JPH04123554A - Data transmitter - Google Patents

Abstract

PURPOSE:To prevent distortion of a band pass filter and deterioration in a demodulation circuit by detecting a phase difference between a transmission carrier signal of a reference signal part and a carrier signal at a receiver side and allowing the carrier signal at the receiver side to trace the transmission carrier signal. CONSTITUTION:A data fed from a data input terminal 1 to a modulation circuit 2 modulates a transmission carrier signal cosomega0t and the result is sent to a radio channel 2. A reception signal at the reception section is converted into a desired frequency and inputted to a band pass filter 5 and converted into a base band signal at a quasisynchronization detector 6, demodulated by a demodulation circuit 7 and the result is outputted to a data output terminal 12. A base band signal is generated from a decoded reference signal decoded by the demodulation circuit 7 and a phase difference detection circuit 8 of a frequency difference calculation means 13 detects a phase difference, it is fed to a phase difference averaging circuit 9, in which an average phase difference gamma is obtained and it is fed to a frequency difference calculation circuit 10. The angular frequency omega obtained therein is fed to a voltage controlled oscillator 11 to control an output of the voltage controlled oscillator 11 so as to be cosomega0t equal to the transmission carrier frequency. Thus, distortion of the band pass filter and deterioration in the demodulation circuit are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a data transmission device used in car telephones and the like.

Conventional technology FIG. 3 shows the configuration of a conventional data transmission device.

In FIG. 3, 14 is a carrier wave c with a carrier angular frequency ωO
A modulation circuit 15 modulates osωoi with data input from the data input terminal 13, and a modulation circuit 15 modulates the output of the modulation circuit 14 input via the wireless line 14a and the angular frequency (ωO+Δ
16 is a bandpass filter that passes the output of the multiplier 15 in a band, and 17 is a data output terminal for demodulating the output of the bandpass filter 16. This is a demodulation circuit that outputs data to 18.

Next, the operation of the above conventional example will be explained. In FIG. 3, data applied to the data input terminal 13 is modulated by a carrier wave with a carrier angular frequency ωO by a modulation circuit 16, and
Data is carried on this carrier wave and guided to the multiplier 15 via the wireless line 14a.

This multiplier 15 on the receiving side combines the output of the modulation circuit 14 input through the wireless line 14a and the angular frequency (ωO + Δω
) to convert to the desired frequency.

Next, the second signal has its noise removed by a bandpass filter 16, and is demodulated by a demodulation circuit 17 to reproduce the original signal.

In this way, even in the conventional data transmission apparatus described above, after Rm is applied to the data of the received signal in the modulation circuit 14, Jl! l
Data can be sent via 4a.

Problems to be Solved by the Invention However, in the conventional data transmission device described above, when a difference occurs between the carrier frequencies of transmission and reception, distortion caused by the Tatamijo filter 16 and characteristic deterioration in the AI modulation circuit 17 (particularly in the demodulation circuit If a synchronous detection method or a vase to compensate for the distortion of the wireless line is added to the system, the deterioration becomes significant), making it impossible to transmit data with high reliability.

The present invention solves these conventional problems, and aims to provide an excellent data transmission device that can transmit data with higher reliability.

Means for Solving the Problems In order to achieve the above object, the present invention modulates a transmission carrier signal using input data and a reference signal inserted from a reference signal insertion circuit, and transmits the modulated signal to the Eagle UiJ line. a modulation circuit for transmitting; A quasi-synchronous detection circuit converts the output into a baseband signal, and outputs the original data by inputting and demodulating the baseband signal, and also converts the transmission carrier from the decoded reference signal obtained by decoding the reference signal. A demodulation circuit that generates a baseband signal of a reference signal with no frequency deviation of the signal, the baseband signal output from the quasi-synchronous detection circuit, and the baseband signal generated from the demodulation circuit for each Nyquist interval. Calculate the average value of the phase difference between the two baseband signals from the phase difference at the discrimination point, and calculate the angular frequency from the average phase difference obtained from the average value obtained for each frame and the Nyquist rate, The present invention is configured to include frequency difference calculation means for shifting the receiving side carrier frequency output from the voltage controlled oscillator by this angular frequency.

Therefore, according to the present invention, by detecting the phase difference between the transmitting carrier signal of the reference signal portion and the receiving side carrier wave signal and tracking the receiving side carrier wave signal with the transmitting carrier signal, the distortion caused by the Tatamijo filter is eliminated. This has the effect that it is possible to prevent pressure and deterioration in the demodulation circuit, and to perform more reliable data transmission.

Example FIG. 1 shows the configuration of an embodiment of the present invention.

In FIG. 1, 1 is a data input terminal, and 2 is a transmission carrier wave signal COSω generated by data introduced from the data input terminal 1 and a reference signal inserted from the reference signal insertion circuit 3.
This is a modulation circuit that modulates Di and transmits it through the wireless line 2a.

4 is a modulation signal transmitted via the wireless line 2a and a carrier wave signal cos(ω
0+Δω)t, and this carrier wave signal c06(ω0+Δcv)t is a carrier wave signal having the same angular velocity as the above-mentioned transmission carrier signal.

5 is a bandpass filter which inputs the output of the multiplier 4, removes its noise component, and passes the output of the multiplier 4 through a band.

6 is a quasi-synchronous detection circuit which inputs the output signal of this bandpass filter 5 and converts it into a baseband signal, and 7 inputs and demodulates the baseband signal output from the quasi-synchronous detection circuit 6. , output the data to the data output terminal 12, and decode the reference signal. ! i! ! A signal is extracted, and a baseband signal of a reference signal without carrier frequency deviation is created using this decoded reference signal.

Reference numeral 8 denotes a phase difference detection circuit constituting the frequency difference calculation means 13, which detects the carrier frequency deviation from the baseband signal output from the quasi-synchronous detection circuit 6 and the decoded reference signal decoded by the demodulation circuit 7. This method detects the phase difference at the discrimination point for each Nyquist interval in the baseband signal of the reference signal that is not present.

Reference numeral 9 denotes a phase difference averaging circuit that constitutes the frequency difference calculation means 13, which inputs the output of the phase difference detection circuit 8 to obtain an average value, and 10 also constitutes the frequency difference calculation means 13. , is a frequency difference calculating circuit that receives the output of the phase difference averaging circuit 9, calculates the angular frequency, and shifts the angular frequency of the carrier frequency output from the voltage controlled oscillator 11 by the calculated angular frequency.

Next, the operation of the above embodiment will be explained.

In the above embodiment, from the data input terminal 1 to the modulation circuit 2
The data applied to the second
As shown in the figure, a reference signal is inserted, the modulation circuit 2 modulates the transmission carrier signal of cosωO1, and the signal is sent out to the radio line 2a.

On the other hand, in the receiving section after the multiplier 4, the received signal is output from the voltage controlled oscillator 11 by the multiplier 4 and
The signal is multiplied by the output of the modulation circuit 2, that is, the modulation signal transmitted via the signal line 2a, and converted to a desired frequency.

The output signal of this multiplier 4 is input to a bandpass filter 5, where noise is removed, and a quasi-synchronous detector 6 converts it into a baseband signal.Furthermore, it is demodulated by a demodulation circuit 7, so that the original data signal is recovered. is reproduced and output to the data output terminal 12.

Further, from the decoded reference signal obtained by decoding in the demodulation circuit 7, a baseband signal of the reference signal without carrier frequency deviation is created.

The phase difference detection circuit 8 of the frequency difference calculation means 13 calculates the phase difference between the baseband signal of the quasi-synchronous detection circuit 6 and the same baseband signal as the transmission carrier signal obtained from the reference signal at the discrimination point for each Nyquist interval. Detected.

The detection signal of this phase difference detection circuit 8 is designated as yI and is sent to the phase difference averaging circuit 9.

In this phase difference averaging circuit 9, jΔθi y++l=e yi(+=1, 2, 3..., n
−+ )−tl) Δθi(i=1.2. ・−, n
-1), smoothing is performed, and the average phase difference Δθ is determined and sent to the frequency difference calculation circuit 10.

In this frequency difference calculation circuit, when the Nyquist (symbol) rate is T, the angular frequency Δω is Δω=Δωθ/T
obtained as.

Next, this angular frequency Δω is sent to the voltage controlled oscillator 11, and Δ
The angular frequency of the carrier signal output from this voltage controlled oscillator 11 is shifted by ω, and the output of the voltage controlled oscillator 11 is adaptively controlled to be CO6ωOt, which is the same as the transmission carrier frequency.

Effects of the Invention As described above, according to the present invention, there is provided a variable g circuit that modulates a transmission carrier signal using input data and a reference signal inserted from a reference signal insertion circuit and transmits the modulated signal to a wireless line; a multiplier that multiplies the modulation signal transmitted through the wireless line and a receiving carrier signal output from the voltage controlled oscillator to convert it to a predetermined frequency; and a multiplier that converts the output of the multiplier to a baseband signal. A quasi-synchronous detection circuit, which inputs and demodulates the baseband signal to output the original data, and also generates a reference signal with no frequency deviation of the transmitted carrier signal from the decoded reference signal obtained by decoding the reference signal. A demodulation circuit that generates a baseband signal of The average value of the phase difference between the two baseband signals is calculated, and the angular frequency is calculated from the average phase difference obtained from the average value obtained for each frame and the Nyquist rate. and a frequency difference calculation means for shifting the receiving side carrier frequency output from the receiving side carrier frequency.

Therefore, by detecting the phase difference between the transmitting carrier signal of the reference signal part and the receiving carrier signal and tracking the receiving carrier signal with the transmitting carrier signal, distortion caused by the bandpass filter and deterioration in the demodulation circuit can be reduced. This has the effect that data transmission can be performed with higher reliability.

[Brief explanation of the drawing]

First, a block diagram showing a schematic configuration of a data transmission device according to an embodiment of the present invention; FIG. 2 is a signal waveform diagram for explaining the device; and third, a schematic configuration of a conventional data transmission device. FIG. 2... Modulation circuit, 2a... Eradication line, 3... Reference signal insertion circuit, 4... Multiplier, 6... Quasi-synchronous detection rtL
Circuit, 7... Demodulation circuit, 8... Phase difference detection circuit, 9
...Phase difference averaging circuit, lO...Frequency difference calculation circuit, 1
1... Voltage controlled oscillator, 13... Frequency difference calculation means. Name of the agent: Patent attorney Akira Koyaharu and two others Figure 1 Frame reference signal Diagnosis signal

Claims (1)

[Scope of Claims] A modulation circuit that modulates a transmission carrier signal using input data and a reference signal inserted from a reference signal insertion circuit and transmits the modulated signal to a wireless line; a multiplier that multiplies the modulation signal and a receiving carrier signal output from the voltage controlled oscillator to convert it to a predetermined frequency; a quasi-synchronous detection circuit that converts the output of the multiplier into a baseband signal; The baseband signal is input and demodulated to output the original data, and the baseband signal of the reference signal without frequency deviation of the transmission carrier signal is generated from the decoded reference signal obtained by decoding the reference signal. The phase difference between the baseband signal outputted from the demodulation circuit, the quasi-synchronous detection circuit, and the baseband signal generated from the demodulation circuit at the discrimination point for each Nyquist interval is used to calculate the position of both baseband signals. The receiving side calculates the average value of the phase difference, calculates the angular frequency from the average phase difference obtained from the average value obtained for each frame and the Nyquist rate, and outputs only this angular frequency from the voltage controlled oscillator. A data transmission device comprising frequency difference calculation means for shifting a carrier frequency of the data transmission device.