETAL 3,317,840

SINGLE SIDEBAND GENERATOR Filed March 25, 1964 8 Sheets-Sheet 7 C6261.

TH/Ql) UPPER SIDEBA N0 ATTORNEY M y W67 J. GUTTMAN E-TAL SINGLE SIDEBAND GENERATOR 8 Sheets-Sheet. 8

Filed March 25, 1964 INVENTORS JULIUS GUTTMAN KIRK FOURCHER JONAS M. SHAPIRO ATTORNEY United States Patent Office 3,317,349 Patented May 2, 1967 3,317,840 SINGLE SlDEiiAND GENERATOR Julius Guttman, White Plains, N.Y., and Kirk Fourcher, Ridgefield, and Jonas M. Shapiro, Stamford, Conn., assignors to Manson Laboratories Inc., Wilton, Conn., a corporation of (Ionnecticut Filed Mar. 25, 1964, Ser. No. 354,526 17 Claims. (Cl. 325-13 7) The present invention relates to a single sideband generator. More particularly, the present invention relates to a radio transmitter circuit arrangement for transmitting a single sideband signal.

An object of the present invention is to provide a new and improved single sideband generator.

In accordance with the present invention, a single sideband generating circuit arrangement comprises a radio frequency generator having a plurality of inputs and an output for producing sideband signals and for modulating audio modulations on a radio frequency carrier. An audio frequency generator having an input and an output connected to an input of the radio frequency generator produces audio modulating signals from an upper sideband input and a lower sideband input. Upper sideband inputs and lower sideband inputs are supplied to the input of the audio frequency generator. A synthesizer having an output connected to an input of the radio frequency generator supplies stable frequencies to the radio frequency generator. A counter having an input connected to the output of the radio frequency generator and another input indicates frequencies of signals produced by the single sideband generating circuit arrangement. A calibrator having an input connected to an input of the radio frequency generator and to the other input of the counter supplies a reference frequency standard signal for the radio frequency generator and for the counter. An output connected to the output of the radio frequency generator derives the modulated radio frequency signals from the radio frequency generator.

In accordance with the present invention, an audio frequency generator for producing audio modulating signals comprises an upper sideband audio unit having an input and an output utilizing an upper sideband input for producing at its output an upper sideband audio modulating signal. The upper sideband audio unit comprises a filter connected to the input of the upper sideband audio unit for passing frequencies below a first predetermined level and for passing frequencies above a second predetermined level, an amplifier, and a coupling which couples the filter to the output of the upper sideband audio unit through the amplifier. An upper sideband input is supplied to the input of the upper sideband audio unit. A lower sideband audio unit having an input and an output utilizes a lower sideband input for producing at its output a lower sideband audio modulating signal. The lower sideband audio unit comprises a filter connected to the input of the lower sideband audio unit for passing frequencies below a first predetermined level and for passing frequencies above a second predetermined level, an amplifier, and a coupling which couples the filter to the output of the lower sideband audio unit through the amplifier. A lower sideband input is supplied to the input of the lower sideband audio unit. A frequency shift keying unit having inputs and an output utilizes a frequency shift keying input signal for producing at its output a frequency shifted signal in which a mark is represented by a signal having a first frequency and a space is represented by a signal having a second frequency different from the first frequency. The frequency shift keying unit comprises an oscillator connected to an input of the frequency shift keying unit and having outputs for producing mark and space signals, a gate connected to inputs of the frequency shift keying unit and to the outputs of the oscillator for gating the outputs of the oscillator, a phase shifter connected between another input of the frequency shift keying unit and the gate for phase inverting the frequency shift keying input signal and for controlling the gate therewith, and a coupling which couples the gate to the input of each of the upper and lower sideband audio units through the output of the frequency shift keying unit. A frequency shift keying input signal is supplied to the inputs of the frequency shift keying unit. A continuous wave unit having inputs and an output utilizes a continuous wave D.C. input signal for producing at its output a continuous wave signal. The continuous wave unit comprises an oscillator connected to an input of the continuous wave unit and having an output and being energized by the continuous wave D.C. input signal for producing a tone signal of predetermined frequency, a gate connected to the inputs of the continuous wave unit and to the output of the oscillator for gating the output of the oscillator, a filter, and a coupling which couples the gate to the output of the continuous wave unit through the filter. A continuous wave D.C. input signal is supplied to the inputs of the continuous wave unit.

In accordance with the present invention, a radio frequency generator for producing sideband signals and modulating audio modulations on a radio frequency carrier comprises a frequency doubler having an input and a pair of outputs for doubling a frequency supplied to it. A one megacycle per second reference frequency standard signal is supplied to the input of the frequency doubler to produce a 2 megacycles per second output signal at the output of the frequency doubler. An upper sideband balanced modulator has a pair of inputs and an output. A lower sideband balanced modulator has a pair of inputs and an output. An output of the frequency doubler is coupled to an input of the upper sideband balanced modulator and supplies the 2 megacycles per second output of the frequency doubler to the upper sideband balanced modulator. An upper sideband audio modulation is supplied to the other input of the upper sideband balanced modulator to produce at the output of the upper sideband balanced modulator a modulated double sideband 2 megacycles per second radio frequency carrier with the carrier partially suppressed. The other output of the frequency doubler is coupled to an input of the lower sideband balanced modulator for supplying the 2 megacycles per second output of the frequency doubler to the lower sideband balanced modulator. A lower sideband audio modulation is supplied to the other input of the lower sideband balanced modulator to produce at the output of the lower sideband balanced modulator a modulated double sideband 2 megacycles per second radio frequency carrier with the carrier partially suppressed. An upper sideband crystal filter eliminates frequencies below 2 megacycles per second. A lower sideband crystal filter eliminates frequencies above 2 megacycles per second. A sideband combiner having a pair of inputs and an output isolates the upper and lower sideband crystal filters from each other and mixes the upper and lower sideband signals to produce a 2 megacycles per second double independentsideband suppressed-carrier signal at its output. The output of the upper sideband balanced modulator is connected to an input of the sideband combiner through the upper sideband crystal filter. The output of the lower sideband balanced modulator is connected to the other input of the sideband combiner through the lower sideband crystal filter. A radio frequency amplifier having an input connected to the output of the sideband combiner, another input and a pair of outputs amplifies the signal at the output of the sideband combiner. A relay is connected to the other output of the frequency doubler. A gate coupled between the relay and the other input of the radio frequency amplifier reinserts the carrier suppressed by each of the upper sideband balanced modulator and the lower sideband balanced modulator in the radio frequency carrier. A mixer has an input connected to an output of the radio frequency amplifier, another input and an output. A frequency tripler having an input and an output triples a frequency supplied to it. The one megacycle per second reference frequency standard signal is supplied to the input of the frequency tripler to produce a 3 megacycles per second signal at its output. A frequency divider having an input connected to the output of the frequency tripler and an output divides the output signal of the frequency tripler in half to a 1500 kilocycles per second signal. The output of the frequency divider is coupled to the other input of the mixer to produce a double independent sideband signal modulated on a 500 kilocycles per second carrier at the output of the mixer. A low-pass filter eliminates frequencies above 500 kilocycles per second. A bandswitch having a plurality of bandswitch contacts and a switch arm connected at one end to an output contact is adapted to selectively contact at its other end one of the plurality of bandswitch contacts. The output of the mixer is coupled to selected contacts of the bandswitch contacts of the bandswitch through the low-pass filter to supply a 500 kilocycles per second double independent sideband signal to the last-mentioned selected contacts of the bandswitch contacts. The other output of the radio frequency amplifier is coupled to selected other contacts of the bandswitch contacts of the bandswitch to supply a 2 megacycles per Second double independent sideband signal to the last-mentioned selected other contacts of the bandswitch contacts. A radio frequency mixer has an input connected to the output contact of the bandswitch, another input and an output. Variable frequency oscillator stable frequencies are supplied to the other input of the radio frequency mixer to produce a difference frequency output signal at the output of the radio frequency mixer. An output coupled to the output of the radio frequency mixer derives selected sideband signals and audio modulated radio frequency carriers from the radio frequency generator.

In order that the present invention may be readily carried into effect, it will now be described with reference to the accompanying drawings, wherein:

FIG. 1 is a schematic block diagram of an embodiment of the single sideband generating circuit arrangement of the present invention;

FIGS. 20 and 2b are a schematic block diagram of an embodiment of a radio frequency generating circuit arrangement of the single sideband generating circuit arrangement of FIG. 1;

FIGS. 3a, 3b, 3c and 3d are a schematic block diagram of an embodiment of an audio frequency generating cir-' cuit arrangement of the single sideband generator of FIG. 1;

FIG. 4- is a schematic block diagram of an embodiment of a simplified synthesizer circuit arrangement of the single sideband generating circuit arrangement of FIG. 1; and

FIG. 5 is a schematic block diagram of an embodiment of a calibrator or reference standard of the single sideband generating circuit arrangement of FIG. 1.

In the figures, the same components are indicated by the same reference numerals. V

The single sideband generator of the present invention is extremely stable and versatile and utilizes the filter method of single sideband generation. The single sideband generator comprises an RF generator or converter 11, and AF generator or modulator 12, a synthesizer 13, a calibrator or reference standard 14 and a fre quency counter 15.

The AF generating circuit arrangement or modulator 12 supplies an audio signal and modulations from direct 100 milli-watts peak effective power.

and remote upper and lower sideband levels to the RF generating circuit arrangement or converter 11. The synthesizer circuit arrangement 13 supplies stable frequencies to the RF generator 11. The counter 15 indicates the frequencies produced by the single sideband generating circuit arrangement. The calibrator or reference standard 14 supplies the reference standard for the counter 15 and supplies the reference standard for the fixed frequency generators in the RF generator or converter. The calibrator or reference standard 14 may also supply the reference standard for the synthesizer 13, if desired. The outputs of the modulator or AF generator 12, the synthesizer13 and the calibrator or reference standard 14 are thus connected to the inputs of the converter 11, the output of the converter 11 is connected to the input of the counter 15, and the output of the calibrator is connected to the input of the counter. The output sidebands are derived from the output of the converter 11.

The converter or RF generator 11 utilizes the filter method of sideband generation. The single sideband crystal filters operate at 2 megacycles per second. The RF generator comprises all the mixers and sideband generators of the system. The normal IF frequency is 2 megacycles or 1.750 megacycles per second with separate modulators and filters for either sideband over the frequency range 300 to 6000 cycles from the carrier. A side step mixer is used to provide a 500 kilocycle per second signal for the 2 to 8 megacycles per second band. The 500 kilocycles per second IF frequency is selected because the lower IF must be used to prevent spurious outputs for the 2 to 8 megacycles per second RF range. This is produced by beating the 2 megacycles sidebands against a 1500 kilocycles per second signal derived from the master source of the calibrator 14; the 2 megacycles per second IF being used in the 8 to 32 megacycle RF range. A low-pass filter in the output of the 500 kilocycle unit insures that all spurious products outside of the IF are down db. The carrier insertion is handled at 2 megacycles per second and offers a variable zero to 40 db range with an infinity position capable of greater than 60 db carrier rejection.

In the converter 11, two separate 6 kilocycles per second audio channels are placed as upper and lower sidebands about a suppressed carrier in the frequency range of 2 to 32 megacycles per second with an output power of V The converter or RF generator 11 comprises a mixer stage, two intermediate amplifier stages and an output stage. A balanced mixer and seven synchronously-tuned circuits provide a minimum of 70 db rejection to image and variable frequency oscillator frequencies. Adequate band overlap is provided and the frequency bands are chosen so that the synthesizer may be made to read the carrier frequency directly without modification to the digital frequency readout.

The modulator or audio frequency generator 12 comprises two audio amplifiers, a teletype FSK or frequency shift key frequency shift adapter, a continuous wave unit and a break-in unit. There are two audio amplifiers, each being used for only one sideband, so that any type of input maybe handled in one channel while another type of input may be handled in the other channel. This also permits one input to be switched to two outputs, thereby permitting double side-band production. Input provisions are incorporated in the modulator 12 for continuous wave, multiplex continuous wave and frequency shift key or FSK signals. The modulator or AF generator 12 also includes input provisions for a local microphone and a remote control box. The power supply provides the operating voltages for the AF and RF generators.

The frequency synthesizer 13 functions on the indirect method of synthesis utilizing double superheterodyne circuitry to discipline three free-running variable frequency oscillators, each phase locked to a one megacycle frequency standard. The synthesizer 13 is continuously tunable over the frequency range of 2 to 34 megacycles, with each frequency having a stability of one part in per day. A single highly stable reference standard comprising a crystal controlled oscillator is used to discipline the synthesizer so that each of the output frequencies has a stability equal to that of the reference frequency. The pulling range of the one rnegacycle oscillator is sufficient to permit continuous coverage between the normal synthesizer intervals. The true carrier output frequency is read directly on the counter without the need for any mixers.

The counter 15 provides a direct visual readout of the RF generator 11 output frequencies in the range of 2 to 34 megacycles per second. No mixers or adders are utilized so that the readout is direct and is the true operating frequency of the single sideband generator. An accuracy of one count would produce with a one second count period a readout accuracy of one cycle at any RF frequency. The reference for the counter 15 is the calibrator 14.

The modulator or AF generator 12 may comprise the modulation arangement of FIGS. 3a, 3b, 3c and 3d. The AF generator 12 includes the input switching to select the mode of eXciter operation and amplifies the modulating signal to be fed to the RF generator or converter 11. The AP generator provides its own supply voltage and the supply voltages for the RF or single sideband generator. The converter, RF generator or single sideband generator 11 provides low level modulation of an RF carrier and filters the carrier to provide sideband operation. The basic RF carrier is povided by the synthesizer 13 which provides continuously tunable frequencies from 2 to 34 megacycles per second at a stability of one part in 10 per day. The RF output of the single sideband generator 11, which is a signal within the frequency band of 1.75 to 32 megacycles per second, is fed to the RF amplifier sections of an external transmitter, not shown in the figures. The output frequencies of the RF generator 11 are also fed to the counter 15 which then directly indicates the actual carrier frequency of the exciter or RF generator.

The audio frequency generator 12 provides full input switching for the exciter or RF generator 11. The modes of operation available are local microphone or handset, remote, with or without automatic gain control, and direct lines, continuous wave keying and frequency shift keying. Each sideband may be independently operated in the same or different modes, since each has its own function switch. Only the upper sideband circuit is discussed hereinafter, since both the upper and lower sideband circuits are identical.

A first upper sideband function switch 21, a second upper sideband function switch 22, a third upper sideband function switch 23, a fourth upper sideband function switch 24 and a fifth upper sideband function switch 25 each have eight

switch positions

1, 2, 3, 4, 5, 6, 7 and 8. A first lower sideband function switch 26, a second lower sideband function switch 27, a third lower sideband function switch 28, a fourth lower sideband function switch 29 and a fifth lower sideband function switch 31 each have eight

switch positions

1, 2, 3, 4, 5, 6, 7 and 8.

In each of the function switches 21, 22, 23, 24, 25, 26, 27, 28, 29 and 31 the number 1 position is OFF, the number 2 position is Test, the number 3 position is Continuous Wave, the number 4 position is Local Microphone, the number 5 position is Remote Line, the number 6 position is Remote Line Automatic Gain Control, the number 7 position is Direct Line and the number 8 position is Frequency Shift Keying.

With the function switches in the number 4 or Local Microphone position, a dynamic microphone 32 or handset is connected to the proper input jack. The voice input is fed through the first upper sideband function switch 21 and the upper sideband audio section comprising a low- 6 pass filter 33, a high-pass filter 34 and four audio amplifier stages 35, 36, 37 and 38. The low-pass filter 33 has an 8 kilocycle cutoff and the high-pass filter 34 passes only frequencies above 200 cycles per second. The effective input frequency range to the

audio amplifier

35, 36, 37 and 38 is 300 to 6000 cycles per second.

Part of the output of the final audio stage 38 is fed back through an automatic gain control amplifier 39 and the second upper sideband function switch 22 to all the

audio stages

35, 36, 37 and 38 as an automatic gain control voltage. The major part of the output of the final audio stage 38 is fed through two

emitter followers

41 and 42. The emitter follower 52 supplies the audio signal as the upper sideband modulation to the RF generator or converter 11 through the third upper sideband function switch 23 and the output terminal 43.

The emitter follower 41 feeds the audio signal through armature 44d and contact 45g of relay &4, the relay being in energized condition, and switch arm 46 and contact 46a of a switch 46, to headphones 47 for monitoring. The relay 44- is energized when a talk switch 48 of the microphone 32 or a handset 49 is closed, or may be continuously energized with a transmit-standby switch 51 in its closed or transmit position. When the relay 44 is energized, it applies B plus voltage of plus and plus 200 volts to the RF generator from a source 52 and a source 53 via the armature 442 and the contact 451' and output terminal 54 and via the armature 44 and the contact 45k and output terminal 55. When the relay 44 is energized, it energizes the transmit lamp 56 when it closes the annature 44] to the contact 45k. The energized relay 44 changes the upper sideband/lower sideband input of the headphones 47 from the

audio output

57 and 58 of the receiver to the audio output of the RF generator via armatures 44b and 44d and energizes an external T/R indicator to indicate the transmit condition via the armature 44c and the contact 45a.

It is thus seen that the local handset switches 48 and 51 control the T/ R or transmit-receive relay 44. The output of the microphone 32 is fed to the input of the upper and lower sideband audio amplifier sections and the amplifier automatic gain control is energized when the function switches are in their number 4 position. The output of the audio amplifier is fed to the converter or RF generator 11 and the audio level may be read on an audio level meter 61, when the function switches are in their number 4 position. When the function switches are in their number 4 position, sidetone is fed into the handset 49 and when the press-to-talk switch 48 is released, the receiver audio is connected to the headphones 47. The switches 48 and 51 enable either sidetone to be monitored on the handset earphone or a headphone.

With the function switches in the number 4 or Local Microphone position, the voice input is also fed through the first lower sideband function switch 26 and the lower sideband audio section comprising a low-pass filter 62, a high-pass filter 63 and four audio amplifier stages 64, 65, 66 and 67. The low-pass filter 62 has an 8 kilocycle cutoff and the high-pass filter 63 passes only frequencies above 200 cycles per second. The effective input frequency range to the

audio amplifiers

64, 65, 66 and 67 is 300 to 6000 cycles per second.

Part of the output of the final audio stage 67 is fed back through an automatic gain control amplifier 68 and the second lower sideband function switch 27 to all the

audio stages

64, 65', 66 and 67 as an automatic gain control voltage. The major part of the output of the final audio stage 67 is fed through two emitter followers 69 and 71. The emitter follower 69 supplies the audio signal as the lower sideband modulation to the RF generator or converter 11 through the third lower sideband function switch 23 and the output terminal 72.

The emitter follower 71 feeds the audio signal through armature 44b and contact 450 of the relay 44, the relay being in energized condition, and switch arm 46 and con- Line position,

tact 46b of the switch 46, to the headphones 47 for monitoring.

With the function switches in the number 7 or Direct Line position, the upper sideband input is fed directly to the RF generator 11 from the input terminal 73 via the third uper sideband function switch 23 and the output terminal 43. The upper side band input is also fed through the first upper sideband function switch 21 to the upper sideband audio section, so that the direct line signal may be monitored in the headphones 47. Information may thus be fed directly to the RF generator 11 without any intermediate amplification or processing in the audio section. This permits the very lowest intermodulation in the system. The audio sideband amplifier is utilized only to provide a sidetone signal on the local handset 49. The single sideband generator may be energized manually or remotely.

With the function switches in the number 7 or Direct Line position, the lower sideband input is fed directly to the RF generator 11 from the input terminal 74 via the third lower sideband function switch 28 and the output terminal 72. The lower sideband input is also fed through the first lower sideband function switch 26 to the lower sideband audio section, so that the direct line signal may be monitored in the headphones 47.

With the function switches in the number 6 or Remote Line Automatic Gain Control position, the upper sideband input is fed from the input terminal 75 to the upper sideband audio section via the first upper sideband function switch 21 in the same manner as the audio input when the function switches are in the number 4 position, except that the relay 44 is energized only by the standby-transmit switch 51 or a remote standby-transmit switch. The sideband amplifier automatic gain control is energized.

With the function switches in the number a or Remote Line Automatic Gain Control position, the lower sideband input is fed from the input terminal 76 to the lower sideband audio section via the first lower sideband function switch 26.

With the function switches in the number or Remote the same operation ensues as when the function switches are in the number 6 position, except that no automatic gain control is fed back to the audio amplifier stages. A balanced phantom or unbalanced line may be :fed to the

remote inputs

75 and 76. The sideband or audio amplifier without automatic gain control amplifies this signal and feeds it to the converter 11 and the audio level meter '61. The single sideband generator may 'be turned on manually or remotely. Sidetone may be monitored by a remote handset.

With the function switches in the number 8 or Frequency Shift Keying or FSK position, the FSK input is fed from the input terminal 77 to an FSK section which functions as an FSK converter. The FSK section is energized by the fourth upper side-band function switch 24 which applies plus 28 volts DC. to oscillator and gate stages of the FSK section. The oscillator stage comprises a 2425 cycles per second oscillator 78 and a 1575 cycles per second oscillator 79 and the gate stage comprises a gate 81 connected to the output of the oscillator 78 and a gate 82 connected to the output of the oscillator 79.

The oscillator 78 provides a 2425 cycles per second Mark signal which is fed to the mark gate 81 as the controlled input. The oscillator 79 provides a 1575 cycles per second Space signal which is fed to the space gate 82 as the controlled input. The switching input to each of the

gates

81 and 82 is the FSK input from the input terminal 77, which is supplied directly to the space gate 82. The FSK input is inverted by a phase inverter 83 for proper phase'relationship before it is applied to the mark gate 81.

The FSK input may be a zero milliamp Space/ 60 milliamp Mark, minus 30 milliamp Space/plus 3O milliamp Mark, or a zero milliamp Space/ milliamp Mark signal,

any one of which will operate the

gates

81 and 82. The output of the

gates

81 and 82 is a frequency-shifted signal in which a Mark is represented by 2425 cycles per second and a Space is represented by 1575 cycles per second. The FSK signal is thus inverted in the lower sideband and normal in the upper sideband. The upper sideband is fed through the first upper sideband function switch 21 in the same manner as the audio input in the number 4 position, except that the relay 44 is energized only by the standby-transmit switch 51 or a remote standby-transmit switch. The upper sideband is thus fed through the first upper sideband function switch 21 to the RF generator 11 through the output terminal 43. The sideband amplifiers are used only for sidetone monitoring. The single sideband generator may be energized manually or remotely. Any of the three common Teletype signals may be utilized.

With the function switches in the number 8 of FSK position, the FSK section is energized by the fourth lower sideband function switch 29 which applies the plus 28 volts DC. to the oscillator and gate stages of the FSK section. The lower sideband is fed through the first lower sideband function switch 26 in the same manner as the audio input in the number 4 position and the lower sideband is fed through the first lower sideband function switch to the RF generator 11 through the output terminal 72.

With the function switches in the number 3 or Continuous Wave position, the plus 28 volt D.C. energizing voltage is applied from the input terminal 84 to a continuous wave section via the fourth upper sideband function switch 24 and the fourth lower sideband function switch 29. The continuous wave section comprises a one kilocycle per second oscillator 85, a gate 86 connected to the output of the oscillator 85, and a low-pass filter 87 connected to the output of the gate 86.

The plus 28 volts DC. is applied to the oscillator which provides the audio frequency input to the gate 86. The gate 85 is switched on and off by the keying input from the input terminal 88. The output of the gate 86 is fed through the low-pass filter 87, with a cutoff of 4 kilocycles to eliminate switching transients, to the third upper and lower sideband function switches 23 and 28, respectively, whence it is fed to the RF generator 11 via the

output terminals

43 and 72, respectively. The keyed one kilocycle frequency is also fed through the first upper and lower sideband function switches 21 and 26, respectively, to the audio amplifiers of the upper and lower sideband audio sections, so that it may be monitored on the headphones 47.

The keying input from the input terminal 88 is fed through a break-in delay to energize the relay 44. The break-in delay arrangement comprises a phase inverter 89, a driver amplifier 91 connected to the output of the phase inverter 89, and a relay 92 connected to the output of the driver amplifier 91. The output of the relay 92 energizes the relay 44. The break-in delay arrangement becomes immediately activated, but has a relatively long delay time, of approximately 0.1 second, so that the relay 92 remains energized when the keying is repeated at a relatively rapid rate.

The number 3 position thus permits the sending of continuous wave with a regular telegraph key; the fast makeshow break relay 92 being utilized to permit the appropriate break-in action with an accompanying receiver. The one kilocycle tone is gated on and off when the key is activated. The sideband amplifier is utilized only as a sidetone monitor in the number 3 position. When the key is released, the receiver output may be heard in the headphones 47.

With the function switches in the number 2 or Test position, the one kilocycle oscillator 85 provides a constant tone which is fed to the single sideband generator and may also be monitored in the headphones 47 if the standbytransmit switch 51 is in the transmit position. The one kilocycle tone is fed to the single sideband generator or RF generator 11 through the upper and lower sideband audio sections and is used for alignment and testing purposes. The audio sideband amplifier automatic gain control is operative. The level of the upper and lower sideband modulations fed to the RF generator 11 may be read on the meter 61 when the meter is switched to the proper sideband via switch arm 93 and contact 93a or contact 93b. The local handset 49 may monitor the output of the sideband amplifier. 7

With the function switches in the number 1 or OFF position, the input to the filters and audio amplifiers is grounded by the first upper and lower sideband function switches 21 and 26, respectively, and the output to the RF generator 11 is grounded by the third upper and lower sideband function switches 23 and 28, respectively. No sidetone may be heard. The channel is thus completely deactivated.

The meter 61 may be switched so that the switch arm 93 contacts the contact 93a to read the upper sideband audio voltage level to the RF generator. The switch arm 93 may be switched to contact the contact 93b to read the lower sideband audio voltage level to the RF generator. The meter 61 may be switched OFF so that it has no input when the switch arm 93 is moved to contact the contact 930.

The converter, single sideband generator or RF generator 11 of FIG. 1 may comprise the converter of FIGS. 2a and 2b. The converter or RF single sideband generator of FIGS. 2a and 2b produces the sideband signals, impresses or modulates the modulation output of the AF generator or modulator 12 on the RF carrier, and amplifies the resultant modulated RF signal to the proper level for transmitter operation. The RF generator also provides for the reinsertion of the suppressed carrier.

A modulated intermediate frequency is generated prior to the generation of the actual RF output in order to maintain the sideband producing filters at a practical quantity. A one megacycle per second reference signal from a reference source such as, for example, an internal one megacycle crystal-controlled oscillator, or from the calibrator 14, is supplied to the RF generator of FIGS. 2a and 211 via an input terminal 101. The one megacycle reference or calibration signal is doubled in frequency in a frequency doubler 102. The 2 megacycle output of the doubler 102 is fed through an RF amplifier 103 to an upper sideband balanced modulator 104 and through an RF amplifier 105 to a lower sideband balanced modulator 106. The upper sideband modulation from the modulator or AF generator 12 is fed to the balanced modulator 104 through an input terminal 107 and the lower sideband modulation from said modulator or AF generator is fed to the balanced modulator 106 through an input terminal 108.

The output of each balanced modulator 104 and 106 is a modulated double sideband 2 megacycle RF carrier with the carrier partially suppressed. The modulated double sideband 2 megacycle RF carrier produced by the balanced modulator 104 is fed to a buffer amplifier 109 which drives a crystal filter 111. The upper sideband crystal filter 111 eliminates all frequencies below 2 megacycles per second. The modulated double sideband 2 megacycle RF carrier produced by the balanced modulator 106 is fed to a buffer amplifier 112 which drives a crystal filter 113. The lower sideband crystal filter 113 eliminates frequencies above 2 megacycles per second. Both filters 111 and 113 greatly attenuate the carrier frequency as well.

The outputs of the filters 111 and 113 are fed to a sideband combiner 114 which functions to isolate the filters 111 and 113 from each other and to mix the upper sideband and lower sideband signals. The output of the sideband combiner 114, which is the sum of the two sideband inputs, is a double independent-sideband suppressedcarrier signal. The double independent-sideband suppressed-carrier signal produced by the sideband combiner 114 is fed to an RF amplifier 115. The 2 megacycle output of the doubler 102 is also fed to a-relay 116 as a carrier control. The 2 megacycle output signal of the doubler 102 energizes the relay 116 and operates a carrier reinsert gate 117 which is connected to the RF amplifier and which permits the carrier to be reinserted, up to full level, in said RF carrier.

One output of the RF amplifier 115 is fed through a second RF amplifier 118 to the upper two ranges, represented by contacts 119s and 119d, of a bandswitch 119. The other output of the RF amplifier 115 is fed to a mixer 121. The one megacycle reference or calibration signal supplied to the input terminal 101 is fed to a frequency tripler 122 which triples it and produces a 3 megacycles per second output signal. The 3 megacycle signal produced by the frequency tripler 122 is supplied to a divide-by-two divider 123 which halves it and produces a 1500 kilocycles per second output signal. The 1500 kilocycle output signal of the divider 123 is supplied to the mixer 121 via a buffer amplifier 124.

The mixer 121 mixes the 2 megacycle double independent-sideband suppressed-carrier signal from the RF amplifier 115 with the 1500 kilocycle signal from the buffer amplifier 124 and produces a difference output which is a double independent-sideband signal about a 500 kilocycle carrier. The carrier may be completely or partially suppressed. The double inclependent-sideband signal modulated on a 500 kilocycle carrier produced by the mixer 121 is fed through an RF amplifier 125 and a low-pass filter 126 to the lower two ranges, represented by contacts 119a and 115%, of the bandswitch 119. The low-pass filter 126 functions to eliminate frequencies above 500 kilocycles per second.

Variable frequency oscillator frequencies from the synthesizer 13 are supplied to an input terminal 127 of the converter arrangement of FIGS. 2a and 2b. The synthesizer frequencies supplied to the input terminal 127 are fed to an RF mixer 128 and the bandswitch 119 output, comprising the generated intermediate frequency which contains the desired intelligence on each sideband, is also fed to the RF mixer 128. The bandswitch 119 feeds 1.75 to 3.75 megacycles per second to the RF mixer 128 when the switch arm 119 contacts the bandswitch contact 11%. The bandswitch 119 feeds 3.5 to 7.5 megacycles per second to the RF mixer 128 when the switch arm 119 contacts the bandswitch contact 1191). The bandswitch 119 feeds 7 to 15 megacycles per second to the RF mixer 128 when the switch arm 119 contacts the bandswitch contact 1190. The bandswitch 119 feeds 15 to 32 megacycles per second to the RF mixer 128 when the switch arm 119 contacts the bandswitch contact 119d- The bands of frequencies from the synthesizer are 2.25 to 4.25 megacycles per second, 4 to 8 megacycles per second, 9 to 17 megacycles per second, and 17 to 34 megacycles per second. The modulated RF frequencies, 500 kilocycles in the lower two bands and 2 megacycles in the upper two bands, are selected for optimum freedom from spurious harmonics, the lowest variable frequency oscillator frequency being five times the intermediate RF, 'and for best sideband separation, the sidebands being separated by 2 megacycles in the high frequencles.

The difference output of the RF mixer 128 is fed through three tuned RF amplifier stages 129, 131 and 132, respectively, to a relay 133. The relay 133 insures radio silence while the single sideband generator is tuned. In the tune condition, the relay 133 switches the output of the single sideband generator to the counter 15 via the output terminal 134, so that the single sideband generator may be accurately tuned to the desired frequency. In the operate condition, the sideband signals produced by the single sideband generator are switched to the transmitter, not shown in the figures, via the output terminal 135.

A meter switch 136 enables a meter 137 to monitor the levels of the one megacycle reference signal, the synthesizer signals, the RF output and the upper sideband and lower sideband modulation inputs. All the sections of the meter switch 136 are grounded in the OFF position.

FIG. 4 is a schematic block diagram of an embodiment of a simplified synthesizer circuit arrangement of the single sideband generating circuit arrangement of the present invention. The synthesizer 13 supplies stable frequencies to the radio frequency mixer 128 of the RF generator 11 and may comprise any suitable known synthesizer circuit arrangement. A preferred embodiment of synthesizer 13, however, is that disclosed in copending patent application Ser. No. 844,982, filed Oct. 7, 1959, entitled 2 to 34 Megacycle Synthesizer Circuit Arrangement and now abandoned. The synthesizer circuit arrangementof FIG. 4 is a simplified version of the synthesizer circuit arrangement of said copending application; it being understood that the preferred embodiment of the synthesizer circuit arrangement is that disclosed in said copending patent application. The stable frequencies produced by the synthesizer circuit arrangement 13 are supplied to the radio frequency mixer 128 to produce a difference frequency output signal at the output of said mixer.

The synthesizer utilizes an indirect method of producing the output frequencies, each of which is electronically phase locked through discriminators to a stable one megacycle per second internal or external standard frequency. A double superheterodyne type of circuit is used with one free-running variable frequency oscillator being disciplined by means of two other variable frequency oscillators, and all three oscillators under the control of the one megacycle standard. The variable frequency oscillator has pull-in and hold-in characteristics which are instantaneous and equal over the entire band, with continuous frequency error correction less than five degrees of one cycle as compared to the standard reference.

The tuning controls provide straight line tuning in which any frequency change across'the entire band is directly proportional to rotation of the controls, as described in said copending application. The synthesizer provides over 64,000 highly stabilized output signals in the range of 2 to 34 megacycles per second. In addition, the reference frequency source of the synthesizer has an internal crystal oscillator which operates at one megacycle per second and is utilized to discipline all output frequencies. A temperature controlled oven maintains the crystal at its optimum operating temperature.

If higher stability than that provided by the internal crystal is desired, any suitable reference standard of superior stability whose output is one megacycle or 100 kilocycles at one volt may be utilized to discipline the output frequencies. The one megacycle calibrator or reference standard 14, for example, may be SO utilized. The reference standard 14 may also be utilized to monitor the frequency of the internal crystal.

The stable output frequencies are provided by three free-running variable frequency oscillators in a double superheterodyne type of circuit with each of the oscillators disciplined, through phase detector fed reactors, by the one megacycle standard frequency. The three freerunning variable frequency oscillators are the main variable frequency oscillator, the kilocycle variable frequency oscillator and the one kilocycle variable frequency oscillator. The desired frequency is selected by operation of a bandswitch, as described in said copending application, to one of the four bands and by rotation of the two manual tuning controls until the frequency appears on a digital readout counter, as described in said copending application.

The synthesizer of FIG. 4 comprises a reference frequency source, a main loop which develops the output frequency, and two incremental loops which control the output of the main loop in 10 kilocycle and one kilocycle steps. The different circuits and loops are all disciplined by the reference frequency signal so that all the available output frequencies have the same stability as the reference frequency.

The main loop comprises a reactance-controlled, variable frequency oscillator whose output frequency is controlled by the D.C. voltage of the phase detector within the loop. The main loop includes two mixer stages and two IF or intermediate frequency stages. This resembles a double superheterodyne circuit whose output, instead of a conventional audio signal, is a D.C. voltage with an amplitude that is determined by the phase coincidence between the second IF signal and the output of the one kilocycle loop.

The one megacycle reference frequency is fed to the spectrum generator circuit which produces kilocycle pulses and a pulse-modulated 100 kilocycle sine wave having a repetition 'rate of 20.4 to 38.4 megacycles per second. The sine wave is fed to the main loop and the 100 kilocycle pulses are simultaneously fed to the 10 kilocycle and one kilocycle loops.

The outputs of the spectrum generator and the main loop variable frequency oscillator are mixed in the first mixer stage to produce a difference that is the first intermediate frequency. The output of the 10 kilocycle incremental frequency loop is mixed with the first IF signal in the second mixer to produce a difference that is the second IF. The second IF is compared in the main loop phas detector to the output of the one kilocycle loop for phase coincidence. The output of the phase detector disciplines the variable frequency oscillator of the main loop, locking it to the selected frequency.

The variable frequency oscillators of the incremental frequency loops are each disciplined through phase detector stages by the 100 kilocycle output pulses of the spectrum generator. The three reference inputs to the main loop, which are the 20.4 to 38.4 megacycle sine wave, the 10 kilocycle loop output and the one kilocycle loop output and which are all derived from the same reference frequency signal, serve to discipline the variable frequency oscillator in the main loop.

As a consequence of the three loops, the output frequencies of the variable frequency oscillator in the main loop are disciplined at three points by signals which are derived from the single reference frequency signal. The stability of the output frequencies is therefore the same as the stability of the one megacycle reference signal. The outputnof the main loop is fed to a divider circuit which passes it through unchanged, divide by one, or divides it by 2, 4 or 8 depending upon the desired output frequency, to provide the four output bands of synthesizer frequencies.

FIG. 5 is a schematic block diagram of an embodiment of a calibrator or reference standard of the single sideband generating circuit arrangement. Any suitable reference standard may be utilized as the reference standard 14. Thus, for example, a controlled crystal frequency source of the type of FIG. 5 may be utilized. This, in effect may be similar to the reference source of the synthesizer circuit arrangement 13.

In the circuit arrangement of FIG. 5, a crystal controlled oscillator produces a reference standard one megacycle output to the RF generator 11 and a one megacycle output to the counter 15. The crystal which controls the oscillator is controlled in an oven to provide the optimum stability conditions.

The counter 15 may comprise any suitable frequency counter arrangement known. The function of the counter 15 is to indicate the frequencies produced 'by the single sideband generating circuit of the present invention.

While the invention has been described by means of specific examples and in specific embodiments, we do not wish to be limited thereto, for obvious modifications will occur to those skilled in the art without departing from the spirit and scope of the invention.

What we claim is:

13 1. Single sideband generating circuit arrangement comprising, in combination,

radio frequency generating means having a plurality of inputs and an output for producing sideband signals and for modulating audio modulations on a radio frequency carrier;

audio frequency generating means having an input and an output connected to an input of said radio frequency generating means for producing audio modulating signals from an upper sideband input and a lower sideband input;

means for supplying upper sideband inputs and lower sideband inputs to the input of said audio frequency generating means;

synthesizer means having an output connected to an input of said radio frequency generating means for supplying stable frequencies to said radio frequency generating means;

counter means having an input connected to the output of said radio frequency generating means and another input for indicating the frequencies of signals produced by said single sideband generating circuit arrangement;

calibrator means having an output connected to an input of said radio frequency generating means and to the other input of said counter means for supplying a reference frequency standard signal for said radio frequency generating means and for said counter means; and

output means connected to the output of said radio frequency generating means for deriving the modulated radio frequency signals from said radio frequency generating means.

2. Single sideband generating circuit arrangement comprising, in combination,

audio frequency generating means having an input and an output connected to an input of said radio frequency generating means for producing audio modulating signals from an upper sideband input and a lower sideband input, said audio frequency generating means comprising,

upper sideband audio unit means having an input and an output utilizing an upper sideband input for producing at its output an upper sideband audio modulating signal, means for supplying an upper sideband input to the input of said upper sideband audio unit means, lower sideband audio unit means having an input and an output utilizing a lower sideband input for producing at its output a lower sideband audio modulating signal, means for supplying a lower sideband input to the input of said lower sideband audio unit means, frequency shift keying unit means having inputs and an output utilizing a frequency shift keying input signal for producing at its output a frequency shifted signal in which a mark is represented by a signal having a first frequency and a space is represented by a signal having a second frequency different from said first frequency, means for supplying a frequency shift keying input signal to the inputs of said frequency shift keying unit means, continu ous wave unit means having inputs and an output utilizing a continuous wave input signal for producing at its output a continuous wave signal, and means for supplying a continuous wave input signal to the inputs of said continuous wave unit means;

3. Single sideband generating circuit arrangement comprising, in combination,

upper sideband audio unit means having an input and an output utilizing an upper sideband input for producing at its output an upper sideband audio modulating signal, said upper sideband audio unit means comprising filter means connected to the input of said upper sideband audio unit means for passing frequencies below a first predetermined level and for passing frequencies above a second predetermined level, amplifier means, and means coupling said filter means to the output of said upper sideband audio unit means through said amplifier means, means for supplying an upper sideband input to the input of said upper sideband audio unit means, lower sideband audio unit means having an input and an output utilizing a lower sideband input for producing at its output a lower sideband audio modulating signal, said lower sideband audio unit means comprising filter means connected to the input of said lower sideband audio unit means for passing frequencies below a first predetermined level and for passing frequencies above a second predetermined level, amplifier means, and means coupling said filter means to the output of said lower sideband audio unit means through said amplifier means, means for supplying a lower sideband input to the input of said lower sideband audio unit means, frequency shift keying unit means having inputs and an output utilizing a frequency shift keying input signal for producing at its output a frequency shifted signal in which a mark is represented by a signal having a first frequency and a space is represented by a signal having a second frequency different from said first frequency, said frequency shift keying unit means comprising oscillator means connected to an input of said frequency shift keying unit means and having outputs for producing mark and space signals, gate means connected to inputs of said frequency shift keying unit means and to the outputs of said oscillator means for gating the outputs of said oscillator means, phase shifting means connected between another input of said frequency shift keying unit means and said gate means for phase inverting the frequency shift keying input signal and for controlling said gate means therewith, and means coupling said gate means to the input of each of said upper and lower sideband audio unit means through the output of said frequency shift keying unit means, means for supplying a frequency shift keying input signal to the inputs of said frequency shaft keying unit means, continuous wave unit means having inputs and an output utilizing a continuous wave D.C. input signal for producing at its output a continuous wave signal, said continuous wave unit means comprising oscillator means connected to an input of said continuous Wave unit means and having an output and being energized by said continuous wave D.C. input signal for producing a tone signal of predetermined frequency, gate means connected to inputs of said continuous wave unit means and to the output of said oscillator means for gating the output of said oscillator means, filter means, and means coupling said gate means to the output of said continuous wave unit means through said filter means, and means for supplying a continuous wave D.C. input signal to the inputs of said continuous wave unit means;

4. Single sideband generating circuit arrangementcomprising, in combination,

modulated double sideband radio frequency carrier producing means for deriving a double independentsideband signal of twice the reference frequency, means for supplying an upper sideband audio modulation to a second input of said modulated double sideband radio frequency carrier producing means, means for supplying a lower sideband audio modulation to a third input of said modulated double sideband radio frequency carrier producing means, mixed means having two inputs and an output, frequency changing means for producing from said reference frequency a signal of one and one-half times said reference frequency, means for supplying the one and one-half times the reference frequency signal produced by said frequency changing means to an input of said mixer means, means coupling the output of said modulated double sideband radio frequency carrier producing means to the other input of said mixer means to produce a double independent sideband signal modulated on a carrier of half the reference frequency at the output of said mixer means to produce a double independent sideband signal modulated on a carrier of half the reference frequency at the output of said mixer means, bandswitch means having a plurality of bandswitch contacts coupled selectively to the output of said mixer means and coupled selectively to the output of said modulated double sideband radio frequency carrier producing means, and a switch arm connected at one end to an output contact and adapted to selectively contact at its other end one of the plurality of bandswitch contacts, means connected to the output contact of said bandswitch means for producing a difference frequency between stable frequencies supplied thereto and frequencies at the output contact of said bandswitch means and for deriving selected sideband signals and audio modulated radio frequency carriers from said radio frequency generating circuit arrangement, and means for supplying stable frequencies to said last-mentioned means;

audio frequency generating means having an input and an output connected to an input of said radio fre' quency generating means for producing audio modulating signals from an upper sideband input and a lower sideband input;

output means connected to the output of'said radio frequency generating means for deriving the modulated radio frequency signals from said radio frequency generating means.

5. Single sideband generating circuit arrangement comprising, in combination,

ratio frequency generating means having a plurality of inputs and an output for producing sideband signals and for modulating audio modulations on a radio frequency carrier, said radio frequency generating means comprising,

frequency doubler means having an input and a pair of outputs for "doubling a frequency supplied to it, means for supplying a one megacycle per second reference frequency standard signal to the input of said frequency doubler means to produce a 2 megacycles per second output signal at the output of said frequency doubler means, upper sideband balanced modulator means having a pair of inputs and an output, lower sideband balanced modulator means having a pair of inputs and an output, means coupling an output of said frequency doubler means to an input of said upper sideband balanced modulator means for supplying the 2 megacycles per second output of said frequency doubler means to said upper sideband balanced modulator means, means for Supplying an upper sideband audio modulation to the other input of said upper sideband balanced modulator means to produce at the output of said upper sideband balanced modulator means a modulated double sideband 2 megacycles per second radio frequency carrier with the carrier partially suppressed, means coupling said output of said frequency doubler means to an input of said lower sideband balanced modulator means for supplying the 2 megacycles per second output of said frequency doubler means to said lower sideband balanced modulator means, means for supplying a lower sideband audio modulation to the other input of said lower sideband balanced modulator means to produce at the output of said lower sideband balanced modulator means a modulated double sideband 2 megacycles per second radio frequency carrier with the carrier partially suppressed, upper sideband crystal filter means for eliminating frequencies below 2 megacycles per second, lower sideband crystal filter means for eliminating frequencies above 2 megacycles per second, sideband combiner means having a pair of inputs and an output for isolating said upper and lower sideband crystal filter means from each other and for mixing the upper and lower sideband signals to produce a 2 megacycles per second double independent-sideband suppressed-carrier signal at its output, means for connecting the output of said upper sideband balanced modulator means to an input of said sideband combiner means through said upper sideband crystal filter means, means for connecting the output of said lower sideband balanced modulator means to the other input of said sideband combiner means through said lower sideband crystal filter means, radio frequency amplifier means having an input connected to the output of said sideband combiner means, another input and a pair of outputs for amplifying the signal at the output of said sideband combiner means, relay means connected to the other output of said frequency doubler means, gate means coupled between said relay means and the other input of said radio frequency amplifier means for reinserting the carrier suppressed by each of said upper sideband balanced modulator means and said lower sideband balanced modulator means in the radio frequency carrier, mixer means having an input connected to an output of said radio frequency amplifier means, another input and an output, frequency tripler means having an input and an output for tripling a frequency supplied to it, means for supplying said one megacycle per second reference frequency standard sigml to the input of said frequency tripler means to produce a 3 megacycle per second signal at its output, frequency divider means having an input connected to the output of said frequency tripler means and an output for dividing the output signal of said frequency tripler means in half to a 1500 kilocycles er second signal, means coupling the output of said frequency divider means to the other input of said mixer means to produce a double independent sideband signal modulated on a 500 kilocycles per second carrier at the output of said mixer means, lowpass filter means for eliminating frequencies above 500 kilocycles per second, bandswitch means having a plurality of bandswitch contacts and a switch arm connected at one end to an output contact and adapted to selectively contact at its other end one of the plurality of bandswitch contacts, means coupling the output of said mixer means to selected contacts of the bandswitch contacts of said bandswitch means through said low-pass filter means to supply a 500 kilocycles per second double independent sideband signal to said last-mentioned selected contacts of said bandswitch contacts, means coupling the other output of said radio frequency amplifier means to selected other contacts of the bandswitch contacts of said bandswitch means to supply a 2 megacycles per second double independent sideband signal to said last mentioned selected other contacts of said bandswitch contacts, radio frequency mixer means having an input connected to the output contact of said bandswitch means, another input and an output, means for supplying variable frequency oscillator stable frequencies to the other input of said radio frequency mixer means to produce a difference frequency output signal at the output of said radio frequency mixer means, and output means coupled to the output of said radio frequency mixer means for deriving selected sideband signals and audio modulated radio frequency carriers from said radio frequency generating circuit arrangement;

6. Single sideband generating circuit arrangement comprising, in combination,

radio frequency generating means having a plurality of inputs and an output for :producing sideband signals and for modulating audio modulations on a radio frequency carrier, said radio frequency generating means comprising,

modulated double sideband radio frequency carrier producing means for deriving a double independentsideband signal of twice a reference frequency having three inputs and an output for producing at its output a double independent-sideband signal of twice the reference frequency, means for supplying a reference frequency standard signal to an input of said modulated double sideband radio frequency carrier producing means for deriving a double independent-sideband signal of twice the reference frequency, means for supplying an upper sideband audio modulation to a second input of said modulated double sideband radio frequency carrier producing means, means for supplying a lower sideband audio modulation to a third input of said modulated double sideband radio frequency carrier producing means, mixer means having two inputs and an output, frequency changing means for producing from said reference frequency a signal of one and one-half times said reference frequency, means for supplying the one and one-half times the reference frequency signal produced by said frequency changing means to an input of said mixer means, means coupling the output of said modulated double sideband radio frequency carrier producing means to the other input of said mixer means to produce a double independent sideband signal modulated on a carrier of half the reference frequency at the output of said mixer means to produce a double independent sideband signal modulated on a carrier of half the reference frequency at the output of said mixer means, bandswitch means having a plurality of bandswitch contacts coupled selectively to the output of said mixer means and coupled selectively to the output of said modulated double sideband radio frequency carrier producing means, and a switch arm connected at one end to an output contact and adapted to selectively contact at its other end one of the plurality of bandswitch contacts, means connected to the output contact of said bandswitch means for producing a difi'erence frequency between stable frequencies supplied thereto and frequencies at the output contact of said bandswitch means and for deriving selected sideband signals and audio modulated radio frequency carriers from said radio frequency generating circuit arrangement, and means for supplying stable frequencies to said last-mentioned means;

audio frequency generating means having an input and an output connected to an input of said radio frequency generating means for producing audio modulating signals from an upper sideband input and a a lower sideband input, said audio frequency generating means comprising,

upper sideband audio unit means having an input and an output utilizing an upper sideband input for producing at its output an upper sideband audio modulating signal, means for supplying an upper sideband input to the input of said upper sideband audio unit means, lower sideband audio unit means having an input and an output utilizing a lower sideband input for producing at its output a lower sideband audio modulating signal, means for supplying a lower sideband input to the input of said lower sideband audio unit means, frequency shift keying unit means having inputs and an output utilizing a frequency shift keying input signal for producing at its output a frequency shifted signal in which a mark is represented by a signal having a first frequency and a space is represented by a signal having a second frequency different from said first frequency, means for supplying a frequency shift keying input signal to the inputs of said frequency shift keying unit means, continuous wave unit means having inputs and an output utilizing a continuous wave input signal for producing at its output a continuous wave signal, and means for supplying a continuous wave input signal to the inputs of said continuous wave unit means;

7. Single sideband generating circuit arrangement comprising, in combination,

radio frequency generating means having a plurality of inputs and an output for producing sideband signals and for modulating audio modulations on a radio frequency carrier, said radio frequency generating means comprising frequency doubler means having an input and a pair of outputs for doubling a frequency supplied to it, means for supplying a one megacycle per second reference frequency standard signal to the input of said frequency doubler means to produce a 2 megacycles per second output signal at the output of said frequency doubler means, upper sideband balanced modulator means having a pair of inputs and an output, lower sideband balanced modulator means having a pair of inputs and an output, means coupling an output of said frequency doubler means to an input of said upper sideband balanced modulator means for supplying the 2 megacycles per second output of said frequency doubler means to said upper sideband balanced modulator means, means for supplying an upper sideband audio modulation to the other input of said upper sideband balanced modulator means a modulated double sideband 2 megacycles per second radio frequency carrier with the carrier partially suppressed, means coupling said output of said frequency doubler means to an input of said lower sideband balanced modulator means for supplying. the 2 megacycles per second output of said frequency doubler means to said lower sideband balanced modulator means, means for supplying a lower sideband audio modulation to the other input of said lower sideband balanced modulator means to produce at the output of said lower sideband balanced modulator means a modulated double sideband 2 megacycles per second radio frequency carrier with the carrier partially suppressed, upper sideband crystal filter means for eliminating frequencies below 2 megacycles per second, lower sideband crystal filter means for eliminating frequencies above 2 megacycles per second, sideband combiner means having a pair of inputs and an output for isolating said upper and lower sideband crystal filter means from each other and for mixing the upper and lower sideband signals to produce a 2 megacycles per second double independent-sideband suppressed-carrier signal at its output, means for connecting the output of said upper sideband balanced modulator means to an input of said sideband combiner means through said upper sideband crystal filter means, means for connecting the output of said lower sideband balanced modulator means to the other input of said sideband combiner means through said lower sideband crystal filter means, radio frequency amplifier means having an input connected to the output of said sideband combiner means, another input and a pair of outputs for amplifying the signal at the output of said sideband combiner means, relay means connected to the other output of said frequency doubler means, gate means coupled between said relay means and the other input of said radio frequency amplifier means for reinserting the carrier suppressed by each of said upper sideband balanced modulator means and said lower sideband balanced modulator means in the radio frequency carrier, mixer means having an input connected to an output of said radio frequency amplifier means, another input and an output, frequency tripler means having an input and an output for tripling a frequency supplied to it, means for supplying said one megacycle per second reference frequency standard signal to the input of said frequency tripler means to produce a 3 megacycles per second signal at its output, frequency divider means having an input connected to the output of said frequency tripler means and an output for dividing the output signal of said frequency tripler means in half to a 1500 kilocycles per second signal, means coupling the output of said frequency divider means to the other input of said mixer means to produce a double independent sideband signal modulated on a 500 kilocycles per second carrier at the output of said mixer means, low-pass filter means for eliminat ing frequencies above 500 kilocycles per second, bandswitch means having a plurality of bandswitch contacts and a switch arm connected at one end to an output contact and adapted to selectively contact at its other end one of the plurality of bandswitch contacts, means coupling the output of said mixer means to selected contacts of the bandswitch contacts of said bandswitch means through said lowpass filter means to supply a 500 kilocycles per second double independent sideband signal to said last-mentioned selected contacts of said bandswitch contacts, means coupling the other output of said radio frequency amplifier means to selected other contacts of the bandswitch contacts of said bandswitch means to supply a 2 megacycles per second double independent sideband signal to said lastmentioned selected other contacts of said bandswitch contacts, radio frequency mixer means having an input connected to the output contact of said bandswitch means, another input and an output, means for supplying variable frequency oscillator stable frequencies to the other input of said radio frequency mixer means to produce a difference frequency output signal at the output of said radio frequency mixer means, and output means coupled to the output of said radio frequency mixer means for deriving selected sideband signals and audio modulated radio frequency carriers from said radio frequency generating circuit arrangement;

audio frequency generating means having an input and an output connected to an input of said radio frequency generating means for producing audio modulating signals from an upper sideband input and a lower sideband input, said audio frequency generating means comprising upper sideband audio unit means having an input and an output utilizing an upper sideband input for producing at its output an upper sideband audio modulating signal, said upper sideband audio unit means comprising filter means connected to the input of said upper sideband audio unit means for passing frequencies below a first predetermined level and for passing frequencies above a second predetermined level, amplifier means, and means coupling said filter means to the output of said upper sideband audio unit means through said amplifier means, means for supplying an upper sideband input to the input of said upper sideband audio unit means, lower sideband audio unit means having an input and an output utilizing a lower sideband input for producing at its output a lower sideband audio modulating signal, said lower sideband audio unit means comprising filter means connected to the input of said lower sideband audio unit means for passing frequencies below a first predetermined level and for passing frequencies above a second predetermined level, amplifier means, and means coupling said filter means to the output of said lower sideband audio unit means through said amplifier means, means for supplying a lower sideband input to the input of said lower sideband audio unit means, frequency shift keying unit means having inputs and an output utilizing a frequency shift keying input signal for producing at its output a frequency shifted signal in which a mark is represented by a signal having a first frequency and a space is represented by a signal having a second frequency different from said first frequency, said frequency shift keying unit means comprising oscillator means connected to an input of said frequency shift keying unit means and having outputs for producing mark and space signals, gate means connected to inputs of said frequency shift keying unit means and to the outputs of said oscillator means for gating the outputs of said oscillator means, phase shifting means connected between another input of said frequency shift keying unit means and said gate means for phase inverting the frequency shift keying input signal and for controlling said gate means therewith, and means coupling said gate means to the input of each of 'said upper and lower sideband audio unit means through the output of said frequency shift keying unit means, means for supplying a frequency shift keying input signal to the inputs of said frequency shift keying unit means, continuous wave unit means having inputs and an output utilizing a continuous wave D.C. input signal for producing at its output a continuous wave signal, said continuous'wave unit means comprising oscillator means connected to an input of said continuous wave unit means and having an output and being energized by said continuous Wave D.C. input signal for producing a tone signal of predetermined frequency, gate means connected to inputs of said continuous wave unit means and to the output of said oscillator means for gating the output of said oscillator means, filter means, and means coupling said gate means to the output of said continuous Wave unit means through said filter means, and means for supplying a continuous wave D.C. input signal to the inputs of said continuous wave unit means;

8. Audio frequency generating circuit arrangement for producing audio modulating signals comprising, in combination,

upper sideband audio unit means having an input and an output utilizing an upper sideband input for producing at its output an upper sideband audio modulating signal;

means for supplying an upper sideband input to the input of said upper sideband audio unit means;

lower sideband audio unit means having an input and an output utilizing a lower sideband input for producing at its output a lower sideband audio modulating signal;

means for supplying a lower sideband input to the input of said lower sideband audio unit means;

frequency shift keying unit means having inputs and an output utilizing a frequency shift keying input signal for producing at its output a frequency shifted signal in which a mark is represented by a signal having a first frequency and a space is represented by a signal having a second frequency different from said first frequency;

means for supplying a frequency shift keying input signal to the inputs of said frequency shift keying unit means;

continuous wave unit means having inputs and an output utilizing a continuous wave input signal for producing at its output a continuous wave signal;

means for supplying a continuous wave input signal to the inputs of said continuous wave unit means;

a plurality of sources of operating voltage; and

switching means interconnecting each of said upper sideband audio unit means, said lower sideband audio unit means, said frequency shift keying unit means and said continuous wave unit means to corresponding ones of said sources of operating voltage for selectively operating said upper sideband audio unit means, said lower sideband audio unit means, said frequency shift keying unit means and said continuous wave unit means.

9. Audio frequency generating circuit arrangement for producing audio modulating signals comprising in combination,

upper sideband audio unit means having an input and an output utilizing an upper sideband input for producing at its output an upper sideband audio modulating signal, said upper sideband audio unit means comprising filter means connected to the input of said upper sideband audio unit means for passing frequencies below a first predetermined level and for passing frequencies above a second predetermined level, amplifier means, and means coupling said filter means to the output of said upper sideband audio unit means through said amplifier means; means for supplying an upper sideband input to the input of said upper sideband audio unit means;

lower sideband audio unit means having an input and an output utilizing a lower sideband input forproducing at its output a lower sideband audio modulating signal, said lower sideband audio unit means comprising filter means connected to the input of said lower sideband audio unit means for passing frequencies below a first predetermined level and for passing frequencies above a second predetermined level, amplifier means, and means coupling said filter means to the output of said lower sideband audio unit means through said amplifier means;

means 'for supplying a frequency shift keying input signal to the inputs of said frequency shift keying unit means;

continuous wave unit means having inputs and an output utilizing a continuous wave signal for producing at its output a continuous wave signal;

a plurality of sources of operating voltage; and

10. Audio frequency generating circuit arrangement for producing audio modulating signals comprising, in combination,

upper sideband audio unit means having an input and an output utilizing an upper sideband input for producing at its output an upper sideband audio modulating signal; means for supplying an upper sideband input to the input of said upper sideband audio unit means;

lower sideband audio unit means having an input and an output utlizing a lower sideband input for producing at its output a lower sideband audio modulating signal;

means for supplying a lower sideband input to the input of said lower sideband audio unit means; frequency shift keying unit means having inputs and an output utilizing a frequency shift keying input signal for producing at its output a frequency shifted signal in which a mark is represented by a signal having a first frequency and a space is represented by a signal having a second frequency different from said first frequency, said frequency shift keying unit means comprising oscillator means connected to an input of said frequency shift keying unitmeans and having outputs for producing mark and space signals, gate means connected to inputs of said frequency shift keying unit means and to the ouputs of said oscillator means for gating the outputs of said oscillator means, phase shifting means connected between another input of said frequency shift keying unit means and said gate means for phase inverting the frequency shift keying input signal and for controlling said gate means therewith, and means coupling said gate means to the input of each of said upper and lower sideband audio unit means through the output of said frequency shift keying unit means;

means for supplying a frequency shift keying input signal to the inputs of said frequency shift keying means;

a plurality of sources of operating voltage; and

11. Audio frequency generating circuit arrangement for producing audio modulating signals comprising, in combination,

means for supplying a frequency shift keying input signal .to the inputs of said frequency shift keying unit means;

continuous wave unit means having inputs and an output utilizing a continuous wave D.C. input signal for producing at its output a continuous wave signal, said continuous wave unit means comprising oscillator means connected to an input of said continuous wave unit means and having an output and being energized by said continuous wave D.C. input signal for producing a tone signal of predetermined frequency, gate means connected to inputs of said continuous wave unit means and to the output of said oscillator means for gating the output of said oscillator means, filter means, and means coupling said gate means to the output of said continuous wave unit means through said filter means;

means for supplying a continuous wave D.C. input signal to the inputs of said continuous wave unit means;

a plurality of sources of operating voltage; and

switching means interconnecting each of said upper sideband audio unit means, said lower sideband

Claims

1. SINGLE SIDEBAND GENERATING CIRCUIT ARRANGEMENT COMPRISING, IN COMBINATION, RADIO FREQUENCY GENERATING MEANS HAVING A PLURALITY OF INPUTS AND AN OUTPUT FOR PRODUCING SIDEBAND SIGNALS AND FOR MODULATING AUDIO MODULATIONS ON A RADIO FREQUENCY CARRIER; AUDIO FREQUENCY GENERATING MEANS HAVING AN INPUT AND AN OUTPUT CONNECTED TO AN INPUT OF SAID INPUT AND QUENCY GENERATING MEANS FOR PRODUCING AUDIO MODULATING SIGNALS FROM AN UPPER SIDEBAND INPUT AND A LOWER SIDEBAND INPUT; MEANS FOR SUPPLYING UPPER SIDEBAND INPUTS AND LOWER SIDEBAND INPUTS TO THE INPUT OF SAID AUDIO FREQUENCY GENERATING MEANS; SYNTHESIZER MEANS HAVING AN OUTPUT CONNECTED TO AN INPUT OF SAID RADIO FREQUENCY GENERATING MEANS FOR SUPPLYING STABLE FREQUENCIES TO SAID RADIO FREQUENCY GENERATING MEANS; COUNTER MEANS HAVING AN INPUT CONNECTED TO THE OUTPUT OF SAID RADIO FREQUENCY GENERATING MEANS AND ANOTHER INPUT FOR INDICATING FREQUENCIES OF SIGNALS PRODUCED BY SAID SIGNAL SIDEBAND GENERATING CIRCUIT ARRANGEMENT;