Anybody know if Chelsea FD is using 470.0875 (Tac 2) in simplex mode? Everyday at 9 AM and 7 PM the dispatcher tests with the Command Car on 470.0875. I never hear the Command Car answer, but the dispatcher apparently does. Does anyone know if the Command Car is answering on 470.0875 or 473.0875?
Chelsea Mass FD - 470.0875 ???
- Thread starter zerg901
- Start date
- Status
jmorrissey23
Member
That is the EMS channel, the test with the Command Car is on the Tactical Channel (482.2875) every morning. Fire Alarm could have been using a multi-select and calling them on all channels which is why you heard them call on 470.0875
I think that Chelsea FD has renamed 470.0875 as "Tactical 2". The traffic usually is a simulcast of the dispatcher from Channel 1 - except when they test with the Command Car. The radio tests now have 3 parts - everyone on Channel 1 - then the Command Car on Tac 1 - then the Command Car on Tac 2. I think they have been doing this for a couple of months now. 470.0875 does not seem to be used for EMS anymore.
xplorer417
Member
hi can you find out what ch ems is on and what the correct tpl/dpl is I have family up there and would like to listen to them while visiting in that area thanks
RKG
Member
A couple of points that might illuminate this discussion a bit:
1) In the typical dispatch system (including Chelsea's) that uses a voted repeated system, the dispatch console listens to the input frequency of a repeated channel. Subscribers generally cannot communicate with dispatch on "direct" because a subscriber on "direct" is transmitting on the output frequency.
2) While it is possible to enable "direct" reception by a dispatcher, it is complicated. You need an additional receiver (programmed for the output frequency) and an additional channel card, and you also need a way of muting this receiver whenever the console transmits over the system (to avoid the "direct" receiver from hearing the console operator's transmission and generating a cascade noise). As of when the Chelsea UHF system was installed, they did not have "direct" receive capacity at the console.
3) Where a department operates on more than one channel, under usual circumstances the dispatcher will "select" one channel and received audio on that channel comes over the left hand speaker, while the right hand speaker produces mixed audio on all the other ("unselected") channels. So it is not uncommon for a dispatcher to speak to a subscriber on one of the channels, have the subscriber respond on one of the other channels, and unless the dispatcher is watching the busy lights, he may not even be aware of this. Moreover, so long as the substance of the traffic is only between this subscriber and the dispatcher (such as a radio check), the fact that other subscribers hear only one side of the discourse is immaterial.
1) In the typical dispatch system (including Chelsea's) that uses a voted repeated system, the dispatch console listens to the input frequency of a repeated channel. Subscribers generally cannot communicate with dispatch on "direct" because a subscriber on "direct" is transmitting on the output frequency.
2) While it is possible to enable "direct" reception by a dispatcher, it is complicated. You need an additional receiver (programmed for the output frequency) and an additional channel card, and you also need a way of muting this receiver whenever the console transmits over the system (to avoid the "direct" receiver from hearing the console operator's transmission and generating a cascade noise). As of when the Chelsea UHF system was installed, they did not have "direct" receive capacity at the console.
3) Where a department operates on more than one channel, under usual circumstances the dispatcher will "select" one channel and received audio on that channel comes over the left hand speaker, while the right hand speaker produces mixed audio on all the other ("unselected") channels. So it is not uncommon for a dispatcher to speak to a subscriber on one of the channels, have the subscriber respond on one of the other channels, and unless the dispatcher is watching the busy lights, he may not even be aware of this. Moreover, so long as the substance of the traffic is only between this subscriber and the dispatcher (such as a radio check), the fact that other subscribers hear only one side of the discourse is immaterial.
I think if you listen closely you will hear -
Ch 1 - most ops - primary channel - dispatch, response, radio tests, etc
Tac 1 - fire alarm guys and fire prevention guys - plus radio tests with Command Car
Tac 2 - 24/7 simulcast of dispatcher from Ch 1, and radio tests with Command Car
I dont think that the Tac 2 radio test is also heard on Ch 1.
Ch 1 - most ops - primary channel - dispatch, response, radio tests, etc
Tac 1 - fire alarm guys and fire prevention guys - plus radio tests with Command Car
Tac 2 - 24/7 simulcast of dispatcher from Ch 1, and radio tests with Command Car
I dont think that the Tac 2 radio test is also heard on Ch 1.
Tac 2 was not used apparently at the recent major gas leak with evacuations. The dispatcher was simulcast from Channel 1, but no portables or mobiles were heard on Tac 2 at all; there was no mention of Tac 2 either. Maybe Tac 2 will only be used for the really really really big one.
jmorrissey23
Member
The MBHSR radios don't even have this channel programmed in, only channel 1 and tactical. My guess is the only use of this channel is it being a backup to channel 1.
ecps92
Member
jmorrissey23
Member
Oh...I didn't see that. I was looking at a Weston FD UHF radio which did not have a EMS zone.
ecps92
Member
Yup - the Command Car is transmitting on 470.0875 - I heard them today on the 9 AM radio test - so the channel is simplex
(Actually - there is the possibility that there is a MO3 in the Command Car that receives 473.0875, and repeats out on 470.0875).
Which leads to the next question. What is 473.0875 used for? if anything
(Actually - there is the possibility that there is a MO3 in the Command Car that receives 473.0875, and repeats out on 470.0875).
Which leads to the next question. What is 473.0875 used for? if anything
Last edited:
- Status
Similar threads
