Baud rates

[sayling]

I wonder if anyone can explain what the importance is of selecting the correct baud rate is when configuring an 'Other NMEA device' in TTN5?

I have the CoPilot iPAQ NS jacket with an h3850 (originally supplied with CoPilot 2), but have been on TTN since version 2. Now that I have TTN5, signal lock has been very, very poor and I have read elsewhere on this forum that I should set the baud rate to 4800 (iirc).

However, I have had similar (poor) results with baud rates of 4800, 57600 and 115200 (or whatever the largest two rates are).

So what is the 'baud' rate, and how does it affect things? Why should it be set to 4800 for the Navman sleeve? What is the effect of selecting a different baud rate?

Finally, I'm sure I've read somewhere on this board that there is a utility that allows you to see what the receiver has locked onto, without hogging the GPS signal - ie it can be run at the same time as TTN5. Can a kind soul remind me what it was, please?

Many thanks for any help

[SharpEye]

Baud rate is the speed of which one device "talks" to another. The baud rate must be the same on both devices to them to be able to talk to each other.

So if the GPS receiver talks at 4800 baud, then the PPC will need to be set at 4800 baud as well.

A friend of mine had a PPC with a built in GPS receiver but did not know what the baud rate should have been. He set TTN5 to 9600 and took a look at the show GPS status screen. The little wheel was spinning indicating that it was receiving information from the GPS receiver, but it would not pick up any satellites. This was because the GPS receiver was "talking" to slowly to the PPC. He reset TTN5 to 4800 baud and got a fix straight away.

BTW is doesn't look like you have tried 9600 baud yet - try it and see if it works.

What baud was the TTN3 set to?

SharpEye

[sayling]

I've tried 4800 and 9600. With each baud rate set, TTN can find the satellites (albeit not very many) and can get a fix - eventually (and I mean after a loooooooooooooooooong time!) - there doesn't appear to be any difference from any of the baud settings?

There was no baud rate settign for TTN3... I just selected Pocket CoPilot GPS Jacket in the first box on the GPS tab and NavMan GPS in the second within the GPS v3.01 412/403 utility...

[peterc10]

Most set ups will work on multiple Baud settings. Mine certainly does.

Don't think it makes any difference to lock on times. How slow is slow and how often do you use it. First time is always slow. After that depends how long since you last used it as to hoiw long it takes. A few days and mine can take up to 5 minutes.

[sayling]

Well, on Thursday evening, I left north Worksop to return to North London. I was working with a client on an industrial estate, parked on top of a slight hill with very little cloud cover. After a soft reset, I stuck the iPAQ on top of the roof of my car for eight minutes, rolling a cigarette and making a few calls. The maximum number of sats picked up was about five or six, with the grey bars peaking at about 70-80% on a maximum of three of those at any one time. No lock after eight minutes.

Set off blind (well, semi blind... used Advanced planning and browsed the first part of the route). Got to Carltoon in Lindrick and realised I had missed a turn somewhere, so pulled over and browsed the map, found where I was and centred the map on my current location. After three minutes, got a lock! Joined the M1 at junction 31...

About an hour and a half later, pulled into the Sainsburys at Grove Farm (just off juntion 21 on the M1) to get some petrol. Lost the lock due to forecourt canopy (though I parked as far as I could away from the pump to keep the GPS in view of as much of the sky as possible). Filled up with petrol, drove about 300 yards to park outside Borders, where I left the car vertically unobscured and re-centred the GPS map to my current locations and went and grabbed a coffee and a biscuit. Returned to my car, eat the biscuit. After about 10 minutes with no lock, despondently set off again...

Got down to Newport Pagnell services, where I again reset the centre, parked and had a 15 minute nap. Woke up - no lock.

Set off again and got held up in traffic just before junction 12 - speed down to a maximum of 25 mph, in spurts. As I passed junction 12, recentred the map. Got a lock after about 5 minutes, which was maintained for the rest of the journey (about three quarters of an hour and 40 miles). Arrived home about 20:00.

The following day at 14:00, soft reset the iPAQ, set current location as home. GPS Info got a fix in about a minute, TTN5 couldn't after 10 minutes. Had to leave (pressed for time) and did a circular route of about 6 miles over 20 minutes (heavy traffic) and no lock achieved at all.

[mikealder]

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