Abstract: Base stations (101, 103, and 105) transmit, and a remote unit (117) receives a radio frequency (RF) location signal. The remote unit (117) then computes an observed-time-difference (OTD) for each base station at particular time t1. Observed differences in received signal times, and are reported to a Mobile Location Center (MLC) (111). Additionally, a Real-Time-Difference receiver (115) receives an RF signal from two or more base stations. The Real Time Differences between the base stations (101, 103, and 105) are computed at a second time. These differences are also reported to the MLC (111). The MLC (111) computes an estimated RTD for the time period t.sub.1 via standard curve fitting algorithms, or simple interpolating algorithms. A corrected Time Difference of Arrival (TDOA) as determined by the remote unit (117) is computed based on the OTD measurements and the estimated RTD measurements.

Abstract: In a data transmitter (200), a precision timing signal receiver (201) provides a precise timing signal (203) to an informationally responsive comparator (205). The informationally responsive comparator compares an output (211) of a controllable oscillator (209) to the precise timing signal to produce a comparison metric. An output of the informationally responsive comparator, comprising a combination of an information signal (207) and the comparison metric, is then used to control the controllable oscillator.

Abstract: A phase lock loop (700) maintains a freewheeling capability while making phase corrections to a sample clock signal based on a precision timing signal. The phase corrections are dispersed over time such that data reception in uninterrupted so that data integrity is maintained during the phase corrections. The phase lock loop (700) includes a first divider circuit (721) having a divisor n, coupled for dividing the incoming clock signal by n to produce a bit clock signal. A second divider circuit (725) is coupled to the bit clock signal for dividing the bit clock signal to produce the sample clock signal.

Abstract: A control station 12 initiates a system timing signal transmission which is re-transmitted from a satellite 14. In response to receiving the system timing signal, the control station 12 then generates a time correction factor which is distributed to a plurality of transmission stations 16, 18. The transmission stations 16, 18 in response to receiving the system timing signal transmission and the time correction factor distributed from the control station 12 generate a time adjustment factor which is used to correct the local transmission clocks 36, 36', thereby providing time synchronization of data transmissions generated from the transmission stations 16, 18.

Abstract: A simulcast transmission system (10) and method provides for time synchronizing data transmissions from a plurality of transmission stations (16, 18). The transmission stations (16, 18) include transmission clocks (36) for controlling the time of transmission of synchronization timing signals and data. The synchronization timing signals indicate a local time of transmission which are transmitted in response to system timing signals received from the control station (12). The control station (12) comprises apparatus (20) for generating and distributing the system timing signals, apparatus (26) for receiving the synchronization timing signals from the transmission stations, and apparatus (20, 22, 28) for generating and distributing time adjustment factor signals to the transmission stations (16, 18) in response to receiving the synchronization timing signals. The transmission clocks (36) are adjusted in response to the time adjustment factor signals for controlling the time of transmission of the data signals.

Abstract: A modulatable oscillator for radio frequencies is disclosed in which the single resonant tank includes a tightly coupled varactor diode for wideband modulation and frequency control. Nonlinearities introduced by the varactor diode are compensated by predistortion of the modulated signal yielding a predetermined modulation characteristic which is maintained over temperature.