Simulcast same frequency repeater system
First Claim
1. In a simulcast communication system including a transmitting station for transmitting a first signal at a given frequency and a same frequency repeater (SFR) for receiving the first signal and for retransmitting the received signal at the given frequency, the SFR having a time delay of T such that the signal transmitted by the transmitter of the SFR consists of said received signal delayed in time by T, said retransmitted signal as received by the receiver of the SFR defining a spillover signal, the improvement:
- comprising;
a. means coupled to the transmitting station for generating a second signal derived by time delaying said first signal in time by approximately T so that said second signal and said spillover signal are in phase with each other at the SFR receiver; and
b. means coupled to said SFR for substantially cancelling said spillover signal, said second signal and said spillover signal being received in phase with each other by said SFR such that the second signal and the spillover signal are substantially cancelled by said cancelling means.
1 Assignment
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Accused Products
Abstract
The simulcast communication system includes a transmitting station for transmitting a first signal at a given frequency and a same frequency repeater (SFR) having a receiver for receiving the first signal and a transmitter for retransmitting the received signal at the same given frequency. The SFR rebroadcasts the received signal with a time delay of T. The receiver of the SFR receives the retransmitted signal as a spillover signal. A mechanism is coupled to the transmitting station for generating a second signal which consists of the first signal delayed in time by T1 which is approximately equal to T. Another mechanism coupled to the SFR substantially cancels the spillover signal and the second signal since the second signal is in phase with the spillover signal. Thus, the signal retransmitted by the SFR differs in phase from the second signal transmitted by the transmitting station only by the propagation delay between the SFR and the transmitting station, whereby the likelihood that a mobile unit will experience simulcast distortion due to the reception of the second signal and the retransmitted signal can be minimized. This invention further contemplates that multiple SFR'"'"'s may be employed wherein each SFR includes a mechanism for cancelling any other retransmitted signals by other SFR'"'"'s as received at each SFR.
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Citations
15 Claims
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1. In a simulcast communication system including a transmitting station for transmitting a first signal at a given frequency and a same frequency repeater (SFR) for receiving the first signal and for retransmitting the received signal at the given frequency, the SFR having a time delay of T such that the signal transmitted by the transmitter of the SFR consists of said received signal delayed in time by T, said retransmitted signal as received by the receiver of the SFR defining a spillover signal, the improvement:
- comprising;
a. means coupled to the transmitting station for generating a second signal derived by time delaying said first signal in time by approximately T so that said second signal and said spillover signal are in phase with each other at the SFR receiver; and b. means coupled to said SFR for substantially cancelling said spillover signal, said second signal and said spillover signal being received in phase with each other by said SFR such that the second signal and the spillover signal are substantially cancelled by said cancelling means. - View Dependent Claims (2, 3, 4, 5, 6, 7)
- comprising;
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8. A method for utilizing a same frequency repeater (SFR) in a simulcast communication system having a transmitting station, said method comprising the steps of:
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a. transmitting a first signal at a given frequency from said transmitting station; b. said SFR receiving said first signal; c. said SFR retransmitting the received signal at the given frequency after a time delay of T; d. said SFR receiving said retransmitted signal as a spillover signal; e. transmitting a second signal from said transmitting station, said second signal consisting of said first signal delayed in time by T1 which is approximately equal to T; f. said SFR receiving said second signal; and g. cancelling signals received by the SFR which are substantially in phase with said spillover signal, whereby said second signal and said spillover signal are substantially cancelled since said second signal is substantially in phase with said spillover signal. - View Dependent Claims (9, 10, 11, 12, 13)
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14. In a simulcast communication system including a transmitting station for transmitting a first signal at a given frequency, a first and second same frequency repeater (SFR) each having a receiver for receiving said first signal and a transmitter for retransmitting the received signal at said given frequency, each SFR having a time delay of T such that each retransmitted signal consists of said received signal delayed in time by T, each SFR receiver receiving a spillover signal consisting of the signal retransmitted by each corresponding SFR, the improvement comprising:
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a. means coupled to the transmitting station for generating a second signal consisting of said first signal delayed in time by T1 which is approximately equal to T; b. first means associated with each SFR for substantially cancelling said spillover signal, said second signal and said spillover signal being received in phase with each other by each SFR such that the second signal and the spillover signal are substantially cancelled by the first cancelling means; and c. second means coupled to said first SFR for substantially cancelling the retransmitted signal by said second SFR as received by said first SFR whereby said retransmitted signal by said first SFR does not contain any substantial components of the signal retransmitted by said second SFR. - View Dependent Claims (15)
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Specification