BT-338 Problem

niko1980 · Occasional Visitor Joined: Aug 03, 2005 Posts: 7

Hi Everyone,

New to this so ALL help is greatly appreciated!

I have just bought a BT-338 receiver and have managed to connect it to my ipaq and to TT5 navigator using the other cabled option and port 6.

Just wanted to ask something, I understand that this receiver is a Sirf receiver and this is a large part of why I bought it. However, when I use Winfast CE, if I choose Sirf I cannot get a connection but when I choose NMEA I get a connection on COM port 6.

Does this mean my GPS receiver is borken or that it is not truly a Sirf receiver?

Also, it takes 5 mins plus to get a signal when I first start the thing! Is this normal??????

Many thanks for advice in advance!!!

Niko

Darren · Posted: Wed Aug 03, 2005 1:45 pm Post subject: Re: BT-338 Problem

newbieinlondon · Occasional Visitor Joined: Jun 30, 2005 Posts: 14

Mine also takes a few minutes from cold start up though I was moving in the car. I wonder there's something wrong with mine too.

niko1980 · Occasional Visitor Joined: Aug 03, 2005 Posts: 7

Darren,

Thanks for the advice! Regarding the 5 mins start up, it seems to happen irrespective. However, to make sure, is there some way of testing this? It happens on cold starts once that is done it gets a fix pretty quick. I read in the forum maybe winfast ce can help but am scared i might mess up the thing using the software so have not tried anything yet.

I have had the receiver for less than a week and really want to figure out if it is faulty so I can do something about it. If it helps I bought the receiver through expansys and the s/n is 024436 (maybe part of faulty batch?).

Also my set up is an ipaq 4150 and I connect using COM port 6 and a baud rate of 38400.

Many thanks again for your help.

Niko

Darren · Posted: Wed Aug 03, 2005 2:48 pm Post subject:

I'd steer clear of Winfast as you risk causing more problems if you screw it up.

A cold start should take no more than 20 - 30 secs. A warm start with a good sky view less than 10.
_________________
Darren Griffin

niko1980 · Occasional Visitor Joined: Aug 03, 2005 Posts: 7

Darren,

Thanks again. Are those times calculated until I get a fix? (i.e. a gps position in 3d). Or is that how long it takes for the code to start streaming on the gps info program?

Thanks,

Niko

Darren · Posted: Wed Aug 03, 2005 3:39 pm Post subject:

Timings are always based on aquiring a 3D fix Smile

_________________
Darren Griffin

niko1980 · Occasional Visitor Joined: Aug 03, 2005 Posts: 7

Hi Darren,

I have done as you suggested and went to the roof of my building 6th floor and did a TTF test using the globalsat provided software GPSInfo.

When I pressed cold start it took 1 - 1.5 minutes to acquire a fix. This was having VTG and WAAS (no idea what these are!) swicthed off (i.e. their box not checked).

I did this 10 times and ten times the fix time was between 1 minute to 1 and a half minutes. Granted this is much better than the 5 mins before but still nothing like your stated 20 - 30. The 20 - 30 sec time you state, is that with a completely clear sky? Or conditions like today sunny with patchy cloud?

Taking into consideration I was very high up with no overhead obstructions and today's weather, is my unit faulty do you think? Or am I doing something wrong? Is WAAS and VTG whatever those are meant to be switched on or off?

Sorry to be a pain! Embarassed

Thanks for all the help AGAIN!!

Niko

Is my unit faulty do you think?

niko1980 · Occasional Visitor Joined: Aug 03, 2005 Posts: 7

ALSO.....

Could it be that the GPSInfo s/w is just slow? What software do you use when doing your time to fix tests?

Thanks in advance.

Niko

cootuk · Occasional Visitor Joined: Jul 17, 2005 Posts: 38

With a clear view, my bt338 takes about 50s to lock.
Inside the reception varies dramatically, with some areas taking quite a few minutes from cold start - all depends how many satellites it can lock on to that it can see.

The gps uses nmea to communicate, though you can change it with software to Sirf mode, and some programs use that mode to interface with it.

niko1980 · Occasional Visitor Joined: Aug 03, 2005 Posts: 7

Hi Cootuk,

Just tried my GPS

niko1980 · Occasional Visitor Joined: Aug 03, 2005 Posts: 7

Hi Cootuk,

Just tried my GPS inside and it did not lock even after 30 mins! Does this ever happen to you? Maybe Darren can shed some more light on this?

Thanks,

Niko

cootuk · Occasional Visitor Joined: Jul 17, 2005 Posts: 38

i have some windows software that monitors what satellites the gps can see and which it has locked on to.
By my window it locks on about six.
As i move it more inside it loses lock on more satellites, and covering it with a hand makes it lose all locks.

Just turned it on after 3 days no use by window, lock within 50s.

If you can get some software to run on your device that shows the satellites and lock, then this will help you work out what it is doing.

ginosergio · Occasional Visitor Joined: May 09, 2005 Posts: 14

Niko, I think you are Italian like me... if I'm right you can PM me in italian.

Some answers for you:

- cold start inside a building take a variable amount of time, from 1 minute to eternity. It depends from the building, the floor, your position, surrounding buildings, etc.etc. You can't do a timing test inside a building, it's useless, IMHO.

- cold start with open sky all around you is the best test. You should consider TTF time until red led gets blinking. Your software can take some more time to see the fix. (PS: I don't think clouds make a sensible difference). In this situation one minute is normal. It can change (more or less) depending how long the receiver was off, and so, how much satellites have moved from last known positions.

- sometimes you can wait 5 minutes to get a fix, even if you are outside; this is a bug of 3.0.2 firmware: it can occur when on cold start all visible satellites signals are below 32db.

You can update your BT-338 to 3.1.1 firmware (I did it) and it will works much better.

Regards

ginosergio · Occasional Visitor Joined: May 09, 2005 Posts: 14

Ehmm... green led, not red...

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