Before you read the rest of this, let me warn you that we decided not to use the Orbit process for the production of the TGV/discriminator chip. I have kept this page for reference, but it is not relevant to the "real" MVD electronics.
First, I will summarize some of the information Tony Moore gave me. He measured the discriminator threshold in millivolts for each of 32 channels in 2 different pre-amp/discriminator chips (i.e. 64 channels total) from an Orbit process prototype run. A "mip" corresponds to 78mV in this scale. Ideally, we wanted to run with a discriminator threshold corresponding to 1/4 mip. However, most channels could not be turned down that low and the channels could not all be adjusted to the same threshold level. I used the results with the "tweak" which is a 2 bit adjustment intended to minimize channel to channel variations in the threshold. The two chips were called "chip red 5" and "chip 2 red" in Tony's faxed message to me. The following plots ( also available in the original postscript versions) summarize these discriminator thresholds.
