1. RFI and Pulsar Data
Rai Yuen
QTT, 18 December 2014

2. The omni-presence RFI
A look at database revealed pulsar profiles are inconsistent.
Common to find 5-6 out of 10 observation data that are heavily contaminated with RFI.
Worse, don’t know the characteristic of the RFI -> removal is hard.
A discount of 10 yr data – but still good.

3. Some RFI information Characteristics:
RFI originates from many sources:
3G signal can be up to million Jy, while pulsar signals are in the order of mJy.
from satellites, mobile phones and car sparks.
Characteristics:
narrowband: communication systems and TV, can be anywhere within the bandpass; lasts for < 1 to > few hundreds of second; power up to +50 dB.
wideband
pulse bursts: power line; 1- ~50 pulses each bursts; power up to +50 dB.
single pulse: ignition (car sparks); lasts from microsecond to hours; power up to +50 dB.
Ways to deal with them but we need to know their nature.

4. Pulse profile for PSR J0837+0610 (B0834+06)
There may be moderate to high RFI, but we do see the pulse.
speculate on the pulse width.
unsure of the pulse components.
hard for statistical studies.
Fit for pulsar timing, centre
of pulse.
If RFI, probably need to discard
it as it is too close to the real
signal.

5. The same pulsar Stockert 25m radio telescope. Now we are talking!
But how to remove
the RFI?

6. RFI Mitigation plan
Our telescope has stepped up to 26m, and need a long-term effective RFI mitigation plan.
Local:
potentially controllable.
regulatory protocols;
identify the signatures of RFI from our equipments.
External:
little we can do.
regularly monitoring of the changes in RFI.
again, identify their signatures and occurrences.
Best - establish a radio quiet zone.

7. Conclusions RFI is everywhere!
What makes a telescope famous is not only for the dish size but equally due to having an effective plan for dealing with RFI.
RFI investigations have begun at XAO with several results.
Required equipments are in place.
We have the required expertises.
It is just a matter of time and collaboration before we have an effective RFI mitigation plan.