Patent EP0276144A2 successfully refreshed from Google Patents.
EP0276144A2
Expired / Lapsed
EP
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Signal receiver for terrestrial and satellite broadcastings
Assignee: Panasonic Holdings Corp
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Filing: 1988-01-20
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Granted: —
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Expires: 2008-01-20
Abstract
Abstract A signal receiver which is capable of receiving and demodulating a satellite broadcasting signal which is an FM signal and a terrestrial broadcasting signal which is an AM signal is disclosed. FM and AM signals are frequency-converted into signals having frequencies in a same intermediate frequency band by making common use of a radio frequency amplifier, a mixer, a local oscillator and an intermediate frequency filter. At the time of reception of an FM signal, the FM signal is demodulated in a phase-locked loop circuit, and a local oscillator is subjected to frequency modulation by a part of the demodulated signal, thereby constituting an FM negative feedback loop, and thus narrowing the occupied bandwidth of the FM signal. At the time of reception of an AM signal, the phase-locked loop circuit is used to regenerate a carrier, and the output signal of the phase-locked loop circuit is input to a multiplier to effect synchronous detection of the input signal. At this time, the FM negative feedback to the local oscillator is utilized to effect automatic frequency control, thereby achieving stabilization of the synchronous detection.
Inventors
- 👤 Seiji Sakashita
- 👤 Hiroaki Ozeki
- 👤 Ippei Kanno
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 11:53
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/44; H03; H03D; H03D5/00
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
303 words
A signal receiver comprising: radio frequency amplifying means for amplifying a radio frequency signal supplied from an input terminal; frequency converting means for frequency-converting the radio frequency signal into an intermediate frequency signal by mixing the radio frequency signal and an oscillation signal from a local oscillator in a mixer; signal selecting means for selecting a desired intermediate frequency signal from the signals having been subjected to the frequency conversion; channel selecting means for generating a signal required to select a desired receive signal; phase-locked loop means having a phase-locked loop circuit which operates in phase with a frequency of the intermediate frequency signal; frequency feedback means for supplying an output of said phase-locked loop means so that an oscillation frequency of the local oscillator in said frequency converting means is changed in accordance with the output of said phase-locked loop means; control signal generating means for generating a control signal for changing respective working bandwidths of said phase-locked loop means, said signal selecting means and said frequency feedback means in response to the signal delivered from said channel selection means; tuning voltage generating means for generating and supplying a tuning voltage corresponding to the desired receive signal to the local oscillator in said frequency converting means in response to the signal delivered from said channel selection means; phase shifting means of π/2 phase-shifting the output of said phase-locked loop means; multiplying means for multiplying the output signal from said phase-locked loop means which has been π/2 phase-shifted in said phase shifting means and said intermediate frequency signal; signal switching means for switching over the respective outputs of said phase-locked loop means and said multiplying means from one to the other; and signal processing means for processing an output of said signal switching means to a signal which is able to be displayed.
Claim 2
Dependent Claim
303 words
A signal receiver comprising: radio frequency amplifying means for amplifying a radio frequency signal supplied from an input terminal; frequency converting means for frequency-converting the radio frequency signal into an intermediate frequency signal by mixing the radio frequency signal and an oscillation signal from a local oscillator in a mixer; signal selecting means for selecting a desired intermediate frequency signal from the signals having been subjected to the frequency conversion; channel selecting means for generating a signal required to select a desired receive signal; phase-locked loop means having a phase-locked loop circuit which operates in phase with a frequency of the intermediate frequency signal; frequency feedback means for supplying an output of said phase-locked loop means so that an oscillation frequency of the local oscillator in said frequency converting means is changed in accordance with the output of said phase-locked loop means; control signal generating means for generating a control signal for changing respective working bandwidths of said phase-locked loop means, said signal selecting means and said frequency feedback means in response to the signal delivered from said channel selection means; tuning voltage generating means for generating and supplying a tuning voltage corresponding to the desired receive signal to the local oscillator in said frequency converting means in response to the signal delivered from said channel selection means; phase shifting means of π/2 phase-shifting the output of said phase-locked loop means; multiplying means for multiplying the output signal from said phase-locked loop means which has been π/2 phase-shifted in said phase shifting means and said intermediate frequency signal; signal switching means for switching over the respective outputs of said phase-locked loop means and said multiplying means from one to the other; and signal processing means for processing an output of said signal switching means to a signal which is able to be displayed.
Claim 3
Dependent Claim
16 words
A signal receiver according to Claim 1, wherein said signal selecting means is a frequency-fixed filter.
Claim 4
Dependent Claim
34 words
A signal receiver according to Claim 1, wherein said signal selecting means is a frequency-variable filter the frequency of which is variable in accordance with a control signal from said control signal generating means.
Claim 5
Dependent Claim
34 words
A signal receiver according to Claim 3, wherein said signal selecting means is arranged such that the pass bandwidth thereof is changeable in accordance with a control signal from said control signal generating means.
Claim 6
Dependent Claim
30 words
A signal receiver according to Claim 3, wherein said signal selecting means is arranged to perform frequency tracking in accordance with a demodulated signal output from said phase-locked loop means.
Claim 7
Dependent Claim
28 words
A signal receiver according to Claim 2, wherein said signal selecting means has Nyquist characteristic by which a carrier corresponding to reception of an AM signal is suppressed.
Claim 8
Dependent Claim
33 words
A signal receiver according to Claim 5, wherein said signal selecting means employs the same pass bandwidth irrespective of whether the signal which is to be received is an FM or AM signal.
Claim 9
Dependent Claim
48 words
A signal receiver according to Claim 4, wherein said signal selecting means changes the pass bandwidth in accordance with a control signal from said control signal generating means which control signal is representative of whether the signal which is to be received is an FM or AM signal.
Claim 10
Dependent Claim
65 words
A signal receiver according to Claim 4, wherein said signal selecting means is arranged such that a signal is passed through a low-pass filter, amplified in a broad-band amplifier and then passed through a high-pass filter, the respective cut-off frequencies of the low- and high-pass filters being changed in accordance with a control signal from said control signal generating means, thereby changing the pass bandwidth.
Claim 11
Dependent Claim
58 words
A signal receiver according to Claim 1, wherein the loop bandwidth of said phase-locked loop circuit is changed in accordance with a control signal from said control signal] generating means so that the bandwidth employed at the time of reception of an AM signal is narrower than that employed at the time of reception of an FM signal.
Claim 12
Dependent Claim
59 words
A signal receiver according to Claim 1, wherein the loop bandwidth of an FM negative feedback loop is changed in accordance with a control signal from said control signal generating means so that the bandwidth employed at the time of reception of an AM signal is narrower than that employed at the time of reception of an FM signal.
Claim 13
Dependent Claim
151 words
A signal receiver according to Claim 10, wherein said phase-locked loop means operated such that an output signal from a phase comparator which detects a phase difference between an oscillation signal from a voltage-controlled oscillator and an input signal is fed back to said voltage-controlled oscillator through a loop filter which effects band limitation so as to minimize the output signal from said phase comparator, said loop filter being composed of a filter section in which the output signal from said phase comparator is input to one of a first resistor and a second resistor and a variable-capacitance element are series-connected between the other end of the first resistor and a ground electrode, and a gain-controlled amplifier which amplifies a signal taken out from the other end of said frist resistor, the loop bandwidth being varied by simultaneously changing the capacitance of said variable-capacitance element and the gain of said amplifier.
Claim 14
Dependent Claim
107 words
A signal receiver according to Claim 10, wherein said frequency feedback loop means includes a filter which comprises a filter section in which the output signal from said phase-locked loop means is input to one end of a first resistor, and a second resistor and a variable-capacitance element are series-connected between the input end and a ground electrode, said first resistor having a coil connected in parallel to it, and a gain-controlled amplifier which amplifies a signal taken out from the other end of said first resistor, the loop bandwidth being varied by simultaneously changing the capacitance of said variable-capacitance element and the gain of said amplifier.
Claim 15
Dependent Claim
89 words
A signal receiver according to Claim 1, wherein said signal processing means comprises a low-frequency amplifier which amplifies a demodulated signal, an inverse characteristic filter which compensates the frequency characteristics of the amplified signal, and a picture and sound signal processing circuit which decodes the compensated signal into a signal which is able to be displayed, whereby the increase in amplitude of the low-requency component of the demodulated signal at the time of reception of an AM signal having a vestigial side-band is suppressed by the inverse characteristic filter.
Claim 16
Dependent Claim
112 words
A signal receiver according to Claim 14, wherein said inverse characteristic filter is arranged such that a signal from the low-frequency amplifier is input to one end of a series circuit formed from a first parallel resonance circuit composed of a frist resistor and a first capacitor and a second parallel resonance circuit composed of a second resistor and a second capacitor, and a third resistor is connected between the other end of said second parallel resonance circuit and a ground electrode, so that a signal is taken out from the node between the third resistor and said second parallel resonance circuit and supplied to said picture and sound signal processing circuit.
References Cited (Backward Citations)
No citation records indexed.
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