I have a few questions concerning MARCS 800Mhz activity here in Stark County. First off, my equipment consists of a Radio Shack Pro96 and a Larsen 800Mhz mobile antenna mounted outside. I have been scanning OSP’s new system for the last few weeks and have some technical questions on how the system works. I hope some people on the BBS will be able to answer my questions on the system.
When I first purchased my scanner in May I filled the entire first bank (50 channels) with 800Mhz MARCS frequencies for Stark and surrounding counties. This way I figured if I was to take the scanner outside the county I would still be able to hear Post 76 units through the other counties towers. I have not had the scanner outside the county for long, so I am not sure if my theory is correct on this. Anyway, I programmed my scanner to trunk with all those frequencies and data channels. It seems to work really nicely. On my RS pro 96 display it will display on the upper left corner the data channel which is being heard and on the second line it will display a "VC" and the frequency where the APCO-25 audio is transmitted. If the scanner is trunking the "VC" will be displayed with the APCO-25 audio frequency as well as the talk group. For Post 76 (Stark county) it is usually 17216. I like these features on this Radio Shack because I can monitor which data channel I am hearing the traffic on as well as the APCO-25 frequency and talk group. Under closer observation I have noticed that I am hearing Post 76 cars coming off of the Massillon, Canton, Wooster, Portage and New Phili data towers. The APCO-25 audio frequencies are the same 866.6125, 867.075, 867.275 and 867.475Mhz, but the units are going through different data towers. I am guessing this is based on where the unit is in the county as to which data tower it uses. I am guessing the system has a voting system based which tower receives the best signal. A few days ago, I was noticing I was missing some of the traffic. I would hear the unit calling base and would not hear the rest of the traffic. I then tried to figure out what was happening. I first checked signals of all the local data sites. I was able to hear the two data sites here in Stark and several in other counties. I then took the Radio shack radio off of trunking so I would hear all the traffic on the four Stark frequencies even if they were not trunking. This seems to solve the problem. I am hearing some units off of the Canton and Massillon tower sites and then some that are not trunking at all. These are Post 76 units that are talking back to Post76. Why would some units be trunking and others not? I then monitored where the units were in the county. Most of the time the unit was relayed through the closed tower. If a unit was in Canton, it showed up going through the Canton data frequency. Most of the units in the North Canton area and close to the Post were going though the repeater, but were not trunked. The post seems to have no problem hearing any of the units no matter if they are trunked or not. If this same unit which is not trunked goes into canton they seem to automaticly be trunking with the canton site. I am wondering if this is automatic or if the officer has to switch between the trunking and no trunking settings. Now this makes me wonder even more. If a unit is in North Canton talkin g to Post 76 through the 800Mhz repeater but not trunked, then can a Post 76 unit in Massillon here the North Canton unit even if the conversation is not being relayed through the Canton or Massillon sites? Also, I have noticed that 76 dispatch seems to be able to have several conversations simultaneously. I have heard a unit talking to Post 76 in the North Canton area Non trunked and another Post 76 unit talking to a unit in Massillon using the Massillon site. The Massillon conversations comes up as talk group 17216, but the non trunked conversation does not come up with any talk group. Since I only have one APCO-25 scanner I can only follow one conversation at a time and can not totally prove that there can be several conversations going on simultaneously. This is not using different talk groups, but different towers.
Could it be that these non trunked units I am hearing are using a data channel that I do not have in my scanner or am not hearing? I have all the ones listed with radioreference.com for my Stark and surrounding area.
Also what happens if a Post 76 unit goes into Columbus? Will the Columbus frequencies then carry the Stark county traffic using the 17216 talk group? What if this unit goes to Columbus, but never keys his radio? Will the system still know he is in Columbus? Do the MARCS radios periodically keyup to tell the system they are there? Another thought is that the MARCS radios have all the data channels and APCO voice frequencies programmed in and when they go out of the local area they will scan to find what ever data channel is active in that area. They when they key up, in lets say Columbus, the unit will be on the correct APCO voice frequencies and the local tower will hear the unit. The talk group 17216 will register with the system as being with Stark Post 76. Then the conversation will be automatically sent through the fiber backbone up to Post 76 and these towers up here. Any of this sound possible?
Another question. Lets say I have only the Stark county frequencies (data and audio) programmed into my scanner. If a Post 76 unit goes into lets say Tusc county, would I still here them. I just heard a Post 76 unit near Tusc county. He was, my guess, automatically voted through the New Phili system. I heard him going though their data site and using the local Canton APCO voice frequency. What would have happed if I would have not had the New Phili data frequency in the scanner? My scanner would have heard the local Canton APCO voice frequency, but the scanner would not have stopped because it would not have seen the data channel telling it to stop, because the only data channel displaying that unit was the New Phili one. The local data channels did not simulcast this. This tells me that the local Post 76 cars must have all the local data frequency for not only Stark, but other counties programmed in and will scan for the strongest one. Also, if he was closer to the Tusc t ower, he would have had to go through it using the APCO-25 voice frequencies as well. He was heard by my scanner on 867.075 (Canton site). If that unit does not hear the Canton data site, then how can the Canton site hear his APCO voice? Is the local Tusc tower hearing the unit on their input frequency and being relayed through to the output of the local Canton tower?
Any comments on how the system works would be appreciated. Thanks and sorry for the long post.
JS
Ohio MARCs Question Post 76 (Stark County)
Linear Mode
