Bruce in Alaska wrote:
In article ,
Ian Malcolm wrote:


N.B. they are only
officially rated to 2 GHz and GPS works at 2.4 GHz but they WILL work in
your application.


Bzzzzt, Nice try, Would you like to try again, for what's behind Cutain
No.3? GPS does NOT run and 2.4Ghz, it uses the 1500 Mhz band for
all the datastreams, Commercial and Miltary.

Bruce in alaska
Thank you for the correction, I was of course mistaken when I thought
it was 2.4 GHz. Where I got that number from, I don't know! It isn't
what you know you don't know that catches you out, but what you think
you know but don't.

I was inspired to dig out my copy of the
ADMIRALTY LIST OF RADIO SIGNALS
SATELLITE NAVIGATION SYSTEMS
NP288 VOL 8 (2001/2002)
for an authoritative reference.

Ahh, Bzzzzt yourself, It does *NOT* use the 1500 Mhz band for *all*
data steams! (Not even if you take the 1500 Mhz band to be 1400 to
1599.9.... Mhz. The above reference says L band, nominally between 1 and
2 GHz) I freely admit you are MUCH MUCH closer to the correct
frequencies than I was though. I see from other threads that you have a
STRONG professional background in marine electronics, while my
proffesional background in electronics is NOT in the marine field.
Perhaps you were oversimplifying for the end user . . .

Now for the prize behind curtain No.3, here is the fourth paragraph from
page 11 of NP288 VOL 8 (2001/2002).

"Each satellite transmits data on two frequencies in the L-band; L1 =
1575.42 Mhz and L2 = 1227.60 MHz. Both frequencies are integer multiples
of the basic 10.23 MHz clock frequency. Dual-channel receivers will
be able to use two frequencies to correct for the effects of ionospheric
refraction. Data transmitted on the L1 and L2 frequencies is encoded
by a Pseudo Random Noise (PRN) modulation. The L5 frequency will be
1176.45 MHz."

To summerize:

Freq/MHz Modulation codes Use & Status (as of 25 Jan 2001)
L1 1575.42 C/A ,P,M civil & military
L2 1227.60 P, M? military *
L5 1176.45 ? civil to be introduced from 2005

* Precise Positioning Service (PPS) is derived from the P code and has
specialist civil applications. L2 will also carry the second civil C/A
signal in the future.

Now then, what's the procedure for claiming the prize from behind
curtain No.3? If I have to sit through a timeshare presentation first,
or flights, batteries or whatever are not included, I decline it and
would prefer you to give it to charity :-)

Seriously, thanks for the heads up on my error, I am fortunate that it
was an error of fact not of principle and did not significantly affect
the validity of my argument and advice.

Whats the weather like with you at the moment and how long is your
boating season? We are very much out of season here, with the London
Boat Show in progress, though some hardy souls including a few members
of my Dinghy club are still racing. Its raining, Its windy and its
fairly cold.
--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk [at]=@, [dash]=- &
[dot]=.
*Warning* SPAM TRAP set in header, Use email address in sig. if you must.
'Stingo' Albacore #1554 - 15' Uffa Fox designed, All varnished hot
moulded wooden racing dinghy circa. 1961