What is the number of one second ticks between Unix time epoch (01 Jan 1970) and GPS time epoch (06 Jan 1980)?
I have seen multiple answers from several sources on the web. One camp claims the answer is 315964800, the other claims it is 315964819. I always thought it was 315964800, but now am not so sure.
I just found my software baseline has been using 315964819 for the last eight years. I have a hard time understanding how it could have been 19 seconds off and no one noticed it when we integrated our embedded devices with other devices.
I think that whoever put 315964819 in the code baseline must have mistakenly used a TAI offset (19 seconds).
From what I understand, Unix time does not include leap seconds, which would indicate to me that 315964800 is the number of ticks between the two epochs. Then I think about how Unix time handles the leap second. It simply repeats the tick count when there is a leap second inserted, and there were 19 leap seconds inserted between 1970 and 1980... I start to wonder if the repeated ticks matter. I do not think so, but someone in this code's history thought so, and it seemed to work....
The long and short of it is I am about to change a constant set in the dark ages of this product that has to do with timing, which is important for the platform, from what it had been to what I believe is more accurate, and I wanted some sort of thumbs-up from more knowledgeable people than me.
Can someone authoritative please step in here?
Also note that I'm only asking about Unix epoch to GPS epoch. I'm pretty sure we've got leap seconds since GPS epoch covered appropriately.