JP3923351B2 - Delay detection receiver - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a delay detection receiver used, for example, in a digital mobile communication system.
[0002]
[Prior art]
In general, a phase signal demodulated by a delay detection receiver is limited by a limiter, and is a nonlinear signal. Therefore, when a digital filter is applied, distortion occurs in the signal. The phase signal is a polar coordinate signal displayed in polar coordinates, and is not suitable for a digital filter that handles a rectangular coordinate signal in a rectangular coordinate system. Therefore, as a method of suppressing the interference wave when using delay detection, an analog bandpass filter is used instead of a digital filter.
[0003]
FIG. 2 is a block diagram showing a configuration of a conventional delay detection receiver using an analog bandpass filter. In the figure, 1 is an analog bandpass filter that attenuates an interference wave included in a received signal, 2 is a limiter amplifier that makes the amplitude of the received signal constant, and 3 is a polar signal that is a phase signal from the output signal of the limiter amplifier. A phase detector 7 is a delay detector that demodulates data from the detected polar coordinate signal by delay detection.
[0004]
Next, the operation will be described.
The analog bandpass filter 1 attenuates the interference wave included in the input reception signal. In this case, for example, in order to suppress the interference wave of the adjacent channel close to the frequency of the desired wave of the reception signal, the cutoff frequency is around Therefore, it is necessary to use the analog bandpass filter 1 having a very steep frequency characteristic. The limiter amplifier 2 makes the amplitude of the received signal constant, and the phase detector 3 detects a polar coordinate signal that is a phase signal from the output signal of the limiter amplifier 2. The delay detection unit 7 demodulates and outputs data from the detected polar coordinate signal by delay detection.
[0005]
If the analog bandpass filter 1 having such a steep frequency characteristic is realized, the group delay characteristic in the pass band is deteriorated, and the reception sensitivity characteristic is deteriorated. Moreover, even if the analog bandpass filter 1 having high performance in both frequency characteristics and group delay characteristics can be realized, there is a disadvantage that it becomes very expensive or large.
[0006]
[Problems to be solved by the invention]
Since the conventional delay detection receiver is configured as described above, if the analog bandpass filter 1 is used only to suppress the interference wave of the adjacent channel close to the frequency of the desired signal of the received signal, the analog bandpass filter 1 The required frequency characteristics are severe and difficult to realize, and even if it can be realized, there is a problem that the analog bandpass filter 1 becomes very expensive or large.
[0007]
The present invention has been made in order to solve the above-described problems, and does not impose strict conditions on the analog bandpass filter 1, and uses an inexpensive and small analog bandpass filter 1 to prevent adjacent channel interference waves. An object is to obtain a delay detection receiver that can be suppressed.
[0008]
[Means for Solving the Problems]
A delay detection receiver according to the present invention includes an analog bandpass filter that suppresses an interference wave included in a received signal, and a first coordinate conversion that converts a polar coordinate signal detected by a phase detection unit into an orthogonal coordinate signal having a constant amplitude. parts and the interference wave included in the rectangular coordinate signal while suppressing the convolution operation, in which a digital filter having an attenuation characteristic which does not cause a waveform distortion due to convolution operation.
[0009]
In the delay detection receiver according to the present invention, the analog bandpass filter and the digital filter suppress the interference wave of the adjacent channel close to the frequency of the received signal.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below.
Embodiment 1 FIG.
1 is a block diagram showing a configuration of a delay detection receiver according to Embodiment 1 of the present invention. In the figure, 1 is an analog bandpass filter that suppresses the interference wave of the adjacent channel included in the received signal, 2 is a limiter amplifier that makes the amplitude of the received signal constant, and 3 is the phase information of the received signal with constant amplitude. It is a phase detection part which detects a certain polar coordinate signal.
[0011]
In FIG. 1, 4 is a coordinate conversion unit (first coordinate conversion unit) that converts a polar coordinate signal into an orthogonal coordinate signal having a constant amplitude, and 5 is a convolution operation of an interference wave of an adjacent channel included in the orthogonal coordinate signal. A digital filter to be suppressed, 6 is a coordinate conversion unit (second coordinate conversion unit) that converts an orthogonal coordinate signal from the digital filter 5 into a polar coordinate signal, and 7 is a delay detection unit that demodulates data from the polar coordinate signal by delay detection. .
[0012]
Next, the operation will be described.
The analog bandpass filter 1 suppresses the adjacent channel signal included in the input reception signal to some extent, and the limiter amplifier 2 outputs the reception signal from the analog bandpass filter 1 with a constant amplitude. The phase detector 3 detects a polar coordinate signal that is phase information of the received signal having a constant amplitude. Since the phase information from the phase detector 3 is a polar coordinate signal, the convolution operation by the digital filter 5 cannot be performed as it is. Therefore, the coordinate conversion unit 4 converts the polar coordinate signal into an orthogonal coordinate signal having a constant amplitude (φ → xy coordinate conversion).
[0013]
The digital filter 5 suppresses the interference wave of the adjacent channel included in the orthogonal coordinate signal by a convolution operation, and outputs an orthogonal coordinate signal from which the interference wave of the adjacent channel is removed. In this case, since the data spectrum with a constant amplitude includes a harmonic component, if the convolution operation by the digital filter 5 is performed, the polar coordinate signal may be distorted. Here, the digital filter 5 having a moderate attenuation characteristic of, for example, 2 to 3 dB and having a filter tap coefficient that does not deteriorate the reception sensitivity due to waveform distortion is used. As described above, the analog channel pass filter 1 and the digital filter 5 are used to improve the adjacent channel selectivity of the delay detection receiver.
[0014]
The coordinate conversion unit 6 converts the orthogonal coordinate signal from which the interference wave of the adjacent channel is removed into a polar coordinate signal (xy → φ coordinate conversion), and the delay detection unit 7 removes the interference wave of the adjacent channel from the polar coordinate signal by delay detection. Data is demodulated and output.
[0015]
As described above, according to the first embodiment, the analog bandpass filter 1 is stricter by using the analog bandpass filter 1 and the digital filter 5 to improve the adjacent channel selectivity of the delay detection receiver. There is an effect that the interference wave of the adjacent channel can be suppressed by using the inexpensive and small analog bandpass filter 1 without imposing conditions.
[0016]
【The invention's effect】
As described above, according to the present invention, by using the analog bandpass filter and the digital filter to improve the adjacent channel selectivity of the delay detection receiver, the analog bandpass filter is not subject to severe conditions, There is an effect that an interference wave can be suppressed by using an inexpensive and small analog bandpass filter.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a delay detection receiver according to a first embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration of a conventional delay detection receiver.
[Explanation of symbols]
1 Analog bandpass filter, 2 Limiter amplifier, 3 Phase detector, 4
Coordinate converter, 5 digital filter, 6 coordinate converter, 7 delay detector.

Claims (2)

An analog bandpass filter that suppresses jamming contained in the received signal;
A limiter amplifier that makes the amplitude of the received signal from the analog bandpass filter constant;
A phase detector that detects a polar coordinate signal that is phase information of a received signal whose amplitude is constant;
A first coordinate conversion unit that converts the polar coordinate signal detected by the phase detection unit into an orthogonal coordinate signal having a constant amplitude;
Thereby suppressing the convolution operation the interference wave included in transformed rectangular coordinate signal by the first coordinate conversion unit, a digital filter having an attenuation characteristic which does not cause a waveform distortion due to the convolution operation,
A second coordinate conversion unit that converts the orthogonal coordinate signal in which the interference wave is suppressed by the digital filter into a polar coordinate signal;
A delay detection receiver comprising: a delay detection unit that demodulates data from the polar coordinate signal converted by the second coordinate conversion unit by delay detection.   2. The delay detection receiver according to claim 1, wherein the analog band-pass filter and the digital filter suppress the interference wave of an adjacent channel close to the frequency of the reception signal.

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