JPH04100431A - Synchronism catching device for frequency spread communication - Google Patents

Abstract

PURPOSE:To shorten the synchronism catching time of the subject device by generating M pieces of hopping patterns signals respectively shifted from each other in phase by the 1/M of a hoping period oh the basis of a clock for sliding and monitoring the correlation between detecting signals by means of a correlation detector. CONSTITUTION:In the case of a spread signal the one period of which is composed of 16 bits, hopping patterns which are different from each other by 8 bits are outputted to hopping frequency synthesizers 9A and 9B and hopping patterns which are shifted 1 bit by 1 bit in phase are outputted by means of a clock for sliding from a clock generator 11. Then correlation is detected by means of a correlation detector 8A or 8B within the period of 8 clocks and a correlation detecting signal alpha or beta is outputted. A selection circuit 12 selects filtrated signals of the sequence on the side to which the signal alpha or betais outputted by means of a select signal gamma and inputs the filtrated signals to a demodulator 13. Therefore, demodulated Signals which are synchronized to each other with the period of 8 clocks are obtained from the demodulator 13.

Description

[Detailed description of the invention] [　Industrial application field　]

The present invention relates to a synchronization acquisition device in frequency hopping spread spectrum communication, and particularly to a technique for obtaining initial synchronization in a short time.

[Conventional technology]

In frequency hopping frequency spread communication, in order to reproduce a signal modulated based on a predetermined time-series hopping pattern, it is necessary not only to generate the same hopping pattern on the receiver side as the hopping pattern on the transmitter side, but also on the receiver side. Their phases also need to match (this is called synchronization). As a receiver for this purpose, there is a normal sliding receiving device that performs synchronization acquisition using sliding correlation by sequentially searching for all patterns and detecting synchronization. However, this normal sliding method has the problem that there is a limit to the interval at which the sliding chip time can be shortened, and that the more frequency slots (number of generated patterns), the longer it takes to acquire synchronization. Various synchronization acquisition devices and methods have been developed for this purpose. As such a synchronization acquisition device, the Japanese Patent Publication No. 6412141
There is a technology disclosed in the publication. This includes one spreading code generator that generates a hopping pattern, one frequency hopping synthesizer driven by the spreading code generator, the output signal of the frequency hopping synthesizer, and the output signal for the output signal. 1/M
(However, M is an integer of 2 or more) A distribution delay means that outputs (MI) signals with delay times increased bit by bit, and M balanced units that receive the same received signal at one input terminal of each. a modulator and one at the output side of each of the balanced modulators.
A band breaker is connected to each other, a detector is connected to each output side of the band breaker, and a low frequency detector is connected to each output side of the detector. a correlation detector connected to the output side of each of the low frequency wave breakers, and one control switch that receives the output signals of the M correlation detectors, The M output signals of the distribution delay means are respectively given to the other input terminals of the M balanced modulators, and the control switcher, based on the output signals of the M correlation detectors, The frequency hopping frequency spread communication synchronization acquisition device is characterized in that the phase of the hopping pattern of the spreading code generator is controlled so as to be in phase with the phase of the hopping pattern of the received signal.

[Invention or problem to be solved]

Similar to the technique disclosed in Japanese Patent Publication No. 64-12141 mentioned above, the present invention also aims to shorten the synchronization acquisition time in frequency hopping spread spectrum communication. In particular, in the technique disclosed in the above-mentioned Japanese Patent Publication No. 12141/1988, variations in delay time occur due to the use of delay elements.

[Means to solve the problem]

To this end, the present invention includes a distributing means for distributing the received signal into M sequences and outputting them, and a sliding clock that uses M hopping pattern signals whose phases are shifted from each other by 1/M periods of the hopping period. one spreading code generator based on the hopping pattern signal, M frequency hopping synthesizers each driven by the hopping pattern signal, the output signal of the frequency hopping synthesizer, and the distribution signal M a balanced modulator, one band connected to each output side of the balanced modulator, and one band connected to each output side of the band decider.
Detectors connected to each other, low-frequency wave generators connected to each output side of the wave detectors, and correlation detection connected to each output side of the low-frequency wave breakers. a tarlock generator that receives the output signals of the M correlation detectors and outputs the sliding clock until a correlation is detected in any of the correlation detectors; and the M correlation detectors. The present invention is equipped with a sequence selector that receives the output signal of the detector and selects the sequence when a correlation is detected in any of the correlation detectors. Further, the spreading code generator may be configured to include M shift register circuits connected in multiple stages.

[Effect]

In the present invention, M hopping pattern signals whose phases are shifted from each other by 1/M period of the hopping period are generated based on a sliding clock obtained from a clock generator, and the hopping pattern signals are used to generate M hopping pattern signals. Each drives a frequency hopping synthesizer. Then, the received signal is distributed into M sequences, and each is balanced-modulated by M balanced modulators based on the distributed signal and the output frequency of the frequency hopping synthesizer, and the output signal of each balanced modulator is After the band reactor liquid is detected, the correlation of the detected signal is monitored with a correlation detector. Therefore, when a correlation is detected in any of the M correlation detectors, the output of the sliding clock is stopped and a series with good correlation is selected, so that the output of the band breaker of this series is When demodulated, a demodulated signal with consistent synchronization can be obtained. The spreading code generator is a linear code generator such as a linear m-sequence code generator or a Gold code generator.

【 Example 】

Embodiments of the present invention will be explained in detail below based on the drawings. In FIG. 1, I is an antenna, 2 is a receiver, and 3 is a power divider that divides the received signal into two streams. 4A is a balanced modulator, 5A is a band resolver, 6A is an envelope detector, 7A is an integrator, 8A is a correlation detector that outputs a correlation detection signal α when synchronization is achieved, and 9A is a frequency hopping synthesizer. , these constitute the first series. Similarly, the second series also includes a balanced modulator 4B and a band breaker 5B.
, an envelope detector 6B, an integrator 7B, a correlation detector 8B that outputs a correlation detection signal β when synchronization is achieved, and a frequency hopping synthesizer 9B. IO is the two frequency hopping synthesizers 9A,
9B is a hopping pattern generation circuit that generates a hopping pattern for frequency control. 11 is a clock generator that outputs a sliding clock for sliding the hopping pattern output from the hopping pattern generation circuit; 14 is the correlation detector 8A, 8B to which the correlation detection signals α and β are input;
a determiner that determines when synchronization is achieved;
15 is a selection circuit 1 to be described later based on the judgment of the judger 14.
This is a controller that outputs a sequence selection signal γ that controls the sequence selection signal γ. Reference numeral I2 denotes a selection circuit into which the outputs of the two bands of band frequency transducers 5A and 5B are input, and which selects one of the reactor liquid outputs in response to the input of the line selection signal γ. Reference numeral 13 denotes a demodulator which obtains a demodulated signal. FIG. 2 is a block diagram showing an example of the internal configuration of the hopping pattern generation circuit IO. In FIG. 2, l0IA, 102A, 103A, 10
4A are shift registers connected in series, 105
A is an EX-OR element 1 that connects the exclusive OR of the output of the first shift register 101A and the fourth shift register 104A to the input of the first shift register;
06A is an output buffer for outputting the 4-bit parallel data output from the four shift registers to the hopping frequency synthesizer 9A, and 107A is an initial setting device for setting the initial value of each shift register. It is latched into each shift register at the rising edge of the sliding clock. The above is the first series of shift register circuits. And l0IB, 102B, 103B, 104B are
105B is an EX-OR element connected as above, 106B is an output buffer connected as above, and 107B is an initial setting device as above. The above is the second series shift register circuit. In the hopping pattern generation circuit 1o having two series of shift register circuits as described above, the initial setting device 1
When the initial value [1111] is set in 07A, the initial setting unit 107B sets the value of the internal state at the 9th clock from the state [1111]. Therefore, each time the sliding clock is input, the shift register circuit connected in feedback sequentially shifts to perform a sliding operation. In the synchronization acquisition device for frequency spread communication having the above configuration, as shown in FIG. 3, in the case of a spreading code in which one cycle consists of 16 bits (16 chips), the hopping pattern generation circuit 10 is initialized. As a result, hopping patterns having an 8-bit difference are output to the hopping frequency synthesizers 9A and 9B. Then, using the sliding clock from the clock generator 11, a hopping pattern whose phase is shifted one bit at a time is output. That is, a hopping pattern sequentially shifted one bit at a time from the first chip is output to the hopping frequency synthesizer 9A, and a hopping pattern sequentially shifted one bit at a time from the ninth chip is input to the hopping frequency synthesizer 9B. Then, even in the worst case, a correlation is detected within 8 clocks by either the correlation detector 8A or the correlation detector 8B, and a correlation detection signal α is generated. β is output. Based on the correlation detection signals α and β, the controller I5 controls the clock generator 11 to stop generation of the sliding clock and to shift from the synchronization acquisition detection mode to the synchronization tracking mode. Then, the selection circuit 12 selects the furnace fluid signal of the series from which the correlation detection signals α and β are output based on the selection signal γ, and inputs it to the demodulator 13. In this way, a demodulated signal that is synchronized within eight clocks can be obtained from the demodulator 13. That is, although the normal sliding method requires a synchronization acquisition time of 16 clocks in the worst case, this synchronization acquisition device for frequency spread communication requires only 8 clocks in the worst case. In other words, since synchronization can be acquired in half the time of the normal sliding method, it is possible to realize time-efficient spread spectrum communication. Naturally, the above embodiment shows an example in which two streams, the first stream and the second stream, are provided, but if the number of streams is M, synchronization acquisition can be achieved in 1/M of the conventional time. It is possible. In addition, since the hopping pattern generation circuit 10 uses a shift register, which is a logic circuit element, it can be easily integrated into an integrated circuit and is suitable for miniaturization, so that the frequency spread communication device can be miniaturized. Effects can also be obtained.

【 effect 】

In this way, by increasing the number of sequences to M, it is possible to acquire synchronization in 1/M of the conventional time, and it is possible to provide an efficient synchronization acquisition device for spread spectrum communication. . In addition, since a shift register, which is a logic circuit element, can be used as the spreading code generator, it is possible to prevent variations in delay time from occurring.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of a synchronization acquisition device in spread frequency communication according to the present invention, FIG. 2 is a block diagram of an embodiment of the internal configuration of a spreading code generator of a synchronization acquisition device in frequency spread communication, and FIG. The figure is a diagram illustrating the sliding operation of the hopping pattern. 3... (power divider) distribution means, IO... (hopping pattern generation circuit) spreading code generator, 9A, 9B.
...Frequency hopping synthesizer, 4A, 4B...
Balanced modulator, 5A, 5B...Band breaker, 6A. 6B... (Envelope detector) Detector, 7A, 7B...
(Integrator) Low frequency waveform, 8A, 8B...correlation detector,
II... Clock generator, 12... (selection circuit) series selector.

Claims (2)

[Claims] (1) Distribution means that distributes the received signal into M sequences and outputs them, and M signals whose phases are shifted from each other by 1/M period of the hopping period
one spreading code generator that generates M hopping pattern signals based on a sliding clock; M frequency hopping synthesizers each driven by the hopping pattern signal; an output signal of the frequency hopping synthesizer; M balanced modulators to which the distribution signals are respectively input, one bandpass filter connected to the output side of each of the balanced modulators, and one bandpass filter connected to the output side of each of the bandpass filters. a low-pass filter connected to each output side of the wave detector, and a correlator connected to each output side of the low-pass filter; a clock generator that receives the output signals of the M correlation detectors and outputs the sliding clock until a correlation is detected in any of the correlation detectors; 1. A synchronization acquisition device for frequency spread communication, comprising a sequence selector that receives an output signal of a detector and selects a sequence when a correlation is detected in any of the correlation detectors. (2) The synchronization acquisition device for frequency spread communication according to claim (1), wherein the spreading code generator includes M plural shift register circuits connected in multiple stages.