New Boston Fire DPL

[garys]

F1 483.1625 D-174 Operations
F2 483.1875 D-265 Fireground 1
F3 483.2125 D-612 Special ops/Fireground 2
F4 483.2375 D-712 Evacuations/Fireground 3
F5 453.650 131.8 Station dispatch (no change)

The following are simplex (non repeated) narrowband channels:

F6 483.150 D-114 Fire academy
F7 483.175 D-125 Fire academy
F8 483.200 D-143 Fire academy
F9 483.225 D-311 Fire academy
F10 483.250 D-411 Fire alarm construction
F11 486.150 D-532 Special ops command
F12 486.175 D-175 Tactical
F13 486.200 D-243 Tactical
F14 486.225 D-026 Tactical
F15 486.250 D-051 Tactical

Thanks to Tim Caldwell http://home.comcast.net/~n1riw/antenna.htm for the list. Change over took place about noon today. Per announcement on Channel 1, they are running everything on portables until the mobiles can be reprogrammed.

 

[Mstrfxit12]

Man I hate when they do this. The amount of stuff I have to program is a pain and just after coming off the BPD retone.. Oh well price of admission.

 

[JimmyMac]

Hello Guy's,

I have questions about the new BFD DPL's. Will I still be able to pick up the BFD on a regular scanner or will I need to use my digital?. Can you also explain why they switched over from a PL to a DPL?.

Thanks so much for the help in advance.

 

[Junior08]

Yes, you can still pick them up with a regular scanner, but if the scanner has DPL tone programming you will need to program to the above ones. DPL (Digital Private Line) does not mean you need a digital scannel.

 

[garys]

The switch over was to reduce some interference issues that they had among their own frequencies. That's why they and BPD use different DPLs for each channel.

Gary

 

[n1das]

The switch over was to reduce some interference issues that they had among their own frequencies. That's why they and BPD use different DPLs for each channel.

Gary

The radio sites are high-RF dense areas, more or less "RF soup" environments.

Looks like it was done to combat or at least be able to live with intermod problems between multiple repeaters at the sites. Using different DPLs won't make the source of intermod problems go away but it will at least make the symptoms go away and the problems much easier to live with because the other repeaters won't get keyed up due to intermod, etc.

Example problem that I know of:
Nashua NH's old UHF 460MHz system occasionally experienced intermod problems between repeaters in the system. The repeaters on all channels (460.1, 460.2, 460.325) all used PL136.5. The system had several receive sites which they voted from. There were times when at least 2 repeaters were in use at the same time and the audio from both along with a lot of other noises would be heard out of both repeatetrs. Had they been using different PL tones on each repeater, the symptoms would never show up although the mechanism that cause the problem was still there. I don't know exactly how the inermod problem occurred nor do I know the particular combinations of frequencies involved, but having a different PL tone on each channel would have helped make the symptoms go away. Nashua NH is now on an 800MHz Motorola TRS.

BPD and BFD have some good people doing their radio work!

 

[n1das]

F12 486.175 D-175 Tactical

Is D175 possibly a mistake??
D175 is not a valid DPL code, or at least not a standard code in the Motorola standard 84 DPL code set or the full 104 DPL/DCS code set.

Could it be D174 or D172??

 

[JimmyMac]

Thanks for the answers!!.

 

[lynskey85]

Is D175 possibly a mistake??
D175 is not a valid DPL code, or at least not a standard code in the Motorola standard 84 DPL code set or the full 104 DPL/DCS code set.

Could it be D174 or D172??

According to the BFD Radio website, Ch. 12 (possibly a phantom channel) has a DPL 351.

The official list is http://www.bfdradio.net/BFD Channels.pdf

 

[brscomm]

Using different PL or DPL codes just masks the problem. Unfortunately, getting all the players together to resolve IM is nearly impossible especially in a high RF area such as downtown Boston. It could be a spurious transmitter, or rusty hardware. To use Nashua's old UHF for an example, if all three repeaters are on the same spot, unless they installed circulators, harmonic filters and bandpass filters, RF from the first two could mix in the 3rd repeater's transmitter even if it is transmitting.

Not a fun thing to fix and it has driven many tech's mad. Not me though, I'm already mad!