JPH0738616A - Data receiver - Google Patents

Abstract

PURPOSE:To eliminate a transmission error due to a carrier frequency difference by establishing quickly and surely the synchronization with a carrier frequency of a received signal based on the result of identification so as to decode QPSK data. CONSTITUTION:An oscillator 12 outputs a recovered carrier signal in a received signal Sa. A detector 13 obtains a base band signal B1 from the recovered carrier signal and the received signal Sa. Based on a zero cross signal detected from the base band signal B1, a clock recovery device 14 recovers a clock signal representing an identification timing of the base band signal B1. An identification device 15 discriminates transmission data from the clock signal Ck and the base band signal B1. A pattern detector 16 detects a pattern of a specific predetermined data string from output data of the identification device 15. A data replacement device 17 replaces output data of the identification device 15 in response to the pattern of the specific data string. QPSK data are decoded in synchronism with the carrier frequency of the received signal Sa based on the output result of the identification device 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data receiving apparatus which is used in a digital automobile telephone system or the like and which decodes QPSK data in synchronization with a carrier frequency of a received signal based on an identification result.

[0002]

2. Description of the Related Art FIG. 6 is a block diagram showing the structure of a conventional data receiving apparatus. In FIG. 6, the data receiving apparatus includes an input terminal 1 to which a received signal is supplied, an oscillator 2 for reproducing a carrier frequency in the received signal, and an input terminal 1.
And a oscillator 3 connected to the oscillator 2 to obtain a baseband signal from the received signal, a zero-cross signal is obtained from the baseband signal from the detector 3, and the baseband signal is identified based on the zero-cross signal. It has a clock regenerator 4 for regenerating a clock signal indicating timing, a discriminator 5 for discriminating transmission data from the clock signal and a baseband signal to obtain a data string, and an output terminal 6 for outputting the data string. is doing.

Next, the operation of this conventional configuration will be described. In FIG. 6, the detector 3 detects the carrier frequency component signal and the received signal in the received signal reproduced by the oscillator 2.
To get the baseband signal. If the transmission data is random data, it is 1 from the identification time of the data to the identification interval on average.
The polarity of the baseband signal changes after / 2 hours.
Therefore, the clock regenerator 4 detects the zero-cross signal output when the baseband signal from the detector 3 changes in polarity. The data discriminating timing is generated by performing the follow-up operation so that the time difference between the zero cross signal and the data discriminating timing becomes 1/2 of the data discriminating interval.

The discriminator 5 discriminates whether the baseband signal is positive or negative at the discrimination timing reproduced by the clock regenerator 4, and outputs a data string based on the discrimination result from the output terminal 6. Further, the frequency of the oscillator 2 is controlled by using the error signal at the time of the discrimination by the discriminator 5 so as to follow the carrier frequency.

As described above, the above conventional data receiving apparatus can decode data without error.

[0006]

However, in the above-described conventional data receiving apparatus, the carrier frequency difference is larger than ± 1/8 of the symbol transmission rate of the transmission data due to the relative accuracy of the oscillators of the transmission station and the reception station. May be.
Therefore, the reception pattern of the phase difference at the receiving station is different from the conventional one, and there is a problem that a transmission error occurs.

The present invention solves such a conventional problem. Based on the identification result, the synchronization with the carrier frequency of the received signal can be quickly and surely established to decode the QPSK data and the carrier frequency difference. It is an object of the present invention to provide an excellent data receiving device that eliminates transmission errors caused by the above.

[0008]

To achieve the above object, a data receiving apparatus of the present invention obtains a baseband signal from an oscillating means for outputting a reproduced carrier signal in a received signal and a reproduced carrier signal and the received signal. Detection means, clock reproduction means for reproducing a clock signal indicating the identification timing of the baseband signal based on the zero-cross signal detected from the baseband signal, and identification for discriminating transmission data from the clock signal and the baseband signal. Means, pattern detecting means for detecting a pattern of a predetermined specific data string from the output data of the identifying means, and data replacing means for replacing the output data of the identifying means according to the pattern of the specific data string. A configuration for decoding the QPSK data in synchronization with the carrier frequency of the received signal based on the output result of the identification means, To have. Also, from the carrier frequency in the received signal to 1/8 of the symbol transmission rate of the transmission data
Oscillation means for obtaining a reproduced carrier signal of a high frequency component, detection means for obtaining a baseband signal from the reproduced carrier signal and a received signal, and detection timing of the baseband signal based on the zero cross signal when detected from the baseband signal. Clock reproduction means for reproducing the clock signal shown, identification means for discriminating transmission data from the clock signal and baseband signal, and pattern detection means for detecting a pattern of a predetermined specific data string from output data of the identification means A data replacing unit that replaces the output data of the identifying unit according to the pattern of the specific data string, and decodes the π / 4 shift QPSK data in synchronization with the carrier frequency of the received signal based on the output result of the identifying unit. This is the configuration.

Instead of the oscillating means in this configuration, the oscillating means is configured to obtain a reproduced carrier signal having a frequency component which is ⅛ lower than the symbol transmission rate of transmission data from the carrier frequency of the received signal.

[0010]

With such a configuration, the data receiving apparatus of the present invention discriminates the transmission data from the clock signal indicating the identification timing of the generated baseband signal and the baseband signal, and the predetermined specific data string. The output data identified by detecting the pattern is replaced. In this case, when the carrier frequency difference is larger than ± 1/8 of the symbol transmission rate of the transmission data, the carrier frequency difference is detected and corrected using a specific data pattern. Therefore, based on the identification result, the synchronization with the carrier frequency of the received signal can be quickly and surely established to decode the QPSK data, and the transmission error due to the carrier frequency difference is eliminated.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a data receiving apparatus of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the data receiving apparatus of the present invention. In FIG. 1, the data receiving apparatus includes an input terminal 11 to which a received signal Sa is supplied, an oscillator 12 for obtaining a reproduced carrier signal S1 of a carrier frequency component of the received signal Sa, and a reproduced carrier signal S1 from the oscillator 12. Signal Sa to baseband signal B
And a detector 13 that outputs 1.

Further, in this data receiving apparatus, a clock regenerator 14 for retrieving a clock signal Ck indicating the identification timing of the baseband signal B1 by obtaining a zero-cross signal from the baseband signal B1 from the detector 13, and a clock A discriminator 15 for discriminating the data transmitted from the signal Ck and the baseband signal B1, and a pattern detector 16 for detecting the coincidence between the data from the discriminator 15 and a predetermined data string and controlling the timing. And have.
The data receiving apparatus also includes a data replacing unit 17 that replaces the data output from the identifying unit 15 according to the pattern detected by the pattern detecting unit 16, and the data replacing unit 1.
The output terminal 18 sends out the data Sd from the S.

Next, the operation of the configuration of this embodiment will be described. In the received signal Sa reproduced by the oscillator 12, the baseband signal B1 is obtained by the wave detector 13 from the reproduced carrier signal S1 and the received signal Sa.

FIG. 2 shows the baseband signal B1 in this case.
It is a figure which shows the example of a change of. In Fig. 2, the initial phase is π
When the transmission data is / 4 and the transmission data is "00", the phase change amount is π / 2. Further, the phase change amount is π in the case of “01”, and the phase change amount is 0 in the case of “10”. Further, in the case of “11”, the amount of phase change is −π / 2.

The discriminator 15 discriminates whether the baseband signal B1 output from the detector 13 is positive or negative at the discrimination timing created by the clock regenerator 14. And the result and Figure 2
The discriminator 15 outputs the data Sd based on the phase transition of. Further, the frequency of the oscillator 12 is controlled by using the error signal at the time of the discrimination by the discriminator 15 so as to follow the carrier frequency. Here, the reproduced carrier signal S1 is ⅛ of the symbol transmission rate of the transmission data as compared with the carrier signal of the received signal.
If it is higher than the above, the discriminator 15 cannot determine the detection of the carrier frequency higher than ⅛.

FIG. 3 is a diagram showing the judgment of the detection of the carrier frequency higher than 1/8 by the discriminator 15. In FIG. 3, the initial phase is π / 4 and the phase change amount is π / 2 when the transmission data is “01”. Further, in the case of “11”, the amount of phase change is π, and in the case of “00”, the amount of phase change is 0. In the case of “10”, the amount of phase change is −π
/ 2. In this way, the discriminator 15 cannot judge detection at a carrier frequency higher than ⅛ of the symbol transmission rate of transmission data, and therefore discriminates based on the normal relationship between the amount of phase change and data. Therefore, the transmission data of "01" is decoded as "00". Also, the transmission data of "11" is decoded as "01", the transmission data of "00" is decoded as "10", and the transmission data of "10" is "11".
Will be decrypted. If the reproduced carrier signal S1 is lower than the carrier signal of the received signal Sa by ⅛ or more of the symbol transmission rate of the transmission data, the discriminator 15 determines that the 1
Detection of carrier frequency lower than / 8 cannot be determined.

FIG. 4 is a diagram showing the decision made by the discriminator 15 to detect a carrier frequency lower than ⅛. In FIG.
The initial phase is π / 4 and the transmitted data is “10”.
In this case, the phase change amount is π / 2. Further, in the case of “00”, the amount of phase change becomes π. In the case of “11”, the phase change amount is 0, and in the case of “01”, the phase change amount is −π /
It becomes 2. In this way, the discriminator 15 cannot judge the detection at the carrier frequency lower than ⅛ of the symbol transmission rate of the transmission data, and therefore discriminates based on the normal relationship between the amount of phase change and the data. Therefore, the transmission data of "10" is "0".
The transmission data of "00" is decoded into "01". Further, the transmission data of "11" is decoded into "10", and the transmission data of "01" is decoded into "11".

Therefore, in the data format as shown in FIG.
In the case of performing the DMA communication, it is determined whether the sync word is detected after being detected as usual, or is detected after being detected at the reproduction carrier frequency which is ± 1/8 or more of the symbol transmission rate of the transmission data. It is detected by the detector 16.

The decoding state of the sync word detected by the pattern detector 16 is determined. If the pattern detected in this judgment is different from the normal pattern, the data replacement unit 17 replaces the data so that the pattern is output as a normal pattern, and the data is output.

It is also possible to correct the frequency deviation obtained by the detected pattern with the oscillator 12. In this case, considering the frequency stability and the convergence time of the oscillator 12, the oscillator 12 corrects a minute deviation, and a large deviation close to the transmission rate of plus / minus (±) symbols / 4 is handled by replacing the data. Is highly effective in terms of reliability of synchronization with the transmitting station and speed of convergence time.

In any case, the polarity of the I signal or the polarity of the Q signal in the four patterns (00, 01, 10, 11) in the data has passed 1/2 hour of the identification interval from the identification time of the data. Since it changes with time, the clock regenerator 14 outputs the baseband signal B1 from the wave detector 13.
, The zero-cross signal output when the polarity change occurs is detected, and the follow-up operation is performed so that the time difference between the zero-cross signal and the data identification timing is 1/2 of the data identification interval and the data identification is performed. Play timing.

[0023]

As is apparent from the above description, the data receiving apparatus of the present invention discriminates the transmission data from the clock signal indicating the identification timing of the generated baseband signal and the baseband signal, and the transmission data is determined in advance. The output data identified by detecting the pattern of the specific data string is replaced. In this case, when the carrier frequency difference is larger than ± 1/8 of the symbol transmission rate of the transmission data, the carrier frequency difference is detected and corrected using a specific data pattern, so the received signal is determined based on the identification result. The effect is that synchronization with the carrier frequency can be quickly and surely established, QPSK data can be decoded, and transmission errors due to the carrier frequency difference are eliminated.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a data receiving apparatus of the present invention.

FIG. 2 is an explanatory diagram showing a change example of a baseband signal in the embodiment.

FIG. 3 is an explanatory view showing the judgment of carrier frequency detection in which the discriminator is higher than ⅛ in the embodiment.

FIG. 4 is an explanatory view showing the determination of carrier frequency detection in which the discriminator is ⅛ or lower in the embodiment.

FIG. 5 is an explanatory diagram showing a data format in TDMA communication in the embodiment.

FIG. 6 is a block diagram showing a configuration of a conventional data receiving device.

[Explanation of symbols]

 12 oscillator 13 wave detector 14 clock regenerator 15 discriminator 16 pattern detector 17 data replacer

Claims (3)

[Claims] 1. An oscillating means for outputting a reproduced carrier signal in a received signal, a detecting means for obtaining a baseband signal from the reproduced carrier signal and the received signal, and a zero-cross signal detected from the baseband signal. Clock reproduction means for reproducing a clock signal indicating the identification timing of the baseband signal, identification means for discriminating transmission data from the clock signal and the baseband signal, and a specific data string predetermined from the output data of the discrimination means Pattern detecting means for detecting the pattern of, and a data replacing means for replacing the output data of the identifying means according to the pattern of the specific data string, and the carrier frequency of the received signal based on the output result of the identifying means. QPS in sync with
A data receiving device characterized by decoding K data. 2. An oscillating means for obtaining a regenerated carrier signal having a frequency component that is ⅛ higher than a symbol transmission rate of transmission data from a carrier frequency in the received signal, and a detecting means for obtaining a baseband signal from the regenerated carrier signal and the received signal. A clock regenerating means for regenerating a clock signal indicating the identification timing of the baseband signal based on the zero-cross signal when detected from the baseband signal, and an identifying means for discriminating transmission data from the clock signal and the baseband signal. A pattern detecting means for detecting a pattern of a predetermined specific data string from the output data of the identifying means, and a data replacing means for replacing the output data of the identifying means according to the pattern of the specific data string. And is synchronized with the carrier frequency of the received signal on the basis of the output result of the identifying means to obtain a π / 4 system Data receiving apparatus characterized by decoding the bets QPSK data. 3. The oscillating means in place of the oscillating means according to claim 2, wherein the oscillating means obtains a reproduced carrier signal having a frequency component that is ⅛ lower than a symbol transmission rate of transmission data from a carrier frequency of a received signal. And a data receiving device.