JP3318683B2 - Spread spectrum communication equipment - Google Patents

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 apparatus, and more particularly, to a spread spectrum modulation / demodulation system using a SAW (surface acoustic wave) matched filter.

[0002]

2. Description of the Related Art First, a conventional spread spectrum communication apparatus will be described with reference to FIG.

The spread spectrum communication apparatus shown in FIG.
1 and a receiving unit 12. When the transmission data is provided to the data modulation unit 13, the transmission unit 11 modulates the phase of the carrier from the carrier wave oscillator 14 with the transmission data, and sends the phase modulated signal to the spread modulation unit 15. Spreading modulator 15
Then, the phase modulation signal is spread-modulated by the PN code sequence from the pseudo random (PN) code generator 16 to generate a spread modulation signal. This spread modulation signal is applied to a band-pass filter (B
After the band is limited by the PF 17, the frequency is converted by the frequency converter 18. Further, after the power is amplified by the power amplifier 19, it is transmitted from the transmission antenna 20 as a transmission signal.

On the other hand, a receiving section 12 receives a transmission signal transmitted from another communication device by a reception antenna 21 as a reception signal. The received signal is amplified by the high-frequency amplifier 22 and then converted to a SAW frequency by the frequency converter 23 and supplied to the SAW matched filter 25, the synchronization tracking circuit 26, and the despreading circuit 27 via the BPF 24 as a frequency converted signal. Can be

[0005] The frequency conversion signal is filtered by the SAW matched filter 25 to become a filter signal.
This filter signal is, for example, a correlation detection signal having a peak for each period of the PN code sequence. This correlation detection signal is supplied to an envelope detector 28, where a peak position is detected. Using the detected peak position as a trigger, the synchronization tracking circuit 26 performs synchronization tracking of the PN code string included in the frequency conversion signal, and generates a synchronization signal. Then, the despreading circuit 27 despreads the frequency conversion signal by the synchronization signal to generate a despread signal. This despread signal is provided to the data demodulator 30 via the BPF 29 and demodulated into demodulated data.

Another example of the conventional spread spectrum communication apparatus will be described with reference to FIG. FIG.
In FIG. 6, the same components as those shown in FIG. 6 are denoted by the same reference numerals, and description thereof will be omitted.

In the transmission section 11, transmission data is given to the changeover switch 31, and the changeover switch 31 is changed according to the transmission data.
Is switched to switch the PN code string input to the spread modulator 15. For example, when the transmission data is “1”, the changeover switch 31 causes the A code generator 32
Are connected to the spread modulation section 15 and the A code is
5 given. On the other hand, when the transmission data is “0”, the switch 31 connects the B code generator 33 to the spread modulator 15, and the B code is
Given to.

[0008] In this manner, the PN according to the transmission data
The code sequence is switched, and the spread wave modulating unit 15 generates the carrier wave 1
The carrier from No. 4 is phase-modulated by the PN code sequence and is spread and given to the frequency conversion unit 18 via the BPF 17.

In the receiving section 12, the frequency conversion signal from the frequency conversion section 23 is supplied to an A-code SAW matched filter 34 and a B-code SAW matched filter 35.
The A-code SAW matched filter 34 obtains an A-code, that is, a first correlation detection signal having a peak for transmission data “1”. Similarly, the B code SAW matched filter 35 obtains a B code, that is, a second correlation detection signal having a peak with respect to transmission data “0”.

The first and second correlation detection signals are supplied to envelope detectors 36 and 37, respectively, where peaks are detected. Then, from the envelope detectors 36 and 37, the first
And a second peak detection signal. The data determination circuit 38 performs a peak determination based on the first and second peak detection signals and outputs demodulated data.

[0011]

However, in the above-described spread spectrum communication apparatus, it is necessary to provide a transmitting unit and a receiving unit with different configurations, and there is a problem that the circuit configuration becomes complicated.

An object of the present invention is to provide a spread spectrum communication apparatus which has a simple circuit configuration and can share a transmitting section and a receiving section.

[0013]

According to the present invention, there is provided a transmitting means for transmitting a spread spectrum signal as a transmitted spread spectrum signal, and a receiving means for receiving the spread spectrum signal as a received spread spectrum signal. A spread spectrum communication apparatus for transmitting and receiving signals using spread signals, comprising an input terminal and an output terminal, wherein the input terminal is connected to the receiving means, the output terminal is connected to the transmitting means, and first and second taps are provided. And a SAW matched filter having a PN pattern electrode having a multiplication signal obtained by multiplying a pulse signal of a predetermined period by a carrier, and selectively applying the multiplication signal to the first and second taps according to transmission data. Switching means for providing, and demodulation means connected to the first or second tap and connected to the reception means. Has the SAW matched filter first when the received spread spectrum signal is given
Alternatively, a correlation detection signal having a peak every one period of the PN code string is output to the second tap, and when the multiplication signal is provided, the transmission means is provided with the spread spectrum signal, and the demodulation means is provided with the correlation detection signal. The spread spectrum communication apparatus is characterized in that the received spread spectrum signal is demodulated into demodulated data based on the following equation.

Further, according to the present invention, there is provided a sending means for sending a spread spectrum signal as a transmission spread spectrum signal, and a receiving means for receiving the spread spectrum signal as a received spread spectrum signal. A spread-spectrum communication device for transmitting and receiving signals through a PN pattern electrode having an input terminal and an output terminal, having a PN pattern electrode having a tap connected to the receiving unit at the input terminal and connected to the transmitting unit at the output terminal. A second SAW matched filter, and supply means for selectively providing a multiplied signal obtained by multiplying a pulse signal of a predetermined period and a carrier to the taps of the first and second SAW matched filters in accordance with transmission data; Demodulated data generating means connected to taps of the first and second SAW matched filters It has the first and the second S
In the AW matched filter, the electrode patterns of the PN pattern electrodes thereof are different from each other, and the first and second SAW matched filters are provided with the taps every one period of the PN code string when the received spread spectrum signal is given. First and second correlation detection signals having peaks are output, and when the multiplication signal is given, the first and second correlation detection signals are sent to the transmission means as the spread spectrum signals, respectively.
, And the demodulated data generating means obtains demodulated data from the first and second correlation detection signals, thereby obtaining a spread spectrum communication apparatus.

[0015]

According to the present invention, since a spread spectrum signal is obtained by using a SAW matched filter and a correlation detection signal having a peak every one period of the PN code string is obtained, the transmitting section and the receiving section can be shared, and therefore, the circuit can be used. The configuration is simple.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments.

Referring to FIG. 1, in this embodiment, FIG.
The same components as those of the spread spectrum communication apparatus shown in FIG. In the illustrated spread spectrum communication apparatus, a SAW is provided between the BPF 24 and the frequency converter 18.
A matched filter 39 is provided.

Here, the configuration of the SAW matched filter 39 will be described with reference to FIG.

The SAW matched filter 39 has an input electrode section 40, a PN pattern electrode section 41, and an output electrode section 42. An input terminal 40a and a ground terminal 40b are formed on the input electrode unit 40, and an output terminal 42a and a ground terminal 42b are formed on the output electrode unit 42 in the same manner. The PN pattern electrode portion 41 has first and second taps (terminals) 41a and 41b as shown.

When an input signal is input to the input terminal 40a in the SAW matched filter 39 shown in FIG.
An output signal appears at the first and second taps of the pattern electrode unit 41. FIG. 3 shows this state equivalently. FIG. 3 shows an example in which a PN signal whose one-chip time length is Δ is supplied to the input terminal 40a as an input signal ( here, +1, -1, +1, +1, -1,-).
1, -1 ). The PN signal is sequentially delayed by the one-chip time length Δ by the delay element 43 to be first to seventh delayed signals. These first to seventh delay signals are weighted by the weighting circuits 44g to 44a , respectively, and then synthesized and transmitted as output signals. In this output signal, the PN signal and the weighting pattern ( weighting in FIG. 3)
As shown in the circuits 44g to 44a, +1, -1, +
1, +1, -1, -1, -1. ) Overlap with each other, an autocorrelation function whose output becomes maximum (+7) is obtained.

On the other hand, when an input signal is input to the first or second tap 41a or 41b in the SAW matched filter 39 shown in FIG. 2, an output signal appears at an output terminal 42a. FIG. 4 shows this state equivalently.
FIG. 4 shows an example in which a single pulse having a time width Δ is given as an input signal. The pulse signal, after being weighted by the weighting circuits 44a to 44 g, the delay element 4
3 and the written pulse train is 44 g
The output pulse is sequentially delayed by time Δ and transmitted as an output signal. This output signal becomes a pulse train according to the weighting pattern.

Accordingly, in FIG. 2, when a signal that is phase-modulated by the same PN code sequence as the PN pattern electrode unit 41 and has the same frequency as the SAW is input from the input terminal 40a, the first and second ports 41a and 41a P from 41b
An output signal (detection signal) having a peak for each cycle of the N code string is obtained. When a signal modulated by a pulse having a one-chip time width Δ and having the same frequency as that of the SAW is input from the first or second port 41a or 41b, the same PN as the PN pattern electrode portion 41 is output from the output terminal 42a. An output signal which is phase-modulated by the code string and has the same frequency as that of the SAW is obtained.

Referring again to FIG. 1, the above-described SAW matched filter 39 is connected to the BPF 24 at an input terminal 40a, and connected to the frequency converter 18 at an output terminal 42a. The first and second taps 41a and 41b are connected to a multiplier 46 via a changeover switch 45.

At the time of transmission, transmission data is given to the changeover switch 45, and the changeover switch 45 is switched according to the transmission data. On the other hand, a pulse signal having a one-chip time width Δ is supplied from the pulse generator 47 to the multiplier 46.
A carrier having the same frequency as that of the SAW is added from the carrier generator 14 to the multiplier 46, and the pulse signal and the carrier are multiplied by the multiplier 46 and added to the changeover switch 45 as a multiplication signal.

For example, when the transmission data is “1”, the selector 46 connects the multiplier 46 to the first tap 41 a. On the other hand, when the transmission data is “0”, the selector 46 connects the multiplier 46 and the second tap 41b. As is clear from the description with reference to FIG.
When a pulse signal having a period equal to the pattern length of the PN electrode portion 41 of the AW matched filter 39 is given, the SAW
From the matched filter 39 to the pattern of the PN electrode portion 41,
That is, a spread signal using the same PN code string as that of the PN electrode unit 41 is output. The spread signal is transmitted as a transmission signal from the transmission antenna 20 via the frequency conversion unit 18 and the power amplification unit 19 as described above.

Generally, the SAW matched filter 3
The output electrode section of No. 9 has band pass characteristics depending on the electrode arrangement and the like, and as a result, it is not necessary to provide a BPF on the output side.

At the time of reception, a transmission signal (spread-modulated signal) is received by the reception antenna 21 as a reception signal. As described above, the received signal passes through the high-frequency amplifier 22, the frequency converter 23, and the BPF 24 to be converted into a frequency-converted signal as the SAW matched filter 39, the synchronization tracking circuit 2, and the like.
6 and the despreading circuit 27.

In the SAW matched filter 39, as described above, a correlation detection signal having a peak for each period of the PN code string is obtained from the second tap 41b as an output of the PN pattern electrode section 41. Then, the correlation detection signal is provided to the envelope detector 28.

The envelope detector 28 detects the peak from the correlation detection signal and supplies the detection signal to the synchronization tracking circuit 26. The synchronization tracking circuit 26 performs synchronization tracking of the PN code string included in the frequency conversion signal based on the detection signal, and generates a synchronization signal. The despreading circuit 27 despreads the frequency conversion signal based on the synchronization signal to generate a despread signal. This despread signal is provided to the data demodulator 30 via the BPF 29 and demodulated into demodulated data.

Next, another embodiment of the spread spectrum communication apparatus according to the present invention will be described with reference to FIG. In this embodiment, the same components as those of the spread spectrum communication apparatus shown in FIG. 1 are denoted by the same reference numerals. In this embodiment, different spreading code strings are assigned according to data.

At the time of transmission, a pulse signal having a one-chip time width is generated from the pulse generator 48 in accordance with the transmission data. For example, when the transmission data is “1”, a pulse signal having a one-chip time width is provided to the multiplier 49 as a first pulse signal, and when the transmission data is “0”, a one-chip time The pulse signal having the width is provided to the multiplier 50 as a second pulse signal. Multipliers 49 and 50 are provided with a carrier having the same frequency as that of the SAW from the carrier wave oscillator 14, and the multipliers 49 and 50 multiply the first and second pulse signals by the carrier to obtain first and second carriers, respectively. A second multiplication signal is generated.

The illustrated spread spectrum communication apparatus includes an A code SAW matched filter 51 and a B code SAW matched filter 52. The A-code SAW matched filter 51 and the B-code SAW matched filter 52 have the same configuration as the SAW matched filter shown in FIG.
1 and the B code SAW matched filter 52 have different PN patterns in the PN pattern electrode portion.

In the A-code SAW matched filter 51, the input electrode section 40 is connected to the input terminal 40a of the frequency conversion section 2 by the input terminal 40a.
3 and the output electrode section 42 is connected to the frequency conversion section 18 at the output terminal 42a. Further, the multiplier 4
9 is the first or second tap 4 of the PN pattern electrode portion 41
The first or second tap 41a or 41b is connected to the envelope detector 36 while being connected to 1a or 41b. Similarly, B code SAW matched filter 5
2 is connected to the frequency converters 23 and 18 and also to the multiplier 50 and the envelope detector 37.

The first and second multiplied signals are supplied to an A-code SAW matched filter 51 and a B-code matched filter 52, respectively. As a result, the transmission data becomes "1".
In this case, a spread signal appears at the output end of the A-code SAW matched filter 51 (hereinafter, this spread signal is referred to as a first spread signal), and when the transmission data is "0", the B code S
A spread signal appears at the output end of the AW matched filter 52 (hereinafter, this spread signal is referred to as a second spread signal). Then, these first and second spread signals are converted by the frequency conversion unit 18.
The signal is transmitted as a transmission signal from the transmission antenna 20 via the power amplifier 19. As described above, the SAW matched filter has band-pass characteristics depending on the electrode arrangement of the output electrode section, and as a result, it is not necessary to provide a BPF on the output side.

At the time of reception, a transmission signal is received as a reception signal by the reception antenna 21, passes through the high frequency amplifier 22 and the frequency converter 23, and is converted into a frequency conversion signal by the A code SAW matched filter 51 and the B code SAW matched filter 52. (Note that in the SAW matched filter, the input side can have band-pass characteristics depending on the electrode arrangement of the input electrode section and the like, and as a result, it is not necessary to provide a BPF on the input side in this embodiment).

When the transmission data is "1", the A code S
A correlation detection signal appears at the tap of the PN pattern electrode portion of the AW matched filter 51 (hereinafter, this correlation detection signal is referred to as a first signal).
When the transmission data is "0", a correlation detection signal appears at the tap of the PN pattern electrode portion of the B-code SAW matched filter 52 (hereinafter, this correlation detection signal is referred to as a second correlation detection signal). Signal).

These first and second correlation detection signals are supplied to envelope detectors 36 and 37, respectively, where peaks are detected. Then, the envelope detectors 36 and 37 transmit the first and second peak detection signals. These first
And the second peak detection signal are supplied to a data determination circuit 38, which performs a peak determination based on the first and second peak detection signals and outputs demodulated data.

In the spread spectrum communication apparatus shown in FIG.
SAW matched filters are used, but one SW
An AW matched filter can also be used. That is, when a spread signal obtained by phase-modulating a carrier with data and spread-modulating with a PN code string is supplied to a SAW matched filter, phase information related to data is stored in a correlation detection signal (correlation peak) output from the SAW matched filter. ing. Accordingly, demodulated data can be obtained by synchronously detecting the carrier phase at the correlation peak using the SAW matched filter. In this case, the configuration of the transmitting unit is the same as the configuration shown in FIG.

[0039]

As described above, according to the present invention, the receiving unit and the transmitting unit are shared by using the SAW matched filter so that the spread spectrum signal is selectively transmitted and the correlation detection signal is obtained. Therefore, there is an effect that devices such as a spread modulation unit and a PN code sequence generator are not required, and the circuit configuration is simplified. Furthermore, SA
Since the W-matched filter has band-pass characteristics on its input side and output side, the band-pass filter can be omitted if necessary.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing an example of a SAW matched filter used in the spread spectrum communication apparatus shown in FIG.

FIG. 3 is a diagram for explaining an operation principle when a signal is applied to the input side of the SAW matched filter shown in FIG. 2;

FIG. 4 is a diagram for explaining an operation principle when a signal is applied to a PN pattern electrode of the SAW matched filter shown in FIG. 2;

FIG. 5 is a block diagram showing another embodiment of the spread spectrum communication apparatus according to the present invention.

FIG. 6 is a block diagram illustrating an example of a conventional spread spectrum communication apparatus.

FIG. 7 is a block diagram showing another example of a conventional spread spectrum communication apparatus.

[Explanation of symbols]

Reference Signs List 11 transmitting section 12 receiving section 13 data modulating section 14 carrier oscillator 15 spreading modulating section 16 PN code generator 17, 24, 29 band pass filter (BPF) 18, 23 frequency converting section 19 power amplifying section 20 transmitting antenna 21 receiving antenna 22 High-frequency amplifier 25, 34, 35, 39, 51, 52 SAW matched filter 26 Synchronous tracking circuit 27 Despreading circuit 28, 36, 37 Envelope detector 30 Data demodulator 31, 45 Switch 32, 33 Code generator 38 Data determination circuit 40 Input electrode part 41 PN pattern electrode part 42 Output electrode part 43 Delay element 44a-44g Weighting circuit 46,49,50 Multiplier 47,48 Pulse generator

Claims (4)

(57) [Claims] 1. A spread spectrum apparatus comprising: a transmitting means for transmitting a spread spectrum signal as a transmission spread spectrum signal; and a receiving means for receiving the spread spectrum signal as a received spread spectrum signal, and performing transmission and reception using the spread spectrum signal. In a communication apparatus, a SAW matched filter including an input terminal and an output terminal, and a PN pattern electrode having first and second taps connected to the receiving means at the input terminal and connected to the transmitting means at the output terminal. Switching means for receiving a multiplied signal obtained by multiplying a pulse signal and a carrier having a predetermined period by a carrier and selectively providing the multiplied signal to the first and second taps according to transmission data; A demodulating means connected to the second tap and connected to the receiving means;
The AW matched filter outputs a correlation detection signal having a peak every one period of the PN code sequence to the first or second tap when the received spread spectrum signal is provided, and transmits the correlation detection signal when the multiplied signal is provided. Means for providing the spread spectrum signal to means, and the demodulation means demodulating the received spread spectrum signal to demodulated data based on the correlation detection signal. 2. The spread spectrum communication apparatus according to claim 1, wherein said demodulation means receives said correlation detection signal and obtains a peak position thereof as a peak detection signal; Synchronization tracking means for receiving the peak detection signal and generating a synchronization signal,
Despreading means for despreading the received spread spectrum signal in accordance with the synchronization signal to obtain a despread signal; and data demodulation means for demodulating the despread signal into the demodulated data. Communication device. 3. A spread spectrum apparatus comprising: a transmitting means for transmitting a spread spectrum signal as a transmission spread spectrum signal; and a receiving means for receiving the spread spectrum signal as a received spread spectrum signal, and performing transmission and reception using the spread spectrum signal. A communication device comprising an input terminal and an output terminal, the input terminal being connected to the receiving means, the output terminal being connected to the transmitting means, and having a tap.
First and second SAW matched filters each having an N-pattern electrode, and the first and second SAW matched filters selectively multiplying a multiplied signal obtained by multiplying a pulse signal of a predetermined period by a carrier in accordance with transmission data And a demodulation data generator connected to the taps of the first and second SAW matched filters. The first and second SAW matched filters each have a PN pattern. The electrode patterns of the electrodes are different, and the first and second SAW matched filters have first and second SAW matched filters each having a peak at each tap of the PN code string at one cycle when the received spread spectrum signal is given. And outputs the correlation detection signal as the spread spectrum signal to the transmission means when the multiplication signal is given. Giving the first and second spread spectrum signal, the demodulated data generating means of the first and the second
A spread spectrum communication apparatus characterized in that demodulated data is obtained from the correlation detection signal. 4. The spread spectrum communication apparatus according to claim 3, wherein said demodulated data generating means includes said first demodulated data generating means.
And envelope detection means for receiving the second correlation detection signal and obtaining peak positions thereof as first and second peak detection signals, respectively, and determining the first and second peak detection signals to obtain the demodulated data. A spread spectrum communication apparatus comprising: