Accession Number : ADA259917


Title :   Suppression of Power Line Harmonic Interference in HF Surface-Wave Radar


Descriptive Note : Technical rept.


Corporate Author : DEFENCE RESEARCH ESTABLISHMENT OTTAWA (ONTARIO)


Personal Author(s) : Leong, Hank


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a259917.pdf


Report Date : Oct 1992


Pagination or Media Count : 31


Abstract : Experimental data of the Cape Bonavista High-Frequency Surface-Wave Radar (HFSWR) facility was contaminated by power line harmonics. The harmonics modulate the radar signal (mainly sea clutter) and replicate it into the Doppler spectrum. The spectral replicas distort the noise and sea clutter statistics in the signal. It is necessary to suppress them before the statistics can be obtained. A new process based on optimizations is presented for suppressing the interference. This process minimizes the spectral power of the sea clutter with respect to the amplitudes and phases of the harmonics. It is capable of removing the spectral replicas without adversely altering the statistics. This process, however, requires adequate modelling of the harmonics. A large number of parameters are required because the harmonics may have a fluctuating fundamental frequency and fluctuating amplitudes. Therefore the process can be numerically complex. To implement our process, one must use approximations in the signal model. If the amplitudes and the fundamental frequency are approximated with constants, the process can still be effective for a short HFSWR data series. For some 256-point data series, more than 20 dB of the peak interference can be reduced. For a long HFSWR data series, the same process can be applied by first dividing it into several short data segments, and then optimizing on the individual segments. With this slightly revised approach, up to 20 dB of the peak interference can be suppressed for a long data series.


Descriptors :   *SURFACE WAVES , *RADAR SIGNALS , *SUPPRESSION , *RADAR INTERFERENCE , FREQUENCY , ANOMALIES , HIGH FREQUENCY , PARAMETERS , CANADA , STATISTICS , PHASE , SIGNALS , AMPLITUDE , REPLICAS , OCEANS , NOISE , POWER , PATTERNS , DATA ACQUISITION , INTERFERENCE , CONSTANTS , SEA CLUTTER , CHANNELS , SURFACES , RADAR , HARMONICS , WAVEFORMS , MODELS , EXPERIMENTAL DATA , OPTIMIZATION


Subject Categories : Active & Passive Radar Detection & Equipment


Distribution Statement : APPROVED FOR PUBLIC RELEASE