JPH04114537A - Data reception equipment - Google Patents

Abstract

PURPOSE:To suppress waveform distortion by providing a means converting a reception signal into an intermediate frequency signal by means of the output of a voltage control oscillator(VCO) and a means impressing a control voltage on the voltage control oscillator so that the frequency deviation of a detected phase is canceled. CONSTITUTION:A phase detector 6 detects the phase of an IF signal 5 based on the oscillator 14 and outputs the detected phase. A decoder 8 obtains decoding data 9 from the time change of the detected phase 7. When the frequency of the output of VCO 3 differs from the frequency of the oscillator in a transmitter, the output of VCO 3 is adjusted and the difference needs to be absorbed since the deterioration of an error rate occurs. A reference frequency controller 10 detects the positive and negative bias of a change amount in the detected phase 7 and outputs a reference frequency control signal 11 so as to cancel it. When it is a digital signal, a DA converter 12 converts it into a frequency control voltage 13 so as to control the output frequency of VCO 3 by the voltage. Thus, waveform distortion owing to the disturbance of a transmission characteristic in a filter can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a data receiving device used in digital wireless communications and the like.

BACKGROUND ART FIG. 2 shows the configuration of a conventional data receiving device. In FIG. 2, 1 is the received signal, which enters the multiplier 2 together with the output of the oscillator 17, and its output is sent to the bandpass filter 4.
, becomes IFF signal 6, enters phase detector 6, becomes detected phase 7, and enters decoder 8 and reference frequency controller 1o.

9 is decoded data. 11 is a reference frequency control signal;
It enters a reference signal generator 16 and outputs a reference signal 16.

Next, the operation of the above conventional example will be explained. In FIG. 2, the received signal 1 is the output of the oscillator 17 (carrier frequency,
That is, the IP signal 6 is obtained by multiplying by IP (intermediate frequency; fo)) in a multiplier 2 and passing through a bandpass filter 4 (center frequency fo). Based on the reference signal 16 (frequency is M-fo; M is an integer), the phase detector 6
Outputs IF signal 6 and output phase 7. The decoder 8 obtains decoded data 9 from the temporal change in the detected phase 70.

Since the frequency of the oscillator 17 does not necessarily match the frequency of the transmitter, there is a risk that this error rate will deteriorate.

For this reason, it is necessary to adjust the frequency of the reference signal 16 to absorb the frequency difference, and the reference frequency controller 1o detects the positive/negative deviation of the amount of change in the detection phase 7 and sends the reference frequency control signal to cancel it. 11 and the reference signal generator 16
and adjusts the reference signal 16.

In this manner, even in the conventional data receiving device described above, the difference between the frequency of the oscillator of the transmitter and the frequency of the oscillator 170 can be detected by the reference frequency controller 1o and absorbed by controlling the reference signal generator 16.

Problems to be Solved by the Invention However, in the conventional data receiving device described above, the difference between the oscillation frequencies of the transmitter and the receiver can only be absorbed after passing through the bandpass filter, and the center frequency of the signal when passing through the bandpass filter is within the band. Unlike the center frequency of the pass filter,
There is a problem in that not only waveform distortion occurs due to disturbance in the transfer characteristic, but also deterioration of the S/N ratio occurs because the band of the bandpass filter is widened in consideration of the frequency shift.

The present invention solves these conventional problems.
In order to absorb the frequency difference in front of the band-pass filter, suppress waveform distortion due to disturbance of the band-pass filter's transfer characteristics, and avoid widening the band of the band-pass filter, 82
- The purpose is to provide an excellent data receiving device in which 'N does not deteriorate.

Means for Solving the Problems In order to achieve the above object, the present invention provides a voltage controlled oscillator (
a conversion means for converting a received signal into an intermediate frequency signal by the output of a VCO), a phase detector for detecting the phase of the conversion output, and a control voltage for applying a control voltage to a voltage controlled oscillator so as to cancel the frequency shift of the detected phase. This is what I did.

Effects The present invention has the following effects due to the above structure. In other words, a voltage controlled oscillator (VCO) absorbs the frequency difference between the oscillators of the transmitter and receiver before the bandpass filter, suppresses disturbances in the transfer characteristics of the bandpass filter, and further takes into account the frequency difference to create a bandpass filter. It is possible to suppress the deterioration of S/N by widening the margin of the filter band.

Embodiment FIG. 1 shows the configuration of an embodiment of the present invention. In Fig. 1, 1 is a received signal, which enters a multiplier 2 together with the output of a VCO (voltage controlled oscillator) 3, whose output passes through a bandpass filter 4, becomes an IP signal 6, enters a phase detector 6, and receives a detected phase. 7 and enters the decoder 8 and reference frequency controller 10. 9 is decoded data. Reference numeral 11 denotes a reference frequency control signal, which passes through a DA converter 12 (if the decoding process is digital processing), becomes a frequency control voltage 13, and controls the VCO 3.

Next, the operation of the above embodiment will be explained. In Fig. 1, received signal 1 is the output of VCO 3 (carrier frequency I
P (intermediate frequency; ro)) is multiplied by a multiplier 2 and passed through a bandpass filter 4 (center frequency fo) to obtain an IFF signal 5.
Oscillation frequency - Mf.

; M is an integer), the relative phase relative to the output of the IF signal 6 and 14 is detected, and the detected phase 7 is output. The decoder 8 obtains decoded data 9 from the temporal change in the detected phase 70. If the frequency of the output of the VCO 3 is different from the frequency of the oscillator of the transmitter, the error rate will deteriorate, so it is necessary to adjust the output of the VCO 3 to absorb this difference, and the reference frequency controller 10 detects this difference. Detects a positive/negative bias in the amount of change in the phase 7, outputs a reference frequency control signal 11 to cancel it, and if this is a digital signal, converts it into a frequency control voltage 13 by a DA converter 12,
The output frequency of VCO3 is adjusted by that voltage.

In this way, according to the above embodiment, by matching the output frequency of the VCO 3 with the frequency of the oscillator of the transmitter, the frequency difference between the transmitter and receiver can be absorbed before the bandpass filter. This has the advantage of being able to match the center frequency of the received signal and suppressing waveform distortion caused by disturbances in the transfer characteristics of the filter. Since the frequency difference between devices can be absorbed, there is no need to extend the band of the bandpass filter excessively in consideration of the frequency difference, and this has the effect of suppressing S/N deterioration.

Effects of the Invention As is clear from the above embodiments, the present invention has the following effects.

(1) Since the oscillation frequency difference between the transmitter and receiver can be absorbed before the band-pass filter, the center frequency of the IF multiplied signal and the center frequency of the band-pass filter can be matched, so there is no disturbance in the transfer characteristics and waveform distortion. can be suppressed.

(2) Since the oscillation frequency difference between the transmitter and receiver can be absorbed before the band-pass filter, it is not necessary to extend the band of the band-pass filter excessively, so that deterioration of S/N can be suppressed.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram of a data receiving device according to an embodiment of the present invention, and FIG. 2 is a schematic block diagram of a conventional data receiving device. 1... Received signal, 2... Multiplier, 3... VCO (
voltage controlled oscillator), 4...bandpass filter, 6.
...IF (intermediate frequency) signal, 6...phase detector, 7
...Detected phase, 8...Decoder, 9...Decoded data,
10... Reference frequency controller, 11... Reference frequency control signal, 12... DA converter, 13... Frequency control voltage, 14... Oscillator, 16... Reference signal generator, 1
6... Reference signal, 17... Oscillator.

Claims (2)

[Claims] (1) a voltage controlled oscillator; a conversion means for converting a received signal into an intermediate frequency signal using the output of the voltage controlled oscillator;
a phase detector for detecting the phase of the output of the converting means; a decoder for decoding data from a time change in the detected phase; and means for applying a control voltage to the voltage controlled oscillator so as to cancel the frequency deviation of the detected phase. A data receiving device comprising: (2) The data receiving device according to claim 1, further comprising a bandpass filter that passes the output of the converting means, and wherein the center frequency of the bandpass filter and the center frequency of the received signal converted to an intermediate frequency are matched.