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Posted by: ncc1701d Mar 6 2019, 02:40 AM

Hello,
I have been doing some research on Pioneer 6. I needed to convert a 2- 36 bit word double precision octal sequence into the number of seconds past 1950. The image Iam uploaded provide examples of what the answers should be after conversion to date. My main question is, does anyone know what MSP and LSP stand for? I was thinking maybe MSP and LSP was some well known JPL abreviation for something.

Posted by: mcaplinger Mar 6 2019, 03:07 AM

Most significant/least significant part.

Floating point double precision is a clue. Pioneer 6 was run by NASA Ames, I'm not sure what computer types they were using (this was long before IEEE floating point standardization.)

Posted by: ncc1701d Mar 6 2019, 03:59 AM

Great! thanks. Thats what I was looking for.

Posted by: nprev Mar 6 2019, 04:06 AM

Admin note: Topic moved to Chit Chat from Mars section.

Posted by: AJAW Mar 10 2019, 06:34 PM

I think the first three octal digits are the exponent (power of two) with an offset applied (which I'm too lazy to work out) followed by the mantissa. The examples do not seem to be the exact number of days I was initially expecting; the bit patterns seem to match the number of seconds part-way through the specified days. They do not seem to be an exact number of seconds, either, so presumably this format recorded higher-precision times than mere seconds.