JPH052872Y2 - - Google Patents

Description

[Detailed explanation of the invention] (Field of industrial application) This invention targets a flying object such as an aircraft, irradiates the target with radio waves modulated with a code having a predetermined period, and collects the reflected waves from the target. This invention relates to a transmitting/receiving device that tracks a target by demodulating the same code with the same code, and has a function of automatically controlling the length of the modulation/demodulation code for modulating and demodulating the radio waves to be transmitted and received.

(Summary of the invention) This invention targets a flying object such as an aircraft, irradiates the target with radio waves modulated with a code having a predetermined period, and demodulates the reflected waves from the target with the same code. In a transmitting/receiving device that tracks a target, when searching for and acquiring a target, by varying the phase modulation code length of the transmitted signal and changing the spread amount of the spectrum of the transmitted wave, the transmitted wave of the transmitting/receiving device The aim is to increase the confidentiality of information and improve the concealment ability.

(Prior Art) FIG. 3 shows a conventional transmitting/receiving device. In FIG. 3, 1 is an antenna, 2 is a transmitting/receiving switch, 3 is a transmission source, and 4a is a phase modulation that modulates the phase of the output of this transmission source 3. 5 is a phase modulation code generator that generates a modulation code for this phase modulator; 6 is a pulse modulator that pulse modulates the output of the phase modulator 4a; 7
is a pulse modulation signal generator that generates a pulse modulation signal for this pulse modulator 6. The pulse-modulated transmission source output is irradiated to the target as a spectrum-spread transmission wave from the antenna 1 via the transmitter/receiver switch 2.

8 is a local oscillator, and 9 is a phase demodulation code generator. 4b, 4c, and 4d are phase modulators, each of which performs phase modulation on the output of the local oscillator 8 with a demodulation code that is the output of the phase demodulation code generator 9. 10a, 10b, 10c are mixers, and the outputs of these phase modulators 4b, 4c, 4d are received by the antenna 1 and are mixed with the transmitter/receiver switch 2.
The received signal is mixed with the received signal. 11 is a timing discriminator, and the mixers 10a, 10b, 1
The timing difference between the phase modulation code of the received signal and the phase demodulation code output from the phase demodulation code generator 9 is detected using the output of 0c. 12a is a band filter that filters the output of the timing discriminator 11; 13 is a demodulation clock generator that supplies a reference clock to the phase demodulation code generator 9; and 14a is a voltage that controls the frequency of the demodulation clock generator 13. 15 is a timing search voltage generator that changes the output frequency of the demodulation clock generator 13 by a predetermined frequency in order to search for the timing of the phase modulation code of the received signal; This is a timing search controller that holds the output of the timing search voltage generator 15 at a constant value when the timing matches the modulation code of the received signal.

17 is a frequency discriminator, and the mixer 10a
12b is a bandpass filter that filters the output of the frequency discriminator 17; 14b is an amplifier that supplies a voltage to control the oscillation frequency of the local oscillator 8; 18 is a clean tooth wave generator that generates a predetermined clean tooth wave for searching for Doppler frequency displacement of the received signal; 19 is a clean tooth wave generator that generates a predetermined clean tooth wave according to the output timing of the frequency discriminator 17 when searching for Doppler frequency displacement; A Doppler frequency search controller that controls the operation of the wave generator 18.

(Problems to be Solved by the Invention) As described above, the conventional transmitter/receiver is configured to perform modulation and demodulation using a code having a fixed sequence length. However, since the sequence length is constant, there is a problem that it is easy to be detected by the other party.

This idea was made to solve the above-mentioned problems. When searching for a partner, use a code with a short sequence length to avoid spreading the signal spectrum. The aim is to create a transmitting/receiving device that is difficult to detect by the other party and is resistant to interference by spreading the spectrum using a long code.

(Means for Solving the Problems) The transmitting/receiving device in this invention modulates and demodulates transmitted and received signals using a phase modulation code generator and a phase demodulation code generator that can generate codes with long sequence lengths and short codes. The length can be selected according to the output of the timing discriminator.

(Function) The transmitting/receiving device according to this invention uses the output of the timing discriminator to control the modulation/demodulation code length, thereby performing modulation and demodulation according to the case of search, ranging, etc.
Demodulation can be performed.

(Embodiment) An embodiment of the transmitting/receiving device according to this invention will be described below with reference to the drawings.

In Figure 1, 1, 2, 3, 4a, 4b, 4
c, 4d, 5, 6, 7, 8, 9, 10a, 10
b, 10c, 11, 12a, 12b, 13, 14
a, 14b, 15, 16, 17, 18, and 19 are the same as the conventional transmitting/receiving device. However, the phase modulation code generator 5 and the phase demodulation code generator 9 are capable of selectively generating codes with short sequence lengths and codes with long sequence lengths. Reference numeral 20 denotes a modulation/demodulation code/mode switch, which switches and changes the code sequence lengths of the phase modulation code generator 5 and the phase demodulation code generator 9.

Next, the operation of the embodiment of the present invention will be explained.

By the same operation as a conventional transmitting/receiving device, the outputs of the mixers 10a, 10b, and 10c become video signals in which the phase modulation of the received signal is demodulated.

The amplitudes of the envelopes of these video signals differ as shown in FIG. 2 when a target is captured. However, 21a in FIG. 2 is the envelope waveform of the output of the mixer 10a, 21b is the envelope waveform of the output of the mixer 10b, and 21c is the envelope waveform of the output of the mixer 10c. Further, 22 is a timing discriminator 11
is the output characteristic of

The timing discriminator 11 discriminates the difference between the signals shown in FIG.
When the demodulated signal at the time of target acquisition is obtained, the modulation/demodulation code/mode switch 20 is operated to switch the code lengths of the phase modulation code generator 5 and the phase demodulation code generator 9. In other words, before target acquisition,
Shorten the code length to reduce spectrum spread and enable high-sensitivity reception, and after target acquisition, increase the code length to improve secrecy, make it difficult to be detected by the other party, and improve anti-jamming performance. .

(Effects of the invention) As described above, the transmitter/receiver of this invention is configured to change the modulation code length of the modulator and the demodulation code length of the demodulator using the output of the timing discriminator. The present invention has the effect of easily creating a device that can ensure high-sensitivity reception and confidentiality after target acquisition, and that it can also be highly accurate.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a transmitting/receiving device according to an embodiment of this invention, FIG. 2 is a block diagram showing an envelope of a demodulated signal output, and FIG. 3 is a block diagram showing a conventional transmitting/receiving device. 1... Antenna, 2... Transmission/reception switch, 3... Transmission source, 4a, 4b, 4c, 4d... Phase modulator,
5... Phase modulation code generator, 6... Pulse modulator, 7... Pulse modulation signal generator, 8... Local oscillator, 9... Phase demodulation code generator, 10a, 1
0b, 10c...Mixer, 11...Timing discriminator, 12a, 12b...Band filter, 13...
...Demodulation clock generator, 14a, 14b...Amplifier, 15...Timing search voltage generator, 16...
...Timing search controller, 17... Frequency discriminator, 18... Sharp tooth wave generator, 19... Frequency search controller, 20... Modulation/demodulation code/mode switch, 21a, 21b, 21c... Envelope of output of mixer, 22... Output characteristics of timing discriminator.

Claims (1)

[Claims for Utility Model Registration] A transmission source, a first phase modulator for phase modulating the output of the transmission source, and a phase modulation code generator capable of generating codes with short and long sequence lengths; A pulse modulator and a pulse modulation signal generator for pulse modulation, an antenna for irradiating the pulse modulated output of the transmission source as a transmission wave, a local oscillator, and a demodulator for phase modulating the output of the local oscillator. a clock generator, a phase demodulation code generator capable of generating codes with short and long sequence lengths, a second phase modulator, a received signal from the target and a demodulated signal which is the output of the second phase modulator; a timing discriminator for controlling the timing of demodulating the phase modulator of the received signal using the output of the mixer; and a frequency discriminator for demodulating the Doppler frequency displacement of the received signal. A transmitting/receiving device comprising: controlling the demodulation clock generator with the output of the timing discriminator, and controlling the local oscillator with the output of the frequency discriminator, wherein the phase modulation is performed according to the output of the timing discriminator. A modulation/demodulation/code/mode switch for switching code sequence lengths of a code generator and a phase demodulation code generator is provided, and when the timing discriminator output indicates target acquisition, the modulation/demodulation/code/mode switch switches. A transmitting/receiving device characterized in that the code generated by the phase modulation code generator and the phase demodulation code generator is switched from a code with a short sequence length before target acquisition to a code with a long sequence length.