Technical Issue - RFI

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Joined: Mon Sep 09, 2013 4:43 pm

Technical Issue - RFI

Postby smyers » Tue Mar 25, 2014 5:15 pm

In the science working groups (particularly Extragalactic) the issue of RFI has come up, mainly from geo-synchronous satellites affecting low-Dec observations.

It is our experience that S-band (and L-band to a lesser extent) suffer strongly from satellite interference in the geo-synchronous "Clarke" belt, which from the VLA appears at Dec -5.5deg or so. In our S-band Stripe82 work we saw a strong effect when we looked at a calibrator near Dec -3.3deg (and only a small effect at Dec 0). This isn't just interferenece you flag out - it actually seems to compress an entire baseband (1 GHz or half of the 2GHz S-band). It seems to be mitigated by observing at azimuths where the worst offending satellites are far off axis but this means at hour angles away from transit. It probably isn't a show-stopper but I'm guessing the region from -2 < Dec < -10 might be problematic from this regard.

We can do some tests to establish the problem zone and possible mitigation. We should identify soon any such tests needed on the array and I can arrange to have them done.

There are likely other tests we want to do for other RFI.

NOTE: We are holding a local NRAO TWG staff meeting on Thursday to start sorting out effort on technical issues. See the TWG wiki page at ... rkingGroup
where we will post progress.

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