JPS6014558A - Psk demodulator - Google Patents

Abstract

PURPOSE:To eliminate various inconveniences caused by a delay line without the need of synchronism by having only to discriminate a section obtained by dividing a range from 0 deg. to 360 deg. having a detected phase difference so as to output ''0'' or ''1'' thereby detecting digitally a signal. CONSTITUTION:In 2-phase phasl modulation, when one phase difference is theta, the other phase difference is theta+180 deg. (or theta-180 deg.). When the demodulation of the differential phase shift modulation DPSK is conducted so that the phase difference preceding one symbol is 0 and the phase difference sucessing one symbol is theta, the data is, e.g., ''0'' and when theta+180 deg. (or theta-180 deg.), the data is ''1''. An input signal is decomposed into the directions 28, 29 of vectors representing two orthogonal reference signals and inputted to a digital system DPSK demodulator 24. The A/D converted signal is stored in a memory by a time corresponding to one symbol, outputted and compared digitally by the signal A/D converted after one symbol to execute the DPSK demodulation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides digital (J) data in which the phase of a carrier wave is modulated.
shift keying) signal w (
13Da L.

This invention relates to a PSK demodulator that restores Chitan.

In the following, DPSK (Differential Ph
ase ShiftKeying, differential phase shift change'
pA)YPSKσ-As an example, one shot of 8A will be explained.

The delay detection method is used to detect the DPSK modulated signal by combining it with a signal delayed by the time corresponding to l symbol.
In order to restore PSK, it is necessary that the phases of both carrier wave components match with considerably high precision. for seven,
A delay line with high precision or a means equivalent to a delay line is required, and it has disadvantages such as difficulty in adjusting the delay time and poor yield of the delay line. Another problem is that stability deteriorates due to temperature characteristics of the delay line, changes over time, etc.

Figure 1 is a block diagram showing an example of the configuration of a PSK demodulator using a delayed detection method. A pass filter, 5 is a determination circuit, and 6 is an output.

FIG. 2 is a signal waveform diagram for explaining the operation of the device shown in FIG. 1. 4 waveforms, and the signal of this waveform is the DPSK signal input signal l in Figure 1.
is input. That is, two-phase DPSK signal (second
Figure (C)) is obtained by inverting the carrier wave (if the phase shift data of aJ is L, and continuing the previous phase if it is 0.
The output waveform of I line 2 is shown. FIG. 2 (el is the output waveform of the mixer 3, and (f) is the output waveform of the low-pass filter 4. tgl is data demodulated with the signal determined by the determination circuit 5 of FIG. 1. That is, the original data is restored by multiplying the DPSK signal input to the '1' device shown in FIG. 1 by a signal delayed by a time corresponding to l symbols. However, if the delay time of the delay line is not set correctly,
No data is restored as shown in dl, tel and (ff, IC in Figure 3).

(dL (eL (gl) corresponds to the waveforms with the same symbols in Fig. 2. If the carrier frequency is cylindrical, a slight error in delay time will cause the direct mixer 3 IC manually output signal to
The carrier wave phase of the symbol-delayed signal is wide (different), resulting in erroneous data recovery.Therefore, at high carrier frequencies, the delay time must be set particularly strictly.

As a means to solve this carrier phase □ problem,
A method has also been considered in which the carrier wave component is removed before DPSK demodulation, and then DPSKDlII4 is performed in the pace band. An example is shown in FIG.

In the figure, 7.8.14 is a mixer, 9 is a 901 phase shifter, 10 is a voltage controlled oscillator, 11.12 is a low-pass filter,
13 is a loop 1 filter, and 15 is a DPSK demodulator.

The circuit shown is the well-known Costas ((:osta) circuit.
s) loop, and this loop demodulates the two-phase phase modulation from the output (base band) of the
Perform demodulation with . In this case, a closed loop must be formed to synchronize the phases of the carrier wave and reference No. 48 (output of the voltage controlled oscillator 10), and the adjustment is complicated.

The object of the invention is therefore to provide a PSK demodulator which does not require synchronization by determining phase differences in a simple digital manner.

To achieve the above object, in a PSK demodulator according to the present invention, the phase of a carrier wave is modulated with data consisting of a digital signal. In a PSK demodulator that demodulates a so-called PSK signal and restores data, a first reference signal of the same frequency as the carrier frequency is used.

a second reference signal having a 90° phase difference with respect to the first reference signal trap, and a first low-pass signal obtained by multiplying the input signal and the first reference signal in a multiplier; and a second low-pass component obtained by multiplying the input signal and the second reference signal in a multiplier as carrier wave phase information. It is preferable to have a means for determining whether the range from 360° to 360° belongs to the range of degrees Celsius and deviation of the range obtained by dividing the range from 360° to 360°.

In an advantageous embodiment of the invention, from 0° to 36°
The range up to 06 is divided into O sections, each of which has a specific digital section, and the means for determining which section the phase of the carrier wave belongs to is based on that specific digital section. output. Those intervals are the first on one axis.

A second low-pass component appears on the other axis.

If we take coordinate axes that are orthogonal to each other and divide the range from ♂ to 360° by a group of @ lines that pass through the origin of the coordinate system, it is an area surrounded by two half-straight lines that are adjacent to each other and start from the origin. . For the section to which the carrier phase belongs, a vector with the same amplitude as the first low-pass component is drawn on one axis, and a vector with the same amplitude as the second low-pass component is drawn on the other axis. This is the interval in which the vector obtained by summing the vectors exists.

The invention is particularly implemented in a two-phase DPSK controller as follows. If the determined interval is the same as the interval determined l symbols ago, then f, data &! oO″ (Ma1koha l”)
, whether the determined section is a section 111 that is symmetric with respect to the origin with respect to the one symbol defined before the symbol, or -1
Near this is K before the l symbol! l'lJ fixed Otta Ward 1u
If it is not the same as l, then the data is L (also 4S'0'') and (・5 form, or the determined interval force''-i symbols, if the interval is symmetrical about the origin with respect to the previously determined interval, The data is ゝ11 (also 1ゝ0'), otherwise the data is 1ゝO'' (also siゝl Q > and (
・U] DPSK demodulation is performed at Sugi. The determined interval curl l symbol is the same as the previously determined interval (smaller (
, iJ), even if it is a symmetric interval with respect to the origin.
It is even more advantageous to have means for determining that an error has occurred.

Hereinafter, the present invention will be explained in more detail using examples without referring to the drawings, but these are merely illustrative and do not go beyond the scope of the present invention.・ro(・ro) Of course, there are many variations and improvements that you will like.

FIG. 5 is a block diagram showing the organization of the U P S l<, torture device according to the present invention. In FIG. 1, 16.17 is a mixer, 18+5
rIEn: Oscillator, 19 is 90#s phase converter, Δ), 21
is a summator and a turntable, z′2. z+ is a sampling circuit and a 24-way digital system DPSK demodulator.

In FIG. 5, the sampling circuit 22
The output from the reference source generator and the input No. 16 σ] If the phase difference is θ, then l/2coSθ and [/2
sioθ. This is due to the fact that the phase is measured based on the output of the reference oscillator. Ray later.

This phase will be called a phase difference. Place 41] Arrived 0 and 1
O given by tan(s+nθ/cosθ)
The present invention will be described in detail by focusing on the case where a two-phase phase modulated D PsK signal with a width of 4N- is used.

In two-phase phase modulation, the phase difference on one side is ``θ'' 1゜1゜, and the phase difference on the other side is θ+180° ((・) θ−tso
6). DPSKo) Ql key is 1 symbol if the phase difference θ before l symbols is θ.For example, the data is O, θ+180°(
If it is 0-1806), it is performed as ゝ11pa. The phase difference θ between the input &f signal and the reference oscillator is
The width 1] is determined by two orthogonal references 4g obtained from the reference oscillator. The principle is shown in FIG. The horizontal axis of FIG. 6 represents the direction of the vector representing the first reference signal passing through path 25 of FIG. 5, and the vertical axis represents the direction of the vector representing the second reference signal passing through path 26 of FIG. Ding. 27 is a vector representing the input signal.

Therefore, 4 and 4 represent the components of input 4g in the direction of the vectors representing the first and second reference signals, respectively. In other words, one human input signal represents two reference signals that are orthogonal to each other, and the direction vector of the signal is decomposed into the digital system D.
PSKrM adjuster 21C is manually powered. Output from the sampling circuit. The phase difference information decomposed into two is subjected to A/D conversion, and the seven D/D converted signals are stored in memory for a time corresponding to one symbol, and then output, and the A/D conversion signal after one symbol is DPSKI toning is performed by digitally comparing the D-converted data with the D-converted data.

For example, if one phase difference is θ, the other is θ+90″ in 2-phase PSK, and θ+90″ in 4-phase PSK.
Either 0°θ-90' or θ+180'°C deviation and 1
It cannot take any other value. Therefore, there is no need to use any exact values to determine these phase differences. The purpose is to determine which section rF+1 the measured phase difference belongs to among the sections divided above.Consider the case as shown in Fig. 7 as a column.As shown in Fig. 7, 1 phase difference 9 (・te0″ to 3
When dividing up to 60” into eight sections from 1 to ■,
Assume that the input (i) is in interval ■.In two-phase PSK, the input signal can take the other state in interval V, and in four-phase PSK.

The other state can be taken only in intervals i, v, and ■, and therefore it is only necessary to determine the interval in which the input signal exists. For example, in FIG. 7, there are eight sections divided into 45" sections. As shown in FIG.
This can be realized by providing threshold values at ±1/J and 00 for each standardized amplitude.

In FIG. 8, the solid line represents cos θ.

The curve drawn with a broken line represents sin θ, and the straight line drawn with a solid line represents a threshold value of ±1/4.

A digital value is given to each of the sections divided into traps, and when the demodulator receives the phase difference information,
Then, it is determined which section the input signal is in, and the section determined as 1 is output as a digital lIin signal. For example, in Figure 8, the digital values from 000 to Ill are humiliated in each section in order from section
Because it is in

000 output. By doing this, the subsequent signal processing 'fiJAy! 'Can be done digitally.

In the above explanation, one section is divided into an orthogonal coordinate system with the fifth reference signal and the second reference signal as the axes.

A group of straight lines passing through the origin (4 am in Figure 7) from 0 to 3
The range is divided into sections up to 60 degrees, and one section consists of an area starting from the origin Z and surrounded by two half-straight lines adjacent to each other. Then, the section in which the input (g) vector exists is determined to be the section in which the carrier phase exists. Demodulation of the SK modulated signal is performed by comparing the carrier phase one symbol before and the phase one symbol later.As mentioned earlier, since this is done in an analog manner, the trap uses a highly accurate In contrast to the need for a delay line, one according to the present invention:
■It is only necessary to store the time corresponding to the symbol in the digital memory. That is, as explained above, determine the interval in which there is a phase difference between the input signal and the reference oscillator, output it as a digital value, store this in memory, and calculate the digital value obtained after l symbols. Compared to the trap, demodulation is performed.

In the case of two-phase L)PSK, the possible sections are two sections that are symmetrical to each other with respect to the origin. Therefore, if the determined interval is the same as the interval determined one symbol before, it can be demodulated as 1. For example, if the data is in a symmetric interval with respect to the 110° origin, it can be demodulated as l. Also, if the interval determined as 1 is the same as the interval determined l symbols ago, 0. Otherwise 1. +11 and its inverse pressure can also be used. Furthermore, according to the present invention, if the interval judged as 1 is not the same as the area +441 judged one symbol before (and is not a symmetrical interval with respect to the origin), an error occurs in τ and 1 is judged as incorrect. You can also do it.

It is clear that the present invention, which has been explained above using D P S K as l+ll, can be applied to the entire No. 48 modulated by PSK.

As explained above, whereas the conventional delay detection method requires accurate synchronization, according to the present invention, the phase difference obtained by dividing the phase difference from 06 to 3606 is obtained by dividing the range from 06 to 3606. 1 just by determining which one is in the
Since the signal detection is done digitally, such as outputting 10'T or 11'', there is no need for synchronization and the various inconveniences introduced by delay lines can be eliminated. The advantage of being able to do this is y].

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of a conventional delay side branch type DPSKI adjuster, Fig. 2 shows the configuration of the device shown in Fig. Figure 3 (C), tdL (eJ and t
fJ is the diagram corresponding to the 21st (.l, tdL Ie) and (fJ when the delay time of the delay line is not set correctly. Figure 4 shows the conventional D
l) A block diagram showing the configuration of the SK bag modulator, FIG. 5 is a block diagram showing the configuration 2 of the DPSK demodulator according to the present invention, and FIG.
The figure is a diagram for explaining the decomposition of the human input signal according to the present invention, Figure 7 is a diagram showing the relationship between the division of phase difference +=1 according to the present invention and the human input signal, and the eighth figure is the section of Figure 7. This is a complete diagram explained by Yun. l... DF'5K48 human power terminal, 2... l symbol delay line, 3... junk, 4.11.12... low pass filter. 5... Judgment circuit, 6... Output, 7. 8.14.
16.17... Mixer, 9.19... 90° phase shifter, 10... Voltage control inset, Ij... Loop filter, 15... D t' SK demodulator. 18... Reference oscillator, 20,2]... Integrator and dumper. ρ, 23... Sampling circuit, 24... Digital DPSK demodulator, 25... First reference signal path, 26... Second reference signal path, 27... Human input signal Table vector, 28...The fifth reference signal is a narrow vector. 4...Vector representing the second reference signal. −99ζ Ge l Figure 2 $2 Mother≠3 Figure (9) □ Abandoned 4 Figure Nest 5 Figure 6 Figure Base 7N Leaf 8 Figure Procedural Amendment (@8) 1 Indication of the Case 1982 Patent Application No. 122171 2 Name of the invention PSK@Ceramics 3 Relationship with the case of the person making the amendment Patent applicant address name (148) Clarion Co., Ltd. 4 agent 〒1
05

Claims (1)

[Claims] (1+ The phase of the carrier wave is changed by 4 times with data consisting of a digital signal. In the so-called PSK demodulator 11'J which demodulates the ff1 signal and restores the data,
A first reference signal having the same frequency range as the carrier wave frequency, and a second reference signal having a phase difference of 90° with respect to the first reference signal, and the input signal and the first reference signal A first low-pass component obtained by multiplying the input signal and the second reference signal in the multiplier, and a second low-pass component obtained by multiplying the input signal and the second reference signal in the multiplier. A means for extracting the phase information as phase information, and a means for determining from the carrier wave phase information which section of the range obtained by dividing the phase of the carrier wave from 1 to 360 degrees into multiple sections. (2) The determining means determines the interval to which the input carrier phase belongs, and outputs a digital value identifying the interval affected by each of the aforementioned intervals. A PSK demodulator according to claim 1, which is characterized in that: Take orthogonal coordinate axes and divide the range from 0° to 360a by a group of surface lines tracing the origin of the coordinate system, and each section is an area surrounded by two adjacent half solutions with the origin and starting point. A PSK fire leg device according to claim 1 or 2, characterized in that: +41 - Draw a vector on the axis of force with the same imaging width as the first low-pass component, and A patent characterized in that a vector having the same amplitude as the second low-pass component is drawn on the axis, and the section in which the vector obtained by summing these vectors exists is determined to be the section to which the carrier phase belongs. Claim: A PSK demodulator according to any one of the preceding claims. (5) A pSK demodulator according to any one of the preceding claims, characterized in that the PSK is DPSK. (6) If it is a two-phase D P S K demodulator and the interval determined by 5 is the same as the interval determined l symbols before,
The data is '0' (or e, +7). If the judged interval is symmetric with respect to the origin with respect to the l symbol pre-judged interval, the data is '0' (or e, +7).
The PSK demodulator according to claim 5, which has the characteristic feature of performing DPSK demodulation in the 1> and (・5 type). If the interval determined is the same as the interval determined l symbols ago, the data is 'o' (or 'l'), otherwise the data is DPSK in the form 1.Lt (or I'OJ).
A PSK demodulator according to claim 5, characterized in that the PSK demodulator performs demodulation. (8) In a two-phase DPSK restorer, if the determined interval is symmetrical about the origin with respect to the interval determined l symbols before, the data shall be 119 (or 'o'); 6. The PSK demodulator according to claim 5, wherein DPSK demodulation is performed for data in the form of 0'' [or 4, +1]. (9) In a two-phase DPSKI modulator, if the determined interval is not the same as the interval determined l symbols ago and is symmetric with respect to the origin, 1) il is not (・). An error occurs. A PSKr modulator according to claim 6, characterized in that it has means for determining.