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Interference

Radio frequency interference is something that should always be kept in mind when observing at the ATCA. In general the lower the frequency, the more difficult it is to find a 128MHz of interference free spectrum.

The plots below display the interference that was observed in September, 2006.

Particular points to note for interference, you should take care to avoid multiples of 128MHz. Also narrow band (a few MHz) interference from mobile phones can be found in harmonics of 824-849MHz.

**Figure G.1:** Radio frequency interference at 20, 13, 6 and 3cm at the Compact Array in September, 2006
$\includegraphics[width=0.45\textwidth]{surv0609_l.ps}$ $\includegraphics[width=0.45\textwidth]{surv0609_s2.ps}$ $\includegraphics[width=0.45\textwidth]{surv0609_c.ps}$ $\includegraphics[width=0.45\textwidth]{surv0609_x.ps}$

**Figure G.2:** Radio frequency interference at 20, 13, 6 and 3cm at the Compact Array in April, 2004
$\includegraphics[width=0.45\textwidth]{l.eps}$ $\includegraphics[width=0.45\textwidth]{s.eps}$ $\includegraphics[width=0.45\textwidth]{c.eps}$ $\includegraphics[width=0.45\textwidth]{x.eps}$

Robin Wark 2006-10-24