Wednesday, February 03, 2010

DoS UHF Changes As Well

Besides the changes going on with the DEA UHF channels, there seem to be some changes afoot with the Department of State Bureau of Diplomatic Security, .

For many years the primary DoS Field Offices used 409.6250 MHz as their nationwide frequency. But recent installations of new P-25 gear has them using 409.5250 MHz, NAC 293. Dallas, Houston, Boston, San Francisco and Washington DC are currently using the new frequency. Originally when the DoS went to P-25 in New York City and Washington DC, they were using a P-25 NAC of N0f0, but sometimes N293 would show up.

Why the change? If you add 9 MHz to the old frequency of 409.6250 MHz, you end up on the DEA's primary repeater of 418.6250 MHz. Accident? Chance? Or will 409.6250 be the new DEA repeater frequency?

DEA Changes In The Works?

Recently there have been some possible changes to the DEA's UHF channel plan. It's been long expected as the DEA original frequencies were not going to be compliant with the NTIA's new UHF federal channel plan, including a 9 MHz repeater offset.

There had long been rumors and some confirmation that the DEA was headed towards VHF to be more interoperable with other Justice Department agencies. But after a recent Justice Department budget stated that the DEA was going to remain on UHF for "tactical" considerations, there has been some guessing as to what would happen with DEA frequency assignments. The original best guess at the DEA's assignements can be found here:

Recently in the Houston area, it has been reported that 418.6750 MHz, which has been a simplex DEA surveillance frequency, is now being repeated on 409.6750 MHz. Both signals were reported as using a NAC of 156. The 409.6750 frequency is a new assignment to the DEA, and seems to be based on being 9 MHz from the original simplex channel.

Also from the same area, probable DEA operations are being heard on 413.9750 MHz, also N156. This frequency has been used as a repeater input channel in some areas, but in the new NTIA channel plan this would be a simplex frequency.

So keep searching the 406-420 MHz band for more changes!