GB1351185A - Radio navigation receivers - Google Patents

Abstract

1351185 Radio navigation DYNELL ELECTRONICS CORP 19 April 1971 [7 May 1970 (2)] 26307/71 Heading H4D In a receiver, responsive to a plurality of received signals of predetermined frequency each of which is transmitted from a different location for a discrete period of time, there is generated a signal, an output representing the phase difference between each received signal and the generated signal is produced and a register means controlled by that output stores an indication commensurate with the magnitude of each phase difference, the register means operating on a time-sharing basis and registering a particular indication only during reception of the relevant received signal. The description is an omega system receiver in which there are transmitted sequentially from stations A, B, C, D, Fig. 3, carriers on 10-2 kHz-hatched rectangles-and 13À6 kHz (for lane identification) timed as shown. General operation, Fig. 4.-A synchronizer 4-12 generates internal reference signals, is controlled by unit 4-13 for synchronizing reference signals with received signals, and produces "on-time" gates, Fig. 9 (not shown), having durations corresponding to those of the received signals and visually compared therewith. A single phase tracker 4-21 is multiplexed to all the received signals. If a detector 4-14 shows that a signal is present it is employed, after pulse width measurement 4-15, to permit fine synchronization of an internal "clock" in conjunction with early and late gates generated within synchronizer 4-12. The description pertains to the 10À2 kHz signals; automatic phase tracking is performed on the 13À6 kHz signals in an analogous manner. Synchronizing.-A crystal oscillator output is divided down to 10À2 kHz and converted to binary-coded-decimal (B.C.D.) form, and further division and conversion to B.C.D. form is employed, Fig. 5 (not shown). Synchronization with received signals is effected by modification of a division ratio. Display and control.-Juxtaposed rows of lights are respectively energized by the "ontime" gates and under the control of the received signals; the division ratio is manually adjusted until the rows are in synchronism and this, "coarse", synchronization may be sufficient. "Fine" synchronization is indicated by a further visual system. The synchronization has no direct effect on the phase measurement but enables maximum available time to be devoted to it. Phase measurement.-A digital phase tracking arrangement is provided, time-multiplexed for each transmitting station's received signals, and phase numbers for each 10À2 kHz received signal are compared to give the corresponding lines of position, Figs. 7 to 14 (none shown). A visual digital display of lane and lane fraction is afforded, and may be written on a chart recorder, Fig. 1 (not shown).