JPH03502155A - Automatic polarization control system for dedicated television receivers - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Background of the invention of automatic polarization control system for TV SILON receiver The present invention generally relates to a TV receiver that receives a wide range of satellite TV signals. Regarding the dedicated (TVItO) receiver, please refer to the ground station antenna for details. o The receiver is automatically tuned to the plane of polarization of a particular channel to which it is tuned at a given time. The present invention relates to an automatic polarization adjustment system that aligns the polarization.

In a TVrtO system, the satellite signal is transmitted through an antenna (usually a parabolic dish). ) and converted to the lower 11th F'' frequency at the antenna site. . This conversion is a downconversion that converts only one channel to the 11th F11 wavenumber. converter, or all channels of the same polarity, from 950 to 1450 pairs (in the range of 2). This can be done with a block converter that converts the frequency to the 11th F block.

This entire block of frequencies is then sent through the coaxial cable to the receiver, where the select a particular channel to watch and/or listen to. This receiver smells Therefore, the 11th F signal is conventionally concentrated at 70klH2 in most TVrtO systems. 21F frequency range.

Signals transmitted by satellites are excited by a transmission antenna before propagating through space. It has a designated wave determined by the mode to wake up. Efficient reception and In order to obtain high video and/or audio characteristics, the TVrtO receiver The antenna subsystem must be properly aligned with the polarization of the received signal. stomach.

Minimizes interference between signals from satellite transponders using adjacent frequency bands. from a transponder using a separate 20MHz frequency band to minimize The signal has a first polarization, e.g. horizontal, while a transformer using an intervening frequency band The ponder has a polarization that is orthogonal to the first polarization, eg, perpendicular.

Frequency modulated signals transmitted on adjacent channels almost always overlap each other. the desired channel to avoid interference from adjacent channels. It is important to have a receiving antenna that precisely adjusts to the polarization of the signal. . The signal from the local microwave link also overlaps the frequency band of the satellite channel. precisely adjust the polarization of the selected signal and the receiving antenna to ground interference (Lerres-trisl 1nterferen) ce) (commonly referred to as °Tbi) can be reduced.

In addition, the proper orientation of the ground station antenna that receives polarized signals from i satellites is determined. The same orient Chiron has the best reception from other satellites. does not mean Today, there are a large number of satellites in geostationary orbit, and these satellites are subject to interference. are azimuthally spaced from each other to avoid Therefore, the ground station antenna When Na is swept across an array of satellites in geosynchronous orbit, the polarization planes of different satellites are are slightly distorted from each other by the azimuthal spacing of the satellites. As a result, The optimal plane of polarization for the ground antenna changes for each satellite. antenna subsystem and the plane of polarization of the signal coming from a given satellite's transponder. In order to Equipped with a polarizer that can adjust the relative alignment with Enchishiron. It is growing.

1- Noise's single wave generator is the best place.''- Tweed horn of the station antenna (r Connect the small probe provided with the eedhorn to an indoor receiver or antenna. A small servo motor powered by a Rotate mechanically. The second type of single wave generator is located at the throat of the freehorn. By changing the voltage applied to the coil wound around the electromagnetic ferrite core Thus, the polarization of the incoming signal is electrically adjusted.

,qm piece The main purpose of this invention is to select the orientation of the antenna and the R unit. automatically ensures optimal alignment relative to the polarization of a given satellite signal The objective is to provide an improved TVRO receiver that will

Another object of the invention is that it can be used with mechanical or electronic polarizers. The present invention is to provide an improved TVr(0) receiver with automatic polarization control system.

Yet another object of the invention is that the automatic wave control system To provide an improved 1'VnO receiver that does not require input or data input. That is.

A further object of this invention is to adapt the automatic wave control system to Ike's standard receiver. , an improved TVRO reception that can be easily and economically installed at relatively low cost. We are here to provide you with a machine.

One other purpose of this invention will be apparent from the following detailed description and accompanying drawings. It will be.

According to this invention, an automatic polarization control system includes an antenna for receiving incoming satellite signals. The antenna is connected to the antenna, and the incoming signal is connected to the antenna. and polarization means for adjusting the relative alignment with the polarization of the TVRO terrestrial TVRO. Provided for stations: This control system generates electrical control signals that control the polarization means means for adjusting the relative alignment of the antenna and signal polarization; A means of detecting the noise level in the satellite (No. 8) received by The control signal is adjusted in response to the noise level detected, and the polarization means are adjusted accordingly. and means for minimizing the emitted noise level.

In a particularly preferred embodiment, the control signal is determined by a predetermined range of values. adjusting the polarization means by a set value of a predetermined range; and the control system detects a minimum noise level detected during adjustment of the control signal. and to store the control signal value corresponding to the minimum noise level. .

Brief description of the drawing For a further understanding of this invention and other objects and advantages thereof, reference may be made to the following description and accompanying drawings. can be best understood by.

Figure 1 is a functional block diagram of a normal TVRO ground station; Figure 2 is the same as Figure 1. FIG. 2 is a diagram of a demodulator used in the system.

FIG. 3 shows an automatic polarization control system according to an embodiment of the invention used in the system of FIG. 1 is a simplified block diagram of the system;

FIG. 4 is a graph showing the polarization rotation effect of a conventional ferrite polarizer.

FIG. 5 is a diagram of a preferred noise detector for use in the system of FIG. 3.

FIG. 6 controls the microprocessor in the control system of FIG. 3 of the present invention. This is a flowchart of the program.

Description of preferred embodiments This invention will be described in some preferred embodiments; Give! ! It will be understood that there is no uniform separation. on the contrary, This invention covers all changes, modifications and equivalent modifications included within the spirit and scope of the claims. This includes the location.

FIG. 1 shows a functional block diagram of a Tll0 ground station that receives satellite signals. This The stem typically contains low noise block (LNB) converters and associated accessories and components. A parabolic dish equipped with an orbiting and position jIfR adjustment mechanism, and a satellite running in an orbit. an antenna 11 that captures signals transmitted from the antenna 11, a tuner 12, and a demodulator 513; , a video processing and amplification section 4 and an audio receiver 15. Equipped with machine system.

The antenna 11 transmits signals from the satellite in the 4 GHz frequency band (3.7 to 4.2 GHz). It receives the transmitted signal and transmits the entire block of frequencies to the block located at the antenna site. converter to the 11th FII wavenumber range of 950 to 1450 MIIz be done. Next, this 11th F signal is sent to the tuner 12 through the coaxial cable, and this The tuner selects a particular channel for viewing and transmits that particular channel's signal to a second Convert to IPln wavenumber range. As this 21st F frequency loss range, vCO is desired. The 21st FvCO frequency is connected to the 11th P block to prevent it from interfering with the signal of Preferably, it is high enough so that it can be greater than the frequency of the clock. 950~! 450) For the 11th F frequency loss range of Illz, this means that the center of the 21st FJM wave number This means that the frequency must be at least 500MHz. Especially preferred The new center frequency of the 21st F is 612M)Iz.

FIG. 2 shows a receiver receiving the second iF output of the same unit 12 of the TVRO system of FIG. r! It is a block diagram of @ container 13. The circuit of this demodulator is the same! 1j1512's most A pair of conventional IP amplifiers 30 and 31 receive the 21st F signal from the final amplifier 25. We are prepared. Both of these amplifiers 30 and 31 have an automatic gain control via resistor 32. Receive control (AGC) signals. The second tF signal from the amplifier Pii31 is filtered 33 to a conventional video detector 34, which detects the frequency modulated signal. demodulating the signal to the baseband (e.g. 0 to IOM) of the original video signal; Generate a composite video output signal. As the '21st F filter 33, the pass band is A passband of this width, preferably approximately 22 Mflz wide, is while removing unwanted noise received by the antenna. , passing important video and audio information.

The AGC feedback loop amplifies the output of the filter 33 and sends it to the 〇〇detection 837. The transmitting IP amplifier 36 is installed. The output of this detector 37 is B and generates a signal strength meter drive signal at terminal 39. This signal strength meter The monitor is usually located on the front panel of the TVrtO receiver.

The v4 audience shown in the figure is also equipped with an IF amplifier 40, which is used for video detection. receives the same input that is sent to the filter 34 and amplifies the input It passes through the router 41. The output of filter 41 is connected to a detector in the form of a diode 42. pass.

The signal that has passed through the diode 42 is smoothed by the amplifier 43, and the receiver receives the signal. The presence of a signal near the center frequency of the channel of a particular satellite being tuned Generates a DC output voltage that can be used for detection. This signal is used in the system of this invention. Although it is not used for systems, it is useful for distinguishing between satellite signals and TI.

The output of the aS shown in Figure 2 has a baseband range from DC to approximately 8.5 II Hz. It has a video information of approximately 15KIIz~42Mll7°. and sub-carry about 4.5-8.5 MHz. of these baseband signals Video information must be displayed on the video monitor or television screen before it is displayed on the video monitor or TV audio processing and amplification section 4, and then the audio signal is passed through an audio tuner. The signal is then sent to one or more speakers to convert the signal into audible sound.

According to a key aspect of the invention, the polarizer is controlled by an automatic system; The motion system generates electrical control signals that control the polarizer to orient the antenna. means for adjusting the relative alignment of the chisiron and the polarization of the incoming signal; and: means for detecting the noise level of a satellite signal received by the antenna; adjusts the polarizer control signal in response to the noise level and, as a result, adjusts the polarizer to and means for minimizing the emitted noise level. Polarizer control signal Using the above noise level to adjust the response to the incoming signal will be becomes faster.

Shown in Figure 3! ! In III, the video output of the demodulator is sent to a noise detector 50. This detector has a magnitude proportional to the noise level of the video baseband signal. generates a DC output. This DC output is converted into an analog-to-digital converter ( ADC) 52 and sent to the microprocessor 53. noise detector 50 and , and the program that controls the microprocessor 53, as shown in FIGS. 5 and 6. This will be explained in detail below with reference to the figures.

The basic function of the microprocessor 53 is to polarize over a predetermined range. generates an output signal that can be used to continuously adjust the polarizer Evaluate the noise level detected at successive setting values to generate the minimum noise level. The first step is to determine the polarizer settings. This setting will then be remembered so that the next When the same channel is selected, the setting value is searched and the polarizer is reset. be able to.

The output signal of the microprocessor controlling the polarization 4 is a digital-to-analog converter. The analog output signal of this converter is sent to a summing junction (DAC) 54. Continuation [Added to 55.

This signal is a command voltage applied to the coil of a normal ferrite core polarizer 56. The other input signal to the summing connection 55, which indicates the actual set value of the - wave generator The signal is transmitted through a fixed resistor 57 connected between the polarizer coil and the ground. determined by the current flowing through it. The addition connection section 55 receives these “command °” and “actual °” inputs. The force signals are added algebraically to produce a ° error proportional to the difference between the two input signals. ° Generate an output signal. Of course, the microprocessor changes the %-polarizer setting. Whenever you generate a signal, there is a gap between the "command" signal and the "actual signal" An immediate mismatch occurs, resulting in an intentional “error” signal that generates polarization 1i15 Change the setting value of 6.

The "error" output signal from summing connection 55 is passed through amplifier 58 to drive the polarizer. A circuit 59 is reached which receives a "command" signal from the microprocessor 53. Apply pressure to DC7 at the level required to set the polarizer 5G at the desired position represented by the symbol. occurs. Several different conventional circuits can be used for driver 59. However, for this purpose, it is recommended to use a two-stage collector output current-limited class B amplifier. is preferable.

As is well known, the ferrite core polarizer 56 is an electromagnetic ferrite core polarizer 56. It has a wire coil wrapped around it. Polarizers are especially designed as controlled phase shifters. A fiber that receives the incoming satellite signal and then passes this signal through a ferrite core. Equipped with a feed horn device. A voltage is applied across the coil by driver 59. When applied, an electromagnetic field of corresponding strength is generated around the ferrite core. this The electromagnetic field interacts with the electromagnetic field generated through the core to drive the plane of polarization of the received signal. a predetermined value corresponding to the magnitude of the DC voltage applied to the coil by the driver 59. Rotate it by the same angle.

Figure 4 shows the influence of changes in the DC voltage from the driver 59 during operation of polarized wave D56. . Figure 4 shows the signal polarization as a function of the i)C voltage applied to the polarizer coil. This is a plot of rotation (in degrees). As shown in the figure, zero voltage causes no phase shift. -18 volts rotates the signal 90° in one direction, and +18 volts rotates the signal 90° in one direction. This rotates the signal 90" in the opposite direction. Actual ferrites available on the market. In a core polarizer, the ferrite core is typically saturated at +14 volts; The voltage corresponds to a signal rotation of ±75@, so the actual full range of signal rotation is approximately 150".

Details of a preferred noise detection PH50 are shown in FIG. In this particular detector , the video baseband signal from the F4 converter I3 is first sent through a bandpass filter 60. However, this filter has a passband centered at approximately 231 FIz and width approximately 500 KHz. It is preferable that the video information has a wide range, sufficiently exceeding the video information in the baseband signal. It is.

Also, the center frequency of 23MHz is the CB multiplied signal of 27MHz, 2111Hz and 24. 11 radio signals to 5 MHz, and 4 MHz output of the crystal oscillator of tuner I2 Avoid interference from harmonics.

The output of the bandpass filter 60 is a normal rtF amplification Pi! 61 and the diode A detector in the form of 62 is reached. This diode 62 connects the AC The output is rectified and the generated signal is passed through a DC amplification WA63 and a low-pass filter 64. Smooth the surface by What is added to the ADC 52 in FIG. 3 is a filter 5. 4 smoothed or C output, but as explained earlier, the magnitude of this DC signal is It varies proportionally to the noise level of the video baseband output from the encoder.

FIG. 6 is a flowchart of a preferred program for controlling microprocessor 53. It is the default. This program is input at step +01, and at this step the polarization The current value P0 of the device mode operator is initialized to the current value l. This value is the polarizer Corresponding to a zero voltage level, the polarizer does not undergo any phase shift.

In step +02, the current 4iiINc of the DC output of the noise detector 50 is read, measure the noise level present in the particular signal to which the receiver is currently tuned. Set. Then, in step 103, operator Pc is set to its initialized value. If the answer is yes, then the noise level and polarizer mode operator The current values Nc and Pc of are set as NL and Pc in step voltage 04, respectively. each of these values is the lowest measured value of the noise level of the current signal. and the corresponding mode operator for which this noise level was measured.

Step 105 is a step to proceed if there is a negative response in step 103 or step 105. This step follows step 104, and the values of Nc and NL are compared. the current The noise level value Ne of is larger than the lowest noise value NL measured previously. If determined and found in step 106, the lowest noise value NL and the corresponding polarization The device mode operator value PL is stored again in step 107. But the current When it is found that the noise level value Nc is lower than the lowest noise level value Nc'' , the current values Nc and Pw are stored as new values Nt and Pt in step 108. be done.

From step 107 or step 108, the system proceeds to step 109; Determine whether the current value Pc of the polarizer mode operator is equal to the maximum value M. This space If the answer in steps is positive, the polarizer has been adjusted over the full range of settings. The result is a polarizer whose currently stored value Pc produces the lowest noise level. This shows that it represents the determined value of . If the answer in step 09 is negative If the polarizer is adjusted over its full range of settings, then the polarizer The current value Pc of the code operator should be incremented and steps 102-109 should be repeated. It shows that. The increase in Pc is performed in step 110, and then the system The process returns to step 102.

Each time the polarizer mode operator value Pc is increased in step 110, the micro An output signal generated from the processor 53 drives the DC voltage output of the polarizer drive 1159. Obviously, the settings of the polarizer 56 can be changed accordingly. Polarizer adjustment range The range is limited by the saturation point of the ferrite core, but the sensitivity of the control system is is determined by the number of increments required to cover the entire range of the polarizer 56. determined.

If the answer in step 09 is affirmative, the system proceeds to step III and this In the step, the polarizer setting value is set to the polarizer mode corresponding to the lowest noise level value NL. The level is adjusted to the level expressed by the decal value PL. In practice, set the polarizer to the highest Instead of directly setting the mode PL of the the hysteresis inherent in the polarizer's ferrite core. It is wise to avoid this effect.

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Claims (13)

[Claims] 1. An antenna for receiving incoming satellite signals; orientation of the antenna; coupled to said antenna, adjusting the relative alignment with the polarization of the incoming signal; A ground station dedicated to television reception, comprising: polarization means; means for generating an electrical control signal to control said relative alignment; and, means for detecting the noise level of a satellite signal received by the antenna; and: adjusting the control signal in response to the detected noise level so that the polarization hand means for adjusting the stage to minimize the detected noise level; A ground station dedicated to television reception, equipped with an automatic polarization control system. 2. The polarization means polarizes the incoming satellite signal in accordance with the orientation of the antenna. Adjust the polarization to selectively determine which polarization of the incoming signal is actually received by the antenna. 2. A ground station exclusively for television reception according to claim 1, comprising a ferrite polarizer having a ferrite polarizer. 3. the antenna comprises a feedhorn comprising a probe; the polarization means comprises a feedhorn comprising a probe; , by rotating the probe to determine which polarization of the incoming signal is actually received by the antenna. 2. A ground station exclusively for television reception according to claim 1, further comprising means for selectively determining . 4. a tuner that selects the signal received from a particular satellite's transponder; and a demodulator for demodulating the signal from the demodulator. Noise in the signal received from the selected transponder upon receiving the video output A ground station dedicated to television reception according to claim 1, which detects a level. 5. Measures the minimum detected noise level for the selected channel and and means for storing a value representing the level of the control signal corresponding to the output noise level. A ground station dedicated to television reception according to claim 1. 6. In response to each channel selection, the control signal is configured to correspond to the stored value. 2. A ground station dedicated to television reception according to claim 1, further comprising means for adjusting the level at which the television reception is performed. 7. Said control signal is adjusted by a predetermined range of values so that the Claim comprising means for adjusting the polarization means according to a predetermined range of setting values. A ground station exclusively for television reception as described in Item 1. 8. Antenna for receiving incoming satellite signals: Antenna orientation and coupled to said antenna, adjusting the relative alignment with the polarization of the incoming signal; A ground station exclusively for television reception, comprising: a polarization means; means for generating electrical control signals to control the stages to adjust said relative alignment; Steps: means for detecting a noise level of a satellite signal received by the antenna; Said control signal is adjusted by a predetermined range of values so that said polarization means for adjusting the means by a predetermined range of setpoints; measure the minimum noise level detected while adjusting the control signal; means for storing control signal values corresponding to the levels; A ground station dedicated to television reception, equipped with an automatic polarization control system. 9. The polarization means polarizes the incoming satellite signal in accordance with the orientation of the antenna. Adjust polarization to choose which polarization of the incoming signal is actually received by the antenna 9. The television reception exclusive device according to claim 8, comprising a ferrite core polarizer determined according to ground station. 10. the antenna comprises a feedhorn comprising a probe; the polarization means rotate the probe to determine which polarization of the incoming signal is actually received by the antenna. 9. The ground station exclusively for television reception according to claim 8, comprising means for selectively determining whether . 11. a tuner that selects the signal received from a particular satellite's transponder; and a demodulator that demodulates the signal from the demodulator. Noise in the signal received from the selected transponder upon receiving the video output 9. The ground station exclusively for television reception according to claim 8, wherein the ground station is configured to detect the signal level. 12. Measure the minimum detected noise level for the selected channel and and means for storing a value representing the level of the control signal corresponding to the detected noise level. 9. The ground station exclusively for television reception according to claim 8. 13. In response to each channel selection, the control signal corresponds to the stored value. 9. The ground station dedicated to television reception according to claim 8, further comprising means for adjusting the level at which the television reception is performed. .