• Spectrum management is an incredibly complex business. Some issues fall into "grey areas". There are good arguements to be made on both sides of this issue. There are a lot of interesting comments made about how interference "not in band" ( supposedly) can still cause problems in certain circumstances:

    This battle will be won or lost based as much on political lobbying as it will on technical issues.


  • It seems like GPS manufacturers are expecting, demanding even, special treament.

    Just about any device I've ever seen has something from the FCC that says "...this device must tolerate interference...."

    If GPS is so darn important (and I don't disagree with that) then it should fall under some of the safety standards that exist for life-saving equipment, and have tighter design tolerances!

    I am reminded of 802.11b spectrum mask measurements. If you had looked at what Wi-Fi radios transmitted ten years ago, you might not have found that even 30% of the radios met that part of the spec.

    These days, it's hard to find a radio that fails, anywhere past the central +/- 11Mhz range. [b]ALL[/b] of the signal is likely below 50 dBr, or even 55 dBr. Forget looking for side lobes, as they are almost non-existant. The graphs go flat outside the primary lobe. That is what good design and filtering can do for you.

    The industry has matured and gotten exponentially better on this technology. GPS manufacturers could do that just as well.

  • Yup. It's a really murky issue this one. There are good points on all sides. Huge, huge bucks are at stake here, along with potentially very large numbers of jobs, and potentially a lot of Wi-Fi related business as well, from the whole convergence thing.

    There are national security issues, etc , etc etc. It is very involved. Lobbyists are scuttling all over the hallways of DC as we speak, for both sides. There are also other issues that have not been made public to a great deal. Usually, these interference fights are fairly straightforward. Wi-Fi ? I'm radar. You will DFS and like it, or I won't let you play, period. Wi-Max ? You're near a military facility in Holland, you can't play period ( megabucks lost on that one ).

    This one is very tricky, and it's anyone's guess how this may come out.

    Even the whole method of testing is being questioned by all and sundry.


  • One of the problems is that there is a lot of older GPS gear out there. Lightsquared have offered some filtering solutions etc.

    What would seem to be fairly simple solutions become lost in the murkiness of who wants what in this game. It's the most complex one I've ever seen, and what seems logical from a technical point of view may not have anything to do with the final outcome.

    There are a lot of political issues as well. I won't put up links here, as it would cause all sorts of problems, but by putting the word "scandal" and a few other key words in Google, some of the issues can be seen.



    It?s worth getting past the enthusiasm/squeeky voices in the following, for the diagrams. Nice basic explanation:


  • It gets like a soap opera at times:

    "Did Bradley really go with her, just to get to Mindi ?.....tune in tomorrow "

    I've been following this for a while, and there are more twists and turns than a corkscrew.


  • Egad.

    What a mess.

    Originally I was on the side of Lightsquared, but after reading just a few artcles, I'm not so sure.

    Politics, money, power, and truth. Have they ever agreed on anything?

  • Also, to make matters more complex, we have the major cellular carriers. Those boys are not happy about some new kid on the block. Loads of cash means loads of lobbyists. Although not much has been heard from them, I'm pretty sure they're not happy about another, potentially revenue-taking-away-from-them outfit.

    When all this comes out in the wash ( whenever that is ), we may never really know all the truth.


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