GPS Warning

[Lonewolf]

What's your source on this?

Russia is widening the gap in EW -- Defense Systems

Perhaps you're unaware that the U.S. Has two GPS systems. Conventional GPS commonly used for navigational systems in your automobile and aircraft. The second is the Military GPS used exclusively by the military and is situated at a much higher altitude in outer space than the lower situated Conventional System.

If the Russians DID as stated in the report you provided, it wasn't the Conventional System they ALLEGEDLY jammed. The test our military is currently conducting is on our Conventional System.

 

[N017RW]

On the surface it would if that were true, but GPS doesnt just use a single carrier frequency nor is that the only thing you could scramble to fubar the system (microwave freqs, communication frequencies, positional frequencies, satelite communication frequencies). All tech has vunerabilites, Glonas seems to have had more of them published than GPS.

You may be misunderstanding my point.

Yes, GPS has more than one channel (frequency) in the L-band, however your UAS receiver is tuned to only one of them, L1, as it is a civilian use. Individual GPS SVs have unique binary codes to differentiate them at the receive/demod stage. (CDMA)

With G-nass, each SV has the same binary code BUT it's own individual transmit frequency to differentiate them at the receive/demod stage. (FDMA)

G-nass was plagued with problems in the past due to Russia's economic probs. Not sure what current 'stats' might be.

 

[N017RW]

Perhaps you're unaware that the U.S. Has two GPS systems. Conventional GPS commonly used for navigational systems in your automobile and aircraft. The second is the Military GPS used exclusively by the military and is situated at a much higher altitude in outer space than the lower situated Conventional System.

Can you please link to that?
Sounds like internet lore.

A quick G-search finds nothing to substantiate what you have said.


The Military L2 channel resides on the same satellites as the civilian L1.
As far as Google is concerned, there are no separate SVs or orbital locations between civi and military.

 

[sar104]

Can you please link to that?
Sounds like internet lore.

A quick G-search finds nothing to substantiate what you have said.


The Military L2 channel resides on the same satellites as the civilian L1.
As far as Google is concerned, there are no separate SVs or orbital locations between civi and military.

You are correct - there are not two separate constellations and I have no idea where anyone would get that idea from. The Space Segment comprises nominally 32 satellites at an altitude of 20,000 km.

 

[N017RW]

You are correct - there are not two separate constellations and I have no idea where anyone would get that idea from. The Space Segment comprises nominally 32 satellites at an altitude of 20,000 km.

It's amazing to me that people POST such rubbish when it is soooo easy to verify.
Their 'credibility rating' takes a real hit.

 

[sar104]

It's amazing to me that people POST such rubbish when it is soooo easy to verify.
Their 'credibility rating' takes a real hit.

If only there were some universally accessible source of information that could be consulted...

 

[drunkpenguin]

GPS Blocking drills have been going on for years. At work we run some equipment that relies heavily on GPS time and some of our sites near military bases can really suffer during these tests. My understanding is they are basically training people on using the equipment so during war time they can kill GPS for the enemy.

 

[Sagebrush]

Perhaps you're unaware that the U.S. Has two GPS systems. Conventional GPS commonly used for navigational systems in your automobile and aircraft. The second is the Military GPS used exclusively by the military and is situated at a much higher altitude in outer space than the lower situated Conventional System.

This is news to me. I teach a legal class titled, GPS for Evidentiary Use. I've never heard of this.

The Defense Department is the steward for the Global Positioning System that utilizes a constellation of 24 satellites that orbit at about 12,500 miles. The FAA administers the WAAS portion of this system that corrects for GPS atmospheric inaccuracy over North America. There are three geosynchronous satellites that broadcast this correction. (And yes, the P3A and P3P are WAAS enabled.)

Here's a good primer:
GNSS Frequently Asked Questions - GPS

Perhaps you could share a link concerning about this military system?

Sagebrush

 

[Imabiggles]

This is news to me. I teach a legal class titled, GPS for Evidentiary Use. I've never heard of this.

The Defense Department is the steward for the Global Positioning System that utilizes a constellation of 24 satellites that orbit at about 12,500 miles. The FAA administers the WAAS portion of this system that corrects for GPS atmospheric inaccuracy over North America. There are three geosynchronous satellites that broadcast this correction. (And yes, the P3A and P3P are WAAS enabled.)

Here's a good primer:
GNSS Frequently Asked Questions - GPS

Perhaps you could share a link concerning about this military system?

Sagebrush

If you teach a class on GPS, one would think you know of the errors intentionally introduced into the civi GPS that is not present in the military GPS signal. One would also like to believe that you could also look up the specs of military grade GPS receivers, see that they can receive both the L1 and L2 signal and notice that the positional accuracy and is publishes as 1/3 better on the military flavor, however some receivers use more advanced calcs (or use better electronics) and do even better than specs.

The problem with those attempting to teach adults is that it seems like the information has to be spoon fed to the instructor, instead of the instructor becoming the defacto expert on the topic with work, research, and organization. Heck, the US government maintains a web page of technical GPS specs and information that explain all this. Sorry Brush - cant find my spoon to feed you the stuff you teach.

 

[N017RW]

If you teach a class on GPS, one would think you know of the errors intentionally introduced into the civi GPS that is not present in the military GPS signal.

The system(s) are always being upgraded ,etc. and occurring as we type but this was eliminated years ago.

This site says its info was updated May 2016:
GPS.gov: New Civil Signals

 

[Imabiggles]

The system(s) are always being upgraded ,etc. and occurring as we type but this was eliminated years ago.

This site says its info was updated May 2016:
GPS.gov: New Civil Signals

the big positional timing error was removed but I was told there exists a wider error tolerance in the signal, timing, and calcs that still exist in L1 signal. I also believe the L1 signal to have uncorrected errors (and introduced errors) in them that the L2 signal does not allow. At the end of the day, I do not consider myself to be a GPS expert, but I do know folks that are literally rocket scientists (well aeronautical/Aerospace engineers as they correct my moniker for them). When I first got a GPS autopilot module for fixed with RC - I learned lots from them.

 

[Sagebrush]

The second is the Military GPS used exclusively by the military and is situated at a much higher altitude in outer space than the lower situated Conventional System.

Uh-huh.

SB

 

[N017RW]

.

... At the end of the day, I do not consider myself to be a GPS expert, ...

Maybe you shouldn't be so judgemental then such as what you think others should know, like: "...If you teach a class on GPS, one would think you know..." for example.

 

[sar104]

the big positional timing error was removed but I was told there exists a wider error tolerance in the signal, timing, and calcs that still exist in L1 signal. I also believe the L1 signal to have uncorrected errors (and introduced errors) in them that the L2 signal does not allow. At the end of the day, I do not consider myself to be a GPS expert, but I do know folks that are literally rocket scientists (well aeronautical/Aerospace engineers as they correct my moniker for them). When I first got a GPS autopilot module for fixed with RC - I learned lots from them.

I think the main point of contention was the claim that there are different constellations, at different altitudes, for the military and civilian streams, not that there is no difference between the accuracy of the two systems, which there is. The accuracy difference is primarily due to military receivers being able to perform ionospheric correction as a result of receiving on two separate frequencies.

 

[Imabiggles]

.


Maybe you shouldn't be so judgemental then such as what you think others should know, like: "...If you teach a class on GPS, one would think you know..." for example.

Maybe I shouldnt, but I am. Oh well.