An Investigation of HF Direction-Finding Accuracy on the Frobisher Bay- Ottawa Auroral Zone Path

• Main Author: Venier, G O
• Other Authors: COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
• Format: Text
• Language: English
• Published: 1980
• Subjects: Direction Finding; Active & Passive Radar Detection & Equipment; *DIRECTION FINDING; *SWEEP FREQUENCY RADAR; ACCURACY; ANGLE OF ARRIVAL; ARRAYS; ARRIVAL; AURORAE; AZIMUTH; CANADA; CIRCLES; DOPPLER EFFECT; DOPPLER SYSTEMS; FREQUENCY; HIGH FREQUENCY; HIGH RATE; MEASUREMENT; POLAR REGIONS; PROCESSING; SAMPLING; SWEEP FREQUENCY TECHNIQUES; TRANSMITTANCE; Zone paths; Frobisher Bay; Canada
• Online Access: http://www.dtic.mil/docs/citations/ADA092312; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA092312

The CRC HF direction-finding array, consisting of a 1181 meter by 236 meter cross, was used to make angle of arrival measurements of waves transmitted over a 2100 km path whose mid point was near the centre of the auroral zone. Swept-frequency transmissions allowed the investigation of the angle variations of individual propagation modes, and fixed-frequency transmissions permitted the measurement of Doppler shifts as well as the sampling of the phase fronts at relatively high rates. E-mode propagation over this path appeared to be entirely of the sporadic variety, but still provided good azimuth accuracy with a median RMS error from the great circle direction around 0.4 degrees for the single-hop case. On the F mode, spreading in range occurred a significant percentage of the time in contrast to experience with lower-latitude paths. This spreading was accompanied by large departures in angle of arrival for this mode from the great circle direction. Two azimuth-estimation techniques were tested on the fixed- frequency data. One used a phase-front planarity test and averaging over relatively frequent samples while the other was based on the separation of modes by Doppler processing. The former technique was found to provide slightly better results than the latter on these data, and its accuracy was, in most cases, close to that which could be obtained from the best mode when separated using swept frequency data.