I Wanna Ride The Bus!

Wednesday, June 14, 2006

GPS Blues (Or is my PDA broken?)

Just before the tax breaks on the home computing initiatives ended, I was fortunate enough to work for a firm which ran the scheme, and I was quick enough to get an order in before the cut-off date.

I ordered a new desktop PC (which I'm writing this on,) and a PDA with built-in GPS for sat nav functionality.

The sat nav worked very well, the GPS reception was fair, it took a bit of time to get a first fix, but it held a signal, and just for the heck of it, in a fit of experimentation, I even managed to get and hold a GPS signal in the middle of a train one day.

That was until I crushed the unit and wrecked the screen.

Never mind, that's what insurance is for, and I rang up the insurance firm, told them the sorry tale, and as I have an accidental damage policy which covers anything (except laptops and mobiles,) outside the home up to a certain amount, they agreed my claim and I sent the PDA off to the value check people to see if it could be fixed, and if not to establish the replacement value.

Now I had to replace the unit under the conditional hire agreement on the home computing initiative thing, the make of PDA was actually a clone of another model - a Mitac Mio A168 - and when I surfed the PDA sites, I found out that the 168 was to be discontinued and replaced with another model, along with it's bigger brother. Both units would have a more sensitive GPS antenna, and so I decided to buy one of these new units.

With the cheque from the insurance, I added a little bit more, so I got the one with bluetooth and wireless internet. It arrived Tuesday morning, I charged up the battery, went outside and fired up the satnav program.

And it is here that the problems started.

I was unable to get an initial fix from a point where I was able to get a very good fix with a less sensitive receiver. It is summer, and the trees were in full leaf, so I moved to the top of a grassy knoll with about 100 yards of clearance all round.

Still no fix. The device was operating, it was capturing one or two satellites, but the third needed to get a fix was very elusive. Considering that a minimum of 7 of 27 satellites in orbit should be visible in the sky at any one time, and the receiver was supposed to be one that could handle lower power reception and 20 channels, this was a bad thing.

20 minutes later, I had switched to another application - actually a game - because I was bored with waiting for a fix to appear, (it was still searching for a fix in the background,) I switched back to the sat nav program, and found that it had six signals on the screen, but had not yet found a fix.

Suddenly three went off the air, and the remaining three's power levels went crashing down. I was getting a stronger signal when touching the screen with my stylus.

I confirmed this by holding the stylus down on the screen, the signals went right up, three new signals appeared, and the first three went through into fix territory. Finally, my PDA knew where I was.

Not so fast. Becasue while I was seated on the grassy knoll, I was actually moving through the world at about 3mph according to the unit, my position, shown as latitude and longitude was constanly shifting about, and I was apparently walking round in ever decreasing circles.

My old unit never did this.

I took the stylus off the screen, the signal strength went through the floor, and about a minute later, the GPS fix on the same grassy knoll was lost.

I am not a happy chappy.

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