[time-nuts] M12+T more confusion

Norman J McSweyn normn3ykf at stny.rr.com
Fri Nov 21 23:43:47 UTC 2008


Chris Kuethe wrote:
> On Fri, Nov 21, 2008 at 3:06 PM, Tom Van Baak <tvb at leapsecond.com> wrote:
>> You are enabling output messages, right? Sounds like the
>> order in which you individually *enable* one or more messages
>> is unrelated to the order in which, once a second(*), all selected
>> messages are *output*. I've never confirmed if they are output
>> alphabetically or by size or priority or what. Does someone know
>> for sure? Or does it matter?
> 
> i've not seen a gps yet that doesn't act like there's a big,
> fixed-order list against which the enabled output messages are checked
> once per reporting cycle. it's not impossible to dynamically schedule
> a specific order of messages at a certain rate by building an array of
> function calls, but that sounds like more work... the first way can be
> done with a single char comparison per message.
Chris,
I'm not much of a programmer **YET**. The approach you suggest is one 
that I would need to take if I was creating a bulletproof app. Using the 
simple method that I've employed definitely isn't.
Don't get much time to play with this stuff. When I do, I try to get 
something to work. It's like anything else. The more you play with it, 
the less intimidating and more familiar it is, hence, more comfortable.
> 
> some messages are certainly more expensive to generate (GSV vs GLL)
> and are probably less interesting - so long has there is a good fix
> and a navigation solution the average user probably won't care too
> much about satellite locations. And the fix data will be more relevant
> if you can output location immediately after it's calculated, rather
> than delaying it 200ms for a satellite status report. Some receivers
> do have certain message types triggered at set time - I hear SiRF's
> ZDA message is supposed to be sync'd with the top of the second.
> 
> 



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