Quantcast

Warning GPS jamming testing

The Rocketry Forum

Help Support The Rocketry Forum:

Tonimus

Well-Known Member
Joined
Jul 9, 2014
Messages
1,511
Reaction score
4
Well, shoot. Here's to hoping that they stop before the end of summer flying season starts.
 

Steve Shannon

Well-Known Member
TRF Supporter
Joined
Jul 23, 2011
Messages
6,610
Reaction score
3,432
Location
Butte, Montana

tmacklin

Well-Known Member
Joined
Feb 1, 2012
Messages
2,227
Reaction score
8
I've begun lining the interior of my house with lead sheet. That crap is heavy!
 

FredA

Well-Known Member
Joined
Jan 19, 2009
Messages
2,170
Reaction score
347
The expected GPS outages will be on June 7, 9, 21, 23, 28 and 30, all from 9:30 a.m. to 3:30 p.m. Pacific time.
 
Last edited:

ksaves2

Lifetime Supporter
TRF Lifetime Supporter
Joined
Nov 25, 2009
Messages
6,049
Reaction score
337
Hmmmmmm, Only issue would be for folks trying to break altitude records that require an "approved" GPS chipset for altitude confirmation. If not going for a record then the concern would be having the ability to find the rocket.
In that regard, RDF facility or flying two transmitters, one GPS one RDF where room allows, might be prudent. Problem would be for those with 900Mhz GPS trackers only. Unless one has acquired the hardware necessary to RDF track on this
band, might be unreliable if ones GPS tracker goes silent at altitude and on descent. If it's only one day the testing is going to be done, then save the flights for later and hope the weather stays good. Kurt
 

Steve Shannon

Well-Known Member
TRF Supporter
Joined
Jul 23, 2011
Messages
6,610
Reaction score
3,432
Location
Butte, Montana
I doubt that gps trackers will go silent. I bet it's more like the "selective availability" that used to be imposed, just a slight random timing inaccuracy imposed to reduce the ability of enemy forces to use our own GPS system for targeting. If you're tracking with two GPS receivers, one to show the rockets location and one to show your location then finding the rocket may not be hampered as both should be offset an equal amount. But of course I'm just guessing.
 

ksaves2

Lifetime Supporter
TRF Lifetime Supporter
Joined
Nov 25, 2009
Messages
6,049
Reaction score
337
I doubt that gps trackers will go silent. I bet it's more like the "selective availability" that used to be imposed, just a slight random timing inaccuracy imposed to reduce the ability of enemy forces to use our own GPS system for targeting. If you're tracking with two GPS receivers, one to show the rockets location and one to show your location then finding the rocket may not be hampered as both should be offset an equal amount. But of course I'm just guessing.
Some of the 70cm GPS trackers become highly variable with their ability to transmit a signal if there is no GPS lock. I think someone mentioned this previously that it would be nice if the Beeline GPS could default to a 1/sec ping if the GPS lock is lost
and then back to the once every 5 seconds APRS position packet if a signal is reacquired.

I've turned on a BLGPS in the basement for setup and testing and noticed a station ID will be transmitted but nothing else if a lock can't be had. It will go silent. I've read where a BLGPS rocket launched and landed quite a distance away but apparently lost satellite lock once landed. The flier could hear a weak packet at very long intervals but not frequent enough to get a DF fix. Rocket was lost.

Conceivably, this could occur if ones tracker lands with the GPS receiver face down. It might maintain a lock with overhead satellites but lock could be lost with constellation shifts. For sport fliers where the last received position is close to the final touchdown, it's not likely to be a problem. For something that goes stupid fast and high, that ends up several miles away on uneven terrain it might be problematic if the GPS tracker goes silent if it loses satellite lock. It's a situation like that where a
separate RDF tracker with the ability to do DF bearings could save the day. Kurt
 
Last edited:

UhClem

Well-Known Member
Joined
Feb 6, 2009
Messages
1,747
Reaction score
235
This is not at all mysterious or unusual.

The military has a lot of GPS aided systems, most or perhaps all with some sort of anti-jam technology. These are sometimes tested in a jamming environment.

I have seen NOTAMs centered on White Sands Missile Range. What do you know, there is a current NOTAM for them:

!GPS 06/035 (KZFW A0073/16) ZFW NAV (WSMR GPS 16-09) GPS (INCLUDING WAAS, GBAS, AND ADS-B) MAY NOT BE AVBL WI A 316NM RADIUS CENTERED AT 323735N1060659W (ELP359049) FL400-UNL DECREASING IN AREA WITH A DECREASE IN ALTITUDE DEFINED AS: 261NM RADIUS AT FL250, 202NM RADIUS AT 10000FT, 221NM RADIUS AT 4000FT AGL, 181NM RADIUS AT 50FT AGL. THIS NOTAM APPLIES TO ALL AIRCRAFT RELYING ON GPS. ADDITIONALLY, DUE TO GPS INTERFERENCE IMPACTS POTENTIALLY AFFECTING EMBRAER PHENOM 300 AIRCRAFT FLIGHT STABILITY CONTROLS, FAA RECOMMENDS EMBRAER PHENOM PILOTS AVOID THE ABOVE TESTING AREA AND CLOSELY MONITOR FLIGHT CONTROL SYSTEMS DUE TO POTENTIAL LOSS OF GPS SIGNAL. 1606090530-1606091330
 
Top