Strange pairing of freqs in Boston area

jack103 · #1 (**permalink**) 10-20-2009, 07:43 PM

For days now I have received encrypted comms from the DEA on 418.6250 nac 156 at the same time I am receiving encrypted comms on what I believe is the State Dept Security Service on 409.5250 nac 293.Anyone care to guess what is going on? It does not seem to be 409.5250 an input to the DEA ch 1. I am using a PRO 106 to receive with at my home 20 miles north of Boston MA.

Squad10 · #2 (**permalink**) 10-20-2009, 10:08 PM

Possibly a cross patch or link?

I'd monitor 416.050 (known Ch.1 analog input), 409.625 (NTIA 418.625 pair), 418.525 (NTIA 409.525 pair) and see what you hear and see.

kennyblues · #3 (**permalink**) 10-20-2009, 11:56 PM

It has been this way for quite a while now, at least a couple of years. 418.6250/416.0500 N-156,409.5250N-293. The 409.5250 N-293 is used by the D.O.S. also. Of course it is kind of hard to tell since the 418.6250 repeater runs about 99% ENC

ecps92 · #4 (**permalink**) 10-21-2009, 10:15 AM

Not everyone has migrated to the 9 Mhz offsets as yet, there are still plenty of Legacy users

Kenny is correct its a mix of DEA and DoS due to mixing the new channels with existing legacy users, and the use of Open RX [dual mode Repeater] passing any input traffic but using the DEA NAC Output

Quote:

Originally Posted by Squad10

Possibly a cross patch or link?

I'd monitor 416.050 (known Ch.1 analog input), 409.625 (NTIA 418.625 pair), 418.525 (NTIA 409.525 pair) and see what you hear and see.

Squad10 · #5 (**permalink**) 10-21-2009, 11:07 AM

Quote:

Originally Posted by ecps92

Not everyone has migrated to the 9 Mhz offsets as yet, there are still plenty of Legacy users

Kenny is correct its a mix of DEA and DoS due to mixing the new channels with existing legacy users, and the use of Open RX [dual mode Repeater] passing any input traffic but using the DEA NAC Output

I get what you are saying about the 9 MHz offsets, Chicago DEA hasn’t even converted to P25 yet...

I’m not familiar with your term Open RX [dual mode Repeater], what are its (DEA/DoS) input and output frequencies? I'm trying to understand how it factors with the OP quote "For days now I have received encrypted comms from the DEA on 418.6250 nac 156 at the same time I am receiving encrypted comms on what I believe is the State Dept Security Service on 409.5250 nac 293."

Sorry for my confusion.

ecps92 · #6 (**permalink**) 10-21-2009, 11:56 AM

My assumptions on this are, based on hearing both Repeaters at the same time.
Although there could be other issues, that we [Scannists] don’t know about.

418.6250 R / 416.0500 156.7 / $156

409.5250 R / 416.0500 $293 Likely configuration

409.5250 R / 418.5250 $293 Should be, but not

Any P25 input on 416.0500 triggers 418.6250 but shows as $156 since the Repeater is programmed to not PASS the NAC, but use $156
However only 156.7 triggers the Rptr in Analog mode

Repeaters can be programmed to PASS PL/NAC [what comes in, is what comes out] or they can be programmed
To be Static on a PL/NAC [What comes in, could be different than the output, in the analog world this is called Cross-Tone or Split Tone]

Quote:

Originally Posted by Squad10

I get what you are saying about the 9 MHz offsets, Chicago DEA hasn’t even converted to P25 yet...

I’m not familiar with your term Open RX [dual mode Repeater], what are its (DEA/DoS) input and output frequencies? I'm trying to understand how it factors with the OP quote "For days now I have received encrypted comms from the DEA on 418.6250 nac 156 at the same time I am receiving encrypted comms on what I believe is the State Dept Security Service on 409.5250 nac 293."

Sorry for my confusion.

ecps92 · #7 (**permalink**) 10-21-2009, 11:57 AM

Thats OK, simple answer is the input is programmed to accept any tone in P25

Quote:

Originally Posted by Squad10

I get what you are saying about the 9 MHz offsets, Chicago DEA hasn’t even converted to P25 yet...

I’m not familiar with your term Open RX [dual mode Repeater], what are its (DEA/DoS) input and output frequencies? I'm trying to understand how it factors with the OP quote "For days now I have received encrypted comms from the DEA on 418.6250 nac 156 at the same time I am receiving encrypted comms on what I believe is the State Dept Security Service on 409.5250 nac 293."

Sorry for my confusion.

Squad10 · #8 (**permalink**) 10-21-2009, 01:06 PM

Quote:

Originally Posted by ecps92

My assumptions on this are, based on hearing both Repeaters at the same time.
Although there could be other issues, that we [Scannists] don’t know about.

418.6250 R / 416.0500 156.7 / $156

409.5250 R / 416.0500 $293 Likely configuration

409.5250 R / 418.5250 $293 Should be, but not

Any P25 input on 416.0500 triggers 418.6250 but shows as $156 since the Repeater is programmed to not PASS the NAC, but use $156
However only 156.7 triggers the Rptr in Analog mode

Repeaters can be programmed to PASS PL/NAC [what comes in, is what comes out] or they can be programmed
To be Static on a PL/NAC [What comes in, could be different than the output, in the analog world this is called Cross-Tone or Split Tone]

Gotcha. Thanks for the explanation. It’s just strange to me how the frequencies are setup. I understand the need to add the P25 option to an already analog repeater, but to mix DEA and DoS, what could the purpose be, maybe a community repeater vote select wide area system? I think a field radio would need to be in scan mode so the operator knows when they hear traffic on either repeater not to transmit avoiding repeater input frequency interference. Too bad it’s encrypted 99% of the time, it would be interesting to hear how it is used.