JPH05122260A - Identification reproducing device - Google Patents

Abstract

PURPOSE:To provide the identification reproducing device for a GMSK demodulator adopting the orthogonal synchronization detection system in which deterioration in the amplitude of an eye pattern of a reproduction output is less and the Viterbi decoding soft discrimination system is applicable as the error correction system. CONSTITUTION:This device is provided with means 4, 5 sampling an in-phase detection output and an orthogonal detection output in each identification timing, means 7, 8 delaying a detection output after sampling by one time slot, means 9, 10 multiplying the detection signal after one time slot delay and the other detection signal before the delay respectively, and a changeover means 12 outputting alternately the two multiplier output signals synchronously with a data rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a discriminating and reproducing circuit in a demodulator of a wireless communication device using a GMSK modulation system.

[0002]

2. Description of the Related Art FIG. 2 shows a first example of a conventional identification / reproduction apparatus using a Costas loop in a GMSK demodulator of a quadrature synchronous detection system, and FIG. 3 shows a second example of a conventional identification / reproduction apparatus using difference processing. For example: Hereinafter, a conventional example will be described with reference to FIGS.

In FIG. 3, the in-phase detection output υ _I and the quadrature detection output υ _Q are obtained by passing the GMSK modulated wave input from the modulated wave input terminal 1 through the quadrature synchronous detector 2.
In the orthogonal synchronous detection method of GMSK, a correct code string cannot be reproduced unless the difference processing is performed on υ _I and υ _Q obtained.

In the conventional device shown in FIG. 3, the detection output υ
_The difference processing is performed for _I and υ _{Q in an} analog manner by the multipliers 9 and 10 and the subtractor 19. However, GMSK
In the modulation method, the phase change at the change point of the data polarity becomes gradual due to the influence of the band limiting filter on the transmission side. Therefore, the distortion of the demodulated signal on the reception side caused by this change is However, there is a problem that the amplitude of the decoded eye pattern is extremely deteriorated depending on the pattern of the code string that is doubled by the above-mentioned analog difference processing. FIG. 4 shows an eye pattern waveform diagram of reproduction output by the identification reproducing apparatus of FIG.

On the other hand, the in-phase detection output υ _I and the quadrature detection output υ _Q before the differential processing have a sufficiently open eye as compared with FIG. 4 as shown in FIG. Therefore, in another conventional example shown in FIG.
In-phase detection output υ _I and quadrature detection output υ _Q with large eye opening
Is judged by the binary judgment devices 15 and 16 with reference to the threshold voltage υ _th . OR gate 17 and EX. The difference processing is logically performed via the OR gate 18 to reproduce the code string without deterioration of the eye.

[0006]

In the circuit shown in FIG. 3 among the above-mentioned prior arts, since the subtraction processing is performed after the analog multiplication processing as the difference processing, the amplitude deterioration of the eye pattern occurs. Further, in the circuit shown in FIG. 2, the difference processing is constituted only by the multiplication processing (EX.OR), but since the data is binarized by the binary discriminator before the correct code string is reproduced, it is decoded. There is a drawback in that the Viterbi decoding soft decision method, in which the analog amount of the amplitude value in the eye pattern of the code string becomes important information, cannot be applied.

The present invention has been made in order to eliminate these drawbacks, the Viterbi reconstruction soft decision method can be applied as an error correction method, and the amplitude deterioration of the eye pattern of the reproduced code string after the difference processing is small. An object is to provide an identification reproducing apparatus.

[0008]

In order to achieve the above object, the present invention provides an in-phase detection output υ in an identification / reproduction device.
After sampling _I and quadrature detection output υ _Q at each identification timing, one detection output is multiplied by the detection output one time slot before the other, and each output is output alternately by a switch synchronized with the data rate. It was done.

[0009]

As a result, the detection signal is sampled without binarizing the amplitude value of the quadrature synchronous detection output, and only the multiplication is performed without performing the subtraction processing that causes the amplitude deterioration of the eye pattern. The playback output is obtained with almost no amplitude deterioration and the soft decision gain is secured, and it is possible to adapt to the Viterbi reconstruction soft decision method.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIG. The modulated wave input terminal 1 is connected to the sampling gates 4 and 5 via the quadrature synchronous detector 2. The sampling gate 4 is connected to the changeover switch 12 via the multiplier 9 and the sign inverter 11, and the sampling gate 5 is connected to the changeover switch 12 via the multiplier 10. Further, the sampling gate 4 is connected to the multiplier 10 via the delay unit 7, and the sampling gate 5 is connected to the multiplier 9 via the delay unit 8. The clock regenerator 3 is connected to the sampling gate 5 and the inverter 6 via the 1/2 frequency divider 13, and the inverter 6 is connected to the sampling gate 4. further,
The clock regenerator 3 is connected to the changeover switch 12, and the changeover switch 12 is connected to the output terminal 14 for the reproduced code.

This operation will be described below. The GMSK modulated wave input from the input terminal 1 is detected as an in-phase detection output υ _I and a quadrature detection output υ _Q by passing through the quadrature synchronous detector 2. The waveforms of υ _I and υ _Q are shown in Fig. 5.

The quadrature detection output υ _Q is a clock signal CLK obtained by dividing the reproduction clock signal synchronized with the data rate by two.
Is sampled by the sampling gate 5, and the in-phase detection output υ _I is sampled by the sampling gate 4 by the clock signal bar CLK which is the inverted clock signal CLK. The sampled signals are delayed by the delay units 7 and 8.
In-phase detection output υ _I is
The quadrature detection output υ _QT before T and the quadrature detection output υ _Q are respectively multiplied by the in-phase detection output υ _IT 1 T before and the multipliers 9 and 10. Furthermore, the output of the multiplier 9 on the in-phase detection output side (υ _I ×
The sign of υ _QT ) is inverted by the sign inverter 11.

The output of the sign inverter 11 and the multiplier 10
FIG. 6 shows an eye pattern waveform diagram of the output of FIG. The signal shown in FIG. 6 is alternately output by the changeover switch 12 every T of one time slot time.

By adopting this circuit configuration, since difference processing can be performed only by multiplication without involving subtraction processing, deterioration of eye amplitude can be prevented, and since the output is not binarized, Viterbi decoding softening is possible. It can be used as judgment data.

[0015]

As described above, according to the present invention, in the GMSK demodulator using the orthogonal coherent detection method, the Viterbi decoding soft decision method can be applied as the error correction method.
Since the amplitude deterioration of the eye pattern of the reproduction code string is small, a receiver with higher demodulation efficiency can be realized, and the effect is remarkable.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall configuration of the present invention.

FIG. 2 is a block diagram showing a conventional example of an identification / reproduction device using a Costas loop in quadrature synchronous detection.

FIG. 3 is a block diagram showing a conventional example of an identification / reproduction device using difference processing.

FIG. 4 is an eye pattern waveform diagram of a reproduction code when difference processing is performed.

FIG. 5 is an eye pattern waveform diagram of an output signal of a quadrature synchronous detector.

FIG. 6 is an eye pattern waveform diagram of an input signal of a changeover switch according to the present invention.

[Explanation of symbols]

 1 Input Terminal 2 Quadrature Synchronous Detector 3 Clock Regenerator 4,5 Sampling Gate 6 Inverter 7,8 Delay Device 9,10 Multiplier 11 Sign Inverter 12 Changeover Switch 13 2 Divider 14 Output Terminal 15,16 Binary Judgment Vessel 17, 18 EX. OR gate 19 Subtractor

Claims (2)

[Claims] 1. In a discriminating and reproducing apparatus for a GMSK demodulator using a quadrature synchronous detection method, a means for sampling the in-phase detection output and the quadrature detection output at each discrimination timing, and each detection output after the sampling for one time. Means for slot delay,
Means for multiplying one detection output signal after the one time slot delay and the other detection output signal before the delay, and switching means for alternately outputting the two multiplication output signals in synchronization with the data rate. An identification / reproduction device comprising: 2. A receiver of the GMSK synchronous detection system comprising the identification / reproduction device according to claim 1.