Phase Coding in Digital SuperDARN Radars to Observe Oblique Scattering

Super Dual Auroral Radar Network (SuperDARN) is a network of HF radars in the mid to high-latitude regions that observe space weather effects on the ionosphere and magnetosphere. These radars typically transmit a single frequency multi-pulse sequence in the 8-22MHz range in a monostatic configuration. Between 2019 and 2020, two radars were reconfigured at certain times to carry out bistatic operations to demonstrate detecting oblique scatter. These operations were limited to intersecting fields-of-view of both radars, and forcing one radar to be receive-only, disrupting regular radar operation. The results of these operations showed a need for a more flexible approach that is not constrained by mode or field-of-view. Since then, some radars in the network have been converted to a Software Defined Radio (SDR) based system. An SDR-based system enables greater configurability in the transmit waveform the radar uses, including the possibility to encode unique radar IDs into the pulse. Operating modes incorporating phase coding are currently in use for their increased range resolution, so phase coding an ID in the transmit pulse would not affect the normal operation of the radar. This work proposes that SuperDARN radar waveforms with phase-coded IDs could be received by low-cost SDRs similar to the PSWS Grape receivers, to study propagation and oblique scattering in the ionosphere.