Forbes Filter Bank Status

April 23, 2007

The FFB system is working.

There have been a few sporadic issues with baseline offsets in the first 512 channels of FFBA, and in alternate groups of 128 channels in FFBA and FB2A.

These offset problems are being addressed. Observer problem reports to David Forbes are welcome.

February 02, 2006

The FFB filterbank system is currently operational with no known problems. The 250kHz filter sections FB2A and FB2B have been installed and are being used.

Two system problems have been solved since December 2005. These are:

1. A Linux driver bug caused the system to occasionally send bad commands to the IF processors and attenuators. This resulted in bad calibration runs and in OTF data for certain 16-channel segments to be high or low by one dB.

2. A problem of bad data when switching receivers was traced to the wrong Rx lock bit being used for the level-adjusting procedure. This has been fixed in the ffb_control software.

November 29, 2005.

The 1 MHz, 2048 channel system is installed at the SMT and is operating satisfactorily.

1. There is one known issue - the attenuator setting is sometimes wrong by one, two or three dB on certain 16 channel segments. This issue will be resolved  after we get the test system operational in the next couple of weeks.

The 250K filterbanks are installed and undergoing checkout.

1. There is one known issue - the calibration occasionally fails due to the zero switch not working. This problem is being addressed.
2. We do need to finish some 250K installation work with regard to
   temperature monitors and card labeling.