Method and means of minimizing simulcast distortion in a receiver when using a same-frequency repeater
First Claim
1. A method of minimizing simulcast distortion when broadcasting an information signal directly to an FM receiver and indirectly to the FM receiver through a same-frequency repeater comprising the steps of:
- generating an RF signal that is amplitude-modulated with the information signal and that is frequency-modulated with the information signal delayed by a predetermined length of time;
broadcasting the RF signal to the FM receiver and to the same-frequency repeater;
detecting the amplitude-modulated signal at the same-frequency repeater and applying the detected signal as frequency modulation to a repeater to produce a repeated RF signal that is inherently delayed in the repeater by the predetermined length of time; and
broadcasting the repeated RF signal to the FM receiver;
whereby the RF signal and the repeated RF signal will both be delayed at the FM receiver, by essentially the predetermined length of time, thereby minimizing simulcast distortion.
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Accused Products
Abstract
Simulcast distortion in a receiver when using a same-frequency repeater is minimized by applying double modulation to a signal that is broadcast to the same-frequency repeater. A voice signal is applied without delay as AM on a carrier to a modulation index of up to 30%, and the same signal is also applied as FM on the same carrier with a time delay equal to the time delay in the same-frequency repeater. The same-frequency repeater detects the AM and applies the detected signal as FM on a carrier that is rebroadcast. Received FM signals are thus delayed by substantially the same amount whether they are received from the original broadcast or the same-frequency repeater.
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Citations
7 Claims
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1. A method of minimizing simulcast distortion when broadcasting an information signal directly to an FM receiver and indirectly to the FM receiver through a same-frequency repeater comprising the steps of:
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generating an RF signal that is amplitude-modulated with the information signal and that is frequency-modulated with the information signal delayed by a predetermined length of time; broadcasting the RF signal to the FM receiver and to the same-frequency repeater; detecting the amplitude-modulated signal at the same-frequency repeater and applying the detected signal as frequency modulation to a repeater to produce a repeated RF signal that is inherently delayed in the repeater by the predetermined length of time; and broadcasting the repeated RF signal to the FM receiver; whereby the RF signal and the repeated RF signal will both be delayed at the FM receiver, by essentially the predetermined length of time, thereby minimizing simulcast distortion. - View Dependent Claims (2, 3, 4, 5)
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6. An apparatus for minimizing simulcast distortion when broadcasting an information signal to a receiver, the apparatus comprising:
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means for modulating a broadcast carrier simultaneously with the information signal as AM and with a delayed information signal as FM; means for receiving the broadcast carrier;
means for detecting the AM to produce a detected signal; and
means for modulating with the detected signal as FM on a repeater carrier that is synchronized to the broadcast carrier; andmeans for broadcasting the repeater carrier. - View Dependent Claims (7)
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Specification