Accession Number : AD0456205


Title :   GENERATION OF ACCURATE FREQUENCY-SWEEP WAVEFORMS BY DIRECT SYNTHESIS


Corporate Author : STANFORD UNIV CA STANFORD ELECTRONICS LABS


Personal Author(s) : Fenwick, R B ; Barry, G H


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/456205.pdf


Report Date : Dec 1964


Pagination or Media Count : 26


Abstract : A signal whose frequency is a continuously varying function of time may be synthesized to any desired accuracy by digitally programming a direct frequency synthesizer. A synthesizer of this type can be modified to obtain phase-coherent frequency switching within a few hundred nanoseconds. The practicality of this mode of synthesizer operation has been demonstrated by the operation of a frequency-synthesized hf meteor radar. Two synthesizers were modified and electronically programmed to generate 100-kc, 1-sec, linear frequency sweeps. The radar achieves close to the theoretically expected range and doppler resolutions of 1.5 km and 1 cps, respectively. It is expected that this extension of the use of frequency synthesizers for generating other than constant- or steppedfrequency signals will find many other applications where signals of precisely time-varying frequency are needed.


Descriptors :   *WAVEFORM GENERATORS , DOPPLER RADAR , FREQUENCY , FREQUENCY CONVERTERS , FREQUENCY MODULATION , HIGH FREQUENCY , PHASE(ELECTRONICS) , RADAR EQUIPMENT , RADAR SIGNALS , RESOLUTION , SYNTHESIS


Subject Categories : Radiofrequency Wave Propagation


Distribution Statement : APPROVED FOR PUBLIC RELEASE