Direct modulation FM data receiver
First Claim
Patent Images
1. A direct modulation FM data receiver, comprising:
- an input signal receiving element for receiving a directly-modulated FM input signal having a channel frequency within a channel frequency range of fc ±
Δ
f wherein fc is the frequency of a carrier signal and Δ
f is a frequency deviation from the carrier signal;
a signal mixer having a first input, a second input, and an output, the first input being connected to the input signal receiving element;
local oscillator signal means for producing and applying, to the second input of the signal mixer, a local oscillator signal having a frequency within the channel frequency range of the FM input signal, but offset from the frequency of the carrier signal by an offset frequency amount δ
f, anddemodulating means, connected to the output of the signal mixer, for distinguishing between signalling tones Δ
f+δ
f and Δ
f-δ
f of an output signal of the signal mixer and deriving, from the signalling tones Δ
f+δ
f and Δ
f-δ
f, an output data signal.
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Abstract
A direct modulation FM data receiver including a mixer (14) having a first input for receiving a directly modulated FM signal (fc ±Δf), where Δf is the deviation and fc the carrier, and a second input for a local oscillator (20) signal (fL) having a frequency within the signal channel but offset from the input signal carrier (fc) by an amount (δf). Demodulating circuits (22 to 30) distinguish between the signalling tones (Δf+δf) and (Δf-δf) and derive a data output signal therefrom.
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Citations
3 Claims
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1. A direct modulation FM data receiver, comprising:
-
an input signal receiving element for receiving a directly-modulated FM input signal having a channel frequency within a channel frequency range of fc ±
Δ
f wherein fc is the frequency of a carrier signal and Δ
f is a frequency deviation from the carrier signal;a signal mixer having a first input, a second input, and an output, the first input being connected to the input signal receiving element; local oscillator signal means for producing and applying, to the second input of the signal mixer, a local oscillator signal having a frequency within the channel frequency range of the FM input signal, but offset from the frequency of the carrier signal by an offset frequency amount δ
f, anddemodulating means, connected to the output of the signal mixer, for distinguishing between signalling tones Δ
f+δ
f and Δ
f-δ
f of an output signal of the signal mixer and deriving, from the signalling tones Δ
f+δ
f and Δ
f-δ
f, an output data signal. - View Dependent Claims (2)
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3. A direct modulation FM data receiver, comprising:
-
an input signal receiving element for receiving a directly-modulated FM input signal having a channel frequency within a channel frequency range of fc ±
Δ
f wherein fc is the frequency of a carrier signal and Δ
f is a frequency deviation from the carrier signal;a signal mixer having a first input, a second input, and an output, the first input being connected to the input signal receiving element; local oscillator signal means for producing and applying, to the second input of the signal mixer, a local oscillator signal having a frequency within the channel frequency range of the FM input signal, but offset from the frequency of the carrier signal by an offset frequency amount δ
f;demodulating means, coupled to the output of the mixer, for distinguishing between signalling tones Δ
f+δ
f and Δ
f-δ
f of an output signal of the signal mixer and deriving, from the signalling tones Δ
f+δ
f and Δ
f-δ
f, an output data signal, anda low pass filter connected between the output of the signal mixer and the demodulating means.
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Specification
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Current AssigneeUS Philips Corporation (Koninklijke Philips N.V.)
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Original AssigneeUS Philips Corporation (Koninklijke Philips N.V.)
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InventorsMarshall, Christopher B.
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Primary Examiner(s)Safourek, Benedict V.
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Application NumberUS06/435,426Time in Patent Office965 DaysField of Search375/80, 375/88, 375/91, 375/97, 455/205, 455/208, 455/324, 307/520, 307/524, 329/107, 329/110, 329/122, 329/150, 329/153, 329/154US Class Current375/337CPC Class CodesH03D 3/00 Demodulation of angle-, fre...H04L 27/148 using filters, including PL...
