Patent EP0139514A2 successfully refreshed from Google Patents.
EP0139514A2
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Digital radio receiving apparatus
Assignee: Fujitsu Ltd
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Filing: 1984-10-12
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Granted: —
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Expires: 2004-10-12
Abstract
Abstract A digital radio receiving apparatus (20) having a transversal demodulator. The transversal demodulator is controlled under a usual internal control mode and an external control mode selectively by means of a control circuit (21). The control circuit (21) is driven every time an alarm signal (ALM) is issued therein when the transversal demodulator functions in an abnormal operation state due to fading of a received signal (Sin). The control circuit (21) is driven under the external control mode wherein the control circuit produces an external control signal (B) to eliminate the alarm signal (ALM).
Inventors
- 👤 Takayuki Ozaki
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 13:08
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/01
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
148 words
A digital radio receiving apparatus having at least a transversal demodulator, a discriminator, and an alarm generator for issuing an alarm signal every time the transversal demodulator works in an abnormal operation state, the transversal demodulator comprising a detector, a transversal equalizer, a carrier recovery circuit, and an equalizing part and being operable to receive an IF received signal, an equalized IF received signal being given to the discriminator to reproduce an original data signal, the reproduced data signal being (partially) received by the equalizing part to produce an internal control signal to be provided via.at least one internal control loop for the related equalization, wherein the equalizing part is operable to cooperate with a control circuit, and the control circuit is operable to provide an external control signal suitable for eliminating the alarm signal to at least one external control path instead of the internal control loop.
Claim 2
Dependent Claim
148 words
A digital radio receiving apparatus having at least a transversal demodulator, a discriminator, and an alarm generator for issuing an alarm signal every time the transversal demodulator works in an abnormal operation state, the transversal demodulator comprising a detector, a transversal equalizer, a carrier recovery circuit, and an equalizing part and being operable to receive an IF received signal, an equalized IF received signal being given to the discriminator to reproduce an original data signal, the reproduced data signal being (partially) received by the equalizing part to produce an internal control signal to be provided via.at least one internal control loop for the related equalization, wherein the equalizing part is operable to cooperate with a control circuit, and the control circuit is operable to provide an external control signal suitable for eliminating the alarm signal to at least one external control path instead of the internal control loop.
Claim 3
Dependent Claim
46 words
An apparatus as set forth in claim 1, wherein at least one switch is provided in respect of the transversal equalizer, the switch being operable to select the internal control loop or the external control path which is selected every time the alarm signal is issued.
Claim 4
Dependent Claim
58 words
An apparatus as set forth in claim 1 or 2, wherein the control circuit is comprised of a read only memory ( R OM) storing a variety of external control data, prepared in advance, on which the external control signal is based, the external control data being sequentially read from the ROM until the alarm signal is eliminated.
Claim 5
Dependent Claim
25 words
An apparatus as set forth in claim 3, wherein the external control data is sequentially read from the ROM by means of a microprocessor unit.
Claim 6
Dependent Claim
27 words
An apparatus as set forth in claim 3, wherein the external control data is sequentially read from the ROM by address signals sequentially supplied from a counter.
Claim 7
Dependent Claim
61 words
An apparatus as set forth in claim 2, wherein the control circuit is operable to cooperate with a distortion detecting part for detecting the distortion of the branched IF received signal, and then the control circuit determines an optimum external control signal for eliminating the alarm signal, which optimum external control signal is suitable to cope with the thus detected distortion.
Claim 8
Dependent Claim
83 words
An apparatus as set forth in claim 6, wherein the distortion detecting part is comprised of a plurality of filters having different filtering frequencies and commonly receiving the branched IF received signal, the filters have individual level detectors, and the output signals from the level detectors are supplied to the control circuit in which the optimum external control data for the external control signal is determined, which data is suitable for suppressing the distortion A by the output signals from the level detectors.
Claim 9
Dependent Claim
86 words
An apparatus as set forth in claim 6, wherein the distortion detecting part is comprised of a voltage controlled oscillator and a detector, the voltage controlled oscillator is controlled by the control circuit so as to produce variable frequency oscillation signals sequentially, the swept variable frequency oscillation signals are supplied to the detector so as to achieve each power detection for the branched IF received signal, and the power detection signal is given to the control circuit to determine the distortion of the IF received signal.
Claim 10
Dependent Claim
99 words
An apparatus as set forth in claim 1, or 2, wherein a variable gain amplifier and an automatic variable gain controller are mounted at the input side of the transversal demodulator, the variable gain amplifier is gain controlled by the equalizing part by way of the internal control loop, the internal control loop and the external control path are selectively selected by means of a switch so as to select the external control path when the alarm signal is issued, and the external control path is connected to the control circuit which is equivalent to the automatic gain controller.
Claim 11
Dependent Claim
42 words
An apparatus as set forth in claim 9, wherein a weighting element for a main tap in the transversal equalizer is removed therefrom and the related weighting value thereof is initially preset to a predetermined value by means of a variable resistor.
References Cited (Backward Citations)
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