GPS - Expectations of UT-41?

Author

Expectations of UT-41?

Mark T.B. Carroll

2007-04-10, 10:33 pm

I have a UT-41, a USB GPS receiver that advertises 12 channels with
-140dBm acquisition sensitivity and -150dBm tracking sensitivity.

Watching the NMEA-0183 data streaming from it, I find that even if I let
it run outside with a clear view of nearly half the sky until it first
gets a 3d fix, then as it continues to run usually it'll only have a 2d
fix, and sometimes for some seconds it'll go back to having no fix at
all.

Should I be expecting better from this unit? I'd have thought that
having a view of a good amount of sky should allow it to get a pretty
secure fix that lasts, once it has a fix at all. (I'm just leaving it
sitting there.)

Is there an alternative USB NMEA-0183 GPS receiver that's not extremely
expensive that will perform much better?

-- Mark

Jack Erbes

2007-04-10, 10:33 pm

Mark T.B. Carroll wrote:
> I have a UT-41, a USB GPS receiver that advertises 12 channels with
> -140dBm acquisition sensitivity and -150dBm tracking sensitivity.
>
> Watching the NMEA-0183 data streaming from it, I find that even if I let
> it run outside with a clear view of nearly half the sky until it first
> gets a 3d fix, then as it continues to run usually it'll only have a 2d
> fix, and sometimes for some seconds it'll go back to having no fix at
> all.
>
> Should I be expecting better from this unit? I'd have thought that
> having a view of a good amount of sky should allow it to get a pretty
> secure fix that lasts, once it has a fix at all. (I'm just leaving it
> sitting there.)
>
> Is there an alternative USB NMEA-0183 GPS receiver that's not extremely
> expensive that will perform much better?
>

Try the Holux GR-213. That has the SiRF III chip set and does very
well. The one you have seems to be a pretty poor performer. Try it on
a metal surface like a car roof, on some designs having a good ground
plane makes a big difference.

The GR-213 can be bought for around US$60 in the U.S. If that is twice
as much as the UT-41 cost, it will probably be at least as twice as good.

Jack

--
Jack Erbes in Ellsworth, Maine, USA (jackerbes at adelphia dot net)
(also receiving email at jacker at midmaine dot com)

Mark T.B. Carroll

2007-04-11, 12:33 pm

Jack Erbes <jackerbes@adelphia.net> writes:
(snip)
> Try the Holux GR-213. That has the SiRF III chip set and does very
> well.

Thanks. I'll give it a try.

> The one you have seems to be a pretty poor performer. Try it on a
> metal surface like a car roof, on some designs having a good ground
> plane makes a big difference.

That's interesting; I'll try that too.

-- Mark

LinkBot