There is a "Sierra Intercom"? That is something I was not aware of. So just to clarify that I have a solid understanding of your first post. The monitors pick up all traffic on the "simplex" direct frequency (output) that is not toned (as far as I understand, the Sierra does not have a "direct" tone like some of the other forests, but they do have the "unconventional" tones on most of the repeater outputs, which I find interesting. So then, talking about a remote base vs. a monitor, it sounds like a monitor is more limited in functionality vs a remote base and a remote base relays "direct" and repeater traffic. So on Forests where there is no tone required for "direct" access, "simplex" traffic on the "output" frequency of the net is passed along to dispatch, no tone necessary, forests that do require a tone for "direct", if the tone is not activated, then the traffic will not be passed along to dispatch? I'm just making sure that I have a correct understanding of what you are saying. I also find it interesting that almost every forest has a different configuration. Thanks,
Bill
Yes, the Sierra Intercom exists, it is a microwave network not sure the freq but you would have to have a microwave antenna and be in direct line of sight to a transmitter to pick it up. the intercom was established by CDF to replace their green phone network it is maintained by the California Department of General Services, it is a pain to deal with since only DGS Radio Techs may service it or its terminals. These was at one time and it is still functioning, but little used VHF radio network. When I started in 2007 these networks North OPS net and South OPS net were all but abandoned. It had been replaced by the CDF intercom. I was told to not use those channels and to ignore any traffic on them. If the CDF intercom failed, our fall back was these channels. however as time goes on I see less and less of these channels. when new or upgraded radio equipment is installed those channels are left out.
Sierra is not one of those forests where only certain tones reach dipsatch. if a field unit use any tone between 1-9, dispatch hears them. Heck we hear them even if they don't use a tone.
So as I understand it on the sierra we have repeaters, monitor/repeaters, repeater/remote bases, and Remote bases. Exsmokey might know of a better term for these.
For the sake of being on the same page;
Repeaters, are set to an input of 169.9250 for Emerg net and 169.8750 for Admin net, all of them only open when they decode the proper tone (1-9 are used). Sierra Repeaters output 172.2250 for emerg net and 171.4750 for admin net. These same repeaters use a CTCSS tones on their output, due to equipment limitation at the dispatch center only tones 1-8 are used. When signals are received by the transceiver at Dispatch they are feed to a tone decoder this decodes the CTCSS tones and triggers a relay that signals the ModUcom which tone is being received.
The Remote Bases. These sites do not repeat anything, but they do allow Dispatch to Transmit and receive transmissions on 172.2250 for emerg net and 171.4750 for admin net.
The remote base-repeater, these sites combine the functions of both sites into one.
The Monitor-repeater, of which Sierra has one, Patterson Tone 9. This is a repeater that also monitors 172.2250 and returns that audio to dispatch. Dispatch has no control over this site, they can only monitor the audio that comes down from it.
the monitor/repeater, remote base/repeater, and remote bases. these have little icons on the ModUcom screen that light up when their respective site is active. otherwise the ModUcom displays a number for for tha tone it is picking up. often the dispatcher sees both as the base transceiver at Fresno is picking up the traffic at the same time as one or more of the monitor/repeater, remote base/repeater, and remote bases out in the field.
I can't say why sierra has equipment that monitors the repeater output freqs, I can guess. maybe exsmokey knows. This does create the curious situation where many field units. presumably not knowing that the sierra radio net is configured this way. Will switch over to the simplex channels and transmit and receive on 172.2250 or 171.4750 no tones. Dispatch hears most of these transmissions and enjoys a few.
hopefully that was clear as mud?