JPS607424B2 - Time division multidirectional multiplex synchronization circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the configuration of a time division multidirectional multiplexing synchronization system.

FIG. 1 is a block connection diagram showing an example of a conventional device, in which 1 indicates PSK (phase shift keying).
(hiftkeying) modulator, 2 is a frequency converter, 3 and 4 are carrier wave oscillators, and PSK modulator 1,
Drives frequency converter 2.

1, 2, 3, and 4 constitute the transmission system of the main station.

Also, 5 and 6 are switches, respectively, and 7 is a voltage holding circuit. One voltage holding circuit 7 is provided for each slave station, and the switches 5 and 6 communicate with the main station sequentially by time division. In synchronization with the switching of the slave station, the voltage holding circuit 7 for the slave station is switched to be connected between the phase comparator 10 and the voltage controlled oscillator 8. 8 is a voltage controlled oscillator, 9 is a carrier wave oscillator, 10' is a phase comparator, 11 is a carrier wave regeneration circuit, 12 is a PSK demodulator, 13 is a mixer, and is controlled by the phase comparator 10, switches 5 and 6, and voltage holding circuit 7. The phase of the output frequency of the voltage controlled oscillator 8 is synchronized with the output phase of the carrier wave regeneration circuit 11.

5, 6, 7, 8, 9, 10, 11, 12, and 13 constitute the receiving system of the main station. Also, in Figure 1, 14,1
5, 16, 17, 18, 19 indicate the receiving system of each slave station,
Reference numerals 20, 21, 22, 23, and 24 indicate the transmission systems of each slave station, and although there are a plurality of slave stations for one master station, only the circuit for one slave station is shown in FIG.

14 is a mixer/server, 15 is a PSK demodulator, 16 is a carrier wave oscillator, 17 is a voltage controlled oscillator, 18 is a carrier wave regeneration circuit, 19 is a phase comparator, a two-way switch, 21 is a frequency converter, and 22 is a PSK modulator. 23 and 2M are respectively carrier wave oscillators.

Further, in FIG. 1, symbols A to C are used for convenience of explanation and indicate signals on each conducting wire. Next, the operation will be explained.

Signal A is a digital signal, and PSK modulation is performed on the output from oscillator 3 in PSK modulator 1 . For example, let the output voltage of the oscillator 3 be R cos (mountain, t tenths,)
Expressed as follows, in two-phase PSK modulation, the logic of signal A is “0”
”, the above phase is PSK modulated to 00,1800, and in 4-phase PSK modulation, the logic of signal A is “00” “0
1”, “10”, “11”, the phase is 00も9
007 PSK modulated to 1800, 2700. In actual FSK modulation, polyphase PSK modulation with four or more phases is also used, but in the following description, for convenience of explanation, two-phase PSK modulation is used.
SK modulation will be explained. cos(of,t180o
)=-cos(■, t0oo), so the output signal S, (t) of PSK modulator 1 is S, (t)=French (t)・co
s(.t+○,)... can be expressed as [1}.

Here, the value (t) is 11 when the logic of the signal A is "0", and -1 when the logic of the signal A is "1". Although the amplitude of S,(t) is generally not 1, it is considered as being normalized to 1. (
In the following, the amplitudes of all signals will be normalized to 1. ) digital signal A and the output voltage R cos of the oscillator 3 (■, t
For example, a ring modulator is used as a circuit for obtaining the signal S, (t) from ◇, ). frequency converter 2,
21, mixers 13 and 14, and PSK modulator 22, for example, ring modulators are used. The signal S,(t) is frequency-converted by the oscillator 4 in the frequency converter 2, and the output signal B of the frequency converter 2 is S,(t)=
ri(t)・cos(mountain 2t+◇2)・・・・・■.

Here, it is assumed that the oscillator 4 is oscillating at an angular frequency and phase of 2-1, 2-, and 2-. Signal B is received by the slave station via the communication channel and becomes signal C, which is frequency-converted by the oscillator 16 in the mixer 14, and the output signal S3(t) of the mixer 14 is SI(t), whiteboard(t), COS(3t)
+? 3).・・・． ...[It becomes 3'.

Here, it is assumed that the oscillator 16 is oscillating at an angular frequency and phase of 31-2, 3-3 and 2. Carrier wave regeneration circuit 1
8, the carrier wave is regenerated from the signal S3(t), but the signal S
If 3(t) is directly added to the filter, the carrier wave cannot be extracted.

The reason for this is that as mentioned earlier, Buddha (t) becomes 11 or -1, and the frequency of 11 and -1 are the same over a long period of time, so the time average of Buddha (t) Value Buddha (
This is because t) is usually considered to be zero. This means that in the case of four-phase modulation, the frequency of the phase being 00 and the frequency of 1800
Since the frequencies of 90o and 270o are the same, it can be considered that the time average value of the amplitude becomes zero in the same way. Therefore, in the carrier regeneration circuit 18, S (
t) and extract the carrier wave from it. In other words, S chamber (t) = Buddha 2 (t) / COS 2 (3 at 3t +) =
Buddha 2 (t) {cos (2 3t + 2 less 3) 11}/2
......[4} and mountain 2 (t
) is always positive and the time average value of 2(t) never becomes 0, so the signal S(t) to cos(2 of 3t+203)
The carrier wave can be extracted using a filter.

In the carrier regeneration circuit 18, the cos(2
The frequency of the carrier wave of 3t + 203
(3t+ = 3) of conveyed objects are obtained. By the way, since noise mixed in the communication path etc. is added to the signal S3(t), the carrier wave extracted by the carrier wave regeneration circuit 18 includes spurious components due to the noise.

In order to remove this spurious component, the voltage controlled oscillator 1
The oscillation frequencies of 7 are phase-synchronized with the output of the carrier wave regeneration circuit 18 via the phase comparator 19. Due to the low-pass filtering effect of the APC (automatic phase control) loop including this phase comparator 19, the spurious component contained in the output of the carrier wave regeneration circuit 18 does not reach the control voltage of the voltage controlled oscillator 17. The output is a highly pure sine wave. Synchronous detection is performed in the PSK demodulator 15, and its output signal D is S3(t)・COS(■3t
+3)=shi(t)・COS2(3t10○3){1
1C○S (2 of 3t 12gu3)}/2 becomes 2 Buddhas (t), and extracts Buddha (t) through a low-pass filter.

PSK modulator 22, frequency converter 21, oscillator 24
, 23 are the same as those of the PSK modulator 1, frequency converter 2, and oscillators 3 and 4, respectively.
In time-division transmission, the slave station transmits signals only during the time allotted to its own station.

Mixer 13, oscillator 9, carrier wave regeneration circuit 11, phase comparator 10, voltage controlled oscillator 8, PS in the receiving system of the main station
The operation of the K demodulator 12 is the mixer 4 and the oscillator 16, respectively.
, the carrier wave regeneration circuit 18, the phase comparator 19, the voltage controlled oscillator 17, and the PSK demodulator 15. However, in the main station, in order to receive and demodulate transmissions from a plurality of slave stations, the switch 5, 6 and a voltage holding circuit 7. One voltage holding circuit 7 is provided for each slave station, and during reception for that slave station, the voltage holding circuit 7 for that slave station controls the output of the phase comparator 10 and the voltage by switches 5 and 6. It is connected between the input of the oscillator 8, and when reception for that slave station ends and reception for another slave station starts, it is disconnected by switches 5 and 6, and the output of the phase comparator 10 for the slave station is stored. Then, when reception to the slave station is resumed, control of the voltage controlled oscillator 8 is started using the voltage stored in the corresponding voltage holding circuit 7. By the way, since the voltage controlled oscillator 8 is controlled by the voltage stored in the voltage holding circuit 7, when switching from one slave station to another, even if the frequency is controlled correctly, there is a phase error, so phase comparison is necessary. The phase-locked loop composed of the voltage control circuit 10, the voltage holding circuit 7, and the voltage-controlled oscillator 8 must be designed to perform a high-speed pull-in operation. This has the disadvantage that it has to be extended to a high frequency range, and then noise cannot be suppressed, making it difficult to design an actual circuit. This invention was made to eliminate the above-mentioned drawbacks of the conventional system, and all carrier waves including the main station and all slave stations are synchronized, and the main station is equipped with an exposure pressure control phase modulation circuit and a voltage holding circuit. The purpose of the present invention is to provide a carrier wave regeneration circuit that can perform multi-directional multiplexing, thereby eliminating the need for a pull-in operation.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a block connection diagram showing an embodiment of the present invention, and the same reference numerals as in FIG. 1 indicate the same or corresponding parts.
However, oscillators 4 and 9 are controlled by the output of oscillator 3 and are phase-locked thereby, and oscillators 16 and 29 are controlled by and phase-locked by the output of voltage-controlled oscillator 17. In this sense, the oscillator 3 is called the main oscillator. 25 again
is a voltage controlled phase modulation circuit. Since the signal conversion process in the circuit shown in FIG. 2 is the same as that in the circuit shown in FIG. 1, its explanation will be omitted.

Let the output frequencies of oscillators 3, 4, 9, 16, 17, and 23 be f3, L,, f9, f, 6, f, 7, and f23, respectively, and L;k, f3, f, 6=k, f,? If selected as follows, the frequency of the signal B will be f40, for example, and the output frequency of the mixer 14 will be f40 f3-f,6. Through the loop, f4 + f3-f,6=f,7, and f
40 et al. = f. 70f. 6, (10k.) f3 = (10k
．． ) from f,7, f3=f,7, and if the loop gain of the phase-locked loop is increased, the phase difference between both inputs of the phase comparator 19 becomes smaller. Also 3=k2f,7,
If selected as: k2f3, the output frequency of the mixer 13 will be f,7+3-f9, but since f,7=f3, f,7+f23-f9=f3, and the output frequency of the oscillator 3. Match.

Therefore, the frequencies of both inputs of the phase comparator 10 are the same, and there is no need to control the oscillation frequency by the output of the phase comparator 10 as in the circuit shown in FIG. That is, in the circuit shown in FIG. 2, the voltage control phase modulation circuit 25 is controlled by the output of the phase comparator 10. The loop gain of the feedback control loop constituted by the voltage controlled phase modulation circuit 25 and the phase comparator 10 is increased to reduce the phase error between both inputs of the phase comparator 10 by 4. The operations of the switches 5 and 6 and the voltage holding circuit 7 are the same as in the case of FIG. This voltage is applied as a control voltage and is controlled so that the phase of its output is almost equal to the output phase of the carrier wave regeneration circuit 11. Therefore, when receiving the same slave station again, this voltage is applied to the switches 5 and 6.
If it is applied to the voltage controlled phase modulation circuit 25 via the voltage controlled phase modulation circuit 25, the output phase of the voltage controlled phase modulation circuit 25 will be almost the same as the output phase of the carrier wave regeneration circuit 11 at that time, even if no pull-in operation is performed at the switching point, resulting in PSK demodulation. Demodulation with high reliability can be performed in the circuit 12.

As described above, according to the present invention, it is possible to eliminate the need for a phase synchronization pull-in operation at the time of switching of slave stations in time division multidirectional multiplexing, and the reliability in the case of coherent detection in PSK demodulation is greatly improved. can be improved.

[Brief explanation of the drawing]

Figure 1 is a block connection diagram L2 showing an example of a conventional device.
The figure is a block connection diagram showing one embodiment of the present invention. In the figure, 1 and 22 are PSK modulators, 2 and 21 respectively.
are frequency converters, 3 is the main oscillator, 4, 9,
16 and 23 are carrier wave oscillators, 5 and 6 are switches, 7 is a voltage holding circuit, 10 and 19 are phase comparators, respectively, 11 and 18 are carrier wave regeneration circuits, and 1
2 and 15 are PSK demodulators, 13 and 14 are mixers, and 17 is a voltage controlled oscillator. Note that the same reference numerals in each figure indicate the same or equivalent parts. Figure 1 Figure 2

Claims (1)

[Claims] 1 When a time-division multidirectional communication path is configured between a main station and multiple slave stations, the main oscillator installed in the main station and all carrier waves used within the main station are set to the output frequency of the main oscillator. means for phase synchronizing, a voltage controlled oscillator provided in each of the slave stations, a carrier wave regeneration circuit for receiving transmission from the master station in each of the slave stations and regenerating a carrier wave from the received output, and an output of the carrier wave recovery circuit. a phase-locked loop for synchronizing the phase of the output frequency of the voltage-controlled oscillator, means for phase-synchronizing all carrier waves used in each of the slave stations with the output frequency of the voltage-controlled oscillator; a voltage-controlled phase modulation circuit that inputs the output of the oscillator, gives an adjustable phase shift amount, and outputs the output; and a carrier wave regeneration circuit that receives transmissions from each of the slave stations in the main station and reproduces a carrier wave from the received output. , a phase comparator for detecting a phase difference between the output of the carrier wave regeneration circuit and the output of the voltage-controlled phase modulation circuit, means for feedback-controlling the voltage-controlled phase modulation circuit using the output of the phase comparator, and each slave station. A voltage holding circuit stores the output of the phase comparator for transmission for each slave station, and when a transmission from one slave station is being received, the output of the phase comparator is subjected to the voltage control phase modulation via the voltage holding circuit corresponding to that slave station. A time division multidirectional multiplex synchronization circuit characterized by comprising a switch added to the circuit.