The Amor Facility

The southern hemisphere meteor orbit radar (AMOR) (geographical coordinates 172° 39' E, 43°34' S) operated by the University of Canterbury, Christchurch, New Zealand designed [1] to provide near-continuous data has been operational since 1990. The facility yields archived orbital information valuable for interplanetary dust studies [2,3], There are three major innovations that characterise this radar facility.

The system uses narrow antenna beams which implicitly locate the meteor and increase the radar gain making possible the detection of smaller particles.

Raw AMOR data can be used to calculate the time intervals between the occurrence of meteor echo profiles on three spaced receivers to determine the particle velocity components in the atmosphere. Two remote sites are located ~ 8 km west and north of the central site which incorporates the system control, transmitting antenna and echo elevation-finding receiving antennas. UHF FM data links transmit signal data from these sites. Employing Fresnel diffraction patterns as the only method of speed measurements employed by some meteor radar systems suffers from two disadvantages. To secure well-defined echo amplitude fluctuations for fast meteors a high pulse sampling rate is necessary, thus introducing aliasing in range measurement. Additionally, processes such as fragmentation may produce multiple sources destroying the resultant Fresnel pattern, and atmospheric wind-shear may distort the echo profile. Routine speed measurements provided by AMOR do not use diffraction patterns but rather the velocity is determined directly from the time intervals between the recording of the echo profiles on 8 km-spaced receivers. This gives a considerable increase in the proportion of meteor observations for which speeds can be determined compared with other Fresnel diffraction methods. However, the system does make use of the overall velocity calibration provided by the archived Fresnel speed values.

Computerised data acquisition, storage, reduction and display make it possible to reduce observational data rapidly. The association of data acquisition and reduction software with diagnostic display routines provides a powerful environment in which to maintain the system while a graphical display suite provides ready access to the AMOR database.

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