On Thu, 05 Jan 2006 22:36:17 GMT, "Chuck S." wrote:

Thanks budgie, I was talking about the Jupiter bd. Another thought was will
it work without an antenna? I guess it will. I will be using it outside on
hill tops so should not have a problem a set of birds to lock on. I see an
output on pin 19 that is mark Epps that may be use to show a lock condition.

Mine has 1pps (one pulse per second, time mark) on pin 19. "Epps" sounds
excitingly similar.

The one I have is: http://www.gpskit.nl/documents/rockw...piter_v230.pdf
which shows pin assignments and gives fairly good guff on the ROM-based start.

On Thu, 05 Jan 2006 23:27:41 GMT, MetalHead
wrote:

(snip)

I have used the older Rockwell GPS stuff and they seem to need to have a
recent almanac transferred to them before they will get a fix. Rockwell
used to distribute a freebie software package that would help you deal
with all the setup stuff. It was called something like Lab_10 or Lab_X
or somesuch. The newer stuff may need less handholding.


That's an interesting observation, Bob. I was watching the NMEA output from
power-up on the Jupiter I am using doing a "frozen start" out of the box without
an antenna. One sentence showed it checking each sat in turn. When it finds
one (which it obviously doesn't do with no ant) it assigns a Rx channel# to it.

When I finished play mode on the pooter end and connected an ant, it went
through each bird in turn, about one per second. So within a minute it had
acquired a set of birds and began processing. As I am using no form of backup,
the Jupiter starts from ROM each time and does a similar "frozen start" i,e,
factory almanac). It consistently achieves a full fix in under 3 minutes.

This surprised me also. As I mentioned earlier, these two system that
this showed up on were very old, 5 channel receivers.

We obviously have different receivers. Mine is a 12-channel unit.

http://www.gpskit.nl/documents/rockw...piter_v230.pdf

Sitting outside, with a clear view of the sky, the receivers would
search through one sat at a time and find one occasionally, but they
would lose them after several minutes. After a couple of hours, they had
not acquired and held enough SV's to get a fix at any time.

With a "sufficient" antenna (I am using a 27dB patch) mine doesn't lose any SV's
unless they drop below the elevation mask. Once it has one, you keep seeing it
in the sentence.

I loaded up an almanac through the tool and either receiver would get a
fix within a few minutes and hold it for the half hour that I left them
to run.

I am assuming that these receivers were running out of ROM as well. Some
GPS systems put an almanac in ROM to improve the cold start fix time,
but I don't know if these are among them.

Mine certainly is, but with the 3 minute TTFF from obsolete ROM it's fine for my
time/frequency purposes.

As for the original poster's other question about needing an antenna, I
would say that unless there is one on the Jupiter board, then yes.

Confirmed. I tried a number of improvised passive antennae on my workbench
(where I get good fixes with a Garmin II+ on its standard antenna) and it never
found a single SV. Never tried outdoors ona passive, went straight to an
active patch on the windowsill ;-)

I made a type-O :-) it is 1pps

"budgie" wrote in message
...
On Thu, 05 Jan 2006 22:36:17 GMT, "Chuck S."
wrote:

Thanks budgie, I was talking about the Jupiter bd. Another thought was
will
it work without an antenna? I guess it will. I will be using it outside on
hill tops so should not have a problem a set of birds to lock on. I see an
output on pin 19 that is mark Epps that may be use to show a lock
condition.

Mine has 1pps (one pulse per second, time mark) on pin 19. "Epps" sounds
excitingly similar.

The one I have is: http://www.gpskit.nl/documents/rockw...piter_v230.pdf
which shows pin assignments and gives fairly good guff on the ROM-based
start.

On Fri, 06 Jan 2006 00:58:19 GMT, "Chuck S." wrote:

I made a type-O :-) it is 1pps

From my observations - and not contradicted by available documentation - that
gives a 1pps from powerup. Yes, even masking that output until a valid fix
would have been nice.