Tower Question

kipper8588 · #1 (**permalink**) 10-09-2009, 08:04 PM

I live in Roscommon County, Michigan. The primary fire/ems dispatch frequency is 155.025. Dispatch does not receive radio traffic from the main tower located at the 911 center itself. Instead, there is a tower in the middle of the county that receives all of the radio traffic on this channel and then dispatch picks up the radio traffic from that tower. This channel however is "not" a repeated station. Tx and Rx are both 155.025 for radios. My question is, how does dispatch hear all of the radio traffic when I hear most of it due to lack of reception. Even though the channel is not repeated, does the tower receive on 155.025 and dispatch picks it up on a slightly different frequency? Hopefully that made sense. Does anyone have any ideas on how this works???

MPSCS · #2 (**permalink**) 10-09-2009, 08:14 PM

The database shows two frequencies:

154.9800, and 155.0250

Are you monitoring both of those? Also, they may have a better antenna, at a higher altitude.

kipper8588 · #3 (**permalink**) 10-09-2009, 08:20 PM

I monitor both of those. Those are 2 separate dispatch channels for different parts of the county. My question was with that main channel 155.025, I was wondering if there is a different frequency that dispatch picks that up on. I know all of the radio traffic goes through that one tower and then dispatch gets it from the tower. Problem is I dont know what frequency that is. It almost has to be another frequency

MPSCS · #4 (**permalink**) 10-09-2009, 08:22 PM

How far are you from that tower, and how far are they from the tower?

rfradioconsult · #5 (**permalink**) 10-09-2009, 09:56 PM

Remote base stations are normally connected to the dispatch center by a leased wirline circuit; could be a separate UHF radio link or perhaps by a point to point microwave shot.

dwh367 · #6 (**permalink**) 10-09-2009, 10:43 PM

Quote:

Originally Posted by rfradioconsult

Remote base stations are normally connected to the dispatch center by a leased wirline circuit; could be a separate UHF radio link or perhaps by a point to point microwave shot.

Depends on how old the system is. Before we installed repeaters at work, we used to link to the towers on 72 MHz.

FLRAILMAN · #7 (**permalink**) 10-09-2009, 11:41 PM

I found quite a few FD/EMS frequencies for your area along with the two frequencies that MCSPS submitted to you, I didn't post them as you are probably already familiar with them however this may be of particular interest to you for the relay frequency.

154.205 MHz KZK224 (FCC Fire Service Frequency Allocation) Houghton Lake, Roscommon County

Hope this helps.

Federal Communications Commission (FCC) Home Page

Kipper8588 I apologize for that error.

FLRAILMAN

kipper8588 · #8 (**permalink**) 10-10-2009, 12:02 AM

I think you have the cities confused. I live in Houghton Lake, Mi. Thats in Roscommon County. Not in Houghton County. But I think you may be on to something here. Are you telling me that dispatch could possibly be connected to the tower by using an actual cable or by a different "relay" frequency. If thats the case, could you possibly look up the relay frequency that links that tower with dispatch?? I would really appreciate it. Like I said, the channel is not repeated. I hear most of the traffic because I have an antenna on my house, but I can not hear all of the traffic because obviously the tower for the county is bigger than my tower. There has to be a link to dispatch somehow im just not quite sure how....I really appreciate the information. Keep it coming, maybe I will get this figured out yet

kipper8588 · #9 (**permalink**) 10-10-2009, 12:05 AM

Quote:

Originally Posted by rfradioconsult

Remote base stations are normally connected to the dispatch center by a leased wirline circuit; could be a separate UHF radio link or perhaps by a point to point microwave shot.

What is a wirline circuit? Is that an actual cable that connect the tower in the middle of the county to dispatch??

kipper8588 · #10 (**permalink**) 10-10-2009, 12:06 AM

Quote:

Originally Posted by FLRAILMAN

I found quite a few FD/EMS frequencies for your area along with the two frequencies that MCSPS submitted to you, These may be of particular interest to you for the relay frequency.

154.205 MHz KZK224 (FCC Fire Service Allocation Frequency)

155.76 MHz KWT818 (FCC list it as a mobile relay interconnect frequency)

4.94 GHz WQHT592 (Possible microwave relay frequency)

Hope this helps.

Federal Communications Commission (FCC) Home Page

FLRAILMAN

I should have replied back to you this way instead of the entire thread. Sorry, just wanted to make sure that you knew I replied back to you

rvictor · #11 (**permalink**) 10-10-2009, 12:31 AM

Quote:

Originally Posted by kipper8588

What is a wirline circuit? Is that an actual cable that connect the tower in the middle of the county to dispatch??

Often it's a leased telephone line. Sometimes communities have their own wired networks that support, for example, fire alarm boxes, police call boxes, or traffic control signals.

Dick

Big_Ears · #12 (**permalink**) 10-13-2009, 02:34 PM

Please keep in mind that the PD/County radio systems contain additional front end & IF circuitry (for adjacent frequency & band rejection) and are narrow-banded and fine-tuned for specific frequencies within a band. The receiving sensitivity is alot better than our scanners, which are designed to cover many frequency bands (30-960 mHz) and inherently have less overall sensitivity. Also, an antenna up on a tower may give their system the "line-of-sight" advantage that you and your scanner don't have, unless your scanner antenna is up at the same elevation.