Doppler correction of transmission frequencies
AssigneeRCA Corporation
InventorLouis Sickles, II
Life of this patent
Estimating the term…
Abstract
Transmissions from a moving, vehicle-mounted transmitter to a remote station are pre-compensated at the transmitter for doppler shift by measuring the doppler shift of signals from the remote station and compensating by the use of a digital multiplier the frequency of transmissions to the remote station in the opposite sense and in an amount equal to the ratio of the nominal transmission to reception frequencies times the measured doppler shift. Application to full and half duplex radios and provisions for frequency shift keying systems are disclosed.
Claims6
Apparatus for pre-compensating for doppler shift in a signal to be transmitted to a remote station comprising:
- a. means, receptive of a signal from said remote station, said received signal deviating in frequency from a predetermined reception frequency due to doppler shift, for providing a digital signal representative of said frequency deviation;
- b. digital multiplier means, responsive to said representative signal, for generating a doppler correction signal indicative of said frequency deviation multiplied by the negative of the ratio of a predetermined transmission frequency for said transmitted signal to said predetermined reception frequency;
- and
- c. means, responsive to said doppler correction signal and to said signal to be transmitted, for translating in frequency said signal to be transmitted according to said doppler correction signal.
Apparatus for compensating for doppler frequency deviations in communications between a first station and a second station comprising:
- a. input means at said first station for receiving signals from said second station;
- b. doppler tracking means responsive to said received signals for generating a digital signal representative of frequency deviations in said received signals from a predetermined reception frequency;
- c. digital multiplier means receptive of said digital signal for providing a first doppler correction signal indicative of said frequency deviation and a second doppler correction signal indicative of said frequency deviation multiplied by the negative of the ratio of a predetermined transmission frequency to said predetermined reception frequency;
- and
- d. means at said first station receptive of said first and second doppler correction signals, said received signals and signals to be transmitted from said first station to said second station at said predetermined transmission frequency for translating in frequency said received signals according to said first doppler correction signal and the signals to be transmitted according to said second doppler correction signal.
Dependencies are inferred from the claim text.