Simulcast auto alignment system
First Claim
1. In a radio frequency simulcasting system including a control center connected to plural radio frequency transmitter sites by plural substantially phase stable distribution links for providing information for simultaneous transmission by each of the transmitters, a method of aligning said system for obtaining and maintaining substantially identical amplitude and time of arrival of the transmitted information in signal overlap areas between two or more of said transmitters, said method comprising the steps of:
- (a) initially adjusting modulation signal amplitude equalization means incorporated in each said distribution link to obtain substantially identical amplitudes of transmitted information in said signal overlap areas;
(b) initially adjusting modulation signal time delay means incorporated in each said distribution link to obtain substantially identical times of arrival of the transmitted information in said signal overlap areas;
(c) periodically transmitting a test signal from said control center to a selected site transmitter for retransmission by said selected transmitter back to said control center;
(d) comparing said retransmitted signal received by said control center with reference data to produce correction information;
(e) adjusting additional amplitude equalization and time delay means incorporated in the distribution link of said selected site so as to compensate for said correction information; and
(f) repeating steps (c) through(e) for each of said transmitter sites until all sites have been tested and adjusted, whereby substantially identical amplitude and time of arrival of transmitted modulation in signal overlap areas are maintained.
8 Assignments
0 Petitions
Accused Products
Abstract
In a multisite radio frequency simulcasting transmission system involving microwave-multiplex distribution paths to several transmitting sites, each path including manually settable amplitude and time delay devices for equalization of the modulation in signal overlap areas among the various transmitter sites, an automatic simulcast alignment device is included in each distribution path whereby transmissions between a control point and each site transmitter are periodically tested and each path is compensated for amplitude and time delay variations to thus maintain equalized amplitude and time of arrival of the modulation in the transmitter site overlap areas. Thus, the instantaneous distribution of the FM modulation sidebands is maintained to be ideally identical in the signal overlap areas.
45 Citations
26 Claims
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1. In a radio frequency simulcasting system including a control center connected to plural radio frequency transmitter sites by plural substantially phase stable distribution links for providing information for simultaneous transmission by each of the transmitters, a method of aligning said system for obtaining and maintaining substantially identical amplitude and time of arrival of the transmitted information in signal overlap areas between two or more of said transmitters, said method comprising the steps of:
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(a) initially adjusting modulation signal amplitude equalization means incorporated in each said distribution link to obtain substantially identical amplitudes of transmitted information in said signal overlap areas; (b) initially adjusting modulation signal time delay means incorporated in each said distribution link to obtain substantially identical times of arrival of the transmitted information in said signal overlap areas; (c) periodically transmitting a test signal from said control center to a selected site transmitter for retransmission by said selected transmitter back to said control center; (d) comparing said retransmitted signal received by said control center with reference data to produce correction information; (e) adjusting additional amplitude equalization and time delay means incorporated in the distribution link of said selected site so as to compensate for said correction information; and (f) repeating steps (c) through(e) for each of said transmitter sites until all sites have been tested and adjusted, whereby substantially identical amplitude and time of arrival of transmitted modulation in signal overlap areas are maintained. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A radio frequency simulcasting system including a control center connected to plural radio frequency transmitter sites by plural substantially phase stable distribution links for providing information for simultaneous transmission by each of the transmitters, said system further including a apparatus for obtaining and maintaining substantially identical amplitude and time of arrival of the transmitted information in signal overlap areas between two or more of said transmitters, said apparatus comprising:
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adjustable modulation signal amplitude equalization means in each of said distribution links for initially obtaining substantially identical amplitudes of transmitted information in said signal overlap areas; adjustable modulation signal time delay means in each of said distribution links for initially obtaining substantially identical times of arrival of the transmitted information in said signal overlap areas; means for periodically transmitting a test signal from said control center to a selected site transmitter for retransmission by said selected transmitter back to said control center; means for comparing said retransmitted signal received by said control center with reference data to produce correction information; additional amplitude equalization and time delay means responsive to said means for comparing for readjusting the modulation signal amplitude and time delay of said selected site in accordance with said correction information; and control means for causing the functions of said means for periodically transmitting, said means for comparing and said additional amplitude equalization and time delay means to be sequentially performed for each said transmitter site until all sites have been tested and readjusted, whereby substantially identical amplitude and time of arrival of transmitted modulation in signal overlap areas are maintained. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. An automatic alignment circuit for use in each of a plurality of distribution paths of a simulcast transmission system, said system including a control center and a plurality of transmitter sites for simultaneously transmitting the same information, said distribution paths each including adjustable modulation signal amplitude equalization means and adjustable modulation signal time delay means for initially obtaining substantially identical amplitude and time of arrival of the transmitted information in signal overlap areas between two or more simulcast transmitter sites, said automatic alignment circuit comprising:
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control means for sequentially transmitting a test signal from said control center to each transmitter site for sequential retransmission of the test signals to said control center; means responsive to each retransmission for comparing each of the retransmitted test signals with reference data to produce sequential correction signals; means responsive to said sequential correction signals for aligning each said distribution path so that substantially identical amplitude and time of arrival of the transmitted modulations in said signal overlap areas are maintained. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26)
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Specification