California Surveyors Forums

I was browsing thru GPS World magazine at lunch and found an JAVAD ad that had a great simple graphic that illustrates the difference between Communications and GPS signal tracking, and a fundamental reasion why LightSquared Engineers do not understand the potential effects on GPS tracking.

Here is the link: http://javad.com/cgi-bin/jgnss/cgi?Action=PollManager
Page down below Mona Lisa

Public notice from the FCC was posted on their website:

http://transition.fcc.gov/Daily_Release ... 1537A1.pdf

Would someone who reads "bureaucratic lingo" better than I please chime in.

Does this posting imply LightSquared needs to PROVE it will not cause interference with GPS? Or is it just one more hurdle everyone needs to jump through?

The only way that the LightSquared signal will not cause interference is if they significantly reduce the output power. Unfortunately, that would probably make their service unusable.

This is easily tested by keying up a 5 watt 2-way radio (entirely different frequenciy band) while close to your GPS receiver. Watch the satellites drop out!

The LightSquared signal was originally planned for 100,000 watt radiated power. I am guessing our recivers would not work within 1,000' of their transmitters. They wanted to put their transmitters on most cell towers. Think about the cell tower spacing in your area!

Thank you to all who took the time to contact the FCC.

Stan

The way I read it is that the FCC is essentially talking out of both sides of their collective mouth saying that they support wireless broadband service AND that they will protect GPS against harmful interference, while at no time admitting that it erred in approving a waiver to broadcast from cell towers on frequencies allocated to low power Satellite broadcasts (next to GPS frequencies) at a power level Billions of times stronger, virtually guaranteeing interference.

Some additional links:

http://www.fcc.gov/document/lightsquared-further-tests

http://www.flightglobal.com/articles/20 ... rence.html

http://www.washingtonpost.com/blogs/pos ... _blog.html

http://www.gpsworld.com/gnss-system/new ... ared-12073

Another article:

http://www.thedailybeast.com/articles/2 ... donor.html

LightSquared: Did White House Pressure General Shelton to Help
Donor? - The Daily Beast

http://www.thedailybeast.com/articles/2 ... did-white-
house-pressure-general-shelton-to-help-donor.html

Not that I'm a dedicated follower of Fox News, but the No. 1 article this morning on Foxnews.com is this new article posted yesterday from The Daily Beast.

http://www.foxnews.com/

We need to post some commments in there about the real issues of this story while it's trending...

http://www.foxnews.com/scitech/2011/09/ ... a-network/

In testimony before the House Armed Services Committee on Thursday, General William Shelton, head of Air Force Space Command, detailed the results of tests from earlier this year intended to quantify the effect of LightSquared's forthcoming network on GPS.

"Aviation receivers operating as far as 7.5 miles from LightSquared transmitters completely lost GPS and were degraded out to distances of more than 16.5 miles," Shelton said. "High precision GPS receivers such as those used for surveying and geological study requiring precise measurements were adversely affected out to 213 miles and totally lost GPS out to 4.8 miles."

http://www.pobonline.com/Articles/Indus ... 0001105800

"LightSquared has signed an agreement with Javad GNSS Inc. to develop a system designed to eliminate related interference issues for high-precision GPS devices."

~~

http://www.rpls.com/blogs/1/131

"LightSquared yesterday threw a Hail Mary pass with its announcement that it is working with Javad GNSS Inc. to develop a system that will eliminate interference issues related to high-precision GPS devices. "See, we told you a simple fix was possible!" the company essentially gloated as it spiked the ball in the end zone. Its rivals, high-precision GPS users, are clamoring for a review of the play.

In a flurry of emails following the announcement, surveyors shared their concerns. And in a standing-room-only crowd at the ION GNSS 2011 conference in Portland, Ore., yesterday evening, a panel representing a broad range of manufacturers and users reiterated the negative results from tests that have been conducted so far. "All of them agreed more testing is needed and more time is needed," said Jered McGrath, PLS, survey project manager for MacKay & Sposito Inc. in Vancouver, Wash."

A great letter was also attached to the POB blog post...

http://www.rpls.com/blogs/1/131

Duncan Marshall sent me this pdf of a LightSquared ad in the local paper.

Wow, the hyperbole and gross distortion of statistics and facts.

Wow, the money being thrown at pushing the LightSquared proposal thru before it is properly tested and proven to have no interference with GPS.

I like the part where it says that precision GPS devices "inappropriately violate our licensed spectrum." The only devices that violate that license are the GPS space vehicle transmitters. The fact that survey-grade receivers depend upon out-of-spectrum frequencies in order to obtain sufficient ranging data isn't a violation of the Lightsquared license, it's merely an unfortunate circumstance. However, it's a circumstance of such magnitude that there's no way Lightsquared should be allowed to get away with its proposal.

The situation is analogous to a prescriptive easement. The FCC knew -- or should have known -- that millions of GPS users were dependent upon very weak signals in and near the GPS frequencies. For it to allow Lightsquared to enforce the technical limits of the spectrum license it bought, with the intention of using that spectrum in a manner inconsistent with its designation (space-based versus ground-based), would be grossly inequitable.

.

Trimble is fighting the good fight for GPS...

New Article and Information Compiled by Carl C. deBaca

A good article published on American Surveyor online...

http://www.amerisurv.com/content/view/9304/2/