BT338 - New Firmware and WAAS

netless · Occasional Visitor Joined: Jun 13, 2005 Posts: 2

Hi, I've got a BT338 recently upgraded to 3.1.1 firmware.
Newbie question, How do I set WAAS enable with Sirf Demo?
And by the way, what's the advantage of using WAAS enable?
I read a thread in this forum that WAAS only remain enable until power off once activated. Can anyone confirm this?

Thanks

lbendlin · Posted: Wed Sep 14, 2005 12:23 am Post subject:

If you are in the UK then you probably use EGNOS anyway.

Both WAAS and EGNOS are variations of SBAS (satellite based augmentation system) - using geostationary satelites to help correct some of the atmospheric skewing of the normal GpS sat data.

This form of DGPS (differential GPS) will increase the position accuracy by a factor of five (plus minus).

However you need to actually see one of the SBAS sats - those are sitting over the oceans, in the same equator belt as the TV sats. This means your receiver will only benefit from WAAS/EGNOS when you have a free view to the south, and are not moving too much.

Basically SBAS is irrelevant for street navigation, but is a nice gimmick to have. It also "sticks" through power resets.

In SirFDemo, switch the receiver to SiRF Mode, enable SBAS, and then switch the receiver back to NMEA 38400 mode.
_________________
Lutz

Report Map Errors here:
TomTom/TeleAtlas NAVTEQ

lostway · Occasional Visitor Joined: Jan 04, 2006 Posts: 16

has anyone use the gpsinfo to active waas yet?

http://www.globalsat.com.tw/english/faq.php?level_id=4

is this true that we just need set once?

iankb · Posted: Sun Jan 08, 2006 8:06 pm Post subject:

Just enabled it for static location in my study, with the GPS sitting on my south-facing window sill. I'm using scanned maps with GPSTuner, which uses averaging to improve the position. Normally, the position of my study (at the back of the house) drifts from one side of the road to the other. With SBAS enabled, it is showing a variance of between 1ft and 9ft, averaging out to between 2ft and 4ft. That's definitely going to be an advantage for hiking and/or geocaching.

I was a little surprised that it improved that much, since I'm on the north side of a hill behind a 30ft-high hedge, and didn't expect to receive EGNOS signals that easily. Obviously the satellites aren't that low in the sky.

I'll try it with CoPilot 6 tomorrow, to see whether it has any effect (good or bad) on road navigation.
_________________
Ian

iPaq 2210
Globalsat BT-338
Seidio G2500 Amplified Vent Mount
CoPilot 6, GPS Tuner 4.2, Navio 3.01
BMW 330ci Sport

Ed31 · Occasional Visitor Joined: Jun 10, 2005 Posts: 14

Hi, I've changed my bt338 to SBAS mode using sirfdemo and GPS information, the receiver saves the sbas channel setting by checking the box enabled in DGPS Source in sirfdemo. But as soon as you power the receiver down then power up and reconnect to sirfdemo, the receiver has changed back to Dgps Source = None.
Does anyone know why it reverts back after powering down, and can someone tell how i can keep it on sbas channel with out having to use sirfdemo everytime?
Thanks in Advance

lbendlin · Posted: Wed Jan 11, 2006 10:45 pm Post subject:

JST · Occasional Visitor Joined: Jun 04, 2005 Posts: 36

Thanks to various notes in this Forum I have managed to turn WAAS on on my BT338 - using both "M-M SiRF Setup" and "SP GPS View".

My question is how do I know if it has picked up a WAAS/EGNOS satellite? Living near Manchester, UK, I guess I am probably too far north to have too much success, but it would be nice to know if I am successful.

I have the following installed on my PocketPC
- GPSinfo2004
- VisuaGPSce
- MemoryMap Pocket Nav OS 2004
- M-M SiRF Setup
- SP GPS View

and on my desktop:
- VisualPC
- SiRFdemo

Hopefully, if I knew what I was looking one of these is sufficient to let me know?

Any help gratefully recieved!

Cheers, Jim

lbendlin · Posted: Thu Feb 09, 2006 9:22 pm Post subject:

Look for the PRNs of the EGNOS sats.
_________________
Lutz

Report Map Errors here:
TomTom/TeleAtlas NAVTEQ

iankb · Posted: Thu Feb 09, 2006 10:47 pm Post subject:

I'm a bit farther south (in Berkshire), and I believe that I have been picking them up. That's because I use a GPS program for hiking called GPSTuner. That can show the the last series of fixes and their average on a real-time radial distance display. Before I enabled EGNOS, my position danced around by at least 15 yards. When I enabled EGNOS, it danced round by only a few feet, and was accurately positioned according to my scanned maps.

The package also allows you to import calibrated maps from Expedia on the web. I then overlaid a road-based track that I had recorded over a map, and it showed that the track matched the roads. Given that, unlike a road navigation package, GPSTuner only see bitmaps, and not road vectors which it could snap to, I was quite impressed by that accuracy. Whether that is down to EGNOS, or just down to GPSTuner's ability to use averaging techniques, I couldn't say.

What I don't know is whether I retain that accuracy when I start driving. But you only really need that accuracy for geocacheing, and only then if the geocaches were registered with an EGNOS-enabled GPS unit.
_________________
Ian

iPaq 2210
Globalsat BT-338
Seidio G2500 Amplified Vent Mount
CoPilot 6, GPS Tuner 4.2, Navio 3.01
BMW 330ci Sport

JST · Occasional Visitor Joined: Jun 04, 2005 Posts: 36

JST · Occasional Visitor Joined: Jun 04, 2005 Posts: 36

P.S. Sorry I keep forgetting to ask...

With reference to Setting WAAS support you say:

Ed31 · Occasional Visitor Joined: Jun 10, 2005 Posts: 14

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