Is it possible to build a device that detects the demodulator clock in a
GPS receiver from a distance of 1 - 2 metres (required), 5 metres
(desired)? I would imagine that a high gain antenna would make it
possible (without detecting actual GPS since it is 'in the noise').

Are there other aspects about a GPS receiver that would make them
detectable at that distance?

Would it tend to false positive on other near clocks/harmonics
(computers operate in the L1 region too). Would a narrow enough filter
prevent that?

With all the indiscriminate tracking (by police - re: USSC case, and
possibly other people trying to track someone) there could be quite a
market for such a detector. Find it and remove it. Better yet attach
it to a city bus.

And it would be legal (vice a jammer).

--
gmail originated posts filtered due to spam.

SNICKER
or to paraphrase P.T. Barnum - You could detect some of the
receivers
some of the time, but not all the receivers all of the time.

Alan Browne wrote:
> Is it possible to build a device that detects the demodulator clock in a
> GPS receiver from a distance of 1 - 2 metres (required), 5 metres
> (desired)? I would imagine that a high gain antenna would make it
> possible (without detecting actual GPS since it is 'in the noise').
>
> Are there other aspects about a GPS receiver that would make them
> detectable at that distance?
>
> Would it tend to false positive on other near clocks/harmonics
> (computers operate in the L1 region too). Would a narrow enough filter
> prevent that?
>
> With all the indiscriminate tracking (by police - re: USSC case, and
> possibly other people trying to track someone) there could be quite a
> market for such a detector. Find it and remove it. Better yet attach it
> to a city bus.
>
> And it would be legal (vice a jammer).
>

On 2011-11-20 15:47 , Richard Owlett wrote:
> SNICKER
> or to paraphrase P.T. Barnum - You could detect some of the receivers
> some of the time, but not all the receivers all of the time.

Unhelpful attitude, wrong attribution and you top post.

--
gmail originated posts filtered due to spam.

In news:(E-Mail Removed) Alan Browne
<(E-Mail Removed)> wrote:

> Would it tend to false positive on other near clocks/harmonics
> (computers operate in the L1 region too). Would a narrow enough
> filter prevent that?

If you're just trying to find something attached to a single vehicle,
you'd have to disconnect the battery to make all the on-board
electronics shut up, but once you did that, anything you could "hear"
with a short-range, wide-band detector should quickly lead you to any
self-powered electronic device that was attached to it.

--
(E-Mail Removed) St. Paul, MN

On 2011-11-20 17:57 , Bert wrote:
> In news:(E-Mail Removed) Alan Browne
> <(E-Mail Removed)> wrote:
>
>> Would it tend to false positive on other near clocks/harmonics
>> (computers operate in the L1 region too). Would a narrow enough
>> filter prevent that?
>
> If you're just trying to find something attached to a single vehicle,
> you'd have to disconnect the battery to make all the on-board
> electronics shut up, but once you did that, anything you could "hear"
> with a short-range, wide-band detector should quickly lead you to any
> self-powered electronic device that was attached to it.

I'd want something more convenient and turn key, hence the narrow band
detection.

With a wide band detector could I add an input filter?

The notion is to make a product that someone would use if he suspected
non-authorized (by him anyway!) GPS tracking surveillance. If the
Supreme Court sides with the police on the current case, I think there
will be a pretty market for such.

--
gmail originated posts filtered due to spam.

Alan Browne wrote:
> The notion is to make a product that someone would use if he suspected
> non-authorized (by him anyway!) GPS tracking surveillance. If the
> Supreme Court sides with the police on the current case, I think there
> will be a pretty market for such.

But of course if the tracking has been authorised then the suspect won't use
the detector to discover and remove the legitimate tracker?

Mike.
--
If reply address is Mike@@mjcoon.+.com (invalid), remove spurious "@"
and substitute "plus" for +.

Alan Browne wrote:
> Is it possible to build a device that detects the demodulator clock in a
> GPS receiver from a distance of 1 - 2 metres (required), 5 metres
> (desired)? I would imagine that a high gain antenna would make it
> possible (without detecting actual GPS since it is 'in the noise').
>
> Are there other aspects about a GPS receiver that would make them
> detectable at that distance?
>
> Would it tend to false positive on other near clocks/harmonics
> (computers operate in the L1 region too). Would a narrow enough filter
> prevent that?
>
> With all the indiscriminate tracking (by police - re: USSC case, and
> possibly other people trying to track someone) there could be quite a
> market for such a detector. Find it and remove it. Better yet attach it
> to a city bus.
>
> And it would be legal (vice a jammer).
>

So I'll bottom post ;/

The answer is still


SNICKER
or to paraphrase P.T. Barnum - You could detect some of the
receivers
some of the time, but not all the receivers all of the time.

*LOL* !!!!!!!!

In article <(E-Mail Removed)>,
Alan Browne <(E-Mail Removed)> wrote:

> On 2011-11-20 15:47 , Richard Owlett wrote:
> > SNICKER
> > or to paraphrase P.T. Barnum - You could detect some of the receivers
> > some of the time, but not all the receivers all of the time.
>
> Unhelpful attitude, wrong attribution and you top post.

OK, bottom posted.

There is not any way to guarantee detection of a properly shielded GPS
receiver by its emissions.

Isaac

On 11/20/2011 9:29 AM, Alan Browne wrote:
> Is it possible to build a device that detects the demodulator clock in a
> GPS receiver from a distance of 1 - 2 metres (required), 5 metres
> (desired)? I would imagine that a high gain antenna would make it
> possible (without detecting actual GPS since it is 'in the noise').
>
> Are there other aspects about a GPS receiver that would make them
> detectable at that distance?
>
> Would it tend to false positive on other near clocks/harmonics
> (computers operate in the L1 region too). Would a narrow enough filter
> prevent that?
>
> With all the indiscriminate tracking (by police - re: USSC case, and
> possibly other people trying to track someone) there could be quite a
> market for such a detector. Find it and remove it. Better yet attach it
> to a city bus.
>
> And it would be legal (vice a jammer).
>

These automotive GPS tracking devices can't get around the laws of
physics. They have to be near the periphery of the car to see the GPS
satellite, right? I would think a visual search is sufficient.

Since a tracking GPS doesn't need to be human readable/programmable, as
in LCD and buttons, it seems to me they could be designed to be very quiet.

The nonlinear junction detector is the standard device for finding bugs
these days. It should work on finding a GPS, though I have no direct
knowledge of this.

I have a cellphone, so I can be easily tracked. ;-) They even have
devices these days to ping your phone and find your location. Totally
illegal in my opinion since they are both transmitting in band for which
only wireless providers are licensed, plus they are spoofing cell site.
If I had a ATT femo cell and hacked it to look like I cell site, the
feds would be on my arse. Because they have those stinkin' badges, they
can break all the rules.

> The answer is still
>
>
> SNICKER
> or to paraphrase P.T. Barnum - You could detect some of the receivers
> some of the time, but not all the receivers all of the time.
>
> *LOL* !!!!!!!!
>
>

What has this to do with a chocolate bar or do you mean snigger??

Jeff