FM broadcast band subcarrier receiver
First Claim
1. An FM subcarrier receiver of the type useful for detection of a relatively high frequency desired subcarrier signal transmitted on an FM carrier which includes a baseband signal and said relatively high frequency subcarrier signal, comprising:
- (a) radio frequency means for receiving a radio frequency signal having frequency modulated baseband and subcarrier components and outputting said baseband and relatively high frequency subcarrier signals;
(b) a high pass filter for receiving the output of said radio frequency means;
(c) a tuned circuit for receiving the output of said high pass filter, said tuned circuit comprising a first inductor of fixed inductance and a first capacitor tuned substantially to the frequency of the subcarrier which one wishes to detect;
(d) a second tuned circuit tuned to said subcarrier which one wishes to detect, said second tuned circuit comprising a second inductor of fixed inductance and a second capacitor, said first and second inductors comprising ferrite cores and adjustably positioned with respect to each other to allow magnetic coupling therebetween; and
(e) a subcarrier demodulator coupled to said second inductor and said second capacitor for providing an audio signal corresponding to the information carried by said desired subcarrier.
0 Assignments
0 Petitions
Accused Products
Abstract
An FM subcarrier receiver of the type useful for detection of a relatively high frequency subcarrier signal transmitted on an FM carrier which includes baseband and relatively high frequency signals is disclosed. It comprises radio frequency circuitry for providing a radio frequency signal having frequency modulated baseband and subcarrier components. High pass filter circuitry receives the output of the radio frequency circuitry. A tuned circuit receives the output of the high pass filter. It comprises a first inductor and a first capacitor tuned substantially to the frequency of the subcarrier which one wishes to detect. A second tuned circuit is tuned to the subcarrier which one wishes to detect. The second tuned circuit comprises a second inductor and a second capacitor. The first and second inductors comprise ferrite cores and are positioned with respect to each other to allow magnetic coupling therebetween. A subcarrier demodulator coupled to the second inductor and the second capacitors provides an audio signal corresponding to the information carried by the subcarrier.
14 Citations
16 Claims
-
1. An FM subcarrier receiver of the type useful for detection of a relatively high frequency desired subcarrier signal transmitted on an FM carrier which includes a baseband signal and said relatively high frequency subcarrier signal, comprising:
-
(a) radio frequency means for receiving a radio frequency signal having frequency modulated baseband and subcarrier components and outputting said baseband and relatively high frequency subcarrier signals; (b) a high pass filter for receiving the output of said radio frequency means; (c) a tuned circuit for receiving the output of said high pass filter, said tuned circuit comprising a first inductor of fixed inductance and a first capacitor tuned substantially to the frequency of the subcarrier which one wishes to detect; (d) a second tuned circuit tuned to said subcarrier which one wishes to detect, said second tuned circuit comprising a second inductor of fixed inductance and a second capacitor, said first and second inductors comprising ferrite cores and adjustably positioned with respect to each other to allow magnetic coupling therebetween; and (e) a subcarrier demodulator coupled to said second inductor and said second capacitor for providing an audio signal corresponding to the information carried by said desired subcarrier. - View Dependent Claims (2, 3, 4, 5, 6)
-
-
7. An FM subcarrier receiver of the type useful for detection of a relatively high frequency subcarrier signal transmitted on an FM carrier, said carrier being modulated with a primary signal comprising a pair of high fidelity audio signals, said pair of signals including a composite audio signal and a stereo audio signal, and said relatively high frequency subcarrier signal having a bandwidth and power less than said primary signal, comprising:
-
(a) a frequency modulation radio receiver for receiving said modulated FM carrier and outputting said composite signal, said stereo signal and said relatively high frequency subcarrier signal; (b) a first tuned circuit for receiving the output of said radio receiver, said first tuned circuit comprising a first single inductor and a first capacitor tuned at a frequency less than 100 kHz and tuned substantially to the frequency of said relatively high frequency subcarrier signal which one wishes to detect; (c) a second tuned circuit tuned at a frequency less than 100 kHz and substantially tuned to said relatively high frequency subcarrier signal, said second tuned circuit comprising a second single inductor and a second capacitor, said first and second inductors comprising ferrite cores and adjustably positioned with respect to each other to allow magnetic air coupling therebetween, said air coupling being substantially the sole coupling between said first and second tuned circuits; (d) first and second support structures for supporting said first and second inductors; and (e) a subcarrier demodulator coupled to said second inductor and said second capacitor for providing a third audio signal corresponding to information carried by said relatively high frequency subcarrier signal. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16)
-
Specification