Sunday, June 03, 2018

TSA Dropped 172.9000 MHz?

Back when the Transportation Security Administration (TSA) began operations in 2002, they were originally under the Department of Transportation (DOT). The radio frequencies that were first standardized to be used by the TSA nationwide included 169.3000, 172.1500 and 172.9000 MHz. These frequencies were culled from the Federal Aviation Administration (FAA) allocations, and they are still shared between the two agencies.

Since the new radio updates that the TSA has undergone, I have noted a distinct lack of any activity on the 172.9000 MHz frequency as I travel across the country. Most airports still have some activity on the 169.3000 and 172.1500 frequencies (as well as others), but mostly silence on the 172.9000. Anyone hearing activity on 172.9000 MHz, please let me know!

Federal/Military use of NXDN

   I recently saw some discussions about some VHF federal frequencies being used for an NXDN IDAS trunked system in Southern California. Monitoring had provided clues to the system users and it appears to be utilized by the Los Alamitos Joint Forces Training Center in Orange County. So far, two frequencies have been identified as being used by this system, and updates can be found here:

163.4125 MHz - LCN1
163.4375 MHz - LCN2
? - LCN3
   While the use of DMR and NXDN digital modes is increasing in the federal VHF and UHF bands, it is a bit unusual for a military facility to go with a non-standard radio system type when other military bases around the world are joining large networked P-25 digital radio systems.