Geodesy

[Pete]

Has anyone fitted the re-radiating aerial to a se7en? The destructions seem to indicate that it should be fitted where it can 'see' the sky but a similar aerial fitted to my Tracker seems to work OK through the nosecone.

 

Any advice would be gratefully received

 

pete

[Chelspeed]

Geodesy uses the GPS satellites to fix it's location so it needs to be able to "see" the satellites.

 

It's using radio signals from the satellites. Radio waves can't pass through metal so in a tin top salloon car you might need a remote aerial. I use a GPS in my tin top and sat on the dash board it can easily see the satellites through the windscreen so the radio waves pass through the glass no problem.

 

In a Caterham the radio waves will easily reach the unit from the open top or through the fabric hood so, unless you sink it deep under the dash, you shouldn't need the re-radiating aerial in a seven.

 

Regarding your Tracker, I would expect radio signals to pass through thin glass fibre on a nosecone even easier than they go through the windscreen. Not sure about carbon fibre though, this is electrically conductive, not sure if it's radio wave transparent or not. If you have a carbon nose it may not work.

 

As an aside, the only point of a Tracker is if no-one knows it's there so I'd be careful about posting too many details on what's effectively a public forum. But then I'm paranoid and all BlatChat listers are nice guys so no problem.

[Red SLR]

Who would ever think 4 years training in Radio Engineering would ever come in handy....!

 

I can confirm GRP will be ok for radio, I would say a caterham nose cone will cause no problems.

 

Tracker is about 5W I think so will have no problems with GRP!

 

The GPS unit does not send out radio signals, it only receives them, thus your antenna should be in a location where it will see as much sky as possible.

 

GPS Spec::::

 

Satellite transmit ::: two L-band frequencies:

L1 = 1575.42 MHz / L2 = 1227.6 MHz

 

Three pseudo-random noise (PRN) ranging codes are in use.

 

The coarse/acquisition (C/A) code has a 1.023 MHz chip rate, a period of 1 millisecond (ms) and is used primarily to acquire the P-code.

The precision (P) code has a 10.23 MHz rate, a period of 7 days and is the principal navigation ranging code.

 

The Y-code is used in place of the P-code whenever the anti-spoofing (A-S) mode of operation is activated.

 

The C/A code is available on the L1 frequency and the P-code is available on both L1 and L2. The various satellites all transmit on the same frequencies, L1 and L2, but with individual code assignments.

 

Due to the spread spectrum characteristic of the signals, the system provides a large margin of resistance to interference. Each satellite transmits a navigation message containing its orbital elements, clock behavior, system time and status messages. In addition, an almanac is also provided which gives the approximate data for each active satellite. This allows the user set to find all satellites once the first has been acquired.

 

And by the way, if you could develop software to control the Almanac you would be a very rich person....

 

 

 

X777CAT

[Chelspeed]

Ahhh, not sure if I wanted to know that lot or not. Clear as.... a grp nosecone. Any thoughts on whether radio transmissions from the satellite will pass through carbon fibre or not?

[Red SLR]

Not likley, GPS needs a clear view of the sky to work.

 

 

 

X777CAT

[Pete]

Thanks chaps. I can now bore all at parties with erudite explanations of sine waves and the like.....smile.gif

 

But where is the best place for the aerial? Morpheous recommend the rear parcel shelf but I'm having trouble finding it on my se7en........

 

pete

 

Edited by - pete on 8 May 2002 21:15:14