My qualifications to speak on this subject come from working in the land surveying business for the past 15 years. All of us in land surveying who depend on GPS for our livelihood are very concerned. If Lightsquared gets approved GPS will go down in a wide area around their transmission towers. A test was recently done on their proposal in Nevada and it totally obliterated the GPS signal. No position information could be obtained anywhere near the test area. LightSquared's proposal that everybody purchase new equipment that filters out their signal is ridiculous. They need to find a frequency that is not adjacent to GPS or shelve their plan because it is incompatible with current civil use of GPS. This opinion is not from a PHD but from a real world GPS user. More information from the pros below and a link to a website with further info. Statement by the National Executive Committee for Space-Based Positioning, Navigation, and Timing December 14, 2011 WASHINGTON -- Today, a government technical group reviewed the findings from last month's testing of LightSquared's proposal to provide new broadband service. The final test report will be sent to the National Telecommunications and Information Administration (NTIA), which advises the President on telecommunications policy, and represents federal agencies to the Federal Communications Commission (FCC). Preliminary analysis of the test findings found no significant interference with cellular phones. However, the testing did show that LightSquared signals caused harmful interference to the majority of other tested general purpose GPS receivers. Separate analysis by the Federal Aviation Administration also found interference with a flight safety system designed to warn pilots of approaching terrain. The findings were presented to the technical steering group which represents the nine federal agencies that make up the National Executive Committee for Space-Based Positioning, Navigation, and Timing. Over the next several weeks, the final analysis of the findings will be completed and a final report will be transmitted from NTIA to the FCC. http://www.gps.gov/news/2011/12/lightsquared/ -----Original Message----- From: montgomery_boats-bounces@mailman.xmission.com [mailto:montgomery_boats-bounces@mailman.xmission.com] On Behalf Of W David Scobie Sent: Wednesday, February 01, 2012 8:48 AM To: For and about Montgomery Sailboats Subject: Re: M_Boats: Check out Coalition to Save Our GPS i too have been following this issue for the last year-ish. a good friend, and college roommate, has a PhD in this stuff (some of his designs have been put into orbit). i have been asking him his opinion on the LightSquared situation. here is his point of view (POV) on the latest that has been discussed here on the Mboat listproc - -- begin a PhD's POV -- Well, what has been said is mostly not true. (except "go sailing with no worries") [note: my friend is also a life-long sailor. - dave] GPS jamming is really easy. The signals are "Sub Thermal" meaning that they are really, really , really weak. Spread spectrum does help with interference, and the next generation of satellites *may* be more powerful, but that is not what I heard. I thought Light Squared said that the next generation of *receivers* may be more resistant to interference. So everyone should just replace their equipment so they can use a crappy radio system. Personally, I think the DoD, FAA, and FCC is going to tell LightSquared to go stuff it. On the other hand, I just read some articles and the authors could be confused. This could be a test about if business controls government, in which case we are screwed. -- end PhD POV -- i look forward to reading other's opinions ... i still use paper charts and dead reckoning as my #1 and #2 navigation tools. GPS is a helplful #3. i'm not a fan of digital charts (chart plotters). i do like the speed over ground feature on a GPS - much better than putting a thru-hull on the boat. :: Dave Scobie --- On Wed, 2/1/12, robbin roddewig <robbin.roddewig@verizon.net> wrote:
Hi Gary, this "threat" from light squared has been a topic for quite a while. When you look at the technical details it is very benign. GPS is inherently immune to a high level of interference due to the spread spectrum nature of the signal (processing gain of 1000 or 30dB). You can always hypothesize a situation where you could jam even a highly resistant system like GPS but these situations tend to be very pathological. The next block of GPS that is under development is even more resistant to interference, as it is targeted for use by commercial airliners. There is not a great understanding of GPS (or Assisted GPS, reference the erroneous statements in the latest practical sailor article on Nav apps) but bottom line is that I would not worry too much about GPS being compromised. Go sailing with no worries!
Robbin
On 2/1/2012 12:14 AM, GILASAILR@aol.com wrote:
_Click here: Coalition to Save Our GPS_ (http://saveourgps.org/)
Conflicting use/frequencies may have an effect on the viability of GPS in the near future - see link for more info.
From "Scuttlebutt".
GO