GPS database modification for mobile scanning

[claubinger]

My question is based on the concept of being mobile in a vehicle. I understand that database coverage for cities/ counties are geographically centered. I wanted to see if it would be better to modify my favorites list data to the actual dispatch center locations? If not able to be gathered then. What to do when I click on a license callsign and list of towers appear ranging from single to multiple sites (example San Joaquin County, Ca under "JRUG" dispatch frequency 159.48 tone 110.9 callsign WRUL810 only has 1 tower shown in a different county, and I'm sure there is not a dispatch center on top of that hill), or when a license has multiple towers under a callsign does that mean that those towers are broadcasting at the same time (Example- Mono County, Ca Sheriff 154.8 no PL tones callsign WNKU887 with 6 towers listed)?
My thought process behind this is that driving around activating geographic centers of towns and counties won't actually produce decent audio if the dispatch or towers are in different locations than the center. Or maybe I leave it alone.

 

[donc13]

Where the "people sit" (dispatch center) makes zero difference, it's where the output frequency transmit tower is that matters.

 

[nd5y]

when a license has multiple towers under a callsign does that mean that those towers are broadcasting at the same time

It depends on the type of system and how it is set up. Often you can't tell by what is listed on the license.

 

[claubinger]

Where the "people sit" (dispatch center) makes zero difference, it's where the output frequency transmit tower is that matters.

How does the communication make it to the output tower from say 20 miles away in the case of San Joaquin county example

It depends on the type of system and how it is set up. Often you can't tell by what is listed on the license.

Are you able to give an example of how to conclude if a system is set up to do this or what type of system leaving out trunked.

I ask this because most dispatch centers have towers

 

[dave3825]

If your radio is Uniden and one that's supported, @ProScan software not only lets you see all the gps data in your favorites list, it also lets you edit it to your liking..

SDS100: - SDS-100 Travelling w/ GPS. Lightest, most compact option?

I have to fly down to Florida in a few weeks and am driving back. I am not going to check a bag but am taking a carryon. I have either the SDS-100 or the SDS-200 to take with me. I want to travel light so this brings me to the SDS-100. (I wish Jon W was still doing the GPS MOD!) What is the most...

forums.radioreference.com

 

[nessnet]

How does the communication make it to the output tower from say 20 miles away in the case of San Joaquin county example

Data circuits.....

 

[nd5y]

Are you able to give an example of how to conclude if a system is set up to do this or what type of system leaving out trunked.

If all the sites have the exact same set of freqencies then it's probably simulcast but there is no way to tell without direct observation.
They could have it set up so only certain sites are used at certain times.
There could be one or more sites that are only for backup use.
The data on the FCC licenses and RRDB might not be the same as real life.

 

[nd5y]

Data circuits.....

Those can be over copper wire, fiber or microwave radio.

 

[Randyk4661]

As I see it, you don't necessarily need to listen to Mount Pilot and Hooterville when you are in Mayberry.
I have narrowed down the CHP offices to only the area they actually cover with the GPS in place of the entire county set in the database.
If you can set the GPS for the local area you want to receive then I recommend it. Sites for trunking really don't matter unless you travel though multiple sites. Talkgroups can be set to just hear the area you are in as you drive.

Set the GPS for how you want to listen, there is right way or wrong way only your way.

 

[donc13]

How does the communication make it to the output tower from say 20 miles away in the case of San Joaquin county example


Are you able to give an example of how to conclude if a system is set up to do this or what type of system leaving out trunked.

I ask this because most dispatch centers have towers

In the older communication systems, the towers at dispatch centers transmitted on the input frequency just like the portable or in car radios did. The actual transmitter site could have been miles away on a hill or foothill site. That actual transmitter site received the input frequency and transmitted on the output frequency. That's why they were called "repeaters"

Modern trunked systems do the same thing but use multiple sites and multiple frequencies to "share the load" and get better usage out of a limited number of frequencies.

 

[ofd8001]

Just because there is a tower at the dispatch center, it doesn't mean that's transmitting directly to units in the field. It could be a microwave tower pushing out signal to a transmitter site some distance away. That transmitter site is the one sending out the "signals" to the field units.

For example, the Minnesota State Patrol has a dispatch center in the Minneapolis-St. Paul area. That dispatch center handles radio traffic for the Thief River Falls area some 350 miles away. There are microwave links from the dispatch center to towers in the district area. Those towers have the transmitters to reach the units in the district. I imagine the CHP may work similarly.

So the "dispatch center" location really doesn't enter in the equation for listening purposes. You do want to know the transmitter tower locations and program those.

 

[GROL]

How does the communication make it to the output tower from say 20 miles away in the case of San Joaquin county example


Are you able to give an example of how to conclude if a system is set up to do this or what type of system leaving out trunked.

I ask this because most dispatch centers have towers

These days, internet or microwave. Old days microwave, dedicated phone lines or repeater input from the remote dispatch.

 

[GROL]

These days, internet or microwave. Old days microwave, dedicated phone lines or repeater input from the remote dispatch.

Forgot about radio relay on other VHF frequencies. I used to receive NC Highway Patrol cars on 42 MHz from a remote receiver site 45 miles away, that relayed the receiver site audio back to dispatch near where I live. There was also a transmitter there, but I could receive the transmitter just fine on 42 MHz. I think the relay was a channel on 72 MHz. Don't remember the exact frequency. Direct reception of the cars on 42 MHz in the area of that receiver site was not possible where I live. Specifically it was me near Salisbury NC, hearing cars in the Wilkes County area.