JPS61189708A - Signal generator - Google Patents

Abstract

PURPOSE:To obtain a signal generator which can produce a stable signal of a desired frequency with low cost by means of simple parts which are capable of the digital control and substantially free from control, by controlling optionally the time intervals of two impulses given from an impulse generator. CONSTITUTION:For the time relation between two impulses of the output of an impulse generator 7, it is supposed that the impulse supplied to the 2nd decentralized delay line 9 has a delay equal to the time difference tau on the basis of the impulse supplied to the 1st decentralized delay line 8. Then two chirp signals are supplied to a mixer 10 and therefore the signals having the sum and difference frequencies emerges at the output of the mixer 10. Then only the difference frequency is extracted by an LPF 11 and the frequency emerging at the output of the LPF 11 is proportional to the time difference tauof two impulses produced by the generator 7. Therefore the control of the output frequency is possible by giving the programmable control to the generator 7 to change the time difference tau of both impulses.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a signal generator that can arbitrarily change the output frequency.

[Prior Art] FIG. 5 is shown in, for example, an electronic communication handbook. It is a block diagram showing a secondary variable frequency programmable signal generator, in which (1) shows a stable frequency f.
A reference signal generator such as a crystal oscillator that generates an OMHz signal, (2) a harmonic generator that obtains harmonics from the output signal of this reference signal generator (1), (3,1)
(3b) (3c) is a selector switch to select the desired harmonic, (4a) (4b) is the frequency 1/1
A frequency divider that divides the frequency to 0, (5a) (5b) is a mixer, (
6a) (6b) is a bandpass filter.

Next, its operation will be explained. Reference signal generator (1)
From the output signal of frequency fO, the harmonic generation circuit (2) generates f
Generates harmonics that are an integral multiple of O. Selector switches (3a), (3b), and (3c) take out signals of frequencies necessary to generate a desired frequency among these harmonics, and the selected harmonics are respectively ntfo.

Let n2fO and n3fo. Selector switch (3a)
The selected harmonic n1fO from is divided by the divider (4a) to obtain 1/10·n1fO, and this signal and the selected harmonic n2fO from the selector switch (3b) are mixed by the mixer (5a).
and the sum frequency signal 1 from the bandpass filter (6a).
/10·n1fo+n2fO is extracted. This signal is divided by the divider (4b) to 1/100・n 1 f
O+ 1/10・n 2 f O is obtained, this signal and the selected harmonic n3fO from the selector switch (3c) are mixed in the mixer (5b), and their sum frequency signal is output from the bandpass filter (6b). 1/100・n1fo+1/1
0·n2fO+n3fO is obtained. In this way, a signal of a desired frequency can be obtained.

[Problems to be Solved by the Invention] Since the conventional signal generating device is configured as described above, it must have a highly stable crystal oscillator as a reference oscillator. The crystal oscillator has a low frequency and the desired frequency is U
In the case of a high band such as the HF band, the multiplier must be increased, making the multiplier and amplifier large-scale and expensive, and the multiplication also increases noise, deteriorating the quality of the final output signal.

In addition, the harmonic generation section requires a nonlinear element, and further requires a demultiplexing filter for each harmonic and an attenuator for level adjustment, resulting in a complicated and expensive circuit configuration.

This invention was made to solve the above-mentioned problems, and provides an inexpensive signal generator that can generate a stable signal at a desired frequency using simple, digitally controlled components that require almost no adjustment. The purpose is to obtain.

[Means for Solving the Problems] The signal generator according to the present invention includes an impulse generator that generates two impulses whose one-hour intervals are controllable, and two impulses from this impulse generator, respectively, which are input to the signal generator. First and second distributed delay lines each outputting a chirp signal having a delay time proportional to the frequency of each input signal, and the output chirp signals of these first and second distributed delay lines are mixed. It consists of a mixer that creates a product of signals, and a low-pass filter that extracts the difference frequency component between the two chirp signals from the output signal of this mixer.

[Function] The two impulses from the impulse generator are the first and
By passing through the second distributed delay line, two chirp signals whose frequency increases with time are obtained, these two chirp signals having a time interval corresponding to the time interval of two impulses. Therefore, the frequencies of both chirp signals at the same time have a constant frequency difference at any time. Therefore, by applying this two-chip signal to a mixer and extracting the difference frequency component using a low-pass filter, a signal with a frequency proportional to the time interval of two impulses can be obtained. By arbitrarily controlling the time interval between these two impulses, a signal of a desired frequency can be obtained.

[Example code] An embodiment of the present invention will be described below with reference to the drawings.

Fig. 1 is a block diagram showing an embodiment of the present invention. In Fig. 1, (7) is an impulse generator whose output time interval between two impulses can be set externally and programmably, and (8) is an impulse generator. (9) a first distributed delay line, which uses one output impulse of the device (7) to generate a chirp signal with a delay time proportional to the frequency;
(10) is a second distributed delay line that similarly generates a chirp signal using another impulse of the impulse generator (7), and (10) is a first distributed delay line (8) and a second distributed delay line. The mixer (11) produces a product of the two chirp signals from the delay line (9), and the low-pass filter (11) extracts the difference frequency component of the two chirp signals from the output of the mixer (10).

Next, its operation will be explained. First, the distributed delay line, which is a key component of this invention, will be explained with reference to FIG. Second
The figure below shows the relationship between the frequency and delay time of this distributed delay line. As shown in Figure 1, distributed delay lines generally have bandpass characteristics, and within that band, the delay time varies with frequency. It changes linearly. If the center frequency of the band is ωO, the delay time at the center frequency ω0 is TO1, the delay time deviation is ΔT, and the slope of the straight line is k, then the frequency within the impulse response is ωa= (, lO+ k (t −To)
""...(1) (tO-ΔT/2<t<TO+ΔT/2
). Therefore, in the time relationship between the two impulses output from the impulse generator (7), the first distributed delay line (
If the impulse input to the second distributed delay line (9) is delayed by a time τ with respect to the impulse input to the first distributed delay line (8), then The frequency change follows equation (1), and the second distributed delay line (9)
The frequency change is according to the following equation (2): ωb = ω0 + k (t + τ −TO)
......(2) (To+ - ΔT/2<t<
To + τ - ΔT/2) When two chirp signals having the frequency relationship of equations (1) and (2) are input to the mixer (10), signals with the sum and difference frequencies appear at the output, and a low When only the difference frequency is extracted by the low-pass filter (11), the output of the low-pass filter (11) has ωc=2 and τ...(3)
A signal appears with a frequency such that (To+τ-ΔT/2<t<ΔT/2). As can be seen from equation (3), the frequency appearing at the output of the low-pass filter (11) is proportional to the time difference τ between the two impulses generated by the impulse generator (7). Therefore, the impulse generator (7
) by programmably controlling the time difference τ between the two impulses, the output frequency can be controlled.

FIG. 3 shows the first and second distributed delays 41 (8
) (9) and the time chirp signal showing the output of the mixer (10), Figure 3a shows the input impulse to the second distributed delay line (9) and the output chirp signal, indicate the output of the mixer (10), respectively.

Figures 4a and 4b show the first and second distributed delay lines (
8), Figure 4c, d are their outputs, and Figure 4e is the input impulses from the mixer (10) to the low-pass filter (
11) is shown.

The above embodiment can be used as a signal source for a frequency agile radar, as the output signal is obtained in the form of pulse modulation, but it is also possible to have multiple systems, control each independently, and add the outputs. By doing so, it is possible to obtain a frequency hopping signal with a high duty ratio or a temporally continuous frequency hopping signal.

[Effects of the Invention] As described above, according to the present invention, a signal generator that can control one frequency of an output signal by simply changing the time interval between two impulses is called an impulse generator distributed delay line, mixer, or low-pass filter. It has the advantage that it can be constructed using parts that are inexpensive and have few adjustment elements.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a characteristic diagram of a distributed delay line used in this embodiment,
FIG. 3 is a time chart showing the impulse response of the distributed line and mixer output, and FIG. 4 is a time chart showing the distributed delay line and mixer output when impulses are generated a plurality of times (twice) in succession. FIG. 5 is a block diagram showing a conventional programmable signal generator. In the figure, (7) is the impulse generator, and (8) is the first impulse generator.
distributed delay line, (9) is the second distributed delay line, (10
) is a mixer, and (11) is a low-pass filter.

Claims (1)

[Claims] An impulse generator that generates two impulses with a controllable time interval, inputs the two impulse outputs from this impulse generator, and outputs a chirp signal with a delay time proportional to the frequency of each input signal. a first and a second distributed delay line; a mixer that mixes the output chirp signals of the first and second distributed delay lines to produce a product of these signals; and a mixer that produces a product of these signals; 1. A signal generating device comprising a low-pass filter for extracting a difference frequency component, and is configured to obtain a signal having a frequency proportional to an interval between impulses generated by the impulse generator.