I nterference Mitigation Tests at Molonglo Daniel Mitchell, Duncan Campbell-Wilson, Frank Briggs

Overview ● RFI mitigation is likely to play an important role in SKAMP data processing. ● The wide bandwidth alone will open the telescope up to a much greater level of RFI. ● Have done some short, preliminary observations with and without RFI to see how effective mitigation is likely to be.

Preliminary RFI Tests. ● MOST has 88 bays (antennas), which will be cross-correlated with all of the others ➔ 88 input correlator. ● Correlator will have 96 inputs ➔ Room for RFI reference antennas. ➔ Use closure relation based "post-correlation" cancellation algorithm to test RFI reduction.

● RFI - Broad-band noise from the RFI site: ➔ Estimated 5000 computer equivalents ➔ Telemetry link to transmitter, variable attenuator & white noise source ● 4 IFs & Sampler box: ➔ Two 778m x 12m MOST arms (with bay masking) ➔ Two orthogonal polarisations from the 6m dish ➔ Record to a PC at 16 Msamples / second / IF RFI Test Range

Short Baselines (bays E01 & W01)

Medium Baselines (bays E22 & W22)

Long Baselines (bays E44 & W44)

Long Baselines (bays E01 & W01)

Summary ● RFI mitigation is likely to play an important role in SKAMP data processing. ● The wide bandwidth alone will open the telescope up to a much greater level of RFI. ● A preliminary look at cancelling RFI from single bay cross-correlations seemed to work well on three baseline scales.