US 4,048,563 AGranted

Carrier-modulated coherency monitoring system

AssigneeThe United States of America as represented by the Secretary of the Navy

InventorEugene F. Osborne

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Abstract

A radio information system is described which uses the exact mathematical tios and the unique periodic angular coherence of the residual RF carrier and the digitally encoded modulation spectral components of the electromagnetic wave as emitted by a source transmitter (or transmitters) to enhance system performance and to provide new instrumentation and measurement capabilities at the receiver apparatus. The digital modulation synchronizing code occupies a wide frequency bandwidth and is encoded for precise repetitive transmission to provide, for example in a satellite navigation system, a means of accurate synchronization and measurement of time and range parameters. Many encoded sequences of either discrete or pseudo-random types may be used as the synchronizing code. However in the description herein the pseudo-random noise (PRN) codes are used for their added advantage in spread spectrum discrimination against intentional interference. The total or composite RF signal typically also includes non-interfering information or message modulation.

Claims10

Dependent claims

In a radio transmission system for transmitting information between spaced location, the combination comprising:

signal source means for generating a carrier signal of radio frequency, f.sub.rf,
source means for generating a synchronizing code having a repetitive time frame which is numerically related to the period, 1/f.sub.rf, of said carrier signal by a predetermined fixed multiplier,
modulator means connected to said carrier signal source and said synchronizing code source for modulating said carrier signal with said synchronizing code,
transmitter means for transmitting said modulated carrier signal,
receiver means for receiving said modulated carrier signal and including means for recovering said carrier signal and said synchronizing code from said modulated carrier signal, and
measurement means responsive to said recovered carrier signal and synchronizing code and including counter means and counter control means, said counter control means being responsive to said synchronizing code for controlling said counter means to register a count of the number of whole and fractional cycles of said carrier signal received in a measurement time interval corresponding to the repetitive time frame of said synchronizing code as received.

3 more elements

Dependencies are inferred from the claim text.