Satelite Reception

[+2202]

Switched on the trusty Garmin in the office this afternoon and got very good satelite reception. The gps was about 1 metre away from a very domestic scale window facing

north with not much satelite activity in that particular quarter.

The other side of the office is some 6 metres away, Its a single storey building with a pitched slate roof but does have a lay in grid ceiling. Plotted out the location on Fugawi and it was about 50 metres out, although other previous readings in the vicinity have been more or less spot on.

I was taken aback to pick up any reception and certainly at home in the study with a window twice as large, I never get anything.

Any theories?

[+Tzus]

Nope!

[+Simply Paul]

Sometimes while logging finds or hides I have my GPSr beside my PC, about 6ft from the 1st floor window (UK 1st floor, not US 1st floor). It often surprises me that it gets a lock and usually indicates something like 6ft from 'Home' - the location of which I took by my front door. And that's through a ceiling, an attic packed with all sorts and a sturdy roof. Conversely, I've struggled to get two readings closer than 100ft apart under a little bit of tree cover in the past. It is, I believe, a funny old world.

 

SP

[+capsecum]

The ability of a GPS to gain a signal lock and hence identify its position is controlled by the CLI circuit. The Ccritical Location Indicator circuit is used to determine whether it is critical for the user to know his/her exact location. The circuit controls the sensitivity of the satellite receiver circuit in an inversely proportional manner.

That is to say when the user knows where they are, at home for example, the device is extremely sensitive and will gain a lock through brick, concrete slate etc. However when it is critical that user can find their location, when looking for a cache (preferably a micro), the CLI circuit is activated, the sensitivity of the device is substantially reduced and trees, clouds an even just the atmosphere will prevent a satellite lock being gained.

 

A similar circuit is used to determine when photocopiers jam and computers crash.

 

Or maybe I'm, just paranoid.

Edited June 8, 2005 by capsecum

[NickPick]

CLI circuit. The Ccritical Location Indicator circuit is used to determine whether it is critical for the user to know his/her exact location.

 

A similar circuit is used to determine when photocopiers jam and computers crash.

 

Or maybe I'm, just paranoid.

That sounds a bit like the Mangelfreuzer switch, which knows when the warranty has expired (either by time of by you tampering with it), and creates intermittent faults to make you call out a service technician.

[+milvus-milvus]

Another question in the same vein:

 

When I fail to get a decent satellite signal, my Etrex asks me "are you indoors?". I'd like to know what difference it makes whether I answer Yes or No to this question? Does it increase it's sensitivity level if I'm indoors? Or does it just give up trying completely? Perhaps it's just a shortcut to enable the CLI circuit..

[Remote Part]

If you choose "Yes" to are you indoors, it will give up trying completely.

Basically it switches the GPS recieving part off, which can help save the batteries (and stops you getting crazy trackpoints).

 

If you choose "No" it will keep on trying to get a signal.

[+milvus-milvus]

If you choose "Yes" to are you indoors, it will give up trying completely.

Basically it switches the GPS recieving part off, which can help save the batteries (and stops you getting crazy trackpoints).

 

If you choose "No" it will keep on trying to get a signal.

Thanks. That's cleared up that little mystery. So I need to remember to turn it off & on again if I then decide to wander outside?

[+The Forester]

Any theories?

Radio waves of the frequency used by our GPSrs ar very poor at penetrating solid materials but are very good at bouncing off radio-reflective surfaces.

 

I suspect that your receiver was picking up bounced signals through the window.

[+MartyBartfast]

Talking of GPS reception, I have recently found that if I am in a bad signal area I can get a signal if I balance the GPS on top of my head I figure that this is because of one of the following:

 

1. It's a bit nearer the satellite so the signal's stronger.

2. The GPS signals don't need to go through any part of my body therefore I'm not acting as a screen.

3. Because it's a bit higher it gets a better "view" through the tops of the trees.

4. The signals are being bounced off my scull & giving the receiver a better chance at picking up the signal.

5. It's just coincidence and I'm making myself look like an idiot for no good reason

 

Anyone got any thougts?

 

BTW it does make it difficult to follow the arrow though

 

(note I don't believe 1 for a moment but I thought I'd include it for the controversy it might generate).

[+John Stead]

Surely it is because your halo focusses the signals!