JPS6290578A - Frequency measuring system - Google Patents

Abstract

PURPOSE:To count at a high speed and with a high accuracy the number of a plurality of high frequency input pulses inputted at the same time by branching high frequency input signals with different frequencies in two by a directional coupler and detecting the upper order of magnitude of the input frequency by an arithmetic and logic circuit from the fact that one of the branched signals passes a BPF. CONSTITUTION:High frequency input signals 1 pulse-modulated by a first BPF group 4 of the titled system are received and the maximum or minimum frequency is selected by an arithmetic sequence circuit 18 from the detecting signals selected by the BPF group 4. The signals 1 branched by a directional coupler 12 are applied to a second BPF group 15 via a delay circuit 13 and a changeover switch group 14 and only selected frequency signals are selectively passed by the BPF group 15. The passes signals are branched in two by another directional coupler 17 and applied to the low and high accuracy correlators 7-2 and 7-3, respectively, of the measuring circuit of a correlator system. The lower digits of the frequency of the output signals of the BPF group 15 is measured by the circuit 18 with high and low accuracies respectively.

Description

[Detailed Description of the Invention] [Summary] In frequency measurement of a pulse-modulated high-frequency input signal, the lowest or highest frequency is selected even for multiple input waves that are temporally input simultaneously, and a bandpass filter measurement method is used. By combining this and the correlator measurement method, we aim to make the device more compact and improve measurement accuracy.

[Industrial application field]

The present invention relates to a frequency measuring device, and more particularly to a frequency measuring method for instantaneously detecting a frequency from a pulse-modulated microwave band high-frequency input.

[Conventional technology]

There are two types of conventional frequency measurement methods: a filter bank method and a correlator method.

FIG. 2 shows a schematic block diagram of a filter bank system. In the figure, 1 is a high frequency input signal,
2 is an amplifier, and 3 is a divider, which has the function of distributing the power of the input signal to the output terminal of the IM while maintaining impedance matching.

4 is the first bandpass filter group (in this figure, the bandpass filter group of cylinder 2 does not exist), which is composed of n bandpass filters, and the passband frequency of each bandpass filter is the same and the passband center is the same. The frequencies are continuous, and the arrangement is such that there is no impassable frequency band within the measurable frequency range.

A detector group 5 is composed of n detectors, and detects the output of each bandpass filter and inputs it to the measurement circuit 6. Measurement circuit 6
has a function of converting the frequency of a high-frequency input signal corresponding to the output of the wave detector 5 and outputting it as a digital value.

In the above configuration, when a high frequency pulse input signal is received, its frequency can be instantaneously measured.

FIG. 3 shows a block diagram of the correlator scheme. In the figure,
The same parts as in FIG. 2 are given the same reference numerals. 7 is a correlator group, for example, three correlators 7-1, 7-2 and 7-3.
Each correlator is provided with delay circuits 7-11.7-21.7-31 having different delay times.

8 is a group of processing circuits, each having a correlator 7-1.7-2.7-
3, and each processing circuit is composed of a circuit that samples and holds the output voltage of each correlator, and a circuit that A/D converts the output. 9 indicates an arithmetic circuit.

In the above configuration, when the high frequency pulse input signal 1 is received, each correlator converts the phase difference between the high frequency input signal and the output of the attached delay circuit into a voltage value at a period corresponding to the reciprocal of the delay time. and output. That is, the higher digits of the measurement frequency can be detected with a short delay time, and the lower digits of the measurement frequency can be detected with a long delay time.

The voltages detected corresponding to each delay time are sampled and held by the processing circuit group 8, and the held voltages are A/D converted and input to the arithmetic circuit 9.

The arithmetic circuit 9 calculates frequency conversion of the digital voltage for each digit range of the measurement frequency corresponding to the delay time, and outputs the total value of the measurement frequency.

[Problems to be solved by the present invention]

Although the four-group bandpass filter method has the advantage of being capable of high-speed processing, it has the disadvantage of low frequency measurement accuracy and the need for a large number of bandpass filters to improve measurement accuracy, resulting in an enormous amount of equipment.

Although the correlator method has the advantage of allowing the equipment to be miniaturized and can measure over a wide band, it has the disadvantage that the correlator output is weak at the lower digits of the measurement frequency, resulting in errors, and It has the disadvantage that it is sensitive to changes and cannot be measured when a plurality of pulse input signals with different frequencies are received at the same time.

The present invention was created in view of the above-mentioned drawbacks of the conventional technology, and it is possible to perform high-speed, high-precision measurement even when multiple pulse signals with different frequencies are input at the same time, and to reduce the size of the device. The purpose is to provide a measurement method.

[Means for solving problems]

The present invention, as shown in FIG.
It is composed of an arithmetic control circuit 18 that selects the lowest or highest frequency signal from the detection signals of the bandpass filter group 4, and a second bandpass filter group 15 that selectively passes only the lowest or highest frequency signal. It also includes a correlator group 7 that performs precise/coarse measurement of the lower digits of the frequency output from the second bandpass filter group 15, so that the frequency of the high frequency input signal 1 is measured using one received pulse. It is characterized by the following.

[Effect]

When a plurality of high-frequency input signals 1 with different frequencies are received, they are split into two by a directional coupler 12, one of which is passed through a bandpass filter 4, and the upper digits of the input frequency are detected by an arithmetic control circuit 18. and select its lowest or highest frequency. The arithmetic control circuit 1 drives the interlocking switch 14 according to the selection signal, and forms a selection circuit for the bandpass filter group 15 that allows only the frequency of the selection signal to pass. This means that the frequency to be measured has been identified.

On the other hand, the other high frequency input signal 1 branched into two by the directional coupler 12 is sent to the interlocking switch 14 by the delay circuit 13.
After delaying the processing time until the directional coupler 17 is driven, only the frequency of the pulse to be measured is separated and extracted by passing through the selection circuit of the bandpass filter 15.
The signal is branched into a correlator 7-2 for measuring the middle digits and a correlator 7-3 for measuring the lower digits.

The arithmetic control circuit 18 calculates the input frequency of the upper digit detected by the bandpass filter 4 and the values output by the correlator 7-2 for measuring the middle digit and the correlator 7-3 for measuring the lower digit. Outputs the total measurement frequency.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

Note that, in order to make the explanation of the configuration and operation easier to understand, the same parts are given the same reference numerals throughout all the figures, and repeated explanation thereof will be omitted.

FIG. 1 shows a block diagram of an embodiment of the invention. In the figure, 10 and 12 are two-branch type directional couplers, and 11 and 16 are amplifiers. The high frequency input signal 1 is split into two by the directional coupler 10, one of which is input to the directional coupler 12 via the amplifier 11, where one of the two split high frequency input signals 1 is shown in FIG. The signal is input to the arithmetic control circuit 18 via the bandpass filter layer group type circuit described above.

A detector 19 detects whether or not the high-frequency pulse input signal 1 is received, and serves to drive the arithmetic control circuit 18. When there are multiple output signals from the detector group 5, the arithmetic control circuit 18 selects only the lowest or highest frequency among them, drives the interlocking changeover switch group 14 with that signal, and controls the output of the second bandpass filter group 15. A bandpass filter that allows the selected frequency to pass is selected from among them, and a pass circuit thereof is created.

Reference numeral 13 denotes a delay circuit that delays the processing time until the arithmetic control circuit 18 selects the output signal of the detector group 5 and drives the interlocking switch group 14 with the selected signal.

As a result, the other high-frequency input signal branched into two by the directional coupler 12 passes through one of the selected second bandpass filters 15 with a light loss, and the loss and the directionality of the next stage are reduced. The signal is input to the correlator-type measuring circuit described in FIG. 3 via the amplifier 1G that compensates for the insertion loss of the coupler 17.

Here, since the upper digits of the frequency of the high frequency input signal are already known by the selection of the second band filter group 15, the correlator 7-2 for measuring the middle digits and the correlator 7-2 for measuring the lower digits. 3 through the directional coupler 17. Correlator 7
Processing circuit group 8 that processes the outputs of -2 and 7-3, respectively.
The description is omitted.

The arithmetic control circuit 18 obtains the upper digit of the frequency of the high frequency input signal l from the output selection signal of the first bandpass filter group 4, the middle digit from the correlator 7-2, and the lower digit from the correlator 7-3. Each is calculated and the total value of the combined measurement frequency is output.

[Effects of the present invention]

As explained in detail above, according to the frequency measurement method of the present invention, it is possible to perform high-speed, high-precision measurement with a single received pulse even for multiple high-frequency pulse input signals of different frequencies that are input simultaneously in time. , and the device can be made smaller.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a block diagram of a conventional bandpass filter layer group method, and FIG. 3 is a block diagram of a conventional correlator method. In the figure, 1 is a high-frequency human input signal, 4 is a first bandpass filter group, 7 is a correlator group, 15 is a second bandpass filter group, 18
indicate arithmetic control circuits, respectively. C mouth F me a thousand or '7F'; skin i47. zsu 7・Lock diagram 61 table/1 O old blowout eyebrows valley 7゛ro 17 concaveff13
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Claims (1)

[Claims] A first receiving a pulse modulated high frequency input signal (1).
a bandpass filter group (4), an arithmetic control circuit (18) that selects the lowest or highest frequency signal from the detection signals of the first bandpass filter group (4), and selectively selects only the selected frequency signal. It is composed of a second bandpass filter group (15) that allows the signal to pass, and also includes a correlator group 7 that performs precise/coarse measurement of the lower digits of the frequency output from the second bandpass filter group (15). , the high frequency input signal (1
) is characterized in that the frequency is measured using one received pulse.