JPS61187454A - Phase device with burst switch - Google Patents

Abstract

PURPOSE:To improve the deterioration in error rate due to phase shift by using a phase device with a burst switch to match the phase difference of two carriers fed to a PSK modulator to 90 deg.. CONSTITUTION:An output wave of a carrier generator 6 divided by a branch circuit 15 becomes waves having a phase difference of 180 deg. through NAND circuits 9-1 and 9-2 and fed to the 1st phase device comprising a variable resistor 10 and a capacitor 12 and the 2nd phase detector comprising a variable resistor 11, a coil 14 and a capacitor 13. In adjusting the variable resistors 10, 11 to advance the phase of the wave through the NAND circuit 9-1 in the 1st phase device and retarding the wave through the NAND circuit 9-2 in the 2nd phase device respectively by 45 deg., the phase difference of the two waves is 90 deg. and the waves are fed to a PSK modulator through NAND circuits 9-3, 9-4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a phase shift key with a burst switch used in, for example, a four-phase phase shift key ink for satellite communication ~ (hereinafter abbreviated as four-phase PSK) burst modulator. It concerns the improvement of utensils.

Generally, when a number of earth stations communicate with each other using a common satellite repeater, a PSK-TDMA (time division multiple access) scheme is often used.

FIG. 2 shows a conceptual diagram of the PSK-TDMA system.

In the figure, earth station A multiplexes, for example, a PCM-modulated transmission signal in a time-division manner (the "Pc)'IT-TDM" part), modulates the carrier wave with this signal to ps, and uses the signal to transmit a PCM-modulated transmission signal into the time slot assigned to the own station. Since the burst PSK waves are sent to each earth station via the satellite repeater, the transmission signal from earth station A is received at each earth station ("PSK-TDMA").
” part).

Here, there are PSK modulation methods such as 2-phase, 4-phase, 8-phase, etc., and the more phases there are, the more the amount of information transmitted by one carrier wave increases, but the performance of the equipment Requirements will become stricter. Therefore, taking these into consideration, the four-phase PSK modulation method is widely used.

FIG. 3 shows a block diagram of a 4-phase PS modulator.

As shown in the figure, two channels of data, data 1 and data 2, applied to terminals IN-1 and IN-2 pass through low-pass filters 1 and 2, respectively, to PSK modulators 3 and 2.
Added to 4.

On the other hand, the output wave from the carrier wave generator 6 is converted by a phase shifter 5 with a burst switch into two waves having a phase difference of 90 degrees, and then applied to the same PSK modulators 3 and 4.

Therefore, the two waves are converted into a two-phase PSK wave using data 1 and 2, respectively, and this wave is combined by a synthesizer 6 and converted into a 2-phase PSK wave.
A wave on the phase PS is taken out from the terminal OUT.

Note that a burst switch (not shown) in the phase shifter 5 is turned on/off by a burst enable signal inputted from the outside, and the four-phase PSK wave becomes burst-like.

Here, if the phase difference between the two carrier waves obtained from the phase shifter 5 deviates from 90 degrees, when the receiving side restores the original data,
Since the error rate deteriorates in proportion to the deviation, it is necessary to reduce the length that can accommodate this deviation.

[Conventional technology]

FIG. 4 shows a block diagram of a conventional phase shifter with a burst switch.

In the figure, for example, the number 10 obtained from the carrier wave generator 6 is
The MHz wave is transmitted through a burst switch 7-1, 7-2, which is made of, for example, an emisotakanpurudodisoku type AND gate.
The signal passes through the 90-degree hybrid circuit 8 and is split into two waves, which are applied to the PSK modulators 3 and 4.

Since the two burst switches 7-1 and 7-2 are turned on and off by an external burst enable signal, the PSK wave described above becomes burst-like.

The reason why two burst switches are provided in series is to reduce leakage signals when the switch is off.

Problems to be solved by the invention C] Commercially available 90 degree hybrid circuits have a phase difference of 90 degrees between the output waves at a specified operating frequency (not necessarily the same as the desired frequency), but at other frequencies Then it deviates from 90 degrees. Therefore, a 4-phase PS using such a carrier wave
When the original data is extracted from the K wave, there is a problem in that the error rate deteriorates by the amount of deviation from 90 degrees.

[Means for solving problems]

The above problem consists of first and second switches that simultaneously turn on and off the divided carrier waves, and shifts the phases of the carrier waves that have passed through the first and second switches so as to create a predetermined phase difference. At least one of them is solved by a phase shifter with a burst switch, which is composed of variable first and second phase shifters.

[Effect]

The present invention converts the output waves of the divided carrier wave generators into waves with a predetermined phase difference through separately provided variable phase shifters.
I added it to the PSK modulator.

Conventionally, if the phase difference of the output wave deviated from 90 degrees, there was no part to compensate for this deviation, so the 4-phase PS
It was generating K waves.

In the present invention, two phase shifters are used to advance the output wave of the carrier wave generator by, for example, +45 degrees and -45 degrees, that is, 9
A wave with a phase difference of 0 degrees is applied to the PSK modulator, but if the phase difference is not 90 degrees, it can be adjusted to 90 degrees. .

Therefore, it is possible to improve the deterioration of the error rate that occurs when the phase difference deviates from 90 degrees.

〔Example〕

The contents of the present invention will be specifically explained below with reference to illustrated embodiments. Note that the same reference numerals indicate the same objects throughout the figures.

FIG. 1 shows a block diagram of one embodiment of the invention.

In the figure, a carrier wave generator 6 is divided by a branch circuit 15.
The output wave of 180 passes through NAND circuits 9-1 and 9-2.
A first phase shifter and a variable resistor 11 constituted by a variable resistor 10 degree capacitor 12 form a wave with a phase difference of 10 degrees.
．． Line ring 14. A second phase shifter consisting of a capacitor 13 is added.

The first phase shifter advances the phase of the wave passing through the NAND circuit 9-1 by 45 degrees, and the second phase shifter advances the phase of the wave passing through the NAND circuit 9-2 by -45 degrees using a variable resistor of 10 degrees. When II is adjusted, the phase difference between the two waves is 90 degrees, and this wave is applied to a PSK modulator (not shown) through a NAND circuit 9-3.9-4.

Here, 9 indicates a switch section, and 9-1 and 9-2 indicate first and second switches.

〔Effect of the invention〕

As explained in detail above, the phase shifter with a burst switch allows the phase difference between the two carrier waves supplied to the ISK modulator to be adjusted to 90 degrees, which improves error rate degradation due to phase shift. In addition, since the AND circuits 9-1 to 9-4 are housed in the same package, this part can be made smaller.

FIG. 2 is a conceptual diagram of the PSK-TDMA system, FIG. 3 is a block diagram of a four-phase PSK modulator, and FIG. 4 is a block diagram of a conventional example.

In the figure, 6 is a carrier wave generator; 9 is a switch, 10.11 is a variable resistor, 12 and 13 are capacitors, 14 is a wire ring, 15 indicates a branch circuit.

Self-sufficient 1st part 2nd @

Claims (1)

[Claims] The first and second channels simultaneously turn on and off the divided carrier waves.
and first and second phase shifters, at least one of which is variable, for shifting the phase of the carrier waves passing through the first and second switches so as to produce a predetermined phase difference. Phaser with burst switch.