JPS6271869A - Frequency detecting device - Google Patents

Abstract

PURPOSE:To improve detection precision by generating a measurement trigger by a measurement timing generating circuit at prescribed intervals of time so as to measure a varying input frequency and then detecting the current frequency. CONSTITUTION:The measurement timing generating circuit 9 generates the measurement trigger at prescribed intervals of time and supplies it to an A/D converter 3 and a channel selecting circuit 4. Then, an input pulse from an input terminal 1 is inputted from a filter bank 2 to the converter 3 and each video output level is measured at every timing of trigger. Then, the channel selecting circuit 4 compares the output level by the trigger and when its channel is higher, a peak detection signal is outputted to an output line 5. A frequency calculating circuit 7 detects the channel number and frequency of the peak detection signal and outputs them to an output line 8. Consequently, the frequency and variation of the input pulse are detected precisely.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a frequency detection device for a parallel filter receiver.

BACKGROUND ART FIG. 3 shows a general configuration of a frequency detection device in a conventional parallel filter receiver. In the figure, (1) is the input terminal, (2) is the filter bank consisting of filters with Gaussian characteristics, (3) is the A/D converter, and (4) is the output level of the own channel and the channels on both sides. (5) is the output line of the peak detection signal, and 4[ia] (tl, b) is used for frequency detection. Channel output-level output lines on both sides (7) are frequency calculation circuits, and (8) is an output line of the calculated frequency.

First, the principle of frequency calculation will be explained.

FIG. 4 shows a model diagram of the output level when one pulse wave of frequency r is input to the filter bank (2) composed of filters with Gaussian characteristics. Here, the filter output level for channel # is shifted from PAk. In the figure, the channel where the filter output peaks (peak “
(:#l) At that time, the difference between the channels on both sides, ,,, +le
+-+) to the center frequency f of #m, the relative frequency Δf is uniquely found. Therefore, the frequency of the input pulse can be found by 11+Δf.

Next, the operation of the configuration shown in FIG. 3 will be explained based on the above principle. The input pulse from the input terminal (1) passes through the filter bank (2) and is attenuated by the relative input frequency with respect to the center frequency of each filter. The A/D converter (3) corresponding to each channel of the filter puncture (2) measures the output level of the output video that has passed through the filter. A channel selection circuit (4) corresponding to each channel detects the pulse rising edge of its own channel,
After a certain period of time after the pulse rises, the output level of the own channel is compared with the output level of the channels on both sides, and if the output level of the own channel is higher than the output level of the channels on both sides, the peak detection signal + b = power Line (5
1 to 1; force. At the same time, output lines (6a), (6b
) F, Output levels of adjacent channels PA, -,,P
Output AI+□'9-. The frequency calculation circuit (7) detects the frequency of the input pulse from the channel number where the peak detection signal exists and the output levels PA+-+, P, ~t+I, and outputs the frequency value to the output line (8).

[Problem that the invention seeks to solve]

Conventional frequency detection devices use the rising edge of the input pulse as a reference and detect the frequency after a certain period of time, which is effective when the frequency within the pulse is constant, but pulse compression (frequency chirp) radar・Like a pulse, the frequency changes within the pulse F! (change), there was a problem that the frequency change within the pulse could not be detected.

The present invention was made to solve the above problems, and an object of the present invention is to obtain a frequency detection device that can detect frequency changes within a pulse.

[Means for solving problems]

The frequency detection device according to the present invention is provided with a timing generation circuit that generates a timing pulse of a predetermined period, and a measurement device supplies this timing pulse as a pulse to an A/D converter and a channel selection circuit.

[For production]

The measurement timing generation circuit according to the present invention outputs a frequency measurement trigger to the A/D converter corresponding to each channel and the channel selection circuit at specified time intervals in order to measure the changing input frequency. At each trigger timing, the frequency at that point in time is detected lJ1.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 2, (1) to (8) are similar to the conventional FIG. (9) is a measurement timing generation circuit that generates an established trigger every specified time (predetermined period), and the measurement trigger timing panorama is determined by the A/Ll converter (3
) and a channel selection circuit (4), respectively.

FIG. 2 shows an example of the output video for each channel of filter bank (2) for a pulse compressed (frequency chart -1°) radar pulse. As can be seen from this figure, by measuring the output level of each channel at specified time intervals and finding the frequency at each specified time interval, it is possible to detect frequency changes within the pulse.

In Figure 1, the input pulse from input terminal (1) is
The signal passes through the filter bank (2) and is attenuated by the relative input frequency with respect to the center frequency of each filter. The measurement timing generation circuit (9) generates measurement triggers at regular time intervals. A/D for each channel of filter bank
The converter (3) uses a measurement trigger to measure the output level of the output video that has passed through each filter. and,
Channel selection port #1f41 corresponding to each channel compares the output level of its own channel with the output level of the channels on both sides using the measurement latch, and if the output level of its own channel is higher than the output level of the channels on both sides. Then, the peak detection signal is output to the output line (5). At the same time, the output line (6aL (6b)) outputs the output level of the channels on both sides.The frequency calculation circuit (7) calculates the frequency using the channel number where the peak detection signal exists and the output level of the channels on both sides. and output the frequency value to the output line (8).

By repeating the above operations at regular time intervals, it is possible to accurately measure the frequency of the input pulse and its frequency change.

〔Effect of the invention〕

As described above, according to the present invention, since a measurement timing generation circuit is provided that generates a measurement trigger for calculating the number of waves at specified time intervals, pulse compression (frequency chirp) radar, which could not be detected conventionally, can be used. This has the effect of being able to accurately detect intra-pulse frequency changes such as.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the frequency detection device according to the present invention, FIG. 2 is an explanatory diagram of the operation of a pulse compression radar used to explain the operation of FIG. 1, and FIG. FIG. 4 is a block configuration diagram of a conventional frequency detection device for a parallel filter receiver, and a model diagram showing the operating principle when one wave is input to the parallel filter receiver. In Figure 1, (2) is a filter bank, (3) is an A/
D converter, (4) is a channel selection circuit, (7) is a frequency calculation circuit, ]9) i is a measurement timing generation circuit. Note that the same reference numerals in the drawings indicate the same or equivalent parts.

Claims (1)

[Claims] A filter bank having a group of bandpass filters arranged in parallel corresponding to each frequency-divided channel, an A/D converter that A/D converts the output signal of each channel of this filter bank, and this A/D conversion. a channel selection circuit that detects the peak level channel using the output level of each channel; and a frequency calculation circuit that detects the frequency of the input signal input to the filter bank from the output levels of the channels on both sides of the peak level channel. The frequency detection device includes a measurement timing generation circuit that generates a measurement trigger timing pulse of a predetermined period and supplies this pulse to the A/D converter and channel selection circuit, and detects a frequency for each measurement trigger timing pulse. A frequency detection device characterized by performing the following.