JP2754772B2 - Signal generator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal generator that receives a pulse signal such as a radar wave and generates a signal having the same frequency as the received wave.

[Conventional technology]

An example of such a conventional signal generator will be described with reference to FIG. As shown in FIG. 4, the signal generator includes a receiving circuit 1, a frequency measuring circuit 2, a frequency control circuit 13,
A pulse signal such as a radar wave is received by a receiving circuit 1, and its carrier frequency is measured by a frequency measuring circuit 2, and is variable through a frequency control circuit 13 using the measured frequency data. By controlling the frequency oscillator 7, a signal having the same frequency as the received pulse signal is generated. That is, the received input signal IN is input from the input terminal to the receiving circuit 1,
After the reception processing such as amplification and unnecessary wave removal is performed, the carrier frequency of the input signal is measured by the frequency measurement circuit 2. As the frequency measuring circuit 2 used here, a superheterodyne receiver, an IFM (Instuntunius Frepuency mesverment) or a channelizer is used. The frequency of the received signal obtained here is used as frequency data for display or the like, and also used for generating a signal having the same frequency as the received signal. The frequency control circuit 13 converts the frequency data into a signal suitable for controlling the variable frequency oscillator 7 and determines the oscillation frequency of the variable frequency oscillator 7.

[Problems to be solved by the invention]

Since the conventional signal generator is configured as described above, a measurement error of the frequency measurement circuit 2 and an oscillation frequency error of the variable frequency oscillator 7 with respect to the frequency data occur, and the frequency of the output signal with respect to the frequency of the received input signal There was a problem that there was a difference.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to obtain a signal generator that generates a signal having the same frequency as a received input signal.

[Means for solving the problem]

A signal generator according to the present invention includes a frequency measuring circuit connected to a receiving circuit, first and second memories for storing an output of the frequency measuring circuit, and connected to the first and second memories. An error calculating means, a frequency control means connected to the first memory and the error calculating means for driving the variable frequency oscillator, and a pulse signal and a part of the output signal of the variable frequency oscillator connected to a preceding stage of the receiving circuit. First switching means for temporally switching and inputting to the receiving circuit, and an output of the frequency measuring circuit connected between the frequency measuring circuit and the first and second memories in conjunction with the first switching means; Second switching means for temporally switching and inputting to the first and second memories, wherein the first memory stores the frequency of the received pulse signal, and the second memory stores the frequency of the output signal of the variable frequency oscillator. frequency Stored, error calculating unit These 2
The frequency difference between the signals is obtained, and the frequency control means controls the variable frequency oscillator based on the outputs of the first memory and the error calculation means so that the frequency difference between the two signals becomes zero.

[Action]

In the signal generator according to the present invention, a part of the output of the variable frequency oscillation is input to the same circuit as the circuit for measuring the frequency of the received input signal while switching the time, and the variable frequency oscillator is similarly input with the received signal frequency. Measure the frequency,
Since the frequency is controlled so as to eliminate the difference, a signal having the same frequency as the received input signal can be generated.

〔Example〕

 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a signal generator according to the present invention. In FIG. 1, 1 is a receiving circuit for amplifying or selecting a received signal IN, 2 is a frequency measuring circuit for measuring the frequency of the signal, and 3 is an input signal frequency as a first memory for storing frequency data of the received signal. A data memory, an output frequency data memory as a second memory for storing data of the output signal frequency, and 5 each memory 3, 4
An error calculator 6 for calculating a difference between the frequency data of the input signal data from the input signal data memory 3 and the error frequency data from the error calculation circuit 7;
Is a frequency control circuit for controlling the frequency. Reference numeral 8 denotes a reception input signal IN and an output signal OUT generated by the variable frequency oscillator 7.
An input changeover switch 9 as a first changeover means for changing over the frequency measurement data, and a data changeover switch 9 as a second changeover means for changing the output destination of the frequency measurement data. In the drawings, the same reference numerals indicate the same or corresponding parts.

Next, the operation of the above embodiment will be described. Here, first, the input switching terminal 8 is operated to select the terminal a on the input side, the receiving signal IN is received by the receiving circuit 1, and the output of the frequency measuring circuit 2 is output to the data switching switch 9
Is stored in the input signal frequency data memory 3 connected to the terminal a. The output of the input signal frequency data memory 3 passes through the frequency control circuit 6, and controls the oscillation frequency of the variable frequency oscillator 7. However, at this time, the measurement error of the frequency measurement circuit 2 and the variable frequency oscillator 7
, The output signal frequency cannot be made to match the input reception frequency. Therefore, in the present invention, a part of the output signal of the variable frequency oscillator 7 is connected to the terminal b of the input switch 8, and the data switch 9 is set to the terminal b in conjunction with the input switch 8, and the frequency of the output signal is changed. Is measured by the frequency measurement circuit 2, and the frequency data is stored in the output signal frequency data memory 4 via the data switching switch 9. Here, the error calculator 5 calculates the difference between the two frequency data stored in the memories 3 and 4 and inputs the output to the frequency control circuit 6. Thereby, the frequency control circuit 6 controls the variable frequency oscillator 7 as a frequency control signal in which the error is corrected, and makes its output frequency closer to the input reception frequency. Therefore, even if the received signal is input only once, the frequency data is stored in the memory 3. Therefore, by measuring and correcting the output signal frequency a plurality of times, the output signal with less error can be obtained. Can be obtained. In this case, since the same frequency measurement circuit 2 is used for the frequency measurement of the signal, the frequency measurement error can be completely eliminated.

In the above embodiment, the case of the direct reception system in which the input received signal frequency is not converted has been described. However, when the reception system of the frequency conversion system is used, as shown in FIG. An output signal may be connected, or an output signal may be connected to the subsequent stage of the input frequency converter 10 as shown in FIG. In any case, the effect of the present invention can be effectively exhibited even if the frequency is converted. However,
2 and 3, reference numeral 11 denotes an output frequency conversion circuit, and reference numeral 12 denotes a local oscillator.

〔The invention's effect〕

As described above, according to the present invention, a part of the output signal of the variable frequency oscillator is temporally switched with the reception signal and input to the frequency measurement circuit, so that the measurement error of the frequency measurement circuit can be ignored, and the reception signal frequency Since the difference between the input signal frequency and the output signal frequency is determined to be zero, there is an effect that an output signal having a small difference from the input signal frequency can be obtained.

[Brief description of the drawings]

1 is a block diagram of a signal generator according to an embodiment of the present invention, FIGS. 2 and 3 are block diagrams showing another embodiment of the present invention, and FIG. 4 is a block diagram of a conventional signal generator. It is. 1 ... Reception circuit, 2 ... Frequency measurement circuit, 3 ... Input signal frequency data memory, 4 ... Output frequency data memory, 5 ... Error calculation circuit, 6 ... Frequency control circuit, 7 ...
... variable frequency oscillator, 8 ... input switching switch, 9 ...
Data switching switch.

Claims (1)

(57) [Claims] 1. A signal generator for generating, by a variable frequency oscillator, a signal having the same frequency as a pulse signal received by a receiving circuit, a frequency measuring circuit connected to the receiving circuit, and an output of the frequency measuring circuit being stored. First and second memories, error calculating means connected to the first and second memories, frequency control means connected to the first memory and the error calculating means for driving the variable frequency oscillator, First switching means connected to a preceding stage of the receiving circuit to temporally switch the pulse signal and a part of the output signal of the variable frequency oscillator and to input the pulse signal and the output signal to the receiving circuit; And a second memory connected between the first and second memories to temporally switch the output of the frequency measuring circuit in conjunction with the first switching means.
A second switching means for inputting to the memory of the above, wherein the first memory stores the frequency of the pulse signal, the second memory stores the frequency of the output signal of the variable frequency oscillator, and the error The calculating means calculates the frequency difference between these two signals, and the frequency control means controls the variable frequency oscillator based on the outputs of the first memory and the error calculating means so that the frequency difference becomes zero. And a signal generator.