Trunked Systems n' Repeater Input Freqs?

[Dave_D]

Hi all,

It's time for my newb question du jour:

I was reading this thread regarding the monitoring of repeater input frequencies for the purposes of isolating reception to local-only events. This sounds like something I'd like to do, but my state (Nevada) employs a trunked shared radio system. The RR DB indicates no repeater input frequencies for trunked systems. What does this mean? Do trunked systems not employ separate input frequencies? How might I isolate my scanner's reception to nearby transmissions?

Any advice fur da newb?

Thank you!

Dave

 

[Joseph11]

For 800 MHz, the input frequencies are 45 MHz down from the output.

 

[Dave_D]

Aha!

And, for example, a trunked system with five frequencies: would it also have five input frequencies? Or, is a single input frequency calculated from, say, the system's primary control channel?

Thank you very much for your help! I greatly appreciate it.

Dave

 

[KCChiefs9690]

Aha!

And, for example, a trunked system with five frequencies: would it also have five input frequencies? Or, is a single input frequency calculated from, say, the system's primary control channel?

Thank you very much for your help! I greatly appreciate it.

Dave

Each output frequency also has an input frequency. For example, a 20 frequency trunked system has 20 input frequencies as well, each 45 MHz below the output frequency.

Hope this helps,

 

[Dave_D]

Yes, this helps lots!!! I can't wait to try this out....

Thanks a million!

Dave

 

[Dave_D]

Woops. One other question:

Should I program the "-45 MHz" input frequencies into a conventional or a trunked system/bank? On the one hand, it seems illogical to create a trunked bank where there is no control channel. But then, a conventional bank is without SIDs, and I really need these to filter out the unwanted fleet traffic, like taxicabs, etc.

Dave

 

[KCChiefs9690]

You don't need to program the input frequencies. All you need to monitor a trunked system, are the control channels and the output frequencies.

 

[W4KRR]

Woops. One other question:

Should I program the "-45 MHz" input frequencies into a conventional or a trunked system/bank? On the one hand, it seems illogical to create a trunked bank where there is no control channel. But then, a conventional bank is without SIDs, and I really need these to filter out the unwanted fleet traffic, like taxicabs, etc.

Dave

If you really want to monitor trunked system input frequencies, program them as conventional, as a trunk tracking scanner won't make use of trunked input frequencies. You won't get talkgroups out of the input frequencies even if they were programmed as trunked.

 

[Dave_D]

Rats!

This is not good, given that our statewide radio system is shared by many, many organizations. Without talkgroup ID filtering, I'll receive all manner of government and taxicab chatter. I may try it anyways, though I'm sure the unwanted chatter will defeat the purpose of isolating reception to my neighborhood. We'll see....

Thank you for your help!

Dave

 

[KCChiefs9690]

Rats!

This is not good, given that our statewide radio system is shared by many, many organizations. Without talkgroup ID filtering, I'll receive all manner of government and taxicab chatter. I may try it anyways, though I'm sure the unwanted chatter will defeat the purpose of isolating reception to my neighborhood. We'll see....

Thank you for your help!

Dave

You can always lock out the users that you don't want to hear. What scanner do you have? Because most have a "closed mode", where you can program talkgroups that you want to hear, and not hear all the other crap.

 

[JohnnyGalaga]

Will your scanner allow you to program the control channel outputs and the voice channel inputs as a trunking system?

 

[car2back]

You can always lock out the users that you don't want to hear. What scanner do you have? Because most have a "closed mode", where you can program talkgroups that you want to hear, and not hear all the other crap.

how can he lock out unwanted TGs while monitoring the input freqs of the Trunked radio system in conventional mode?

 

[W4KRR]

Will your scanner allow you to program the control channel outputs and the voice channel inputs as a trunking system?

No, you cannot program trunked system repeater inputs as part of a trunking system. Only the output frequencies can be used for trunking. The inputs would have to be monitored as conventional channels only.

 

[Dave_D]

You can always lock out the users that you don't want to hear. What scanner do you have? Because most have a "closed mode", where you can program talkgroups that you want to hear, and not hear all the other crap.

FWIW, my scanner is a spiffy new Uniden BCT15.

I've gone ahead and programmed the input freqs into a conventional system and, no surprise, the volume of unwanted communications has dropped. Of the few signals received, it's kinda cool knowing that they're nearby (more or less as determined by signal strength & quality), but then there's no telling who's talking. By the sounds of things, it's almost exclusively police cruisers, but I really miss seeing "Police/Sheriff" in the display, along with all of the other scrolling goodies.

Perhaps I'll use this conventional system as a general proximity alarm and then enable/disable the trunked system manually when I want the IDs or both sides of the conversation.

BTW, would it be technically feasible for a scanner to grab the talkgroup information for a repeater input frequency from the respective trunked system's control channel?

Dave

 

[b52hbuff]

Perhaps I'll use this conventional system as a general proximity alarm and then enable/disable the trunked system manually when I want the IDs or both sides of the conversation.

BTW, would it be technically feasible for a scanner to grab the talkgroup information for a repeater input frequency from the respective trunked system's control channel?

Dave

It is a very poor proximity detector. In a conventional repeatered system with a single user per frequency, at least you know who is nearby when you receive a signal on the repeater input.

On a TRS with hundreds of users, do you really care that the dog catcher just keyed up next to you??