Limiting Trunking Chatter

[pro95new]

Question: Is there a way to limit irrelevant chatter on trunked frequencies?

Background: Trunking is big here, so not only do you get police and fire (great), but you get metro train and other irrelevant and, frankly, irritating chatter. Since they all use trunking, is there any way to limit what is received to only emergency (fire and police).

Using Win95 and an old Radio Shack Pro-95

Thanks.

[aharry]

Yes, don't search the trunked system, which stops on any talk group that isn't locked out. Scan the system after programming in the talkgroups you actually are interested in.

[W5JSS]

Originally Posted by pro95new

Question: Is there a way to limit irrelevant chatter on trunked frequencies?

Background: Trunking is big here, so not only do you get police and fire (great), but you get metro train and other irrelevant and, frankly, irritating chatter. Since they all use trunking, is there any way to limit what is received to only emergency (fire and police).

Using Win95 and an old Radio Shack Pro-95

Thanks.

Program in only the talkgroups you want to hear, and run that bank in "Closed" mode (a "-" will appear under the bank during scanning).

[n5ims]

Originally Posted by W5JSS

Program in only the talkgroups you want to hear, and run that bank in "Closed" mode (a "-" will appear under the bank during scanning).

Another option is to program in the talkgroups you DON'T want to hear and lock them out. That way you can still stay in "Open" mode to catch those talkgroups that may not have yet been identified. Depending on the system, locking out the undesired (to you anyway) talkgroups may be fewer entries than entering those you are interested in.

[DickH]

Originally Posted by aharry

Yes, don't search the trunked system, which stops on any talk group that isn't locked out. Scan the system after programming in the talkgroups you actually are interested in.

SCAN & SEARCH are Uniden functions. The PRO-95 is a GRE product.

[DickH]

Originally Posted by pro95new

Question: Is there a way to limit irrelevant chatter on trunked frequencies?

Background: Trunking is big here, so not only do you get police and fire (great), but you get metro train and other irrelevant and, frankly, irritating chatter. Since they all use trunking, is there any way to limit what is received to only emergency (fire and police).
Using Win95 and an old Radio Shack Pro-95 Thanks.

The PRO-95 has two trunking modes, OPEN and CLOSED.
In OPEN mode you will hear all active talk groups (your situation).
In CLOSED mode you will hear only the talk groups you have entered into the scan lists (lower right in WIN95).
To toggle between OPEN and CLOSED modes press FUNC then 5.

[JoeyC]

In order to do any of the above recommendations you must program the system AS A TRUNKED RADIO SYSTEM. It is not clear from the original post if he has even done that. If you don't, then open and closed mode won't mean a thing and scanning and searching aren't going to accomplish anything either.

[gmclam]

Originally Posted by pro95new

Question: Is there a way to limit irrelevant chatter on trunked frequencies?

Using Win95 and an old Radio Shack Pro-95

Welcome to RadioReference.com!!! I love my PRO-95s for 800 MHz trunking. Also, WIN95 is the total way to go to program them (the price can't be beat either).

1. I assume you are dedicating a bank to a trunked system. You will see a "pulldown" selection menu in WIN95 that let's you select "conventional" or one of several different types of trunked systems. Set this to the type of system you are monitoring.

2. When you program in the control channel frequencies, make sure each is set to the correct mode - not FM! So if the system you are monitoring is Motorola, set EACH frequency to MO.

3. Program in the talkgroups you want. This is the best way so that you can also take advantage of the "alpha tag" capability of the scanner. Alpha tagging is when you can label each channel (conventional frequency or talkgroup) with PLAIN TEXT to ID it.

4. Up near the top of each bank in WIN95 there is a check box for "closed". CHECK IT.

5. Make sure the sub groups next to the talkgroups you have programmed are ON. There are 5 checkboxes next to them; one for each sub group of 20 talkgroups.

6. Download to the scanner and you should be good to go.

[pro95new]

gmclam - thanks for writing. Okay, we're in the same area (Fair Oaks) and me - Folsom. Some follow-up questions using your sequence:

1. As you know, there's Sac (trunk 3 apparently) and Sac Co (trunk 4). Don't know if they are conventional, MOT or EDACS. Presumably, they're Sac (PD) and Sac (SO), but beyond that, I have no clue.

2. Win95 is preset to FM, but can change of course, but I have no idea to which/what.

3. Okay, but how do I change to Alpha if the people are using trunked traffic? For example, my understanding is that in the old days when a mic was keyed, it would open a specific frequence (e.g., 42.5200), but with a trunked system, when the key is pressed, the message/voice goes through a computer system and is assigned a particular and changing frequency. Thus, how does one know which is which? If I use the L/Out element of the Pro95 to lock out a particular caller - assuming I'm quick enough to get to the button on the Pro-95, won't I be locking out anyone else who might be assigned that same frequency at any particular time? (Sorry, trunked traffic makes little sense to me other than this feeble grasp just articulated).

4. I can easily do what you say and click the box to "closed" but shouldn't I do it AFTER I do 1 through 3 (above)? Also, what does it do?

5. You mention talk groups. What are they? Are they Police, fire, Sheriff's Department, CHP, or what? And, if I'm correct, how do I identify "talkgroups" if random frequencies are being assigned via a trunked system?

Finally, again, all I realistically want to do is listen to police, Sheriff and CHP, but can accept listening to fire/ambulance, but would just as soon not. What I reaaaaaaaly don't want to list to are the public works, corrections and the damned light rail people blithering on.

And, now that I have blithered on too much, I'll stop and sit here confused by all this.

Thank you for being willing to guide.

[DickH]

This may help you to understand trunking.

Motorola Trunking:
The object of trunking is to allow many users to share a relatively few frequencies.
A trunking system is controlled by a computer. Information (data) is exchanged between the system radios and the computer on a control channel, sometimes called a data channel. It sounds like a strong buzz.
A large system can have up to 28 freqs., 4 of which may be used as control channels. The control channel may be changed once a day or as often as the programmer decides. Some scanners need only the control channels to track an entire system. Just put in the 4 Control Channels.

Each group of users (Fire, Police, etc.) is assigned TALK GROUPS. In a Motorola Type II system, the most common type, TGs are usually in 32 number steps starting with 16 and going up to 65536; 16, 48, 80 --- 4656, 4688, 4720 --- 28944, 28976, etc. System radios can have more than 100 TGs programmed into them.

After all the freqs. have been entered and it is "trunking", the Banks become SCAN LISTS where you enter the Talk Groups you want to hear.
Use the Talk Group numbers in the DEC column, not in the HEX column.

When a user pushes the talk button on his radio, data is sent to the computer. The computer chooses an unused freq. and sends that data to all the radios using the TG of the originating unit. This all happens in a fraction of a second and it happens EVERY TIME a radio is used.

EXAMPLE:
Fire Dispatch calling Engine 4 (TG 4528 on 856.7125)
Engine 4 answering Dispatch (TG 4528 on 852.2625)
Respond to 73 Elm Street (TG 4528 on 855.9625)
Engine 4 responding (TG 4528 on 851.6375)

If you have entered TG 4528 into your scanner, it will decode the control channel data and change your scanner freqs. to follow the conversation on TG 4528.

[gmclam]

Originally Posted by pro95new

gmclam - thanks for writing. Okay, we're in the same area (Fair Oaks) and me - Folsom. Some follow-up questions using your sequence:

1. As you know, there's Sac (trunk 3 apparently) and Sac Co (trunk 4). Don't know if they are conventional, MOT or EDACS. Presumably, they're Sac (PD) and Sac (SO), but beyond that, I have no clue.

There are two SITES, one considered to be the "city site" and one considered to be the "county site". But most of the radio traffic is on both sites. An exception (EXAMPLE) would be something like a fire totally inside the city on let's say Fire Tac B7, it might only appear on the city site.

What you need to program is the 4 control frequencies for each site. I've found I have better control over them by putting them into separate banks. I may turn one bank or the other off depending on where I am. Each of these frequencies is set to MO. And the bank must be set to "Motorola". And if you want to control/limit what you hear, you should close the bank.

Data for the system can be found here and you only need the frequencies shown in red or blue.

2. Win95 is preset to FM, but can change of course, but I have no idea to which/what.

The TRS control channel frequencies in Sacramento would be set to MO. Most other frequencies are set to FM. If you listen to aviation stuff, that would usually be AM.

3. Okay, but how do I change to Alpha if the people are using trunked traffic?

Program in the TALKGROUPS (TGs) you want to hear. The PRO-95 can hold 100 per bank (Mine are the same in both banks). That is where you put the text tag for trunked stuff.

For example, my understanding is that in the old days when a mic was keyed, it would open a specific frequence (e.g., 42.5200), but with a trunked system, when the key is pressed, the message/voice goes through a computer system and is assigned a particular and changing frequency. Thus, how does one know which is which?

The scanner learns which frequency is assigned from the control channel. That's why they call them "trunk tracking" scanners.

If I use the L/Out element of the Pro95 to lock out a particular caller - assuming I'm quick enough to get to the button on the Pro-95, won't I be locking out anyone else who might be assigned that same frequency at any particular time? (Sorry, trunked traffic makes little sense to me other than this feeble grasp just articulated).

If you press L_OUT while the TG is active, it will lock out the TG (not the frequency). If you happen to press MAN then press L_OUT you'll lock out the control channel frequency - that's not what you'd usually want to do. To unlock talkgroups it is not too user friendly on the PRO-95/etc.

4. I can easily do what you say and click the box to "closed" but shouldn't I do it AFTER I do 1 through 3 (above)? Also, what does it do?

The order of when & what you type into WIN95 does not matter. None of it gets into the scanner until you "upload to scanner". Then the whole works is uploaded (that is you can not just upload a portion of data).

5. You mention talk groups. What are they? Are they Police, fire, Sheriff's Department, CHP, or what? And, if I'm correct, how do I identify "talkgroups" if random frequencies are being assigned via a trunked system?

Go to the link I provided above. That is the Sacramento Regional Radio System. It first lists the frequencies used for each site, then it lists all the talkgroups. Fortunately, the TGs are the same between the sites.

Finally, again, all I realistically want to do is listen to police, Sheriff and CHP, but can accept listening to fire/ambulance, but would just as soon not. What I reaaaaaaaly don't want to list to are the public works, corrections and the damned light rail people blithering on.

CHP is in it's own world. There are a long list of issues for listening to them. When it comes to Police (Sacramento, Folsom, etc), Sacramento Sheriff, Sacramento Fire or Sac Metro Fire; they are all on the Sacramento TRS. Each just uses a different set of TGs. The key is to program what you want, and make sure the bank used for the system is closed (an open bank will let you hear ALL TGs).

[pro95new]

1. For Sacramento PD, SO, Folsom PD, etc. do you have a couple of screenshots so I understand where the frequencies go (e.g., those that are red and blue from the list you directed me to) (868.63750c, etc.)

2. Is there a service I can pay for and use that simply downloads all that I need into the Win95 or other software and them upload it into the Pro-95?

3. I looking at the trunked stuff you directed me to, I see DEC, HEX, MODE, ALPHA TAG, DESCRIPTION and TAG, but have no clue where to put that information into the Win95 program. What is what? Again, a screenshot would be very helpful.

As always, thank you for your help, patience and expertise.

[gmclam]

Originally Posted by pro95new

1. For Sacramento PD, SO, Folsom PD, etc. do you have a couple of screenshots so I understand where the frequencies go (e.g., those that are red and blue from the list you directed me to) (868.63750c, etc.)

I have sent you a PM. I am not able to post certain files here (I am near my limit too).

2. Is there a service I can pay for and use that simply downloads all that I need into the Win95 or other software and them upload it into the Pro-95?

There are services for the newer scanners, scuh as PSR-300 (which uses WIN97); but not that I know of for the PRO-95. I can do this for you since you are close; but since you already have the software and cable it will be fairly easy for me to send you a file that you can put into the scanner yourself.

3. I looking at the trunked stuff you directed me to, I see DEC, HEX, MODE, ALPHA TAG, DESCRIPTION and TAG, but have no clue where to put that information into the Win95 program. What is what? Again, a screenshot would be very helpful.

Talkgroups (TGs) are identified by a number that can be in DEC (decimal) or HEX (hexadecimal). The software will accept either radix.

Mode for conventional channels would be AM, FM or perhaps P25 (which is digital). The actual mode of the frequency in the scanner for the Sacramento trunked frequencies is MO (Motorola). However TGs can be analog or digital. But the PRO-95 can only let you hear analog. The Los Rios college TGs are digital and if you want to hear them you'll need a digital scanner (such as the PSR-500).

Description tells you in English what the TG is used for. TAG puts TGs into a category as to how the TG is used (dispatch, tactical, etc). Alpha Tag is what is programmed into some radios that describe the TG in a few characters. These names are often cryptic and I rarely use them.

One great thing about the PRO-95 is that it will display the "bank text" alpha tag on line 4 for a conventional channel. Then it displays the alpha tag for the frequency on line 3. If done correctly, you can get up to 24 characters to describe a channel.

For trunked channels (TGs) the alpha tag of the control channel frequency is on line 3 and the alpha tag of the TG is on line 4, so again you can get up to 24 characters to describe a channel.