JP2586481B2 - Ternary PSK communication device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase shift keying communication apparatus for transmitting / receiving a phase train data signal by phase shift keying, and more particularly to phase shift keying a ternary level data signal. Ternary PSK to demodulate
Related to a communication device.

(Prior Art) There is a strong demand for high-speed digital data communication of multilevel level phase shift keying (PSK), and there are several types of ternary level methods. Exists. Usually, -1, 0, +1 as ternary levels
Use these in carrier phase -90.
Some ternary PSK communication devices are configured to correspond to degrees, 0 (no carrier wave), and +90 degrees. In a ternary PSK communication device,
The one using the sine wave PSK is superior from various points. The data information is transmitted by a series of code data on which a carrier called a “chip” is superimposed.

(Problems to be Solved by the Invention) In a conventional phase shift keying communication device, in connection with phase shift keying, a dedicated side for performing phase shift, sine wave shape shaping and filtering of a signal is provided on the transmitting side. It is necessary to provide a signal processing circuit and a dedicated signal processing circuit for performing phase shift and filtering of the signal on the receiving side.

As described above, the conventional phase shift keying communication device needs to include a dedicated circuit for each signal processing such as phase shift and filtering, so that the configuration of the entire device becomes complicated, and it is necessary to provide individual circuits. Accordingly, there is a problem that insertion loss increases and frequency characteristics deteriorate.

An object of the present invention is to eliminate such disadvantages of the prior art, and an object of the present invention is to provide a ternary PSK communication apparatus that can simplify the configuration of a signal processing circuit related to modulation and demodulation.

(Means for Solving the Problems) According to the present invention, there is provided a transmitting section for transmitting a data signal of a pulse train by phase-shift keying and a receiving section for demodulating the phase-shift keyed received signal. In the value PSK communication device, the transmitting unit includes a polarity identification circuit that separates the first and second logic levels of the data signal, and outputs the polarity identification circuit to a pulse signal having a pulse width corresponding to the frequency of the carrier wave. A pair of first pulse generators to be converted and a pulse signal from the pair of first pulse generators are phase-shifted so as to be in opposite phases to each other, correlated with each other, shaped into a sine wave, and filtered. A first SH-wave ultrasonic piezoelectric device having a zero-order symmetric mode and a function of outputting a phase-shifted output so as to be in opposite phases to each other, and an output of the first SH-wave ultrasonic piezoelectric device having a zero-order symmetric mode And outputs a signal subjected to phase shift modulation An adder for detecting the envelope of the phase-shift keyed received signal, and the reception signal based on the signal of the first envelope detector. A second pulse generator that generates a pulse train signal synchronized with the carrier signal included in the received signal, and a phase shift between the received signal and the signal from the second pulse generator so that the phases are opposite to each other. A second SH-wave ultrasonic piezoelectric device having a zero-order symmetric mode having a function of outputting a phase shift so that the phases are opposite to each other, and a second SH-wave ultrasonic device having a zero-order symmetric mode. An adder for adding the outputs of the acoustic piezo-electric devices, a pair of second envelope detectors for detecting the envelope of the output of the adder, and signals from the pair of second envelope detectors having different levels. Each is determined by the threshold A pair of a circuit for generating a pulse signal,
A ternary PSK communication device comprising: a signal reconstructing circuit for performing a logical operation on the pulse signals from the pair of circuits to generate a signal composed of a ternary pulse train.

(Operation) In the transmitting unit, the outputs of the data signals whose polarity has been identified are converted into pulse signals having a pulse width corresponding to the frequency of the carrier wave, and the pulse signals are mutually transmitted by a zero-order symmetric mode SH wave ultrasonic piezoelectric device. The phases are shifted so as to be in opposite phases, the two are combined, the waveform is shaped into a sine wave, filtered, and then phase shifted so as to be in opposite phases to each other and output. The output signals are added and sent to the receiving side. On the receiving side,
The envelope component of the phase-shift-modulated received signal is detected,
Based on the envelope component, a pulse train signal synchronized with the carrier signal contained in the received signal is generated. The received signal and this pulse signal are phase-shifted by the zero-order symmetric mode SH-wave ultrasonic piezoelectric device so that they are out of phase with each other, and after being synthesized, they are phase-shifted so that they are out of phase with each other. Is output. These outputs are added to detect an envelope component, and the envelope component signals are respectively determined at thresholds of different levels to become pulse signals, logically operated, and re-formed into a signal comprising a ternary level pulse train. Be built.

(Embodiment) FIG. 1 is a circuit diagram showing a transmission unit 100 according to an embodiment of the present invention. In the figure, 101 is a polarity identification circuit,
Data U having ternary levels (-1, 0, 1) is input, and data at +1, -1 level is selected and output. The +1 and -1 level data of the polarity identification circuit 101 are input to pulse generators 102 and 103, respectively. The pulse generators 102 and 103 generate a pulse having a width equal to a half cycle of the center frequency f ₀ of the carrier according to the input, and supply the pulse to the SH-wave piezoelectric device 104 in the zero-order symmetric mode.

As will be described in detail later, the SH wave piezoelectric device 104 is an element having a piezo electric ceramic plate, and functionally equivalently, shifts the pulses from the pulse generators 102 and 103 to a reference phase. Phase shift units 105 and 106 for generating pulses having phases different by 90 degrees and -90 degrees,
A multiplier that multiplies, that is, correlates, the outputs of the phase shift units 105 and 106
107, a waveform shaper 108 for shaping the output of the multiplier 107 into a sine wave waveform, a transmission filter 109 for extracting a signal component from the output of the waveform shaper 108, that is, for filtering, and a transmission filter 109.
Are shifted by 90 degrees with respect to the reference phase and-
Phase shift units 110 and 111 for forming sine waves having a phase difference of 90 degrees
Consists of

Outputs of the phase shift units 110 and 111 are applied to an adder 112, and the adder 112 outputs a sine wave PSK signal. This sine wave PSK signal is transmitted to the receiving unit 200 described below.

FIG. 2 is a waveform diagram illustrating the operation of the sine wave PSK modulation circuit 100. As shown in FIG. 2A, the polarity identification circuit 101 represents ternary level data [+1, 0, -1, 0, -1, 0], and has a carrier frequency f ₀ = 2.3 MHz and a bit rate f _bit = 20k
A bit / s data signal is input. Polarity identification circuit 101
Identifies the phase of such data and
And 103, the pulses shown in FIGS. This causes the pulse generators 102 and 103 to output waveforms as shown in FIGS.

In the SH-wave piezoelectric device 104, there is leakage through the gap between the comb-shaped electrodes described below, so this is somewhat expressed as a negative polarity pulse, but it is not so much as to be a problem here. .

The SH wave piezoelectric device 104 includes the phase shift units 105 and 106, the multiplier 107, the waveform shaper 108, the transmission filter 109, and the phase shift unit 1 described above.
Signal processing for phase shift, sine wave shaping, filtering, and phase shift is performed by the functions of 10 and 111.
Sine wave as shown in FIG. 2f
A PSK signal is obtained. In this case, the phases of the modulation signals forming the sine wave PSK signal are [+90 degrees, 0 degrees, and +90 degrees, respectively.
Degree, 0 degree, -90 degree, 0 degree, -90 degree, 0 degree]. However, the data corresponding to 0 degrees is based on the fact that it does not take the form of a signal as a chip and has zero amplitude.

FIG. 3 is a circuit diagram of a receiving unit 200 corresponding to the sine wave PSK modulation circuit 100 of FIG. The sine wave PSK signal, which is a received signal, is input to the amplifier 206 and amplified. The output of the amplifier 206 is input to the envelope detector 207, and the envelope is detected. The output of the envelope detector 207 is input to the threshold value judgment circuit 208. Discrimination of the signal level is performed according to a predetermined threshold value. Threshold judgment circuit
208 supplies a signal as a result of the discrimination to the pulse generator 209. The pulse generator 209 generates a pulse having the same width as that of the pulse generator 102 according to the input signal.

The zero-order symmetric mode SH wave piezoelectric device 210 is composed of a piezo electric ceramic plate,
And the output of the pulse generator 209 is input. The SH-wave piezoelectric device 210 has substantially the same configuration as the SH-wave piezoelectric device 104 in FIG. 1, and has a function-equivalent phase shift of -90 degrees and +90 degrees with respect to the reference phase, respectively. The phase units 211 and 212 are multiplied by the outputs of the phase shift units 211 and 212, that is, the multiplier 213 correlates, the reception filter 214 that filters the output of the multiplier 213, and the output of the reception filter 214 is +90. Phase shifter 215 for phase shift of degrees and −90 degrees
And 216. Outputs of the phase shift units 215 and 216 are both input to the adder 217.

The output of the adder 217 is supplied to envelope detectors 218 and 219 which are a pair of circuits. Envelope detector
218 and 219 detect the envelope of the output of the adder 217, and supply the resulting envelope signals to threshold value judgment circuits 220 and 221 respectively.

The threshold value determination circuits 220 and 221 perform threshold value determination on the envelope signal at different predetermined levels, and supply the results to the pulse generators 222 and 223.

The pulse generators 222 and 223 have a function of converting the envelope signal into a pulse. The outputs of the pulse generators 222 and 223 are supplied to offset delay circuits 224 and 225, respectively, and delayed to correct the offset, and then input to a three-level signal reconstruction circuit 226.

The three-level signal reconstruction circuit 226 includes an offset delay circuit 224
And a function of outputting a three-level signal by logically judging the outputs of the signals 225 and 225, and reproduces the original three-level signal.

FIG. 4 is a waveform diagram for explaining the operation of the receiving section 200.
The operation of the receiving unit 200 will be described with reference to this waveform diagram.
The sine wave PSK signal is input to the amplifier 206 and amplified,
The signal has a waveform as shown in FIG. This signal is subjected to envelope detection by the envelope detector 207, and becomes a signal having a waveform as shown in FIG. 4B. This signal becomes a signal whose threshold value is determined by the threshold value determination circuit 208, and is input to the pulse generator 209.

The pulse generator 209 generates a pulse as shown in FIG. 4C according to the output signal of the threshold value judgment circuit 208. This pulse is a clock signal synchronized with the sine wave PSK signal.
This pulse is applied to the SH wave piezoelectric device 210 and subjected to the following processing. First, the phase is shifted by +90 degrees by the phase shifter 212 and input to the multiplier 213. On the other hand, the signal from the amplifier 206 is shifted by -90 degrees by the phase shift unit 211 and
Entered into 13. Multiplier 213 correlates the signal shifted by +90 degrees from phase shifting section 212 with the signal shifted by -90 degrees from phase shifting section 211. The multiplied signal is received by the receive filter.
After the unnecessary components are removed by 214, the phase shift units 215 and 216
Respectively. The phase shifter 215 outputs a signal having a waveform shifted by +90 degrees as shown in FIG. 4D. Phase shift unit
This output of 215 is the first output of the SH wave piezoelectric device 210, and the second output, which is out of phase and shifted by -90 degrees, is the phase shifter.
Output from 216.

An adder 217 adds the outputs of the phase shifters 215 and 216, and a pair of envelope detectors 218 and 219 respectively perform envelope detection on the signal obtained by the addition, as shown in FIGS. , A signal indicating the envelope of the sine wave PSK signal is obtained. The threshold value determination circuits 220 and 221 perform threshold value determination on the outputs of the envelope detectors 218 and 219 at predetermined levels of different values.

The signals of the threshold decision circuits 220 and 221 are
The pulses are pulsed by 2 and 223, respectively, and delayed for offset correction by offset delay circuits 224 and 225, thereby obtaining pulse train signals as shown in FIGS. As a result, only the maximum amplitude is pulsed with respect to the signal train d in FIG.

The three-level signal reconstruction circuit 226 includes an offset delay circuit 224
And 225 when the signal from both is high, and -1 when the signal from the offset delay circuit 224 is low and the signal from the offset delay circuit 225 is high. A signal composed of a ternary pulse train as shown is output. That is, U = + 1 data is obtained from the signal sequence g on the threshold value judgment circuit 220 side where the high threshold value is set, and the signal sequence h on the threshold value judgment circuit 221 side where the low threshold value is set. Obtains a positive pulse train corresponding to U = ± 1. (U = + 1) of these g and (U =
± 1) are multiplexed to finally reconstruct the ternary signal i. As is clear from the comparison with the original signal shown in FIG. 4j, the signal i has a phase delay (about 7 μs) associated with two passages of the acoustic section (SH wave element) during modulation and demodulation. It can be seen that the original signal is reproduced.

FIG. 5 is a schematic diagram showing the structure of the SH wave piezoelectric devices 104 and 210. Piezoelectric ceramic plate
300 is housed in a 14-pin IC package and has a length L of 16m
m, the width is 8 mm, the thickness is 0.15 mm, and the polarization direction is parallel to the electrode fingers as shown by the arrow P. 0.84mm / 2 for piezo electric ceramic plate 300
There are provided three finger pairs of inter digital transducers 301 and 302 arranged in a comb-shape different from each other according to the distance between them, and are connected to pins 1, 13; The distance between the inter digital transducers (IDTs) 301 and 302 is 6.72 mm, and the signal propagation delay operates in a single mode of 3.20 μs.

The sine wave modulation signal s (t) applied to the IDT 301 is expressed as follows.

s (t) = | U | · P (t) cos (2πf ₀ t−Uπ / 2)
(1) where, U is a data string of ternary levels, P (t) is the waveform of the envelope, f ₀ is equal carrier frequency to the center frequency. Phase -90 degrees of the sine wave modulation signal s (t), takes one of 0 degrees or +90 degrees, the response time T _C to an impulse of the base band is expressed as follows.

T _C = 2L _IDT / v = 2n / f ₀ , where v is the speed of the SH wave and L _IDT is the ID in the propagation direction
The length of T301, n is the number of IDT finger pairs. During the T _bit chip period, the data transmission rate is f _bit (= 1 / T _bit )
It is.

FIG. 6 shows that the SH wave piezoelectric device 301 has a width of 1 / 2f ₀ (for example, 217n).
It is an envelope waveform diagram which shows the response when the impulse of s) is applied. That is, it is a time response characteristic of the SH wave piezoelectric device expressed only by the envelope component excluding the carrier wave. When the impulse a is applied (see FIG. 6), the SH-wave piezoelectric device 301 converts the signal b having an envelope component corresponding to the amplitude weighting function P (t) over T _C as shown in the figure. ID
It is induced at T302 (corresponding to the output of the SH wave piezoelectric device 104 in FIG. 1, see the pulse response output in the modulation unit shown in FIG. 6). When the signal b having the envelope component P (t) is applied to the SH-wave piezoelectric device 301 (see FIG. 6), an envelope signal as shown in c is induced (the SH-wave piezoelectric device in FIG. 3). 210, see the synchronous detection processing output in the demodulator shown in FIG. 6).

Thus, the impulse response of the SH wave element is extracted in the form of a burst wave (this signal is called a “chip”). In order to PSK modulate the carrier in the chip, the pulses are switched into the IDT's two sets of interdigital electrodes according to the data to provide -90 degrees and +
90 degree phase state is given. The SH wave element in the demodulation unit is the same as the SH wave element in the modulation unit, but uses two input electrode fingers of the element. The received sine wave PSK signal of FIG. 2f (corresponding to FIG. 6) is applied to one of them via an amplifier 206. Further, since the envelope component of the burst wave is constant irrespective of the phase state of the carrier component, the pulse signal after the envelope detection is applied to the other input electrode finger. As a result, when it reaches the output electrode finger as an SH wave, synchronous detection becomes possible. This takes into account the fact that the two electrode fingers are shifted by 180 degrees from each other, and as a result of phase synthesis of the signal trains a and c in FIG. Thus, a signal sequence d is obtained.

FIG. 7 shows the SH wave piezoelectric device 104 having a width of 1 as in FIG.
FIG. 7 is a carrier waveform diagram showing a response when an / 2f ₀ (for example, 217 ns) impulse is applied. In FIG. 7, a
Is a single impulse of 1 / 2f ₀ applied to the SH-wave piezoelectric device 104, b is the signal waveform at the output end of the SH-wave piezoelectric device 104, and c is the SH
The signal waveform at the output end of the wave piezoelectric device 210 has a delay of 3.20 μs from the signal waveform b. d is a continuous impulse of 1 / 2f ₀ applied to the SH wave piezoelectric device 104 (400 bits /
s) and e are signal waveforms at the output end of the SH-wave piezoelectric device 104 responding to d continuous impulses, and f are signal waveforms at the output end of the SH-wave piezoelectric device 210 responding to d continuous impulses. .

FIG. 8 shows the speed of propagation (km / s) and the conversion efficiency of the modulation of the SH wave piezoelectric devices 104 and 210 for the zero-order symmetric (S ₀ ) mode SH wave, that is, the electromechanical coupling constant K ² (%). Frequency (MH
z) A characteristic diagram showing characteristics. As shown in the figure, the speed does not change much even when the frequency changes or the electrodes of the IDTs 301 and 302 are open or short-circuited, and is almost constant,
It shows that it has low dispersion characteristics. Further, the electromechanical coupling constant k ² shows a tendency to decrease gradually with increasing frequency. Note that, as shown in FIG.
Substrate of the present invention by SH wave, electromechanical coupling constant k ² 20%
Is over. This is SAW on a general substrate (LiNbO ₃ )
This indicates that the signal processing is extremely high and the signal processing is easy, as compared with the case where k ² is about 5%.

FIG. 9 is a characteristic diagram of the insertion loss versus frequency of the SH wave piezoelectric devices 104 and 210, and it can be understood from the diagram that the characteristics of both are well matched.

(Effect of the Invention) As described in detail above, according to the present invention, ternary PSK
By introducing a zero-order symmetric mode SH wave with high conversion efficiency into a core part of modulation and demodulation when configuring a communication device, the circuit configuration of the entire system can be significantly simplified. In addition, in order to configure a device for signal processing due to an excellent electromechanical coupling coefficient k ² which is four times the value of using LiNbO ₃ , it is extremely effective in low voltage driving and noise resistance, In addition, transmission characteristics with excellent phase characteristics can be realized due to low dispersion characteristics in which the propagation speed of the SH wave is substantially constant with changes in frequency, and the synchronization characteristics are also relatively good.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a transmission unit according to an embodiment of the present invention, FIG. 2 is a waveform diagram for explaining the operation of the transmission unit in FIG. 1, and FIG. 3 is a demodulation signal of the transmission unit in FIG. FIG. 4 is a waveform diagram illustrating the operation of the receiving unit in FIG. 3, FIG. 5 is a schematic configuration diagram of the SH wave piezoelectric device, and FIGS. 8 and 9 are characteristic diagrams of the SH wave piezoelectric device. 101: polarity discriminating circuit, 102, 103, 209, 222, 223: pulse generator, 104, 210: SH wave piezoelectric device, 207, 218, 219: envelope detector, 226: three-level signal Building circuit.

Claims (4)

(57) [Claims] 1. A ternary PSK communication apparatus comprising: a transmitting unit that transmits a data signal of a pulse train by performing phase shift modulation, and a receiving unit that demodulates the received signal subjected to phase shift modulation. , A polarity discriminating circuit for separating first and second logic levels of a data signal, and a pair of first pulse generators for converting the output of the polarity discriminating circuit into a pulse signal having a pulse width corresponding to the frequency of the carrier wave And the pulse signals from the pair of first pulse generators are phase-shifted so that the phases are opposite to each other, and the two are correlated. Phase-shift-modulated signal obtained by adding the output of the first SH-wave ultrasonic piezoelectric device having a zero-order symmetric mode and having the function of outputting the resultant signal, and the output of the first SH-wave ultrasonic piezoelectric device having the zero-order symmetric mode. And an adder that outputs A first envelope detector for detecting an envelope of the phase shift keyed received signal, and a pulse train synchronized with a carrier signal included in the received signal based on the signal of the first envelope detector. And a second pulse generator for generating the signal of the above, the received signal and the signal from the second pulse generator are phase-shifted so that the phases are opposite to each other, and the two are correlated, The second SH of the zero-order symmetric mode having the function of shifting and outputting the phase
Wave ultrasonic piezoelectric device, an adder for adding the output of the second SH wave ultrasonic piezoelectric device in the zero-order symmetric mode, and a pair of second envelope detectors for detecting the envelope of the output of the adder. A pair of circuits for determining a signal from the pair of second envelope detectors with thresholds having different levels from each other to generate a pulse signal, and performing a logical operation on the pulse signal from the pair of circuits to generate a pulse signal. A ternary PSK communication device comprising: a signal reconstruction circuit that generates a signal composed of a pulse train of a value level. 2. The circuit according to claim 1, wherein said polarity discriminating circuit separates the first and second logic levels from a data signal corresponding to 1 and −1, respectively. Value PSK communication device. 3. The pulse generator according to claim 1, wherein said first and second pulse generators generate a pulse train signal having a width equal to a half cycle of a center frequency of a carrier frequency of a transmitting unit. 3. The ternary PSK communication device according to item 1 or 2. 4. Each of the first and second SH-wave ultrasonic piezo-electric devices in a zero-order symmetric mode includes a pair of inter-digital digital devices arranged at a predetermined distance on a piezo-electric ceramic plate. Having a transducer,
2. The interdigital transducer of claim 1, wherein each of said interdigital transducers has a pair of interdigitated electrodes disposed along said polarization axis of said piezoelectric ceramic plate so as to mesh with each other.
Item 4. The ternary PSK communication device according to any one of Items 3 to 3.