Trunked Radio Systems

[wb1aij]

  The city of Hartford, Ct. has had a trunked radio system (EDACS) for years. There are 16 frequencies used by all departments of the city including police, fire, schools, public works, park dept., etc. One of the 16 frequencies was a control freq. containing digital data to control  all of the radios in the system. If the scanner was programmed properly the digital frequency,which is always active, would be used by the scanner to follow the conversations but it would never be routed to the audio section.
  Lately I have noticed that the scanner seems strangely silent when scanning Hartford. I found that I can still hear transmissions on the frequencies if I monitor in manual mode but when in scan mode it doesn't follow the system. I also noted that the digital channel is silent when I try to hear it in manual mode. Did something change in the way trunked systems work now?

[K3ZS]

Some systems change the digital channel regularly.     In my area they change the digital channel every day.    It is to discourage scanner people that don't have trunk trackers from listening.    They may have added a channel also that you don't have programmed.    This web site usually has the latest trunking info, you have to register but there is no charge:

http://www.radioreference.com/

[WA1GFZ]

monitor a channel in manual mode. If you hear noise rather than voice could mean they changed over to secure mode. I'm surprised they still ran voice.

[Ralph W3GL]

They might have switched to APCO-25 coding...

[wb1aij]

Well, AM Fone Technical Forum contributors have come through for me. Well done & thanks. I went to "radioreference.com" & found out that the Hartford trunked system HAS made some changes. They gave up 4 860.xxx mhz frequencies & picked up 4 others in the 854-859 mhz range. I am confident that as soon as I reprogram the Hartford bank of the scanner I will be hearing all of the "dirt" that the city has to offer again. O'BOY!
 How did I ever get along without the internet for 45 years? Thanks also to Al Gore, its inventor.

thanks again to one of the largest "brain banks" in the world, AM FONE.

Bob Tomlin
WB1AIJ

[W1AEX]

Good to know Bob. I enjoy listening to the HTFD PD "informal" intercom communications from unit to unit. There's usually some funny chatter that takes place as they assume no one can hear them. I have not listened for a couple of months so was also unaware that they had changed things around. Looks like I'll need to re-program my scanner to be able to hear them again.

[flintstone mop]

I thought there were scanners that could look for the control channels on a Trunked radio system. Motorola told us that it was to spread the "wear" of the transmitters over the enitre system. We had a 10 channel system and there were 4 control channels. The  Quantar units would be switched every 24 hours. If the system hiccupped the "brain" would automatically switch control channels. The units in the field will scan for control channels when first turned on or if you go out of range.
Moto stuff was expensive but it worked almost all the time. MaNature would be the only one who could kill it, or we would lose a T-1 line

Fred

[W1AEX]

I thought there were scanners that could look for the control channels on a Trunked radio system.

I'm not sure about the newer scanners Fred. In the case of my older BC-780 I have to populate the correct group of frequencies (usually ten or so) in the scan bank. From what Bob has found, it appears that they have moved 4 of the frequencies out of the 860 range to the 854-859 range. Once the correct frequencies are programmed, the scanner will find the control channel and start group scanning the system.

[WA1GFZ]

seems to me the Hartford Police were pissed off at Motorola when I worked for them in the 90s. A lot of the 860 MHz band went to Nextel if I remember

[flintstone mop]

seems to me the Hartford Police were pissed off at Motorola when I worked for them in the 90s. A lot of the 860 MHz band went to Nextel if I remember

It was quite a freq war going on. There was a serious interference issue caused by Nextel and they were constantly visiting us with a million dollar check for us to give up our 900mhz freqs.
My former employer got tired of the high cost to maintain a radio system and went with another vendor.....the name doesn't come to memory...
Fred

[wb1aij]

The Motorola System only needs the control frequency & it will populate the scanner with all the other frequencies; the Ge/Ericson system needs to have the control frequency programmed in the 1st channel of the group & all of the others to follow. I reprogrammed by Radio Shack Pro-95 with the info from the "radioreference" website & it chatters away non-stop now. Works like it is supposed to. Now I just have to fix the intermittant squelch.

[WB6NVH]

Be aware that the majority of 800 MHz law enforcement systems will be changing sub-bands as part of an agreement with Sprint-Nextel to swap allocations as an effort to reduce interference.  Nextel is picking up the tab to either reprogram thousands of police radios or buy them new ones.  The details are handled on a case by case basis by the FCC TA (transition administrator.) Most systems are still in the negotiation phase despite deadlines already having run long ago.  In other words, it's a total mess in most areas.  When they finally do change, you will have some reprogramming to do once again.

[W1RKW]

Bob,  Rob,
What do you guys use for a modern day scanner?  I have an old BC 200XLT that is dead for my area in Colchester. I can't get the State PD or local PD.  Would like to monitor what is going on.  

Bob

[WA1GFZ]

I would think most dept's are going secure and good luck cracking the code.

[K9PNP]

We just rebanded all the 800/900's in the county which use the state-wide trunking system.  Big contract deal thru the state.  They forgot to tell us they changed some of the functions on the radios at the same time.  Apparently another 'state standard' deal.  More time to spend retraining all the users after we figure out exactly what the changes are.

[W1AEX]

Bob,  Rob,
What do you guys use for a modern day scanner?  
Bob

Hi Bob,

I'm afraid I have not kept up with any of the APCO 25 scanners. I still use a 10 year old Uniden BC 780 XLT which will handle local trunk tracking duties, but cannot do anything with the CT State Police, which is currently running APCO 25. I mostly listen to the 118 - 136 Mhz aircraft traffic coming and going at Bradley International, so I have not (yet) felt the urge to buy anything newer. I hear the same rumors that Frank mentioned about local police and fire departments who are considering moving to secure protocols and that makes me wonder about dropping $400 - $600 on a scanning receiver that could quickly turn into a very expensive doorstop. I guess only time will tell...

Rob

[wb1aij]

Bob,  Rob,
What do you guys use for a modern day scanner?  
Bob

I use a five year old Radio Shack Pro-95. It can handle the GE-Errickson & Motorola Trunking Systems but NOT the digital systems used by the state police. The state police still have their old 42 mhz radios but most of their chatter is gone from that system. They still have their old call letters on those radios; I can remember back in the 50s my dad , who was a trooper from the middle 50s to the middle 70s giving the call letters "KCA788" which is still the Hartford or Colchester Barracks call.