JPH0317467Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to an automatic tuning receiving device used in radio direction finders and the like.

When using a variable frequency radio frequency amplifier, in order to automatically sweep the reception frequency band or manually change it, the reception frequency band is changed by changing the amplification center frequency of the radio frequency amplifier and changing the oscillation frequency of the local oscillator. It is designed to tune to the frequency.

With this structure, a predetermined fixed local oscillator is provided, and this local oscillator is switched to a variable local oscillator and connected to a frequency converter to supply the local signal, thereby changing the oscillation frequency of the fixed local oscillator. It is desired that the amplification center frequency of a high-frequency amplifier be automatically controlled so as to receive radio waves of a predetermined frequency corresponding to the following. For example, when receiving radio waves for emergency communication, it is desirable to quickly and automatically become in a reception state for the desired frequency rather than tuning to the frequency of the radio waves.

From this point of view, in the past, an automatic tuning receiver as shown in FIG. 2 has been used to automatically tune to a predetermined frequency. That is, the received signal from the loop antenna 11 is supplied to the variable frequency high frequency amplifier 13 via the goniometer 12, and this amplified output is supplied to the frequency converter 14, where it is frequency-converted by the local signal from the local oscillator 15. The intermediate frequency obtained from the converter 14 is amplified by an intermediate frequency amplifier 16.

When the tuning frequency of the tuning circuit 17 of the variable local oscillator 15, that is, the oscillation frequency of the variable local oscillator 15 is changed, the amplification center frequency of the high frequency amplifier 13 also changes automatically in conjunction with it, so that the frequency always corresponds to the oscillation frequency of the local oscillator. received signals are converted into the same intermediate frequency signal.

A fixed local oscillator 18 is provided in addition to such a variable local oscillator 15. This fixed local oscillator 18
When the variable local oscillator 15 is switched by the switch 19 and connected to the frequency converter 14, conventionally, the tuning circuit 17 of the variable local oscillator 15 is connected to the frequency converter 14.
is disconnected from the oscillator body portion 15a containing the active element by a switch 21, and this tuning circuit 17 is connected to the output side of the fixed local oscillator 18. In this way, the oscillation signal of the fixed local oscillator 18 is supplied to the tuning circuit 17, and the oscillation signal of the fixed local oscillator 18 is supplied to the phase shift circuit 22 which shifts the phase by 90 degrees, and the output of the phase shift circuit 22 and the tuning circuit The motor 24 is controlled so that this phase difference becomes zero, and each tuning frequency of the tuning circuit 17 and the variable frequency high frequency amplifier 13 is controlled by the motor 24. By setting the amplification center frequency of the high frequency amplifier 13 to correspond to the oscillation frequency of the fixed local oscillator 18, the high frequency amplifier 13 is automatically tuned so as to obtain a reception frequency corresponding to the oscillation frequency of the fixed oscillator 18. .

In such an automatic tuning receiving device for a receiving circuit equipped with a variable frequency high frequency amplifier, a tuning circuit of a variable frequency high frequency amplifier or a tuning circuit of a variable local frequency oscillator is determined by a signal obtained by comparing and detecting the oscillation frequency of a local frequency oscillator with a set receiving frequency. etc. are controlled by a motor, a tolerance range is set for comparison detection, and the control of the tuned circuit is stopped within the tolerance range by cutting off the motor control input at points before and after the tolerance range. , JP-A-55-83331, JP-A-51-5721, etc., and when a point slightly beyond the normal tuning point is detected in the control of such a motor, a small pulse signal in the reverse direction is generated. A means of controlling the vehicle so that it stops at the regular tuning point by giving a
40641 and others.

[The problem that the idea attempts to solve]

In an automatic tuning receiving device used in a radio direction finder, etc., it is desirable to be able to tune as quickly as possible, since it is necessary to find the direction of a communication with a very short received signal in addition to listening to the communication content.

For such a purpose, it is sufficient to increase the speed of the motor and provide a control input that causes it to operate at high speed, but with the conventional control means described above, the higher the speed, the more
Due to the inertia of the motor, the amount of overshooting the tuning point becomes large, and as a result, the pulse signal in the opposite direction becomes large.As a result, the inertia causes the motor to go back too far and stop after going back and forth around the tuning point. This causes the inconvenience of lacking sex.

Therefore, there is a problem in that it is expected to provide a device with a simple and inexpensive configuration that eliminates these inconveniences.

According to this invention, when a fixed local oscillator is switched and connected to a frequency converter instead of a variable local oscillator, the oscillation frequency of the variable local oscillator separated from the frequency converter and the oscillation frequency of the fixed local oscillator are counted. The variable local oscillator and high frequency amplifier are controlled so that the difference between the two frequencies is eliminated.
That is, the oscillation frequency of the fixed local oscillator and the oscillation frequency of the variable local oscillator are compared and the oscillation frequency of the variable local oscillator is automatically controlled so that the two match. In this way, the amplification center frequency of the high frequency amplifier corresponding to the oscillation frequency of the variable local oscillator is automatically set.

[Means to solve the problem]

This idea is obtained by comparing and detecting the frequency of the above-mentioned tuned circuit, that is, the motor that varies the tuned frequency, and the frequency set by a predetermined operation, that is, the set frequency and the change in the tuned frequency. In an automatic tuning receiving device having a tuning control configuration that adjusts the tuning frequency within a predetermined range with an allowable range before and after the set frequency by controlling the motor using a detection signal generated by the set frequency, the above-mentioned allowable range is A predetermined range setting means for setting a predetermined range by increasing the predetermined range by increasing the predetermined frequency when the preset frequency is low and when the predetermined frequency is high; Give one reverse polarity pulse to brake the motor in the reverse direction,
The above problem can be solved by providing a braking control pulse generating means that generates a plurality of reverse polarity pulses for rotating the motor in the reverse direction when a detection signal indicating that the other end of the above predetermined range is detected is obtained. It was designed to be solvable.

〔Example〕

Examples will be described below with reference to figures. In Fig. 1, parts corresponding to those in Fig. 2 are given the same reference numerals.
In this invention, the output of the fixed local oscillator 18 and the output of the variable local oscillator 15 are supplied to a frequency counting comparator 26, and the respective oscillation frequencies of these two local oscillators are counted and compared. The motor 24 is controlled according to the comparison result so that the oscillation frequencies of both local oscillators 15 and 18 match. In this case, the frequency count comparator 26 is made to operate only when the changeover switch 19 is switched to the fixed local oscillator 18 side, that is, when the fixed local oscillator 18 is connected to the frequency converter 14.

By doing this, there is no need to use the phase shift circuit 22 or the phase comparator 23 shown in FIG. The output of the variable local oscillator 15 and the output of the fixed local oscillator 18 may be compared by the frequency counting comparator 26, and the motor 24 may be controlled by the output, and the frequency counting comparator 26 may perform digital processing. It is less susceptible to temperature fluctuations and aging, and is a fixed local oscillator.
Frequency converter 1 is created by providing multiple
4 or when the frequency synthesizer is used as a fixed local oscillator and the fixed local oscillation frequency is switched, correct automatic tuning is performed at any frequency.

Next, an example of the frequency count comparator 26 will be explained with reference to FIG. In FIG. 3, a counting circuit 27 for counting the oscillation frequency _r from the fixed local oscillator and a counting circuit 28 for counting the oscillation frequency _l for the variable local oscillator are provided. These counting circuits 27, 2
The counting results of 8 are respectively latched in latch circuits 31 and 32, and the respective frequencies latched in the latch circuits 31 and 32 are compared with each other in a comparator circuit 33.

For example, as shown in Figure 4A, the oscillation frequency _l of the variable local oscillator is different from the oscillation frequency _r of the fixed local oscillator.
The frequency is controlled so that the frequency is between a frequency Δ lower than Δ and a frequency Δ higher than Δ, that is, within the shaded area in FIG. 4A. Therefore, the variable local oscillation frequency _l
and the fixed local oscillation frequency _r - Δ, and the fixed frequency _r + Δ and _l are compared. In the results of these comparisons, if _l is lower than _r - Δ, _l can be increased, and if _l is higher than _r + Δ, _l can be controlled to be lower. In order to detect these frequency comparisons by the comparator circuit 33, the following operation is performed.

In FIG. 3, a fixed local oscillation signal is inputted from a terminal 34, is amplified by an amplifier 35, and its amplified output is supplied to a NAND gate 36 and an AND gate 37. AND gate 3
7 is opened by applying a signal to terminal 38 indicating that the fixed local oscillator is connected to the frequency converter.
Therefore, the fixed local oscillation signal amplified by the amplifier 35 passes through the gate 37, is further amplified by the amplifier 39, and is detected by the detection circuit 41. The detection output drives the transistor 42, which drives the rail 43, and switches the relay contact 43a to disconnect the motor drive terminal 44 from ground, thereby making it possible to control the motor 24. The output of the detection circuit 41 is also supplied to a level conversion amplifier circuit 45. The output of this amplifier circuit 45 becomes a low level output, which is inverted by an inverter 46, and the gate 47 is opened by the output. An oscillating local signal from a fixed local oscillator is supplied to an amplifier 49 through a terminal 48, and its amplified output passes through a gate 47 and is supplied to a gate 51.
It is counted by the counter 28 through the gate 51.

On the other hand, the clock generator 52 generates a clock as shown in FIG. 27 and 28 for counting. Further, the clock from the clock generator 52 is supplied to a frequency dividing circuit 53, and the frequency is divided by two from output terminals 54 and 55 as shown in FIGS. A signal with is obtained. These are gate circuits 56, 57
is supplied to

A signal indicating which of a plurality of fixed local oscillators, four in this example, is selected is supplied from a terminal 58, and one gate in each gate circuit 56, 57 is opened in response to the signal. Gate circuit 56,5
One setting gate in each of the setting circuits 61 and 62 for setting the tuning tolerance range Δ is selected by the output of 7. That is, in this example, different Δs are set depending on the oscillation frequency of the selected fixed local oscillator. When the oscillation frequency _r of the fixed local oscillator is low, Δ is set to be small, and when it is high, Δ is set to be large.

In other words, with this setting, the allowable range Δ is set to be large when the set frequency is high, and set small when the set frequency is low.

The setting circuits 61 and 62 are the counting circuits 27 and 62, respectively.
Outputs corresponding to the set frequencies among the outputs of the 28 counting stages are respectively inputted as inverted signals to the set gates. The outputs of the flip-flops 63 and 64 are commonly input to these setting gates, and the outputs of the corresponding gates in the gate circuits 56 and 57 are also input respectively.

For example, if the output of terminal 54 is high level and the output of terminal 5
8 is at a high level, the gate 6 of the gate circuit 5 corresponding to the high level terminal is open, and the gate circuit 57 is closed. Therefore, setting circuit 61 is enabled and setting circuit 62 does not operate. When the gates 36 and 51 are opened, the counting circuit 2
7 and 28 count fixed local signals and variable local signals, respectively, as described above. The counting circuit 28 continues to count the variable local signals, but when the fixed local signal reaches the value set by the setting circuit 61, the counting circuit 27 that counts the fixed local signals starts counting the fixed local oscillator and the setting gate corresponding to the selected fixed local oscillator at that time. When all the input outputs of the counting circuit 27 become high level, a low level is output from the setting gate, and the output of the setting circuit 61 causes the flip-flop 63
is reset, and the output of the flip-flop 63 resets the counting circuit 27 through the NAND gate 65, but the counting circuit 27 immediately counts the fixed local oscillation signal. By resetting the flip-flop 63, a low level is commonly applied to each setting gate of the setting circuit 61, making the setting circuit 61 invalid. Therefore, the counting circuit 27 continues counting regardless of the setting circuit 61.

In other words, the setting circuit 61 is valid only for the period shown in FIG. 5D. After counting the set Δ, it is reset and starts counting the fixed local oscillation signal again. Therefore, during the period when the terminal 54 is at a high level, that is, at the high level in FIG. 5B, the counting circuit 2
7 counts the frequency _r - Δ, and the counting circuit 28 counts _l . When the output of this terminal 54 becomes low level, the monostable multivibrator 66 is driven, and the trigger pulse obtained from this drives the count value _r - Δ of the counting circuit 27 from the latch circuit 3.
The count value _l of the counting circuit 28 is latched by the latch 31a in the latch circuit 32.
latched to a.

Next, when the output at terminal 55 becomes high level, in this case gate circuit 57 is opened and gate circuit 56 is closed. Therefore, setting circuit 61 is disabled and setting circuit 62 is enabled. In this state, the fixed local signal and the variable local signal are again counted by the counting circuits 27 and 28, respectively, but when the counting circuit 28 reaches the set value Δ, the counting circuit 28 is instantaneously counted through the NAND gate 67 by the output of the setting circuit 62. The flip-flop 64 is reset by the output of the setting circuit 62, and the operation of the setting circuit 62 is invalidated by the output. At the moment the output of the terminal 55 becomes low level, the monostable multivibrator 68
The count value _r of the counting circuit 27 is latched in the latch 31b in the latch circuit 31, and the count value _l -Δ of the counting circuit 28 is latched in the latch 32b in the latch circuit 32.

The above is repeated, and in the comparator circuit 33, each content of the latches 33a and 32a of the latch circuit,
That is, the frequencies _r - Δ and _l are compared, and the contents of the latch circuits 31b and 32b, that is, the frequencies _r and the frequencies _l - Δ are compared.

As a result of this comparison, if the frequency _l is lower than the frequency _r - Δ, the comparison circuit 3
If the frequency _r is smaller than the frequency _l - Δ, the output terminal 71 of the comparison circuit 33 becomes high level as shown in FIG. 4C. In states other than these, the terminals 69 and 71 are at low level.

When terminal 69 goes high, the high level is fed through gate 72 and further through OR gate 73 to one input terminal of comparator 74, at which time the other side of comparator 74 is given a low level, For example, the output will be at a high level. The high level is applied to the motor 24 from the terminal 44 as a signal for driving the motor 24 (FIG. 1) in forward rotation, for example. As a result, the frequency _l of the variable local oscillator is controlled to be increased.

Conversely, when the terminal 71 is at a high level, its output is given to the other terminal of the comparator 74 through gates 75 and 76, and at that time, a low level is given to the one of the comparators 74, and the output of the comparator 24 becomes a low level, and a reverse signal is given to the motor 24 from the terminal 44 to operate to lower the oscillation frequency _l of the variable local oscillator.

In this way, the variable local oscillator frequency _l approaches the fixed local oscillator frequency _r , for example closer than a low frequency, and when the variable local oscillator _l reaches the frequency _r - Δ, at that moment the output of the terminal 69 is as shown in FIG. 4B. The level becomes low as shown in , and the correction means operates. That is, the monostable multivibrator 77 is driven by the level change, and a pulse as shown in FIG.
8 and 76 in turn and is supplied to the comparator 74.
Therefore, a signal of the opposite polarity is applied to the motor through the terminal 44, causing the motor to rotate in reverse, and controlling the motor 24 to rapidly stop the motor.

However, due to the inertia of the motor 24, the variable local oscillation frequency _l may become higher than _r +Δ. Therefore, the output of monostable multivibrator 77 drives monostable multivibrator 79 to obtain an output as shown in FIG. 4E, which is applied to pulse oscillator 83 through gates 81 and 82. While the output of the monostable multivibrator 79 is at a high level, the pulse oscillator 83 operates and generates a pulse with a small pulse width as shown in FIG. 4F. The pulses are provided to comparator 74 through gates 84 and 76 in sequence. Therefore, the oscillation frequency _l of the variable local oscillator gradually _decreases each time a pulse is applied from a state that is too high than the frequency _r + Δ.
becomes lower. In this process, the local oscillation frequency _l
When becomes lower than _r + Δ, the output at terminal 71 becomes a low level, gate 81 closes, and corrective action on motor 24 is stopped.

Conversely, the local oscillation frequency _l is the fixed local oscillation frequency _r
When the frequency _l is lower than the state where it is higher than the current level, the terminal 71 is at a high level, and this drives the motor continuously, so that _l is controlled to be low, and when the output of the terminal 71 is at a low level, A stable multivibrator 86 is driven and its output is passed through gates 87 and 73 in sequence to a comparator 74.
A signal is applied to the opposite side of the motor to apply a reverse brake to the motor and drive the monostable multivibrator 88, whose output drives the pulse generator 82 through gates 89 and 82 in sequence. The output is passed through gate 91 to comparator 74.
is applied and corrective action is taken on the motor.

Note that when switching to the fixed local oscillator, the output of the comparator circuit 33 is initially set so that the motor 24 is controlled in a predetermined manner (as described above). In other words, the fall of the output of the amplifier 45 drives the monostable multivibrator 95,
The output of that output is logically ANDed with the output of the inverter 46 in a circuit 96, and the output of the circuit 96 is
7,98. Therefore, depending on the state of the output terminal 69 of the comparator circuit 33, an output is obtained from either gate 97 or 98, the flip-flop 99 is set or reset by the output, and the output is sent to the monostable multivibrator 77 through the OR gate 101. Initial settings are made depending on whether or not to drive. Gates 102 to 104 are connected to terminals 69, 71, monostable multivibrator 77,
This is for determining to which input side of the comparator 74 the output of the comparator 86 is to be supplied.

As described above, according to the automatic tuning receiving device of this invention, the oscillation frequency of the variable local oscillator is controlled to match the oscillation frequency of the fixed local oscillator, and the frequency is controlled by counting and comparing, so that it can be used in various environments. It is difficult to be affected by changes or changes over time, and it is possible to synchronize correctly, and it is also easy to automatically correct for overshoot, as shown in the example shown in Figure 3. Automatic tuning is performed, so it is possible to obtain a receiving device with a good signal-to-noise ratio.

Furthermore, in the frequency comparison, the oscillation frequency _l of the variable local oscillator is within a predetermined frequency range _r −Δ to _r +Δ centered on the oscillation frequency of the fixed local oscillator.
The controller is controlled while the detection output is obtained, and _l is lower than or higher than l.
Once _r − Δ ~ _r + Δ, the control is the opposite of that up to that point, that is, if the control had been to increase _l , the control to lower _l is performed slightly, that is, the fourth
Figure D, further perform the control in Figure 4 F as necessary,
This correction control allows the receiver to rapidly tune to a frequency corresponding to the oscillation frequency of the fixed local oscillator. Therefore, even short-term communications can be reliably received.

In addition, the output of the frequency counting comparator 26 is supplied to and cut off from the control unit 24 in conjunction with the control of the manual tuning/automatic tuning switch 19, and the manual/automatic switching operation is simple and simple. Automatic tuning during reception using a fixed local oscillator also occurs in a short time.

In addition, to compare frequency counts, for example, one frequency signal to be compared with each other is up-counted by a reversible counter, the other frequency signal is down-counted, and the state of the counter is changed to the state when the counting is finished. Thus, a comparison output can be obtained.
Alternatively, count one signal with one counter, latch the counted value in a latch circuit, then count the other signal with that counter and latch it with another latch circuit, or input it into the counter without latching. It is also possible to compare the count value latched in the latch circuit with the count value latched in the latch circuit.

[Effect of idea]

According to this idea, the tolerance range is set so that it is small at low frequencies and wide at high frequencies, and when a general detection signal within the tolerance range is obtained, one reverse polarity pulse is given to the motor. The range setting With braking control,
Drive control is obtained that matches the frequency changes in the moving parts of the tuned circuit.

In other words, in general, the relationship between the amount of frequency change and the fixed amount of movement in the movable part of a tuned circuit is that, as can be easily understood from the scale of the frequency dial, the amount of frequency change is small at lower frequencies; Since the amount of frequency change is large at high frequencies, if the control conditions were set to the same tolerance regardless of the frequency as in the conventional system, the control conditions would be too strict at high frequencies and too lenient at low frequencies. Although this will cause some inconvenience, if you set it up like this idea, you will be able to perform drive control with control conditions that match the frequency.
In addition, by braking control, pulse-like reverse polarity braking is applied at the same time as one end of the allowable range is applied, so that the braking does not go too far and reverse, and in most cases, the inertia is drastically reduced. It is possible to stop the motor within a predetermined range, and even if the brake is not fully applied and the motor exceeds the other end of the allowable range, the motor is gradually pulled back by pulsed reverse polarity drive, allowing the motor to speed up. However, when detecting one end, one reverse polarity pulse is generated, and when the other end is detected, multiple reverse polarity pulses are generated. It has the advantage of being able to be provided at low cost by simply adding a simple configuration.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a conventional automatic tuning receiving device, Fig. 2 is a block diagram showing an example of an automatic tuning receiving device according to this invention, and Fig. 3 is a logic circuit diagram showing a specific example of the frequency counting comparator. , FIG. 4, and FIG. 5 are diagrams for explaining this invention, respectively. 13: Variable frequency high frequency amplifier, 14: Frequency converter, 15: Variable local oscillator, 16: Intermediate frequency amplifier, 18: Fixed local oscillator, 19: Switch, 26: Frequency counting comparator, 24: Variable high frequency amplifier and variable local section Motor as a control part to control the frequency of the oscillator.

Claims (1)

[Claims for Utility Model Registration] 1. A motor that varies the frequency of a tuned circuit (hereinafter referred to as the tuned frequency), and a comparison between a frequency set by a predetermined operation (hereinafter referred to as the set frequency) and the change in the tuned frequency. An automatic tuning receiving device ( (hereinafter referred to as the device), a) the tolerance range is made smaller when the set frequency is lower and larger when the set frequency is higher;
a predetermined range setting means for setting the predetermined range; b. one reverse polarity pulse for braking the motor in the reverse direction when the comparison detection detects one end of the predetermined range and the detection signal is obtained; and then, when the detection signal detecting the other end of the predetermined range is obtained, braking control pulse generation means for generating a plurality of reverse polarity pulses for returning the motor in the reverse direction. A device featuring: 2. The device according to claim 1 of the Utility Model Registration Claim, wherein a) the automatic tuning receiving device is configured with an automatic tuning receiving device for a direction finder, and b) the tuning circuit is configured to tune the received signal to a variable frequency high frequency amplifier. a fixed local section that generates the local frequency; A device characterized in that the frequency of a frequency oscillator is configured as the set frequency.