Multi-mode detector circuit

Claim 2

In a wave-signal receiver of the type having an intermediatefrequency amplifying channel alternately operable for translating a wide band FM signal at a first predetermined frequency and a narrow band FM signal at a second different predetermined frequency; a ratio detector circuit comprising: a first interstage transformer coupled to said channel for translating output signals from said intermediate-frequency amplifying channel at said first predetermined frequency, said first interstage transformer having a pair of tuned secondary windings resonant at said first predetermined frequency and a first tertiary winding; a second interstage transformer coupled to said channel for translating output signals from said intermediate-frequency amplifying channel at said second predetermined frequency, said second interstage transformer having a tuned secondary winding resonant at said second predetermined frequency and a second tertiary winding coupled to said first tertiary winding; means for coupling said secondary winding of said second interstage transformer between said pair of secondary windings of said first interstage transformer; and means coupled across said pair of secondary windings of said first interstage transformer for demodulating said wide band and narrow band FM signals from said intermediate-frequency amplifying channel.

Claim 3

A detector circuit as described in claim 1, wherein said coupling means connects said secondary winding of said second interstage transformer in series with

Claim 4

A detector circuit as described in claim 2, wherein said pair of secondary windings of said first interstage transformer is tuned to resonance at said first predetermined frequency by means comprising a first capacitor coupled across the outside terminals of said pair of windings and said secondary winding of said second interstage transformer is tuned to resonance at said second predetermined frequency by means comprising a second capacitor coupled across its end terminals and wherein said first capacitor presents a substantial impedance at said second predetermined frequency and said second capacitor presents a negligible impedance at said first predetermined frequency.

Claim 5

A detector circuit as described in claim 1, wherein said first predetermined frequency is substantIally 10.7 MHz and said second predetermined frequency is substantially 455 KHz to minimize interaction between said first and second interstage transformers.

Claim 6

A detection circuit as described in claim 1, wherein said tertiary windings are connected in series, one end of the series combination being connected to a point intermediate the ends of the secondary winding of said second interstage transformer and the other end of the series combination being connected to an audio frequency output terminal.

Claim 7

In a wave-signal receiver of the type having an intermediate-frequency amplifying channel alternately operable at first and second different predetermined frequencies, said first frequency being substantially higher than said second frequency, a detector circuit comprising: a first interstage transformer coupled to said channel for translating output signals from said intermediate-frequency amplifying channel at said first predetermined frequency, said transformer having a pair of tuned secondary windings resonant at said first predetermined frequency and a first tertiary winding; a second interstage transformer coupled to said channel for translating output signals from said intermediate-frequency amplifying channel at said second predetermined frequency, said transformer having a center-tapped tuned secondary winding resonant at said second predetermined frequency, and a second tertiary winding connected in series with said first tertiary winding; means for coupling said secondary winding of said second interstage transformer in series with and between said pair of secondary windings of said first interstage transformer; means connecting the free end of said first tertiary winding to said center-tap of said secondary winding, and the free end of said second tertiary winding to an audio frequency output terminal; and means comprising a ratio detector circuit having first and second detector diodes coupled across respective ones of the outside terminals of said pair of tuned secondary windings for demodulating frequency-modulated signals at said first and second predetermined frequencies from said intermediate-frequency amplifying channel and developing audio signals at said output terminal.

Claim 8

In a wave-signal receiver of the type having an intermediate-frequency amplifying channel alternately operable at first and second different predetermined frequencies, said first frequency being substantially higher than said second frequency, a detector circuit comprising: a first interstage transformer coupled to said channel for translating output signals from said intermediate-frequency amplifying channel at said first predetermined frequency, said transformer having a pair of tuned secondary windings resonant at said first predetermined frequency and a first tertiary winding; a second interstage transformer coupled to said channel for translating output signals from said intermediate-frequency amplifying channel at said second predetermined frequency, said transformer having a center-tapped tuned secondary winding resonant at said second predetermined frequency, and a second tertiary winding connected in series with said first tertiary winding; means for coupling said secondary winding of said second interstage transformer in series with and between said pair of secondary windings of said first interstage transformer; means connecting the free end of said first tertiary winding to said center-tap of said secondary winding, and the free end of said second tertiary winding to an audio frequency output terminal; and means comprising a ratio detector circuit having first and second detector diodes coupled across respective ones of the outside terminals of said pair of tuned secondary windings for demodulating frequency-modulated signals at said first and second predetermined frequencies from said intermediate-frequency amplifying channel and developing audio signals at said output terminal.

Claim 9

A detector circuit as described in claim 6, wherein said ratio detector has a filter capacitor coupled across a pair of diode load resistors, the voltage thereon being related to the amplitude of said frequency-modulated signals, and wherein AGC-amplifying means are further provided for applying said filter capacitor voltage to said amplifying channel to main-tain the level of said frequency-modulated signals constant.

Claim 10

A detector circuit as described in claim 7, wherein switch means are further provided for disconnecting said filter capacitor to enable one of said diodes to detect an amplitude modulated signal at one of said predetermined frequencies, and the other of said diodes to peak-rectify said signal to develop an AGC voltage for application to said AGC amplifying means.

Claim 11

A detection circuit as described in claim 4, wherein said ratio detector includes a pair of oppositely poled diodes and a filter capacitor coupled across said diodes; and switch means for disconnecting one terminal of said filter capacitor to enable detection of 455 KHz amplitude modulated signals by one of said diodes.