Re: [LEAPSECS] BBC radio Crowd Science

2017-02-06 Thread Tom Van Baak
> That's where my question is. A GPS receiver would read the UTC metadata > supplied in the GPS signal to generate UTC 23:59:60 from the primary GPS > time, right? Correct. > We see from this discussion there are several ways folks use to > calculate this conversion, but what method to use

Re: [LEAPSECS] BBC radio Crowd Science

2017-02-06 Thread Brooks Harris
On 2017-02-06 06:30 PM, Tom Van Baak wrote: I'm not a GPS expert. IS-GPS-200G is dense. The TAI-UTC value is signaled, but how its encoded is complicated, and when its updated is unclear to me. See 20.3.3.5.2.4 Coordinated Universal Time (UTC). Can anyone speak to that and this topic? What does

Re: [LEAPSECS] BBC radio Crowd Science

2017-02-06 Thread Tom Van Baak
> I'm not a GPS expert. IS-GPS-200G is dense. The TAI-UTC value is > signaled, but how its encoded is complicated, and when its updated is > unclear to me. See 20.3.3.5.2.4 Coordinated Universal Time (UTC). Can > anyone speak to that and this topic? What does GPS do? Is it clear? Or > does it

Re: [LEAPSECS] BBC radio Crowd Science

2017-02-06 Thread Zefram
Warner Losh wrote: >Actually it doesn't. I couldn't follow the logic on that argument at >all, Let me see if I can work through it more clearly, and more in the terminology that you have used. The first case below is one that you have addressed in detail; the others are what I derive from it

Re: [LEAPSECS] BBC radio Crowd Science

2017-02-06 Thread Brooks Harris
On 2017-02-06 12:11 PM, Warner Losh wrote: On Mon, Feb 6, 2017 at 6:39 AM, Zefram wrote: Warner Losh wrote: So either there's some weird math that lets one subtract two numbers that are different and get 0 as the answer, or the delta has to change at the start. To the extent

Re: [LEAPSECS] BBC radio Crowd Science

2017-02-06 Thread Warner Losh
On Mon, Feb 6, 2017 at 10:58 AM, Zefram wrote: > Warner Losh wrote: >>Saying that the two numbers are the same is improper. Or rather, it >>depends on which time scale you are looking at them in if they are >>improper. > > The numbers are not on any time scale. The numbers are

Re: [LEAPSECS] BBC radio Crowd Science

2017-02-06 Thread Zefram
Warner Losh wrote: >Saying that the two numbers are the same is improper. Or rather, it >depends on which time scale you are looking at them in if they are >improper. The numbers are not on any time scale. The numbers are derived from the time values, but are a different thing. >However, if you

Re: [LEAPSECS] BBC radio Crowd Science

2017-02-06 Thread Tom Van Baak
> Also, I'll note that bulletin C says from 0h, which is a time > expressed to only one significant digit. That's a lame excuse to bring up significant digits. Everyone knows that "0h" means midnight, the one at 00:00:00 (as opposed to the one at 24:00:00). Are you now going to criticize a

Re: [LEAPSECS] BBC radio Crowd Science

2017-02-06 Thread Warner Losh
On Mon, Feb 6, 2017 at 6:39 AM, Zefram wrote: > Warner Losh wrote: >>So either there's some weird math that lets one subtract two numbers >>that are different and get 0 as the answer, or the delta has to change >>at the start. > > To the extent that they're different, the things

Re: [LEAPSECS] BBC radio Crowd Science

2017-02-06 Thread Zefram
Warner Losh wrote: >So either there's some weird math that lets one subtract two numbers >that are different and get 0 as the answer, or the delta has to change >at the start. To the extent that they're different, the things being subtracted are not numbers. The expression "TAI - UTC" is