ODL: Status and Issues Mike Regan, Eddie Bergeron, Kevin Lindsay, & Doug Long

Outline Using warm reference pixels to test for EMI How to drop bits to improve data compression Current Issues and Testing

Raw reference pixels look significantly different on a warm detector RMS is 5 times higher Standard deviation of the RMS is 20 times higher. COLD WARM

Our selectable noise source, the fans in the readout electronics.

Filtering out the 1/f noise leads to an RMS that is only 10% higher when warm.

Webb generates a lot of data and has only one 8 hour contact a day. The assumption has always been that we could do lossless 2:1 compression in hardware. Using simulations with CRs and bad pixels -> 1.7:1 What if we drop low order bits? –1 bit = 1.9:1 –2 bits = 2.1:1 –3 bits = 2.5 :1 What is the noise effect?

You can drop up to three bits and have no effect on the noise. Drop 5 bits Drop 4 bits

The noise effect is larger for reference pixels. Drop 5 bits Drop 4 bits Drop 3 bits

We have many issues we are investigating that will not be dealt with in instrument testing.