[evlatests] 451.5 MHz RFI blip

[Vivek Dhawan]

Ken & I studied this a day or 2 ago (after Mert's message).

We found the 4-min pulse to be much weaker than before.
These data were taken without the solar attenuator. It used
to saturate even with the 20dB solar attenuator in place.

It is still quite apparent in the 'psum' data, i.e. total power
in the IF band covering 448-576MHz (IF 4 in the plot attached).

The period is very clear, but not every pulse is the same
strength (we were tracking a source, the sidelobes were
moving).  It is about 20dB above noise in a 128MHz subband.

Working backwards, assuming I did this correctly, it seems to
be consistent with a few 10's of watts transmitted by a low-gain
anenna from ~40km away, 1MHz BW, into our isotropic sidelobes.


On 02/26/2015 05:07 PM, Huib Intema (NRAO) wrote:
> Hi all,
>
> In today's P-band test data I have *not* (clearly) seen the 4-minute RFI
> blip at 451.5 MHz. Since the test consists of three 5-minute scans with
> gaps of a few minutes, I may have missed it since the new blip-rate is
> reported to be once every 10 minutes. It may also be that, since the
> blip power was lowered, it is now difficult to separate from other RFI
> sources. I'll keep monitoring this.
>
> -- Huib
>
>
>
>
>
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