Can't see SiRF output - should I be able to...?

Roop · Occasional Visitor Joined: Feb 23, 2004 Posts: 3

Hi All,

New here so please fogive any faux pas. I recently bought the TomTom GPS package with the wired mouse where the cable enters via the corner of the housing. I understand this is possibly a Leadtek chip and should support SiRF mode and also WAAS EGNOS (where available). I have run both GPSTweak 0.9 and WinFast navigator but can see no output on the SiRF screens. I get the NMEA readouts just fine - scrolling away happily, can see the sat fixes and signal strengths but as soon as I switch to SiRF screens everything stops.

NMEA is Com1 / 4800 and works fine. Whatever I set the comm parameters of SiRF I seem to get nothing. I think I'm blatantly missing something here...! Any help appreciated.

I'd also like to enable augmentation (EGNOS test signal etc) just to have a play really. What app do I need to do this...?

My hardware is Dell Axim X5 with cradle, GPS on Com1

Thanks in advance,

Roop

lbendlin · Posted: Mon Feb 23, 2004 4:30 pm Post subject:

The protocol is called SiRF Binary, and for a reason... Unless you have a good application that can display non-displayable characters (sic) you will not "see" much when you switch to SiRF.

Remember, NMEA is limited to about 40 characters off the 256 possibles, so the NMEA transmission has a high level of redundancy. SiRF is using all possibilities and thus has no (or much less) redundancy.

Enabling WAAS/EGNOS has nothing to do with the output protocol. You can leave your receiver on NMEA and still receive WAAS enhancement signals.

Now I think the TomTom serial receiver (leadtek 9531 I believe) doesn't support WAAS at all... but I'm not sure. Having the SiRF chipset doesn't automatically mean WAAS support.
_________________
Lutz

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Roop · Occasional Visitor Joined: Feb 23, 2004 Posts: 3

Thanks for the info Lutz. I was aware that NMEA and SiRF are just two different protocols and nothing in fact to do with augmentation of the regular GPS signals, just thought I'd combine my two queries into one post.

My GPS mouse is based on a Leadtek 9532 SiRF II chipset which supposedly supports SBAS (WAAS/EGNOS/DGPS).

When I run Winfast navigator I can see the raw output from NMEA, I can see the satellites listed on the signal strength page along with the diagram showing the view of the sky and the satellites in view. On the navigation page I see my lat and long, velocity etc. As soon as I switch to SiRF all of the above go blank.

I also used GPStweak 0.9 and same thing there. I switch to SiRF and everything stops. Try and interrogate the unit for WAAS/EGNOS status etc - nothing. There muts be something else I need to do...?

Is there a problem with these apps on the Axim X5...?

Thanks again for your help.

Roop

lbendlin · Posted: Mon Feb 23, 2004 11:16 pm Post subject:

The SiRF protocol is BINARY. Your applications simply don't know how to display a binary stream. (NMEA is ASCII, not BINARY)

This should not, however, stop the unit from reporting the position and altitude etc. If that's not the case then maybe you haven't really switched to SiRF, or the speed is not right.
_________________
Lutz

Report Map Errors here:
TomTom/TeleAtlas NAVTEQ

Roop · Occasional Visitor Joined: Feb 23, 2004 Posts: 3

Thanks Lutz,

I tried different communications speeds and COM parameters to no effect - will try again when I have some time.

Roop

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