"Mid-week" RFI in 16cm band

Information about the ATCA Forum, this forum system, and a place to experiment with posting if you want to.

Moderator: Mark.Wieringa

"Mid-week" RFI in 16cm band

Postby ste616 » Wed Mar 23, 2011 4:49 pm

You may have heard people talking about something called "mid-week RFI" that affects ATCA data in the 16cm band (spanning 1.1 - 3.1 GHz). This RFI has a very distinctive signature that is fairly easy to see during observations or reduction.

There are two main lines that will appear very strong, with frequencies near 1265 MHz and 1310 MHz. With a normal centre frequency of 2100 MHz, these lines will appear at channels 1860 and 1815 respectively (the 16cm band is inverted), and each line will be about 10 MHz wide. Below is a plot covering the channels 1600 to 2000 of a normal 16cm observation while the mid-week RFI was visible.

midweek_rfi_16cm.jpg (70.03 KiB) Viewed 31794 times

This doesn't seem to only affect those channels though, as the entire spectrum appears to get quite ugly when this RFI is present, as seen below.

lotsarfi_16cm.jpg (72.71 KiB) Viewed 31794 times

When this RFI is not present, the spectrum (at the same scale) looks rather more useful:

norfi_16cm.jpg (51.63 KiB) Viewed 31794 times

If you see this RFI, you are encouraged to report it by submitting a Fault Report, including the time you saw it, and for how long it affected you. It is a good idea to do this for any RFI you feel is causing you difficulty, at any frequency.
Jamie Stevens
ATCA Senior System Scientist
Site Admin
Posts: 217
Joined: Thu Feb 04, 2010 3:27 pm
Location: Paul Wild Observatory Narrabri NSW

Return to Information

Who is online

Users browsing this forum: No registered users and 1 guest