US5414385A
Expired / Lapsed
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Dual mode FM quadrature detector
Assignee: Matsushita Communication Industrial Corp
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Filing: 1994-02-22
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Granted: 1995-05-09
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Expires: 2014-02-22
Abstract
Abstract A dual mode quadrature detector (15) uses the same components for both narrow band and wide band operation and provides an output amplitude which is independent of the mode of operation selected. A multiplier (32) provides a demodulated output signal (16) which is responsive to the phase difference between a signal (14) at one input (32A) and a phase shifted version of the signal at the other input (32B). A capacitor (30) and a phase shifting circuit (31) provide the phase shifted version of the signal. The phase shifting circuit (31) is responsive to a mode control signal (24) for determining the phase shift which is provided. The phase shift at the maximum frequency deviation of the narrow band signal is the same as the phase shaft at the maximum deviation of the wide band signal so that the output amplitude from the detector (15) is the same for both narrow band and wide band operation. The phase shift provided is controlled by varying the quality factor (Q) of the phase shifting circuit (31). This is achieved by controlling the amount of resistance placed in parallel with a tuned circuit (33, 34) in the phase shifting circuit (31). A higher Q is obtained by using a higher resistance, and a lower Q is obtained by using a lower resistance.
Inventors
- 👤 James A. Worsham, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 23:19
CPC Classifications
H; H03; H03D; H03D3/00; H03D3/02; H03D3/06
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
161 words
A frequency modulated (FM) signal detector responsive to a mode control signal for demodulating an input FM signal to provide a demodulated output signal, comprising in combination: a tuned circuit, having a variable quality factor (Q) and connected to said input FM signal, responsive to said mode control signal being in a first state for providing a phase shifted input FM signal having a first phase shift by providing a first Q, and responsive to said mode control signal being in a second state for providing said phase shifted input FM signal having a second phase shift by providing a second Q; a multiplier having a first input connected to said input FM signal and a second input connected to said phase shifted input FM signal, for providing a product signal by multiplying said input FM signal and said phase shifted input FM signal; and a filter for removing undesired signals from said product signal to provide said demodulated output signal.
Claim 2
Dependent Claim
161 words
A frequency modulated (FM) signal detector responsive to a mode control signal for demodulating an input FM signal to provide a demodulated output signal, comprising in combination: a tuned circuit, having a variable quality factor (Q) and connected to said input FM signal, responsive to said mode control signal being in a first state for providing a phase shifted input FM signal having a first phase shift by providing a first Q, and responsive to said mode control signal being in a second state for providing said phase shifted input FM signal having a second phase shift by providing a second Q; a multiplier having a first input connected to said input FM signal and a second input connected to said phase shifted input FM signal, for providing a product signal by multiplying said input FM signal and said phase shifted input FM signal; and a filter for removing undesired signals from said product signal to provide said demodulated output signal.
Claim 3
Dependent Claim
58 words
The FM detector of claim 1 wherein said tuned circuit comprises: a first capacitor connected between said input FM signal and said second input of said multiplier; and a parallel resonant circuit connected between said second input and a reference point, and responsive to said mode control signal for providing either said first Q or said second Q.
Claim 4
Dependent Claim
71 words
The FM detector of claim 2 wherein said parallel resonant circuit comprises: a second capacitor connected between said second input and said reference point; an inductor connected in parallel with said second capacitor; and a resistor circuit, connected in parallel with said second capacitor, and responsive to said mode control signal for providing either said first Q or said second Q by providing either a first resistance or a second resistance.
Claim 5
Dependent Claim
52 words
The FM detector of claim 3 wherein said resistor circuit comprises: a first resistor; a second resistor; and a switch, connected to said first resistor and said second resistor, and responsive to said mode control signal for connecting either said first resistor or said second resistor in parallel with said second capacitor.
Claim 6
Dependent Claim
75 words
The FM detector of claim 3 wherein said resistor circuit comprises: a resistor having a tap point, said resistor providing a resistance value, said tap point providing a portion of said resistance value; and a switch, connected to said resistor and to said tap point, and responsive to said mode control signal for connecting either said resistor in parallel with said second capacitor or said portion of said resistor in parallel with said second capacitor.
Claim 7
Dependent Claim
60 words
The FM detector of claim 3 wherein said resistor circuit comprises: a first resistor; a second resistor connected in series with said first resistor to form a series resistor; and a switch, connected to said series resistor, and responsive to said mode control signal for connecting either said first resistor or said series resistor in parallel with said second capacitor.
Claim 8
Independent Claim
106 words
A method responsive to a mode control signal for demodulating an input frequency modulated (FM) signal to provide a demodulated output signal, comprising the steps of: responding to said mode control signal being in a first state for providing a phase shifted input FM signal having a first phase shift, and responding to said mode control signal being in a second state for providing said phase shifted input FM signal having a second phase shift; providing a product signal by multiplying said input FM signal and said phase shifted input FM signal; and providing said demodulated output signal by removing undesired signals from said product signal.
Claim 9
Independent Claim
106 words
A method responsive to a mode control signal for demodulating an input frequency modulated (FM) signal to provide a demodulated output signal, comprising the steps of: responding to said mode control signal being in a first state for providing a phase shifted input FM signal having a first phase shift, and responding to said mode control signal being in a second state for providing said phase shifted input FM signal having a second phase shift; providing a product signal by multiplying said input FM signal and said phase shifted input FM signal; and providing said demodulated output signal by removing undesired signals from said product signal.
Claim 10
Dependent Claim
40 words
The method of claim 7 wherein said step of responding to said mode control signal comprises providing said phase shifted input FM signal by varying the quality factor (Q) of a tuned circuit in response to said mode control signal.
Claim 11
Dependent Claim
33 words
The method of claim 8 wherein said step of responding to said mode control signal comprises varying the resistance of a resistor in said tuned circuit in response to said mode control signal.
Claim 12
Dependent Claim
173 words
A dual mode frequency modulated (FM) signal receiver, comprising in combination: a receiver front end for receiving an input RF signal and providing an intermediate frequency (IF) signal; a tuned circuit, having a variable quality factor (Q) and connected to said IF signal, responsive to a mode control signal being in a first state for providing a phase shifted IF signal having a first phase shift by providing a first Q, and responsive to said mode control signal being in a second state for providing said phase shifted IF signal having a second phase shift by providing a second Q; a multiplier having a first input connected to said IF signal and a second input connected to said phase shifted IF signal, for providing a product signal by multiplying said IF signal and said phase shifted IF signal; a filter for removing undesired signals from said product signal to provide a demodulated output signal; and a controller, responsive to a control signal contained in said IF signal, for providing said mode control signal.
Claim 13
Dependent Claim
173 words
A dual mode frequency modulated (FM) signal receiver, comprising in combination: a receiver front end for receiving an input RF signal and providing an intermediate frequency (IF) signal; a tuned circuit, having a variable quality factor (Q) and connected to said IF signal, responsive to a mode control signal being in a first state for providing a phase shifted IF signal having a first phase shift by providing a first Q, and responsive to said mode control signal being in a second state for providing said phase shifted IF signal having a second phase shift by providing a second Q; a multiplier having a first input connected to said IF signal and a second input connected to said phase shifted IF signal, for providing a product signal by multiplying said IF signal and said phase shifted IF signal; a filter for removing undesired signals from said product signal to provide a demodulated output signal; and a controller, responsive to a control signal contained in said IF signal, for providing said mode control signal.
Claim 14
Dependent Claim
59 words
The dual mode FM receiver of claim 10 wherein said tuned circuit comprises: a first capacitor connected between said IF signal and said second input of said multiplier; and a parallel resonant circuit connected between said second input and a reference point, and responsive to said mode control signal for providing either said first Q or said second Q.
Claim 15
Dependent Claim
73 words
The dual mode FM receiver of claim 11 wherein said parallel resonant circuit comprises: a second capacitor connected between said second input and said reference point; an inductor connected in parallel with said second capacitor; and a resistor circuit, connected in parallel with said second capacitor, and responsive to said mode control signal for providing either said first Q or said second Q by providing either a first resistance or a second resistance.
Claim 16
Dependent Claim
54 words
The dual mode FM receiver of claim 12 wherein said resistor circuit comprises: a first resistor; a second resistor; and a switch, connected to said first resistor and said second resistor, and responsive to said mode control signal for connecting either said first resistor or said second resistor in parallel with said second capacitor.
Claim 17
Dependent Claim
77 words
The dual mode FM receiver of claim 12 wherein said resistor circuit comprises: a resistor having a tap point, said resistor providing a resistance value, said tap point providing a portion of said resistance value; and a switch, connected to said resistor and to said tap point, and responsive to said mode control signal for connecting either said resistor in parallel with said second capacitor or said portion of said resistor in parallel with said second capacitor.
Claim 18
Dependent Claim
62 words
The dual mode FM receiver of claim 12 wherein said resistor circuit comprises: a first resistor; a second resistor connected in series with said first resistor to form a series resistor; and a switch, connected to said series resistor, and responsive to said mode control signal for connecting either said first resistor or said series resistor in parallel with said second capacitor.
References Cited (Backward Citations)
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