RF Shorts – Oct. 20, 2011
October 20, 2011
LightSquared Offers a Filter/Antenna Interference Solution for High-precision GPS Users
Mike C. reports in FieldTechnolgies.com article LightSquared Reveals GPS Device Solutions for Interference Issues that Javard GNSS has developed an external antenna "roughly the size of an enterprise WI-FI access point and a ceramic filter smaller than a pencil. Javad would make the filter and incorporate it into the antenna. The package would sell for under $200. Two other companies have also created LightSquared-compatible components than can be integrated into receivers. PCTEL has developed LightSquared-compatible chipsets and Partron America has created a filtering component that costs only $8.
Replacement antennas would be easy to install on the old GPS receivers with detachable antennas and precision GPS units with external antennas but I don't see how the filters could economically be installed in the large number of low cost self contained GPS navigation devices with no external antenna connection.
State Broadcasters Express Concerns over Spectrum Repacking
The National Association of Broadcasters released a letter from the Washington State Association of Broadcasters to Senator Patty Murray explaining the potential impact of repacking broadcasters in the state following voluntary incentive auctions. Other state broadcaster associations have sent similar letters to their respective senators. The letter says, "We are not opposed to incentive auctions, but ask for your help in making sure these auctions are done correctly and with careful consideration of the impact it will have on our nation's free over-the-air television service, a service that has served Americans well for many years."
The letter says that for 120 MHz of broadcast spectrum to be reclaimed, 83 of the 84 Washington State full power stations and TV translators/LPTV stations impacted by incentive auctions and repacking would not have a channel and would have to share with another station or cease to exist. The letter specifically asks Senator Murray for help ensuring that "before the FCC can repack the television band, or before the FCC can release broadcast spectrum, that Congress require that a new memo of understanding agreement or treaty with Canada be finalized."
If you are having trouble understanding all this spectrum talk, the FCC's Infographic Spec it out! might help. It has large graphics, big numbers and little text. By leaving out complicated details such as forced relocation of TV stations to new channels and possibly new locations and the cost of wireless broadband it is able to focus solely on the benefits of more spectrum for new, innovative technologies.
Does Prolonged Cellphone Use Cause Brain Tumors?
Another article has appeared questioning whether cellphone usage increases the risk of brain tumors. Rafael Castillo, writing in the Philippine Daily Inquirer, asks Does prolonged cell phone use cause brain tumors?. The author recognizes the concerns about cell phones and brain tumors, but points to research that doesn't show a clear link between the two, noting patients with brain tumors do not report more cellphone use compared to the control group and there is no clear link between the side of the head on which the brain tumor occurred and the side of the head where the cellphone was usually used. Castillo cautions that the studies were not able to track people for a long period of time, so there may be impacts we haven't seen yet. He also said the largest data source was a series of studies called the Interphone studies that were led by the wireless communications industry.