EP0122657A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Receiver for RF signals comprising a pair of parallel signal paths
Assignee: Koninklijke Philips NV
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Filing: 1984-03-27
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Granted: —
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Expires: 2004-03-27
Abstract
Abstract The receiver comprises a pair of signal paths arranged in parallel between an RF-input (5) and a superposition circuit (8) and includes, arranged in succession, a pair of first mixing stages (1, 1 min ) the signals from an RF-tuning oscillator (To), being applied in a phase quadrature relationship to these first mixing stages a pair of filtering elements (3, 3 min ) for signal selection and a pair of second mixing stages (2, 2 min ), the signals from a fixed LF-oscillator (Fo), being applied also in a phase-quadrature relationsip to these second mixing stages. The superposition circuit comprising an adding stage (8) arranged between outputs of the two signal paths and producing a first output signal (1). An amplitude and phase balance between the two signal paths is established by an amplitude and phase control of the signals in the two signal paths in dependence on the amplitude and phase of the image interference in the output signal of the superposition circuit. <??>The amplitude of this image interference component is measured by detecting the image interference component phase-synchronously, the reference frequency being the detection carrier, and the phase of this image interference component is measured by detecting the image interference component synchronously by means of a detection carrier whose phase is shifted through 90 DEG relative to the reference frequency. The of necessity equal frequency position between the reference frequency and its image interference component is obtained by means of frequency mirror-inversion.
Inventors
- 👤 Wolfdietrich Georg Kasperkovitz
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-28 18:20
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/44; H04N5/50; H03; H03D; H03D1/00; H03D1/22; H03D1/24; H04B; H04B1/00; H04B1/06; H04B1/16; H04B1/30; H04B1/302
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
298 words
A receiver for receiving a signal modulated on an RF-carrier, comprising a pair of signal paths arranged in parallel between an RF-input and a superposition circuit and including, arranged in succession, a pair of first mixing stages for mixing down the frequency of the received modulated RF-carrier to a low frequency, mixing signals being applied in a phase quadrature relationship to these first mixing stages from an RF-tuning oscillator, a pair of filtering elements for signal selection and a pair of second mixing stages for up-converting the frequency of the selected modulated carrier, mixing signals being applied also in a phase quadrature relationship to these second mixing stages from a fixed LF-oscillator, these second mixing stages being connected to inputs of the superposition circuit, the superposition circuit comprising an adder or a subtracting stage arranged between outputs of the two signal paths and producing a first output signal, characterized by means connected to the two signal paths for producing a second output signal which relative to the first output signal is mirror-inverted around the frequency of the fixed oscillator and one of said output signals being applied to a carrier selection circuit one side of which is connected on the one hand to a carrier input of a first synchronous demodulator and on the other hand to a carrier input of a second synchronous demodulator via a 90°-phase shifter and which other output signal is applied to signal inputs of the two synchronous demodulators, these two synchronous demodulators being connected to an amplitude control unit and to a phase control input, respectively, of a controllable balancing arrangement via low-pass filters, this controllable balancing arrangement comprising an amplitude and a phase control circuit for a mutually balancing the amplitudes and phases of the signals in the two signal paths.
Claim 2
Dependent Claim
298 words
A receiver for receiving a signal modulated on an RF-carrier, comprising a pair of signal paths arranged in parallel between an RF-input and a superposition circuit and including, arranged in succession, a pair of first mixing stages for mixing down the frequency of the received modulated RF-carrier to a low frequency, mixing signals being applied in a phase quadrature relationship to these first mixing stages from an RF-tuning oscillator, a pair of filtering elements for signal selection and a pair of second mixing stages for up-converting the frequency of the selected modulated carrier, mixing signals being applied also in a phase quadrature relationship to these second mixing stages from a fixed LF-oscillator, these second mixing stages being connected to inputs of the superposition circuit, the superposition circuit comprising an adder or a subtracting stage arranged between outputs of the two signal paths and producing a first output signal, characterized by means connected to the two signal paths for producing a second output signal which relative to the first output signal is mirror-inverted around the frequency of the fixed oscillator and one of said output signals being applied to a carrier selection circuit one side of which is connected on the one hand to a carrier input of a first synchronous demodulator and on the other hand to a carrier input of a second synchronous demodulator via a 90°-phase shifter and which other output signal is applied to signal inputs of the two synchronous demodulators, these two synchronous demodulators being connected to an amplitude control unit and to a phase control input, respectively, of a controllable balancing arrangement via low-pass filters, this controllable balancing arrangement comprising an amplitude and a phase control circuit for a mutually balancing the amplitudes and phases of the signals in the two signal paths.
Claim 3
Dependent Claim
55 words
A receiver as claimed in Claim 1, characterized in that the said means comprise a further superposition circuit, one of said two superposition circuits comprising an adding stage and the other superposition circuit comprising a subtracting stage, this adding stage producing the said one output signal and this subtracting stage producing said other output signal.
Claim 4
Dependent Claim
66 words
A receiver as claimed in Claim 1, characterized in that the said means comprise a multiplying circuit a first input of which is connected to the two signal paths via the superposition circuit and a second input to an output of the fixed LF-oscillator, to which second input an oscillator frequency is applied which is twice the oscillator frequency applied to the two second mixing stages.
Claim 5
Dependent Claim
117 words
A receiver as claimed in any of the preceding Claims for receiving television signals, characterized in that the frequency of the RF-tuning oscillator when being correctly tuned to a broadcast transmission is located between the picture and the sound carriers of the desired television signal, that the frequency of the mixing signals applied to the second mixing stages from the fixed LF-oscillator is at least equal to the highest signal frequency in the signal at the output of the two filtering elements and is of the order of magnitude thereof, and that the carrier selection circuit is adjusted to one of the said carriers in the first or second output signal applied to the carrier selection circuit.
Claim 6
Dependent Claim
88 words
A receiver for receiving television signals as claimed in Claim 4, characterized in that the carrier selection circuit is adjusted to the picture carrier in the first or second output signal applied to the carrier selection circuit, this carrier selection circuit being connected for an automatic gain control via a gate circuit and a peak detector to a variable amplifier device connected to the two signal paths, this gate circuit being controlled by means of a gate signal derived from the line synchronizing signal of the received TV-signal.
Claim 7
Dependent Claim
75 words
A receiver for receiving television signals as claimed in Claim 4 or 5, characterized in that the carrier selection circuit is adjusted to the picture carrier in the first or second output signal applied to the carrier selection circuit, which output signal is also applied to a synchronous video detector included in the processing arrangement via a high-pass filter, this carrier selection circuit also being connected to a carrier input of the synchronous video detectoro
Claim 8
Dependent Claim
108 words
A receiver for receiving television signals having a frequency-modulated sound carrier as claimed in Claim 4, characterized in that the carrier selection circuit is adjusted to the centre frequency of the frequency-modulated sound carrier in the first or second output signal applied to the carrier selection circuit, which output signal is also applied to a first input of a multiplying circuit, that an output of the carrier selection circuit is connected to a second input of the multiplying circuit and an output of the multiplying circuit is connected via an integrator for an automatic gain control to a variable amplifier connected to one of the two signal paths.
Claim 9
Dependent Claim
180 words
A receiver for receiving television signals having a frequency-modulated sound carrier as claimed in Claim 4 or 7, characterized in that the carrier selection circuit is adjusted to the centre frequency of the sound carrier in the first or second output signal applied to the carrier selection circuit and is connected to the two synchronous demodulators via a phase-controlled loop, which phase controlled loop comprises a phase detector connected to the carrier selection circuit, a loop filter and a voltage-controlled oscillator having an in-phase and a quadrature output, which in-phase output is connected to the carrier input of the first synchronous demodulator and which quadrature output is connected to the phase detector and also to the carrier input of the second synchronous demodulator, an output of the lopp filter being connected to an audio signal processing unit and one of the said output signals being applied via a high-pass filter to a signal input of a synchronous video detector and to a picture carrier regenerator, this picture carrier regenerator being connected to a carrier input of the synchronous video detector.
Claim 10
Dependent Claim
119 words
A receiver as claimed in any of the preceding Claims, characterized in that the carrier selection circuit is connected to the two synchronous demodulators via a phase-locked loop, this phase locked loop comprising a phase detector connected to the carrier selection circuit, and also a loop filter and a voltage-controlled oscillator having an in-phase and a quadrature output, which in-phase output is connected to the carrier input of the first synchronous demodulator and which quadrature output is connected to the phase detector and also to the carrier input of the second synchronous demodulator, and that an output of the loop filter is connected to a control input of the RF-tuning oscillator via an integrator for an automatic frequency control.
Claim 11
Dependent Claim
57 words
A receiver for receiving television signals as claimed in Claim 6 or 8, characterized in that the two filtering elements are sixth-order low-pass filters having a 3 dB cross-over frequency of the order of 2.25 MHz and the high-pass filter is of the second order having a 3 dB cross-over frequency of at least substantially 1.5 MHz.
Claim 12
Dependent Claim
80 words
A receiver as claimed in any of the preceding Claims, characterized in that the phase-control circuit comprises a first adding circuit arranged between the outputs of one of the two oscillators and one of the two mixing stages to which mixing signals are applied by this oscillator and also, arranged between one of the said outputs and the adding circuit, a first level controller a control input of which is connected to the phase control input of the balancing device.
Claim 13
Dependent Claim
102 words
A receiver as claimed in Claim 11, characterized in that the phase control circuit is of a balanced structure and comprises a second adding circuit, these two adding circuits each being connected via a first input and an output between on the one hand the respective outputs of the fixed oscillators and on the other hand the second mixing stages, and each being cross-connected via a second input and the first and second level controller, respectively, to the said outputs of the fixed oscillator, these two level controllers being connected to the phase control input of the balancing arrangement via control inputs.
Claim 14
Dependent Claim
57 words
A receiver as claimed in any of the preceding Claims, characterized in that the amplitude control circuit comprises a third level controller connected between one of the outputs of one of the two oscillators and the mixing stage connected thereto, a control input of the controller being connected to the amplitude control input of the balancing arrangement.
Claim 15
Dependent Claim
73 words
A receiver as claimed in Claim 13, characterized in that the amplitude control circuit is of a balanced structure and comprises a fourth level controller, these third and fourth level controllers, respectively being included between the output of the fixed oscillator on the one hand and the pair of second mixing stages on the other hand respectively, and to the amplitude control input of the balancing arrangement via a control signal balancing circuit.
Claim 16
Dependent Claim
65 words
150 A receiver as claimed in any of the Claims 11 to 14, inclusive, characterized in that each of said level controllers comprises a multiplying circuit a first input of which is connected to an output of the fixed oscillator, a second input to one of the two control inputs of the balancing arrangement and an output to an output of the relevant level controller.
References Cited (Backward Citations)
FR2374785A1
Cited
GB2052196A
Cited
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