Hi,
The fact they refer that atmospheric s/n degradation and dropouts etc
being replayed precisely lead me to think this is just a spectrum
rec/play machine (no mod/demod of any kind)
like the ham-oriented "time machine" but for GPS.
http://www.expandedspectrumsystems.com/prod2.html
Luis Cupido.
ct1dmk.
Bob Camp wrote:
Hi
It's not real clear that they do anything more than sample the RX and play it back for the TX.
Bob
Sent from my iPhone
On Nov 25, 2010, at 9:39 AM, "J. Forster" <[email protected]> wrote:
Agreed. The trick is to properly partition what is done in hardware ane
what is done in software. This could eliminate a lot of logic hardware.
Clearly, the RF stuff and modulator are hardware.
Ditto PR code generation.
Everything else in SW, I think.
FWIW,
-John
===============
Hi
One bit serial at 16 MHz isn't all that fancy any more. Sounds like a
shift register feeding a couple filters.
The money must be in the receive side.
Bob
On Nov 24, 2010, at 5:14 PM, [email protected] wrote:
Hi,
found an interesting unit. I think it is not for the usual pocket
money for a time-nuts.
have a look...
http://www.chronos.co.uk/pdfs/rac/labsat.pdf
Rgds Ernie.
-----Original Message-----
From: John Green <[email protected]>
To: [email protected]
Sent: Mon, Nov 22, 2010 6:43 pm
Subject: [time-nuts] GPS jamming susceptibility
Given that this is an extremely sensitive topic and completely illegal
lso, let me just state at the outset that I have no interest in
amming anyone's GPS. A while back, I was looking at one of those
hinese discount electronics websites, I'm sure we all have, and
oticed a GPS jammer for sale. I had been wanting to do some jamming
usceptibility testing for quite some time but had never got around to
uilding a generator to test with. The thing was cheap so I ordered
t. After it arrived, I opened it up, first thing, to see how it was
ade. It has a dual 555 oscillator, a couple of analog switches, a 1.9
Hz VCO, a single amplifier. It doesn't look capable of putting out
ore than 50 milliwatts or so into a 2 inch antenna. I was somewhat
ubious that it would do anything, so I took it to the bench where the
3801 lives and turned it on. Within 2 seconds, the holdover LED lit.
immediately turned it off and within a few more seconds, the
oldover LED was back off. The GPS antenna is perhaps 35 feet away
ith a cinder block wall, a brick wall, and a metal roof in between. I
lso put a 15 Db attenuator between it and the antenna with almost the
ame result. I am going to do more testing with it wired into the GPS
ownfeed an an adjustable attenuator in line just to see how much
ignal it takes. That way, there will be little danger of messing with
nyone's reception. It is just a simple sweeper so it must do its job
y brute force. I am amazed that it took so little to shut my Z3801
own. Has anyone here had any actual experience testing GPS receivers
or susceptibility?
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