JPH0993162A - Spread spectrum communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain high speed data communication while keeping desired communication quality by effectively utilizing a limited occupied frequency band to the utmost. SOLUTION: Transmission data in n-bit are fed to terminals 1-0, 1-1,..., 1-n and a rectangular wave is outputted from PN code generators 2-0, 2-1,..., 2-n in response to the M series code with a shifted phase. Then switches 3-0, 3-1,..., 3-n are operated in response to transmission data to set on/off of the transmission of a rectangular wave and the waves are added by an adder 4 and the sum is used for a transmission signal. At a receiver side, a correlation device 9 is used to apply correlation processing to the reception signal and a rectangular wave and the peak position of the correlation output is used to judge whether or not the rectangular wave with a phase shift is included in the reception signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread spectrum communication device suitable for high speed data communication.

[0002]

2. Description of the Related Art One of wireless communication systems in which an occupied frequency band is limited is spread spectrum communication in which signal energy is scattered over a frequency band wider than a base band for transmission. In this spread spectrum communication, a wide frequency band is shared by a large number of channels, and a signal of a specific channel is obtained by signal processing on the receiving side, unlike a normal narrow band modulation method.

A conventional spread spectrum communication will be described below with reference to the drawings. FIG. 4 is a block diagram showing a first configuration example of a conventional spread spectrum communication device.

In the figure, reference numeral 50 is a baseband modulator for primary-modulating a transmission signal corresponding to digital data to be transmitted. The primary modulation performed by the baseband modulator 50 is FSK (Frequency Shift Keying), B-PSK (Binary Phase Shift Keying), and Q-PSK (Quadrature PSK; 4). Phase shift keying)).

Reference numeral 51 is a transmission side PN (Pseudo Noise) code generator. Here, the PN code is a code sequence that randomly takes a value of ± 1 at a speed far higher than the bit rate of transmission data, and has a periodicity of repeating a random bit pattern of a constant code length. The bit in the PN code is especially called a chip. Below, PN
The time of one cycle of the random pattern of the code is called the chip time length. The transmission side PN code generator 51 outputs a rectangular wave corresponding to the PN code. 52 is the baseband modulator 5
A transmitting side multiplier for multiplying the output of 0 and the output of the transmitting side PN code generator 51, and 53 is a transmitting antenna.

Reference numeral 54 is a receiving antenna, and 55 is a receiving side multiplier. 56 is a receiving side PN code generator, and is a transmitting side P
It outputs the same rectangular wave as the rectangular wave output from the N code generator 51. Reference numeral 57 is a demodulator corresponding to the modulation method of the baseband modulator 50.

In such a configuration, the PN code is multiplied by the transmission side multiplier 52 on the transmission signal which is primarily modulated by the baseband modulator 50. This operation is called secondary modulation or spread modulation, whereby the frequency band of transmission data is spread. Then, the transmission signal subjected to such modulation is
It is inputted to the reception side multiplier 55 via the transmission antenna 53 and the reception antenna 54, and is multiplied by the same code sequence as the PN code. This operation is called despreading, and when the same PN code sequence is multiplied twice, all the chips become +1. Therefore, the primary modulated wave is reproduced and the demodulator 57 obtains the transmission data.

Next, spread spectrum communication by correlation reception using a conventional SAW convolver will be described. FIG. 5 is a block diagram showing a second configuration example of a conventional spread spectrum communication device. In addition, the same components as those in FIG. 4 are represented by the same symbols, and the description thereof will be omitted.

In the figure, reference numeral 58 is a baseband modulator for primary-modulating a transmission signal. The primary modulation in the baseband modulator 58 is performed by the FSK modulation method in which the transmission data has a frequency f0 when it is "0" and the frequency f1 when it is "1".

Reference numeral 59 denotes the received signal, the output of the oscillator 60 and P
SAW (Surface Acoustic Wave; which outputs a cross-correlation waveform with a reference signal multiplied by the output of the N code generator 56)
Surface acoustic wave) is a convolver.

Here, the SAW convolver has a SAW propagation section that multiplies two signal waveforms and a gate electrode that integrates the multiplication result, and outputs a convolution of two input signals. Is a device. SAW
The convolver 59 is used as a correlator utilizing the function of the SAW convolver, receives the received signal and the time-reversed reference signal, and includes a frequency component close to the center frequency of the reference signal in the received signal. Output a correlation output in which a peak appears only when

The oscillation frequency of the oscillator 60 is f1, and the output of the oscillator 60 and the PN code generator 56 on the receiving side.
And the output of are multiplied by the multiplier 61. The B-PSK signal with the center frequency f1 generated by this is the SAW
It is used as a reference signal for the convolver 59.

In such a structure, the transmission signal FSK-modulated by the baseband modulator 58 is further spread-modulated and transmitted from the transmission antenna 53. The waveforms of the transmission signal, the FSK signal, and the spread-modulated signal at this time are shown in FIG.

The signal transmitted from the transmitting antenna 53 is
The SAW convolver 5 receives the signal by the receiving antenna 54.
9 is input. Then, the SAW convolver 59 outputs a correlation output in which a peak appears only when the center frequency of the received signal is f1, and the transmission data can be obtained by detecting and correlating the correlation output.
FIG. 7 shows the received signal, the correlation output, the detection output, the waveform shaping output, and the waveform of the transmission signal obtained by these at this time.

[0015]

By the way, FSK, P
When a digital signal is modulated by a modulation method such as SK, the modulated signal has a constant bandwidth, and this bandwidth becomes wider as the bit length of the modulated signal becomes shorter. That is, the faster the data, the faster the FSK signal, P
The SK signal has a wide band. Therefore, when high-speed data communication is performed by the conventional spread spectrum communication, a wide frequency band is already occupied at the stage of the primary modulation, and the secondary modulation (spread modulation) is further performed, so that a wide frequency band is occupied. It will be. Therefore, in a limited occupied frequency band, the data communication speed is limited, and there is a problem that it is difficult to further increase the speed of data communication.

Further, in the spectrum communication device, the maximum S / when a certain PN code is used by correlation reception is obtained.
In order to obtain N, the modulation cycle of the primary modulation, that is, the bit length of the transmission data must be equal to or longer than the chip time length, and the reception side must obtain a correlation output for one PN code cycle. In order to perform high-speed data communication under such restrictions, it is sufficient to increase the chip rate, but increasing the chip rate widens the occupied frequency band. On the other hand, the S / N can be improved by lengthening the PN code period, but at the same time, it is necessary to lengthen the bit length of the transmission data, so that the data communication speed becomes slow. Therefore, in the conventional spread spectrum communication, it is extremely difficult to increase the speed of data communication while maintaining a constant communication quality in a limited occupied frequency band.

The present invention has been made in view of these problems, and makes maximum use of a limited occupied frequency band without increasing the occupied frequency band, while maintaining desired communication quality. An object of the present invention is to provide a spread spectrum communication device that enables high speed data communication.

[0018]

According to the first aspect of the present invention,
When a code start position coincides with an input terminal to which n-bit transmission data is supplied, a peak appears in the correlation, and when the code start position deviates, a code sequence having less correlation is defined as a PN code, and each bit of the transmission data is set. N waveforms having different phase shifts corresponding to one cycle of the PN code corresponding to different code start times according to the data in each bit of the transmission data supplied to the input terminal. And a transmission signal generating means for outputting a transmission signal combined with the transmission signal, a transmission means for transmitting a transmission wave corresponding to the transmission signal, and a reception means for receiving the transmission wave and outputting a reception signal according to the reception wave. , The waveform of the received signal and the P
It is characterized by having a correlation processing means for outputting a correlation waveform with a waveform corresponding to the N code, and an output means for outputting received data based on the peak position of the correlation waveform.

According to a second aspect of the present invention, in the spread spectrum communication device according to the first aspect, the transmission signal generating means uses a M sequence code as a PN code, and each bit of the transmission data has each of the PN. The n waveforms having different phase shifts corresponding to one cycle of the PN code corresponding to the code start time at which the code start position shift is 1 chip or more are supplied to the input terminal. It is characterized in that it is a transmission signal generation means for outputting a transmission signal synthesized according to the data in each bit of the transmission data.

According to a third aspect of the present invention, in the spread spectrum communication apparatus according to the first or second aspect, the transmission signal generating means supplies the PN code generator for outputting the n waveforms and the input terminal. N switches for turning ON / OFF the transmission of the waveform corresponding to each bit according to the data in each bit of the transmitted data, and the n switches. Is a transmission signal generating means having an adder for adding and outputting the respective waveforms transmitted via the.

According to a fourth aspect of the present invention, in the spread spectrum communication device according to the third aspect, the PN code generator outputs the M-sequence code generation circuit and an output of the M-sequence code generation circuit to the first-stage shift register. And a shift register connected in n or more stages, the contents of which are shifted according to the code generation clock in the M-sequence code generation circuit.

According to a fifth aspect of the present invention, in the spread spectrum communication device according to any one of the first to fourth aspects,
The correlation processing means is a SAW correlator in which taps are arranged according to the PN code.

The invention according to claim 6 is the spread spectrum communication device according to any one of claims 1 to 5,
The output means converts the received data into an n-bit parallel signal format based on the peak position of the correlation waveform output from the correlation processing means during the time corresponding to one cycle of the PN code, and outputs the converted data. It is characterized by being a means.

The invention according to claim 7 is the spread spectrum communication device according to any one of claims 1 to 5,
The output means is an output means for outputting received data in a serial signal format based on the peak of the correlation waveform output from the correlation processing means at a time interval corresponding to one chip of the PN code. .

The invention according to claim 8 is the spread spectrum communication device according to any one of claims 1 to 7,
The transmission signal generation means always synthesizes a waveform having a specific phase shift of the waveform corresponding to the PN code regardless of the content of the transmission data, and each bit of the n-bit transmission data is identified by the specific bit. Corresponding to a waveform other than a waveform having a phase shift, the output means selects a correlation output having a waveform other than the peak based on a peak of the correlation output having the waveform having the specific phase shift, It is characterized in that it is an output means for outputting reception data corresponding to the data in each bit of the bit transmission data.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a spread spectrum communication device according to an embodiment of the present invention.

In the figure, 1-0, 1-1, ..., 1-n
Is the n-bit digital data D0, D1, ...
This is a terminal to which Dn is supplied.

2-0, 2-1, ..., 2-n are PN code generators. In this embodiment, M-sequence code (Maximum Leng
th linear shift register sequence code) is used as the PN code. The M-sequence code is a kind of random code sequence, and has a periodicity of repeating a random bit pattern having a constant code length.

The characteristics of the M-sequence code will be described. For the M-sequence code, "1" is set to "1" and "0" is set to "-".
When the autocorrelation is made to correspond to 1 ", there is a characteristic that a peak appears when the bit patterns completely overlap, and almost no correlation occurs when the bit patterns deviate by 1 bit or more. The correlations when the patterns are overlapped are 9, and the correlations when the patterns are deviated by 1 bit or more are all -1. In addition, there is almost no cross-correlation between different M sequence codes.

PN code generators 2-0, 2-1, ..., 2-
The n outputs the rectangular waves in which "1" of the same M-sequence code corresponds to "1" and "0" corresponds to "-1", with their phases shifted. In order to output this phase-shifted rectangular wave, the M-sequence code start time ti (i = 0, 1, ..., N) in each PN code generator 2-0, 2-1, ..., 2-n. Be ti = t0 + k × i × T. Here, t0 is a transmission start time, k is an integer other than 0, and T is a code generation clock cycle of the PN code generator (time length of one chip).

As a result, each PN code generator 2-
The phases of the rectangular waves output from 0, 2-1, ..., 2-n are made to correspond to M-sequence codes shifted by k × i chips. However, this chip shift is set to be less than one cycle of the M-sequence code so that waveforms do not completely overlap. Therefore, for example, k =
When 1, the maximum of n is the number of chips in one cycle minus 1.
The chip time length is Tm, and the transmission data D0, D1,
, Dn are supplied in the same cycle as the chip time length Tm.

, 3-n are switches which are turned on when the transmission data D0, D1, ..., Dn are "1" and turned off when they are "0". Here, switch 3
The ON / OFF operation of −0, 3-1, ..., 3-n is started from the M sequence code start time ti in the PN code generator corresponding to each switch, and the ON / OFF state is the chip time length Tm. Hold for a while. As a result, the terminal 1-
A rectangular wave for one cycle of the M-sequence code is sent to the adder 4 from the PN code generator corresponding to the terminal of 0, 1-1, ..., 1-n whose transmission data is “1”.

The adder 4 includes switches 3-0, 3-1,
, 3-n of the PN code generators 2-0, 2-1 ,.

Reference numeral 5 is an oscillator for outputting a carrier wave having a carrier frequency f. Here, the carrier frequency f is the center frequency in the communication frequency band assigned to communication. Reference numeral 6 is a multiplier that multiplies the output of the adder 4 and the output of the oscillator 5. Reference numeral 7 is a transmission antenna for transmitting a transmission wave according to the output from the multiplier 6.

Reference numeral 8 is a receiving antenna. Reference numeral 9 is a correlator that performs a correlation process on the input signal. The received signal corresponding to the received wave of the receiving antenna 8 is input, and the correlation output is output to the detection / waveform former 10.

The correlator 9 includes a correlation processing device such as a digital matched filter, a SAW correlator, or a SAW device such as the SAW convolver described above, and a down converter for converting a received signal into a frequency band suitable for the correlation processing device. Composed. Here, the correlation processing device is
Correlation processing is performed on the same rectangular wave as the rectangular wave output from the PN code generators 2-0, 2-1, ..., 2-n and the received signal.

The detector / waveform generator 10 detects and waveform-shapes the correlation output from the correlator 9 and outputs it to the serial-parallel converter 11 as a pulse signal having a constant level and a constant width. The serial-parallel converter 11 converts the pulse signal output from the detection / waveform shaper 10 into parallel data for each chip time length Tm, and outputs the parallel data.

Next, the operation of the spread spectrum communication device according to the above embodiment will be described. First, while supplying power to each device, terminals 1-0, 1-1, ..., 1-
, n is supplied to the transmission data D0, D1, ..., Dn to start communication. Then, the PN code generator 2-0 sends the transmission start time.
The rectangular wave output is started from t0, and thereafter, the PN code generators 2-1, 2-2, ...
The rectangular wave output is started from x1 × T, t0 + k × 2 × T, ..., T0 + k × n × T. At the same time, switch 3
The ON / OFF operation of −0, 3-1, ..., 3-n is also started.

As an example, a terminal 1-j (j is 0
Assuming that the transmission data Dj supplied to any of the integers up to n is “1”, the time is tj (t0 + k × j ×).
When it becomes T), the switch 3-j corresponding to this terminal 1-j is turned on. When the switch 3-j is turned on, the rectangular wave started to be output from the PN code generator 2-j is input to the adder 4. The ON state of the switch 3-j is maintained for the chip time length Tm. As a result, a rectangular wave corresponding to one cycle of the M-sequence code is sent to the adder 4 from the time tj to the time tj + Tm.

On the other hand, when the transmission data Dj supplied to the terminal 1-j is "0", the switch 3-j is turned off.
Then, the rectangular wave started to be output from the PN code generator 2-j is not transmitted.

At the beginning of transmission, the PN code generator 2
When the rectangular wave output is started from -j, the switch 3-
j turns ON (or OFF). After that, the rectangular wave output of the PN code generator 2-j is continued as it is, and the switch 3-j outputs O according to the transmission data Dj for each chip time length Tm.
By being turned N / OFF, transmission of a rectangular wave corresponding to the M-sequence code for one cycle is turned ON / OFF.

In this way, the terminals 1-0, 1-1,
, 1-n, the output of the PN code generators 2-0, 2-1, ..., 2-n corresponding to the terminal whose transmission data is "1" is transmitted according to each code start time. . As a result, based on the transmission data D0, D1, ..., Dn, a rectangular wave corresponding to the M-sequence code whose phase is shifted is added by the adder 4
Sent to

In the adder 4, as described above, the switch 3-
The rectangular waves transmitted via 0, 3-1, ..., 3-n are added. As a result, a transmission signal in which all rectangular waves to be transmitted are superimposed is generated and input to the multiplier 6.

In the multiplier 6, the input output of the adder 4 and the carrier wave are multiplied. As a result, the transmission signal is shifted to the frequency band assigned as the communication frequency band, and the corresponding transmission wave is transmitted by the transmission antenna 7.

The transmitted wave transmitted from the transmitting antenna 7 is
It is received by the receiving antenna 8. Then, the received signal corresponding to the received wave of the receiving antenna 8 is input to the correlator 9.

The correlator 9 performs a correlation process using the received signal and the same rectangular wave as the rectangular wave output from the PN code generators 2-0, 2-1, ..., 2-n. Due to this, from the property of the M-sequence code described above, if a received signal from a certain time t ′ to a time Tm contains a rectangular wave having the same waveform and the same phase as the rectangular wave, the received signal at the time t ′ + Tm A peak appears in the correlation output.

Here, as described above, since the transmitting side transmits a rectangular wave by shifting the phase for each of the transmission data D0, D1, ..., Dn, the peak of the correlation output is due to the phase shift. Appears at corresponding time intervals.

For example, transmission data D0, D1, D2, ...
Assuming that Dn is D0 = 1, D1 = 0, D2 = 1, ..., Dn = 1, when time Tm elapses after the reception antenna 8 starts to receive the transmission wave corresponding to the transmission data, D0 A peak corresponding to = 1 appears. Assuming that the time when this peak appears is t0 ', the peak does not appear at time t0' + k * 1 * T because D1 = 0. Then
At time t0 '+ k * 2 * T, a peak corresponding to D2 = 1 appears. Thereafter, similarly, the transmission data D3, D4, ..., D
For each n−1, a corresponding correlation output is obtained when the time corresponding to the phase shift of each transmission rectangular wave has elapsed from the time t0 ′.

When the time becomes t0 '+ k × n × T, a peak corresponding to Dn = 1 appears, and transmission / reception of the transmission data D0, D1, ..., Dn given as an example above is completed. However, the transmission data D0, D1, ..., Dn are each time Tm.
It continues to be supplied every time. Therefore, when the time becomes t0 '+ Tm, the correlation output corresponding to the transmission data D0 supplied after the transmission data D0 is obtained, and thereafter, the correlation corresponding to the transmission data D1, D2, ... Output is obtained.

The correlation output thus obtained is converted into a pulse signal having a constant level and a constant width by the detector / waveform former 10 and input to the serial-parallel converter 11.

As described above, since the correlation output is a serial signal output at fixed time intervals, the serial-parallel converter 11 converts the pulse signal into the chip time length T.
It converts each m to a parallel signal and outputs the received data in the form of parallel data.

Since the chip time length Tm includes one set of transmission data D0, D1, ..., Dn, the output of the serial-parallel converter 11 is the terminals 1-0, 1.
Same contents as the data when supplied to -1, ..., 1-n
The data has the same format.

As a result, the one-bit data communication per one chip time length Tm of the PN code is conventionally performed, but the maximum number of chips of one cycle of the PN code is -1 (Tm / T).
-1) Bit data communication becomes possible. Normally, the number of chips in one PN code period is several tens, so that the data communication speed is considerably improved.

Next, with reference to FIG. 2, various configuration examples of respective components of the spread spectrum communication apparatus of the above embodiment will be described more specifically. The operation is similar to that of the above embodiment, but details will be described as necessary.
In addition, components that are similar to those in FIG. 1 and that do not particularly affect the characteristics of the device are denoted by the same symbols, and description thereof is omitted.

In the figure, reference numerals 21-0 to 21-7 are terminals to which 8-bit transmission data D0 to D7 are supplied and correspond to the terminals 1-0, 1-1, ..., 1-n in the above embodiment. To do. Although the data is supplied to this terminal every chip time length Tm in the above-described embodiment, it is not necessarily limited to such a form. For example, transmission data may be temporarily held by providing appropriate buffers at these terminals, and the transmission data may be sequentially discharged by a clock corresponding to the chip time length Tm. In short, from each PN code generator to which each terminal corresponds,
It suffices that the rectangular wave corresponding to one cycle of the PN code can be transmitted. In addition, D0 shown in FIG.
= 0, D1 = 1, ..., D7 = 1 are examples of transmission data.

22 is a shift register 22r-1 to 22r
-5, shift registers 22a to 22j and EX-OR
A PN code generator including an (exclusive OR) circuit 22x, which uses an M-sequence code as a PN code.

As shown in the figure, the shift registers 22r-1 to 22-2
In the M-sequence code generation circuit 22M composed of the 2r-5 and the EX-OR circuit 22x, when the contents of the shift registers 22r-1 to 22r-5 are shifted by the code generation clock, the output of the shift register 22r-5 becomes M.
A sequence code can be obtained. Incidentally, M-sequence code period when the shift register is a 5-stage is 31 (2 ⁵ -1) bits, in FIG shift register 22r-2 22
Although the EX-OR having the contents of r-5 is fed back, the M code sequence of various bit patterns can be obtained by changing the shift register connected to the EX-OR circuit 22x.

The M-sequence code output from the shift register 22r-5 is further shifted to the shift registers 22a, 22b, ..., 22j provided at the subsequent stage for each code clock. In this way, the shift registers 22a-22j
It is possible to obtain the M-sequence code with each chip shifted from the output of, and it is possible to output a rectangular wave corresponding to the M-sequence code with the chip shifted without providing a plurality of PN code generators.

23-7 are turned on when the transmission data D0, D1, ..., D7 are "1", respectively.
It is a switch that is turned off when “0”, and corresponds to the switches 3-0, 3-1, ..., 3-n in the above-described embodiment. These switches correspond to the shift registers 22c, 22d, ..., 22j, respectively, as shown, and are 2 + p (p = 0, 1,
.., 7) Turns ON / OFF the transmission of a rectangular wave according to the M-sequence code with a chip shift (delay). The rectangular wave from the shift register 22a is input to the adder 4 as a reference signal regardless of the content of the transmission data.

Here, as an example, the operation when the transmission data is the illustrated transmission data example D0 = 0, D1 = 1, ..., D7 = 1 will be described.

The rectangular wave from the shift register 22a is continuously input to the adder 4 from the start of transmission when the first output of the shift register 22r-5 is made. Now, assuming that the transmission of the transmission data example is started from time ts when time Tm × q (q is an integer) has elapsed from the start of transmission, the switch 23-1 is turned on at time ts + 3T.
And the rectangular wave from the shift register 22d becomes the adder 4
Begins to be sent to. Next, at time ts + 5T, the switch 23-3 is turned on, and the rectangular wave from the shift register 22d starts to be sent to the adder 4. Hereinafter, similarly, time t
The switch 23-4 is ON at s + 6T, the switch 23-5 is ON at time ts + 7T, and the switch 23 is at time ts + 9T.
-7 turns ON, and the rectangular wave from each shift register starts to be transmitted. In the figure, the ON / OFF states of the switches 23-0 to 23-7 at this time are shown.

The ON (or OFF) state of each switch is held for the chip time length Tm. As a result, the phase difference between the reference signal and the reference signal is 3 chips of M-sequence code,
A rectangular wave for one cycle having a phase difference corresponding to five chips, six chips, seven chips, and nine chips is input to the adder 4. Each switch is ON (or OF
After the F) state is held for the chip time length Tm, it is turned on or off depending on the next transmission data.

In this way, the rectangular waves having different phases are input to the adder 4, and the adder 4 generates a transmission signal in which all the rectangular waves are superposed. It should be noted that the generation of the transmission signal described here is merely an example, and it may be any as long as it can transmit a rectangular wave having a different phase for each bit of the transmission data.

The generated transmission signal is multiplied by the carrier wave in the multiplier 6, and the corresponding transmission wave is transmitted by the transmission antenna 7. Then, the received signal received by the receiving antenna 8 and corresponding to the received wave is input to the SAW correlator 29.

The SAW correlator 29 corresponds to the correlator 9 in the above embodiment. Although the down converter for converting the received signal into the frequency band suitable for the SAW correlator 29 is omitted, it may be appropriately provided as necessary.

Here, the SAW correlator is a SAW device that has taps arranged according to a fixed code sequence and that performs correlation processing between the waveform of the code sequence and the input signal waveform by spatial integration. There is no time delay in correlation output. The correlation output due to this becomes a peak when the outputs of the respective taps are added when the input signal waveform matches the waveform of the code sequence. In the SAW correlator 29, PN
The taps are arranged in accordance with the M-sequence code generated in the code generator 22 so that the peak of the correlation output appears when the input received signal includes a waveform corresponding to the M-sequence code.

Here, as an example of the correlation processing by the SAW correlator 29, the above-mentioned transmission data example D0 = 0, D1 =
A case where a transmission signal of 1, ..., D7 = 1 is received will be described with reference to FIG.

The received signal continues to be SAW from the start of reception.
It is input to the correlator 29. When the received signal including one cycle of the rectangular wave of the reference signal is input to the SAW correlator 29, a peak appears in the output as shown by the correlation output a in FIG. After that, when time 3T elapses, the received signal containing the rectangular wave for one cycle from the shift register 22d is input to the SAW correlator 29, and the peak shown in the correlation output d appears. Then, when time 2T elapses,
The received signal including the rectangular wave for one period from the shift register 22f is input to the SAW correlator 29, and the peak shown in the correlation output f appears. Subsequently, 1 from the shift register 22g after the lapse of time T, the shift register h after the lapse of time T, and the shift register j after the lapse of time 2T.
The received signal including a rectangular wave for a period is input to the SAW correlator 29, and the peaks shown in the correlation outputs g, h, and j appear.

The correlation output thus obtained is converted into a pulse signal having a constant level and a constant width by the waveform former 30. In the SAW correlator, the peak is output as shown in the correlation output of FIG. 3, so the detection operation is not required. Transmission data example D0 = 0, D1 = 1, ..., D7 = 1
In this case, the pulse signal output from the waveform shaper 30 is shown in the waveform shaping output of FIG.

The output pulse signal of the waveform former 30 is input to the serial-parallel converter 11, and the chip time length T
It is converted into a parallel signal for each m and output. As a result, the original transmission data is obtained.

In the above embodiment, the receiving side outputs the data in the parallel signal format, but the data may be output in the serial signal format as it is. This is useful when the transmission data is not a parallel signal supplied at a cycle of a chip time length Tm but a serial signal supplied at a cycle of a time length T of one chip. In this case, it is necessary to distribute the supplied serial signal to the terminals 1-0, 1-1, ..., 1-n by a distributor.

The phase shift of the waveform output from the PN code generator only needs to have a small correlation, and is not limited to the one described in the above embodiment. For example, in the case of the M-sequence code, it is sufficient if there is a phase shift corresponding to one chip or more and less than one cycle, and a phase shift of any number of chips may be used within that range.

In addition, since there is almost no cross-correlation between different M-sequence codes, multiple communication is possible by changing the codes, and the reference signal in the above embodiment is introduced even in the same M-sequence code. And can be time-division multiplexed.

[0074]

As described above, according to the present invention,
A peak appears in the correlation when the code start positions coincide with each other, and the correlation decreases when the code start positions deviate from each other. A waveform corresponding to the PN code is used and the waveforms are associated with different phase shifts for each bit of the transmission data. By the correlation processing on the side, the reception data corresponding to each bit of the transmission data is output at time intervals corresponding to the respective phase shifts. As a result, data communication can be performed at the same time interval as the chip rate at the maximum, and high-speed data communication becomes possible.

Further, since the high speed data communication according to the present invention is performed by shifting the phase of the same waveform, the occupied frequency band is only the frequency band of this single waveform. Therefore, there is no expansion of the frequency band due to conventional baseband modulation, and without expanding the occupied frequency band,
It is possible to obtain the effect that high-speed data communication can be performed while making the most effective use of the minimum required occupied frequency band.

Further, in the present invention, since the correlation processing is performed on the waveforms having different phase shifts on the receiving side, the peak of the correlation output is reduced as compared with the case of using the waveform of a constant phase. There is nothing to do. That is,
There is no decrease in S / N due to the increased data communication speed. As a result, an effect that high-speed data communication is possible while maintaining desired communication quality is obtained.

Particularly, according to the invention described in claim 2, PN
Since the M-sequence code is used as the code, there is no correlation between waveforms having different phase shifts due to the nature of the M-sequence code. As a result, the peak of the correlation output on the receiving side clearly appears, and the transmitted data can be reliably reproduced.

According to the invention of claim 3, PN
By the coordinated operation of the code generator and the switch and the addition operation in the adder, it is possible to generate a transmission signal that enables high-speed data communication as described above. In this case, according to the invention as set forth in claim 4, since the configuration of the PN code generator can be simplified, it is possible to generate the transmission signal with a simple configuration.

On the other hand, regarding the correlation processing on the receiving side, since the SAW correlator is used in the invention according to claim 5, there is no delay due to the integration operation, and the received data is obtained in real time according to the phase shift of each waveform. be able to. Then, unlike the case of multiplexing using different code sequences, since the data is transmitted by using the same waveform with the phase shifted, the SAW correlator on the receiving side only needs to correspond to one PN code. The effect is obtained.

In addition, according to the invention described in claim 6, since the received data is output in the parallel signal format, the received data can be obtained in the same form as the transmitted data when being input to the input terminal. On the other hand, according to the invention described in claim 7, since the received data is output in the serial signal format, it is effective when the original transmission data is supplied in the serial signal format.

According to the invention described in claim 8, since the predetermined reference signal is transmitted, it is possible to perform data communication by using this reference signal for frame synchronization, time division multiplexing and the like. The effect is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a spread spectrum communication device according to an embodiment of the present invention.

FIG. 2 shows a spread spectrum communication device of FIG.
It is a figure for explaining various examples of composition and the operation concretely.

FIG. 3 is a diagram showing waveforms of a correlation output and a waveform shaping output obtained on the receiving side with respect to an example of transmission data.

FIG. 4 is a block diagram showing a first configuration example of a conventional spread spectrum communication device.

FIG. 5 is a block diagram showing a second configuration example of a conventional spread spectrum communication device.

6 is a diagram showing waveforms of a transmission signal, an FSK signal, and a spread-modulated signal in the spread spectrum communication device of FIG.

7 is a diagram showing a received signal, a correlation output, a detection output, a waveform shaping output, and a waveform of a transmission signal obtained by these in the spread spectrum communication apparatus of FIG.

[Explanation of symbols]

1-0, 1-1, ..., 1-n, 21-0, 21-1,
... 21-7 Input terminals 2-0, 2-1, ..., 2-n, 22 PN code generator 3-0, 3-1, ..., 3-n, 23-0, 23-1,
... 23-7 switch 4 adder 7 transmission antenna 8 reception antenna 9 correlator 10 detection / waveform shaper 11 serial-parallel converter 22M M-sequence code generation circuit 22a, 22b, ..., 22j shift register 29 SAW correlator 30 waveform Molding machine

Claims (8)

[Claims] 1. A PN code sequence, in which an input terminal to which n-bit transmission data is supplied, a peak appears in the correlation when the code start positions coincide, and a correlation decreases when the code start positions deviate
N waveforms having different phase shifts corresponding to one cycle of the PN code in which each code of the transmission data is associated with a different code start time are supplied to the input terminal. Transmission signal generation means for outputting a transmission signal synthesized according to the data in each bit of the transmission data, transmission means for transmitting a transmission wave according to the transmission signal, and receiving the transmission wave, to the received wave Receiving means for outputting a corresponding received signal, correlation processing means for outputting a correlation waveform between the waveform of the receiving signal and a waveform corresponding to the PN code, and receiving data based on a peak position of the correlation waveform A spread spectrum communication device having output means. 2. The spread spectrum communication device according to claim 1, wherein the transmission signal generation means uses a M sequence code as a PN code,
Each bit of the transmission data has a different phase shift corresponding to one cycle of the PN code corresponding to the code start time at which the shift of the code start position of each PN code is 1 chip or more. A spread spectrum communication device, which is a transmission signal generation means for outputting a transmission signal obtained by synthesizing a plurality of waveforms according to the data in each bit of the transmission data supplied to the input terminal. 3. The spread spectrum communication device according to claim 1, wherein the transmission signal generating means outputs the n waveforms.
Depending on the data in each bit of the transmission data supplied to the N code generator and the input terminal, the transmission of the waveform corresponding to each bit is turned on / off at a cycle corresponding to one cycle of the PN code. A spread spectrum communication device comprising transmission signal generating means having n switches and an adder for adding and outputting respective waveforms transmitted through the n switches. 4. The spread spectrum communication device according to claim 3, wherein the PN code generator has an M-sequence code generation circuit and an output of the M-sequence code generation circuit input to a first-stage shift register, and the M-sequence code generation circuit. A spread spectrum communication device, comprising: a shift register connected in n or more stages, the contents of which are shifted according to a code generation clock in a code generation circuit. 5. The spread spectrum communication device according to claim 1, wherein the correlation processing means is a SAW correlator having taps arranged according to the PN code. apparatus. 6. The spread spectrum communication device according to claim 1, wherein the output unit outputs the correlation output from the correlation processing unit during a time corresponding to one period of the PN code. A spread spectrum communication device, which is output means for converting received data into an n-bit parallel signal format based on a peak position of a waveform and outputting the converted data. 7. The spread spectrum communication device according to claim 1, wherein the output unit outputs the correlation waveform output from the correlation processing unit at a time interval corresponding to one chip of the PN code. A spread spectrum communication device, which is an output unit that outputs received data in a serial signal format based on the peak of. 8. The spread spectrum communication device according to claim 1, wherein the transmission signal generation means outputs a waveform having a specific phase shift of the waveform according to the PN code of the transmission data. It is characterized by always synthesizing regardless of the content, and making each bit of the n-bit transmission data correspond to a waveform other than the waveform having the specific phase shift, and the output means outputs the specific phase shift. It is an output means for selecting a correlation output having a waveform other than that having a peak of a correlation output having a waveform as a reference and outputting reception data corresponding to data in each bit of the n-bit transmission data. Spread spectrum communication device.