[aprssig] Terrestrial Threat to GPS Has Now Hit The Mainstream Media

[Shawn KC8SNE]

There is a very large coalition setup to try to prevent this from
becoming a disaster. The member list has some very heavy hitters on it
however I do not see any ham radio related organizations on the list.
The website is: http://www.saveourgps.org/

Thanks,

Shawn KC8SNE

On Tue, Apr 12, 2011 at 12:14 AM, Brian Webster
<bwebster at wirelessmapping.com> wrote:
> Bernard,
>
>                 Light Squared is planning on deploying a cellular type
> network of high powered transmitters in spectrum that was previously
> designated for satellite services which is why it is right next to the GPS
> band. They will be high power directional antennas designed to deliver high
> speed internet services. Make no doubt that they will run high power and do
> so over channels that will be from 5 to 20 MHz wide. Signals like this have
> a high potential to swamp the GP receiver that are sensitive down to -158
> dBm! I work in this wireless ISP industry. They will deploy the cheapest
> radios they can to keep the cost of deployment down. My fear is that this
> cheap radios will not have enough filtering in them to keep from splattering
> signal in to the GPS band. While this level of signal won’t be an issue for
> a radio that can only hear down to -90 dBm or so, those GPS receivers at
> -158 will have a hard time rejecting those signal especially when it becomes
> a cumulative problem with hundreds of these towers deployed all over. These
> wireless internet networks are design to offer residential broadband
> service. They will be almost continuous duty cycles from the tower side.
>
>
>
> Thank You,
>
> Brian N2KGC
>
> www.wirelessmapping.com
>
> www.Broadband-Mapping.com
>
>
>
> From: aprssig-bounces at tapr.org [mailto:aprssig-bounces at tapr.org] On Behalf
> Of Bernard Van Haecke
> Sent: Sunday, April 10, 2011 1:53 PM
> To: TAPR APRS Mailing List
> Subject: Re: [aprssig] Terrestrial Threat to GPS Has Now Hit The Manstream
> Media
>
>
>
> This is a non issue unless the jammer is sitting on a sat or airplane.
>
> If terrestrial and uses high power, he will be DF'ed in no time.
>
> Otherwise, this story is a joke.
>
> Bernard
>
> Sent from my EVO android phone
>
> On Apr 10, 2011 10:44 AM, "Alex Carver" <kf4lvz at yahoo.com> wrote:
>>
>>> From: "Rahn Abbott"
>>>
>>> Ummmm, you do know that that US Military GPS units and your
>>> Garmin Etrex are
>>> not listening to the same radio signals right? You do know
>>> military and US
>>> government GPS runs on a completely different system?
>>
>>
>> No, the military listens to both L1 at 1.57542 GHz (the "civilian" GPS
>> signal) and L2 at 1.22760 GHz, the military-only GPS signal. They use both
>> signals in order to determine delays caused by the ionosphere which improves
>> the accuracy of the military GPS receivers. If interference is caused to the
>> L1 signal it will affect both civilian and military users.
>>
>> A military GPS receiver and a civilian GPS receiver both listen to L1 but
>> they each use a different chipping code (civilian uses unencrypted C/A and
>> military uses both unencrypted C/A and encrypted P). Only the military GPS
>> receiver listens to L2 at the same time.
>>
>> Later on there will be new codes (L1C and M) as new satellites are put in
>> orbit but they will still have both civilian and military codes sitting on
>> L1. In addition, civilians will soon have access to L2 in the form of a
>> civilian code on L2 (L2C) which will allow for some basic ionospheric
>> corrections to improve accuracy and reduce drift. It won't be as accurate as
>> the military receivers but better than the current L1-only receivers.
>>
>> _______________________________________________
>> aprssig mailing list
>> aprssig at tapr.org
>> https://www.tapr.org/cgi-bin/mailman/listinfo/aprssig
>
> _______________________________________________
> aprssig mailing list
> aprssig at tapr.org
> https://www.tapr.org/cgi-bin/mailman/listinfo/aprssig
>
>