Recently there have been posts about certain receivers not viewing the latest satellite because their firmware has not been upgraded. Question is "how lame are these receivers or their manufacturers?"
Last night I took a Z-12 (about as old as you can get) out in front of the house and turned it on. The first satellite it captured was PRN 06, the newest GPS 2F satellite, just turned on last week. This receiver had not run in over a month so there is no way that 06 was in the ephemeris that was in the receiver. Next it grabbed 04 and 17, all of which happened to be about directly overhead.
I am trying to imagine the problems that other receivers may have in collecting the GPS data.
Paul in PA
I think it also is regional... that is, related to the almanac. So, it will know what to look for.
N
On a cold start the Z-12 usually starts looking for PRN 1-12 then runs through the whole constellation of 32. I can tell it not to look for certain sats but that takes pre planning, which I do not usually bother to do. I am assuming 6 got grabbed first because the newer satellites have higher power L2 signals. The Z-12 locks on to L2 first due to a unique algorithm that had the US military thinking Ashtech had used military technology. That uniqe technology may keep the Z-12s running after other older L2 receivers can noi longer figure it out. Some are out of service now because the manufacturer has not updated the firmware.
Paul in PA