JP2827581B2 - Digital receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a four-phase phase modulation type digital receiver. In particular, the present invention relates to a receiver that extracts timing at the time of demodulation based on amplitude information.

[0002]

2. Description of the Related Art As shown in FIG. 4, a conventional digital receiver for performing timing extraction based on amplitude information converts a high frequency signal into an intermediate frequency signal and outputs the intermediate frequency signal.
A demodulator 2 for outputting a digital signal from the intermediate frequency signal; and an amplitude information detector 4 for detecting an amplitude fluctuation component from the intermediate frequency signal and providing the demodulator 2 with baud timing for extracting the digital signal. .

[0003]

In this conventional example, when a strong electric field is input, the output signal is saturated due to the influence of the gain of the high-frequency amplifier and the frequency conversion mixer inside the high-frequency receiving unit, and the amplitude fluctuation component is lost. Therefore, it is difficult to extract the timing in the amplitude information detection unit, and there is a disadvantage that the baud timing cannot be given to the demodulation unit.

An object of the present invention is to eliminate such a disadvantage and to provide a digital receiver which can always detect an amplitude component.

[0005]

According to the present invention, there is provided a high-frequency receiving section for inputting a high-frequency receiving signal subjected to four-phase modulation and outputting an intermediate-frequency signal, and inputting and providing an intermediate-frequency signal from the high-frequency receiving section. A demodulator for extracting and outputting a digital signal in accordance with the baud timing obtained, an intermediate frequency signal being input from the high frequency receiver, detecting an amplitude variation component thereof, and providing an amplitude for giving the baud timing to the demodulator. A digital receiver provided with an information detecting section, an intermediate frequency signal is input from the high frequency receiving section to detect an electric field intensity component thereof, and electric field information detecting section controls a gain of the high frequency receiving section in accordance with a result of the detection. It is characterized by having a part.

Here, it is desirable that the electric field information detecting section detects the electric field intensity component of the intermediate frequency signal input from the high frequency receiving section for each baud timing obtained by the amplitude information detecting section. .

[0007]

The electric field strength of the input signal is detected, and the gain of the high-frequency receiving unit is reduced so that the output of the high-frequency receiving unit is not saturated when a strong electric field is input. As a result, even when a strong electric field is input, the baud timing is extracted and the amplitude component can always be detected during demodulation.

[0008]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of this embodiment.

In this embodiment, as shown in FIG. 1, a high-frequency receiving unit 1 for inputting a four-phase modulated high-frequency receiving signal and outputting an intermediate-frequency signal, and an intermediate-frequency signal input from the high-frequency receiving unit 1 A demodulation unit 2 that extracts and outputs a digital signal in accordance with the given baud timing, and an intermediate frequency signal that is input from the high frequency receiving unit 1 to detect an amplitude fluctuation component thereof. And an amplitude information detecting unit 4 for giving a timing. Further, as a characteristic feature of the present invention, a baud timing obtained by the amplitude information detecting unit 4 is used to obtain an electric field intensity component of the intermediate frequency signal input from the high frequency receiving unit 1. And an electric field information detector 3 for controlling the gain of the high frequency receiver 1 according to the detection result.

Next, the operation of this embodiment will be described. The four-phase modulated signal input to the high-frequency receiver 1 is converted into an intermediate-frequency signal and output, demodulated by the demodulator 2 and output as a digital signal. Here, the baud timing at which the demodulation unit 2 extracts a digital signal is given from the amplitude information detection unit 4 that detects an amplitude fluctuation component from the above-mentioned intermediate frequency signal and extracts the timing. At the same time, the electric field information detector 3 monitors the electric field strength from the intermediate frequency signal at each baud timing. Here, when a four-phase phase modulation signal of a strong electric field is input, the intermediate frequency signal of the amplitude is saturated due to the saturation action of an active element such as a transistor inside the high-frequency receiving unit 1; 3
Detects a strong electric field condition and lowers the gain of the high-frequency receiver 1,
Avoid saturation of the intermediate frequency signal. The reason why the electric field detection is performed at each baud timing is that accurate information can be obtained only at the baud timing due to amplitude fluctuations due to the four-phase modulation signal.

FIG. 2 is a block diagram of another embodiment. Here, a double-spar heterodyne type digital receiver is used, and the detection of amplitude and electric field information is performed by RSSI (Received Signal S).
(Trainth Indicator) signal. FIG. 3 shows the output characteristics of the RSSI signal with respect to the input electric field. Here, the four-phase modulated signal input to the antenna 5 is converted into a first intermediate signal by the first mixer 10 and further converted to a second intermediate signal by the second mixer 13. Then, the signal is detected as a digital signal by the digital detector 17 via the intermediate wave amplifier 16 and the data terminal 2
1 outputs digital data, and the clock terminal 22 outputs its clock component. Further, the bit synchronization unit 19 is configured to output the RSSI output from the intermediate wave amplifier 16.
The amplitude fluctuation component is detected from the signal,
Gives the baud timing for detecting the digital signal. Here, the comparator 18 is set to the reference voltage Vref, that is, the voltage V1 shown in FIG. 3, and the above-mentioned baud timing is given as a comparison timing. That is, V1 is the output voltage at the time of the input electric field A immediately before the RSSI output becomes saturated. The switch 9 supplies a voltage to the high-frequency amplifier 7 in the normal ON state. In this state, when the electric field of the four-phase modulation signal input to the antenna 5 increases, the RSSI output voltage also increases. At this time, if the input electric field exceeds the point A, the output of the comparator 18 is inverted and the switch 9 is turned off, so that no voltage is supplied to the high frequency amplifier 7, so that the gain there is reduced. As a result, the apparent input electric field decreases, and the output voltage of the RSSI decreases. In this embodiment, the power supply of the high-frequency amplifier 7 is controlled, but it is also possible to control the power supplies of the first mixer and the second mixer as needed.

[0012]

As described above, according to the present invention, when a strong electric field is input, the gain of the receiver is reduced to prevent the receiver from becoming saturated, so that the amplitude fluctuation component can always be improved. This has the effect of being able to detect and provide stable baud timing.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing the configuration of a second embodiment of the present invention.

FIG. 3 is a diagram showing characteristics of electric field intensity information in a second embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 High frequency reception part 2 Demodulation part 3 Electric field information detection part 4 Amplitude information detection part 5 Antenna 6 Antenna filter 7 High frequency amplifier 8 Interstage filter 9 Switch 10 First mixer 11 First local oscillator 12 First intermediate wave filter 13 Second mixer 14 Second Local Oscillator 15 Second Intermediate Wave Filter 16 Intermediate Wave Amplifier 17 Digital Detector 18 Comparator (COMP) 19 Bit Synchronizer 20 Power Supply Terminal 21 Data Terminal 22 Clock Terminal 23 Reference Voltage Terminal

Claims (1)

(57) [Claims] 1. A high-frequency reception signal modulated by four-phase modulation is input.
A high-frequency receiving unit for outputting an intermediate-frequency signal by inputting an intermediate-frequency signal from the high-frequency receiving unit.
Digital signal according to the baud timing
An output demodulation unit, and an intermediate frequency signal input from the high frequency reception unit and its amplitude
Detects fluctuation components and gives baud timing to the demodulation unit.
Digital receiver equipped with an amplitude information detector
Input the intermediate frequency signal from the high frequency
The intensity component is detected, and the high-frequency reception is performed according to the detection result.
Equipped with an electric field information detector that controls the gain of the, The electric field information detection unit is input from the high frequency reception unit
The electric field strength component of the intermediate frequency signal is obtained by the amplitude information detector.
It is a configuration that detects each set baud timing Be prepared
A digital receiver characterized by the following.