In a public notice released on Tuesday, the FCC followed the recommendations of the National Telecommunications and Information Administration (NTIA) in declaring that additional tests of LightSquared LLC’s proposed operations in the lower L-band are “needed to ensure that any potential commercial terrestrial services offered by LightSquared will not cause harmful interference to GPS operations.” Tuesday’s public notice comes on the heels of a September 9 letter from NTIA Chief Larry Strickling to U.S. Deputy Defense Secretary William Lynn and U.S. Deputy Transportation Secretary John Porcan in which Strickling calls for the development of a joint interagency testing plan to assess potential interference between LightSquared’s proposed operations in the lower L-band and cellular or personal/general navigation devices that receive GPS signals from adjacent spectrum bands. Setting a target completion date of November 30, Strickling said that, “based on the data collected to date, NTIA expects that limited further testing (1) will confirm the validity of the prior measurements collected in testing by the Technical Working Group (TWG) evaluating LightSquared’s modified operating proposal, and (2) will provide NTIA and the federal agencies with the necessary data to determine what, if any, additional operating restriction is necessary in order to mitigate remaining interference issues.” Noting that previous tests conducted by the TWG “demonstrated that some receivers were more resistant than others to the lower 10 MHz signal,” Strickling asked that the test plan “include a retest of the ten devices that were shown by the TWG testing to be more susceptible to the lower 10 MHz scenario.” Strickling further acknowledged “there will later need to be a second phase of testing to evaluate proposed mitigation plans for high-precision and timing [GPS] receivers which would commence once LightSquared develops a filtering solution to avoid interference.” Concurring with NTIA’s assessment, the FCC stated: “we are satisfied that the process that was established through the conditional authorization, as well as the consultation process that exists between the FCC and NTIA, is meeting our objective to fully understand the potential for harmful interference and develop solutions before LightSquared is permitted to deploy service.”