urn:nasa:pds:context:instrument:uwo_meteor_radar.cmor.cmor_inst 1.0 1.10.0.0 Product_Context 2020-02-18 1.0 Initial export from OLAF urn:nasa:pds:context:telescope:uwo_meteor_radar.cmor instrument_to_telescope Webster, A.R., P.G. Brown, J. Jones, K.J. Ellis, and M. Campbell-Brown, Canadian Meteor Orbit Radar (CMOR), Atmos. Chem. Phys. Discuss. 4, 1181-1201, 2004. Jones, J., P. Brown, K.J. Ellis, A.R. Webster, M. Campbell-Brown, Z. Krzemenski, and R.J. Weryk, The Canadian Meteor Orbit Radar: system overview and preliminary results, Planetary and Space Science 53, 413-421, 2005. Canadian Meteor Orbit Radar (CMOR) Radio-Radar The Canadian Meteor Orbit Radar (CMOR) is located at the University of Western Ontario (UWO) meteor radar complex near Tavistock, Ontario, and has been in operation since late 2001. It consists of three separate interferometric radars, synchronized in transmission and reflection and operating from a single site. Details of the system may be found in Jones et al. (2005) and Webster et al. (2004). The three systems operate at 17.45, 29.85, and 38.15 MHz. The "orbit" component of the system applies only to the 29.85 MHz system which has two outlying remote stations (6.2 and 8.1 km respectively from the main site) providing reflections from portions of the meteor trail not directly accessible from the specular reflections to the main site. For these echoes, the interferometry from the main site provides sufficient information to permit measurement of velocity vectors for individual meteors. Each of the three systems has seven antennae and seven separate receivers. For the 17 and 38 MHz systems all seven receivers are used for reception (to boost signal to noise levels) but only five are used for determination of the measured echo direction using interferometry. The 29 MHz system uses the two extra receivers to record signals from the two outlying stations. The transmit and receive antennae have broad (nearly all-sky) gain patterns. The transmit antenna is a vertically directed horizontally-polarized three-element Yagi with G = 7.6 dB(i) (relative to an isotropic radiator) and a beam width to the 3 dB points of 30 degrees. The receive antennae are all two-element vertically directed horizontally polarized Yagis with G = 6.5 dB(i) and beam widths of 45 degrees to the 3 dB points. Directions to each echo are measured using the relative phase difference between the antennae within each of the 5-element interferometer arrays. The interferometric error is less than 0.5 degrees for echoes with elevations above 30 degrees found for simulation for echoes with SNRs of 15 dB. Due to the degradation in interferometric accuracy at low elevations, no echoes are processed with their nominal elevation is below 20 degrees. All receivers are cosmic noise limited. The variation in noise levels is controlled principally by galactic cosmic noise at HF/VHF frequencies and produces a diurnal noise variation of 2 dB for the 29 and 38 MHz systems. The 17 MHz system suffers from heavy terrestrial interference during the day, limiting useful echo detections to night-time hours only. For the 29 MHz orbital system, the absolute minimal detectable signal strength corresponds to meteors with radio magnitudes near +9. However, effective counting statistics for 29.85 MHz are complete only to +8 due to the roll-off in sensitivity as the absolute detection threshold is reached - this is the effective detection limit for the radar and corresponds to meteoroids of ~10^-7 kg mass for an average velocity of 30 km/sec. References: Jones, J., P. Brown, K.J. Ellis, A.R. Webster, M. Campbell-Brown, Z. Krzemenski, and R.J. Weryk, The Canadian Meteor Orbit Radar: system overview and preliminary results, Planetary and Space Science 53, 413-421, 2005. Webster, A.R., P.G. Brown, J. Jones, K.J. Ellis, and M. Campbell-Brown, Canadian Meteor Orbit Radar (CMOR), Atmos. Chem. Phys. Discuss. 4, 1181-1201, 2004.