Telecommunications – Transmitter and receiver at separate stations
Patent
1993-03-26
1995-10-03
Pham, Chi H.
Telecommunications
Transmitter and receiver at separate stations
455 542, 455 63, 455 674, 455 69, 455 71, 342418, 379 63, H04Q 738, H04B 110, H04B 726, G01S 352
Patent
active
054559642
ABSTRACT:
The frequency and power of transmissions in a mobile communication system, such as an air-to-ground telephony system, are stabilized without a priori knowledge of the system gain factors or frequency references. The ground station monitors the available channels and modifies a vacant channel broadcast message to provide information that the channel is available. In this way, the air terminals have knowledge of all available channels. The ground station transmits a pilot signal. Upon request by a user for a dial tone at the air terminal, the air terminal selects a vacant channel and scans for the pilot signal. The air terminal estimates a distance to the ground station and sets a power level of a seizing transmission based on the estimated distance. The air terminal also estimates a Doppler frequency shift of the selected channel due to the relative movement of the air terminal with respect to the ground station and sets a frequency of the seizing transmission based on the estimated Doppler frequency shift. The air terminal then transmits a channel seizing signal at a reduced bandwidth less than a full normal bandwidth to the ground station at the set level and frequency. The ground station measures the level and frequency of the seizing signal and transmits to the air terminal information acknowledging the seizure of the selected channel and reporting the level and frequency of the seizing signal. The air terminal corrects the transmitted level and frequency and then switches the transmission bandwidth to the full normal bandwidth at the corrected level.
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Brandt Andrew W.
Clewer John R.
D'Souza Allan A.
Kim Seok-Ho
Malcolm James E.
Claircom Communications Group, Inc.
Pham Chi H.
Wisler Mark D.
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