JPH11205090A - Equalizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an equalizing filter output through digital signal processing by storing the inverse characteristics of a filter corresponding to the temperatures in a ROM. SOLUTION: The frequency of a second multiplier 6 is converted into a baseband signal by means of a signal generated from a second oscillator 7. Next, the baseband signal is sent to an A/D converter 8, converted into a digital signal and sent to an equalizing filter 11. The temperature of a second band-pass filter 5 is detected by a temperature sensor 9, and this temperature information is sent to a control part 10. For example if the temperature is -20 deg.C, 0 deg.C, 20 deg.C, and 40 deg.C, then information '00', '01', '10', and '11' is sent, respectively. A ROM table is provided in advance at the control part 10, and equalizing filter coefficients are outputted from an address corresponding to the inputted temperature information. An output of the A/D converter 8 is outputted from an output terminal 13, by performing equalization of filtering through the equalizing filter 11, while the equalizing filter coefficient is used at the control part 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital mobile radio.

[0002]

2. Description of the Related Art The prior art will be described with reference to FIG. The intermediate frequency band received signal f1 (f1
= 55 MHz) is band-limited through the first band-pass filter 2. The band-limited signal is supplied to a first oscillator
4 and the first multiplier 3, the second intermediate frequency band signal f2 (f2 = 4
50 MHz). The second intermediate frequency band signal f2 is band-limited by the second band-pass filter 5 and sent to the second multiplier 6. The second multiplier 6 is frequency-converted into a baseband signal by a signal generated from the second oscillator 7. The baseband signal is then sent to an A / D converter 8, converted to a digital signal, and sent to an equalization filter 11.

[0005] Filter coefficients having inverse characteristics of the first band-pass filter 2 and the second band-pass filter 5 are obtained in advance and stored in the ROM 12. Therefore, using the output of the A / D converter 8 and the filter coefficient of the ROM 12, the filter is equalized by the equalization filter 11, and the output terminal 13
Output from

[0004]

In the prior art, when the characteristics of the band-pass filter change with temperature, there is a drawback that equalization of the filter is not performed normally.

An object of the present invention is to eliminate the above-mentioned drawbacks and to perform equalization corresponding to a change in filter characteristics due to temperature.

[0006]

In order to achieve the above object, an equalizer according to the present invention is provided with a temperature sensor, and the inverse characteristic of a filter corresponding to a temperature is stored in a ROM so as to correspond to each temperature. This realizes the equalization of the filtered filter.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG. The reception signal f1 (f1 = 55 MHz) in the intermediate frequency band input from the input terminal 1 passes through the first bandpass filter 2 and is band-limited. The band-limited signal is frequency-converted by the first oscillator 4 and the first multiplier 3 into a second intermediate frequency band signal f2 (f2 = 450 MHz). The second intermediate frequency band signal f2 is band-limited by the second band-pass filter 5 and sent to the second multiplier 6. The second multiplier 6 is frequency-converted into a baseband signal by a signal generated from the second oscillator 7. The baseband signal is then sent to an A / D converter 8, converted to a digital signal, and sent to an equalization filter 11.

The temperature of the second bandpass filter 5 is detected by a temperature sensor 9, and information on the temperature is sent to a control unit 10. For example, if the temperature is −20 ° C., information “00” is sent, if it is 0 ° C., “01”, if it is 20 ° C., “10”, and if it is 40 ° C., information “11” is sent. The control unit 10 is provided with a ROM table in advance, and outputs an equalization filter coefficient from an address corresponding to the input temperature information. Therefore, the output of the A / D converter 8 is equalized by the equalization filter 11 using the equalization filter coefficient of the control unit 10 and output from the output terminal 13.

In the above embodiment, the temperature sensor is provided only for the filter that limits the band of the intermediate frequency signal.
It goes without saying that a filter for limiting the band of the received signal may be provided.

[0010]

As described above, according to the present invention, equalization of a filter corresponding to a temperature change can be realized.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing an embodiment of the related art.

[Explanation of symbols]

1: input terminal, 2: first bandpass filter, 3: first multiplier, 4: first oscillator, 5: second bandpass filter, 6: second multiplier, 7: second Oscillator,
8: A / D converter, 9: temperature sensor, 10: control unit,
11: Equalization filter, 12: ROM,

Claims (1)

[Claims] A converting means for converting a frequency of a received signal;
A band-pass filter for band-limiting the signal frequency-converted by the conversion unit, an A / D converter for A / D-converting the signal band-limited by the band-pass filter,
A temperature sensor for detecting the temperature of the bandpass filter;
A control unit that outputs an equalization filter coefficient based on the temperature detected by the temperature sensor, and equalizes a signal sent from the A / D converter by the equalization filter coefficient input from the control unit An equalizer characterized by having a digital equalizing filter for obtaining the output of the equalizing filter by digital signal processing.