EP0074858A2
Expired / Lapsed
EP
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Radio receiver
Assignee: International Standard Electric Corp
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Filing: 1982-09-15
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Granted: —
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Expires: 2002-09-15
Abstract
Abstract A multi-mode radio receiver divides the radio frequency input into two channels and in each channel mixes it with the carrier wave frequency. A quadrature shift in the mixing carrier wave frequencies enables base band signals to be filtered from the mixer outputs. The analogue quadrature signals are converted to digital form and processed digitally to reproduce the original modulating signal for am, fm or pm transmissions. For ssb modulation the mixing frequency is the side band centre frequency instead of carrier frequency.
Inventors
- 👤 John Kenneth Goatcher
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 02:16
CPC Classifications
H; H03; H03D; H03D3/00; H03D3/007; H03D1/00; H03D1/22; H03D1/24; H03D5/00; H03D2200/00; H03D2200/0001; H03D2200/0025; H03D2200/0035; H03D2200/0041; H03D2200/005; H03D2200/0052; H03D3/006; H03D7/00; H03D7/16; H03D7/165
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
112 words
A radio receiver comprising a first signal path in which a received signal is mixed with a local oscillator frequency running at the main transmission frequency and then filtered to give a first mixed signal defined as an in-phase signal (I), a second signal path in which the received signal is mixed with the local oscillator frequency but with a relative phase shift and then filtered to provide a second mixed signal defined as a quadrature signal Q, characterized in that an analogue to digital converter stage is provided to digitise the-I and Q signals and in that a digital signal processor is arranged to demodulate the digitised I and Q signals.
Claim 2
Dependent Claim
112 words
A radio receiver comprising a first signal path in which a received signal is mixed with a local oscillator frequency running at the main transmission frequency and then filtered to give a first mixed signal defined as an in-phase signal (I), a second signal path in which the received signal is mixed with the local oscillator frequency but with a relative phase shift and then filtered to provide a second mixed signal defined as a quadrature signal Q, characterized in that an analogue to digital converter stage is provided to digitise the-I and Q signals and in that a digital signal processor is arranged to demodulate the digitised I and Q signals.
Claim 3
Dependent Claim
27 words
A radio receiver as claimed in claim 1 characterized in that a digital to analogue converter is provided to convert the demodulated digital signals into analogue signals.
Claim 4
Dependent Claim
43 words
A radio receiver as claimed in claim 1 characterized in that the digital signal processor includes means to derive amplitude (R) and/or phase (θ) of the modulation signals from the digitised I and Q signals to provide demodulation of amplitude and/or phase modulation.
Claim 5
Dependent Claim
43 words
A radio receiver as claimed in claim 3 characterized in that the digital signal processor has means to derive the phase 6 of the modulating signal and to differentiate 6 with respect to time t to derive de/dt, constituting demodulation of frequency modulation.
Claim 6
Dependent Claim
84 words
A radio receiver as claimed in claim 3 characterized in that the digital signal processor includes means to derive both R and 6 and has means to subtract or add phase at the offset frequency to the phase angle 6 to provide a new phase angle φ and has means to derive R Sin φ or R Cos φ to produce digitised single side band demodulation for upper or lower single side band modulation depending respectively on whether the phase is subtracted or added.
Claim 7
Dependent Claim
91 words
A radio receiver as claimed in claim 3 characterized in that the digital signal processor is provided with means to derive the output of any combination of at least two of: a) 6 for phase modulation b) R for amplitude modulation c) dΘ/ dt for frequency modulation d) R Sin φ or R Cos φ for single side band modulation (t and θ being defined as in claims 4 and 5) to provide a radio receiver capable of receiving and demodulating at least two of the four specified forms of modulation.
Claim 8
Dependent Claim
54 words
A radio receiver as claimed in claim 3 characterized in that it incorporates feedback control circuits from the digital signal processor whereby R and/or θ in their digitised form are employed to control respectively amplification within the two channels and/or the relative phase shift in the second channel as compared with the first channel.
References Cited (Backward Citations)
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