It would seem you have a section of data line acting as  an antenna,=20
perhaps poor ground, shield, loose connection or cold solder  joint acting=
 as a=20
detector of sorts. It's highly unlikely that normal  terrestrial based=20
communications would effect a GPS device since most work hand  in hand, ar=
e=20
separated by substantial frequency differences and selective  filtering so=
 best to=20
look else ware for your Gremlin.
=20
 In some cases RF permeates a wire pair that is  close to a wavelength=20
and/or multiples of an offending signal, the antenna  effect. For example,=
 if=20
the offending VHF frequency has  a quarter-wavelength of 15 inches make su=
re=20
that pair of wires is less  or more then 15 inches and not multiples of th=
e=20
15 inches.  Another dirty and cheap trick is putting a small loose  loop=
 in=20
your data line or using a iron torrid suited for the specific  offending=
=20
frequency range.=20
=20
Another avenue for RF is through the power source  interconnection, this=
=20
type of RF clamping is easily accomplished by  using a 25 pf capacitor (I'=
ve=20
found works well @ VHF)  from  an input (power or signal) to ground. The=
=20
offending RF is seen as an  AC signal and bypassed to ground allowing the=
 DC=20
power or data to  continue unimpeded. Lastly, I have had success lifting=
 the=20
ground from  one end of a shielded cable, you may have to experiment with=
 what=20
end that  affords you the best results if any.
=20
 I'm trying to cover most bases here because your  situation is vague and=
 I=20
can't see the actual installation but I can sure  understand the=20
aggravation. =20
=20
Regards,
Cliff
=20
=20
In a message dated 11/1/2010 12:44:05 P.M. Eastern Daylight Time, =20
jonfr@......... writes:

Hi,

I have never had a GPS signal jammed because of some  other transmitters
that are being used close to my GPS  antenna.

Regards,
J=F3n Fr=EDmann.

> Hello  PSN:
>
> Many of you have this gps receiver to get good times on  your graphs
> and over time you should learn any  problems.
>
> I have found one Which I do not know how to  beat.
>
> There seems to be RFI related problems
> where the  in the presence of a high energy RF field
> of some frequency the GPS  signal or A/D board is being
> jammed and the lock is lost and an alarm  will sound.
>
> This problem is not the fault of of the  device
> but simply related to the fact the unwanted RF signal
>  has penetrated the electronics.
>
> Can anyone tell me if they  have successfully won
> the battle of when like a police car or fire  truck
> or other government car is outside in the neighborhood with a 25  watt
> transmitter maybe 100ft away and using their radio  ?
>
> It wipes out my data and everything for a minute or  so.
>
> This mostly happens in the winter when the city
>  here grows three times its normal population.
>
> Comments  ?
>
> geoff
>
> or, grumbly in  Arizona.
>
>
>  __________________________________________________________
>
>  Public Seismic Network Mailing List (PSNLIST)
>
> To leave this  list email PSNLIST-REQUEST@.............. with
> the body of the message  (first line only): unsubscribe
> See  http://www.seismicnet.com/maillist.html for more  information.
>


__________________________________________________________

Public  Seismic Network Mailing List (PSNLIST)

To leave this list email  PSNLIST-REQUEST@.............. with=20
the body of the message (first line  only): unsubscribe
See http://www.seismicnet.com/maillist.html for more  information.




<=
FONT id=3Drole_document   color=3D#000000 size=3D2 face=3DArial>
It would seem you have a section of data line act=
ing as=20
an antenna, perhaps poor ground, shield, loose connection or cold solder=
=20
joint acting as a detector of sorts. It's highly unlikely that normal=
=20
terrestrial based communications would effect a GPS device since most work=
 hand=20
in hand, are separated by substantial frequency differences and selective=
=20
filtering so best to look else ware for your Gremlin.
 
 In some cases RF permeates a wire pair that=
 is=20
close to a wavelength and/or multiples of an offending signal, the an=
tenna=20
effect. For example, if the offending VHF frequency has=20
a quarter-wavelength of 15 inches make sure that pair of wires=
 is less=20
or more then 15 inches and not multiples of the 15 inches.=20
Another dirty and cheap trick is putting a small loose=20
loop in your data line or using a iron torrid suited for the specific=
=20
offending frequency range. 
 
Another avenue for RF is through the power source=
=20
interconnection, this type of RF clamping is easily accomplished=
 by=20
using a 25 pf capacitor (I've found works well @ VHF)  =
;from=20
an input (power or signal) to ground. The offending RF is seen as an=
=20
AC signal and bypassed to ground allowing the DC power or data t=
o=20
continue unimpeded. Lastly, I have had success lifting the groun=
d from=20
one end of a shielded cable, you may have to experiment with what end =
;that=20
affords you the best results if any.
 
 I'm trying to cover most bases here because your=
=20
situation is vague and I can't see the actual installation but I can=
 sure=20
understand the aggravation.  
 
Regards,
Cliff
 

In a message dated 11/1/2010 12:44:05 P.M. Eastern Daylight Time,=20
jonfr@......... writes:
Hi,

I have never had a GPS signal=
 jammed because of some=20
  other transmitters
that are being used close to my GPS=20
  antenna.

Regards,
J=F3n Fr=EDmann.

> Hello=20
  PSN:
>
> Many of you have this gps receiver to get good time=
s on=20
  your graphs
> and over time you should learn any=20
  problems.
>
> I have found one Which I do not know how to=20
  beat.
>
> There seems to be RFI related problems
> whe=
re the=20
  in the presence of a high energy RF field
> of some frequency the=
 GPS=20
  signal or A/D board is being
> jammed and the lock is lost and an=
 alarm=20
  will sound.
>
> This problem is not the fault of of the=20
  device
> but simply related to the fact the unwanted RF signal
=
>=20
  has penetrated the electronics.
>
> Can anyone tell me if th=
ey=20
  have successfully won
> the battle of when like a police car or fi=
re=20
  truck
> or other government car is outside in the neighborhood wit=
h a 25=20
  watt
> transmitter maybe 100ft away and using their radio=20
  ?
>
> It wipes out my data and everything for a minute or=20
  so.
>
> This mostly happens in the winter when the city
&=
gt;=20
  here grows three times its normal population.
>
> Comments=
=20
  ?
>
> geoff
>
> or, grumbly in=20
  Arizona.
>
>
>=20
  __________________________________________________________
>
&g=
t;=20
  Public Seismic Network Mailing List (PSNLIST)
>
> To leave=
 this=20
  list email PSNLIST-REQUEST@.............. with
> the body of the=
 message=20
  (first line only): unsubscribe
> See=20
  http://www.seismicnet.com/maillist.html for more=20
  information.
>


________________________________________=
__________________

Public=20
  Seismic Network Mailing List (PSNLIST)

To leave this list email=
=20
  PSNLIST-REQUEST@.............. with 
the body of the message (first=
 line=20
  only): unsubscribe
See http://www.seismicnet.com/maillist.html for mo=
re=20
  information.