P25 800 MHz simulcast system

[jbspeed79]

Been reading many posts on p25 simulcast. Our county radio system has about 5 towers placed all over the county. I’m assuming for different coverage areas and tac depts. Please explain how the radio system works and if I need to be able to pick up all the towers to hear the different tac departments. Right now I have one local tower newr my
Home that comes In great one min and then the bars drop next min. I’m guessing the control channel. Not sure what antenna I should be buying either a discone for multiple directions or one pointing in the towers direction. I use a bcd996p2Thanks

 

[hiegtx]

Been reading many posts on p25 simulcast. Our county radio system has about 5 towers placed all over the county. I’m assuming for different coverage areas and tac depts. Please explain how the radio system works and if I need to be able to pick up all the towers to hear the different tac departments. Right now I have one local tower newr my
Home that comes In great one min and then the bars drop next min. I’m guessing the control channel. Not sure what antenna I should be buying either a discone for multiple directions or one pointing in the towers direction. I use a bcd996p2Thanks

Simulcast distortion issues are extremely location specific. All of the transmit towers transmit the same radio traffic, on each of the sub-sites (transmit sites). You can't simply 'program a single tower' to get a specific talkgroup. If that TGID is active, the exact same thing is transmitted from each of sub-sites, at the exact same time. Since those towers are at varying distances from your location, the signals arrive at your location at slightly different times, not in sync with each other. It's enough of a distraction for the scanner that it might not hear anything at all, or what you do hear is distorted, If you are in the exact right place, such as within a quarter mike of one of the sites, that very strong signal might wash out the out of sync transmissions from the other sites. If you are using the antenna that came with your 996P2, try moving the scanner around in your house. At times, a move of a foot or so makes all the difference in the work between hearing the system, or not getting it. There are several things you can try, such as aiming a directional antenna at one specific sub-site, or using "less" antenna, even down to just using a paper clip. Several suggestions are in the Wiki article on Simulcast. One might work, or may not.
Simulcast digital distortion - The RadioReference Wiki

While the 996P2 is a good scanner, it is not a good choice for serious simulcast difficulties. The only true scanners set up to handle simulcast problems are the Uniden SDS100 & SDS200. I would try the suggestions on the Wiki page, as well as moving the scanner around. At times, if your house has metal siding, or foil backed insulation in the walls, you might find that one sweet spot where it works out. Here's a map of the site's towers for your county's system:

 

[jbspeed79]

Thanks

 

[jbspeed79]

Thanks

So I live near the northern border. For example If the southern tac 3 departments transmit down there closest to their tower, the northern tower will transmit the same transmission? Gotcha just reread that better

 

[hiegtx]

So I live near the northern border. For example If the southern tac 3 departments transmit down there closest to their tower, the northern tower will transmit the same transmission? Gotcha just reread that better

Right. All the transmit sites broadcast the exact same radio traffic, such as a specified talkgroup ID, at the same time. Those arrive at your scanner enough out of sync to confuse the scanner.

 

[tvengr]

Are you able to receive the trunked system clearly with the back of scanner antenna? If so, a better antenna may increase reception problems when dealing with simulcast sites. What is your city? If you are very close to one of the towers, it can override the out of phase interference from the other towers. Using software to program your scanner is far faster and easier than programming the scanner manually using the menus. I use Butel ARC-XT Basic for programming my BCD325P2 and BCD996P2. ProScan is also excellent. Both have a free trial period to determine which one you like better. If you don't plan on using DMR or NXDN, you can use FreeSCAN which is free but is no longer supported. All public safety n Clinton County is on the P25 trunked system and analog conventional frequencies. Be aware that the county sheriff dispatch is fully encrypted on the trunked system and cannot be received by any scanner. Other law dispatch is encrypted part of the time. The only DMR conventional frequency is the Plattsburgh City School District:

Frequency	License	Type	Tone	Alpha Tag	Description	Mode	Tag
453.950	WQJG942	RM		PCSD Ops	School District Operations	DMR	Schools

There is also a DMR amateur radio trunked system: BrandMeister NY Linked Amateur Radio Network Trunking System, Regional, New York
Receiving either one would require the DMR paid upgrade for your scanner. I will be very happy to help with your programming. Please let me know if you have any other questions.

 

[jbspeed79]

I do use free scan to upload my scanner. It does seem to work good for me I can pick up the control channel from the back of my scanner but sometimes I get five bars sometimes I get two or none I do try to change the squelch from time to time but usually I leave it at one. Right now I am using a general base antenna on the peak of my roof it Hass to be in a general specific spot or I lose signal. I only live probably 5 miles from the nearest tower but I think I have reception issues where my house is located. It’s that picky so I am trying to pick up that signal from that tower better like five bars are usually here the northern departments really good it’s when it comes down to the southern portion of the county that’s where the signal drops off when they start talking and it’s either jumbled or I don’t get a signal.
I have messed around with antennas in the house outside the house all over the place and it seems that I need a rooftop antenna or I cannot pick up the control channel

 

[jbspeed79]

I do use free scan to upload my scanner. It does seem to work good for me I can pick up the control channel from the back of my scanner but sometimes I get five bars sometimes I get two or none I do try to change the squelch from time to time but usually I leave it at one. Right now I am using a general base antenna on the peak of my roof it Hass to be in a general specific spot or I lose signal. I only live probably 5 miles from the nearest tower but I think I have reception issues where my house is located. It’s that picky so I am trying to pick up that signal from that tower better like five bars are usually here the northern departments really good it’s when it comes down to the southern portion of the county that’s where the signal drops off when they start talking and it’s either jumbled or I don’t get a signal.
I have messed around with antennas in the house outside the house all over the place and it seems that I need a rooftop antenna or I cannot pick up the control channel

Unfortunately, someday I’ll be able to purchase the SDS 200 but I cannot at this moment

 

[jbspeed79]

Unfortunately, someday I’ll be able to purchase the SDS 200 but I cannot at this moment

One of my buddies does the broadcast for scanner world. It’s just not the same as having your own scanner to make things easier. I only use it for one system the 800 MHz digital system. I have an old scanner that’ll pick up the analog frequencies that I use.

 

[tvengr]

On the simulcast system, you should receive all of the talkgroups equally well for the entire county. The fact that the signal is so tricky to receive leads me to believe that you are suffering from the effects of simulcast distortion. That is typical behavior. While using the back of scanner antenna, turn on the attenuator to see if reception improves. With simulcast, less signal is more. Also, try moving the scanner around the room, you may find a sweet spot where it works OK. Paul, the former Uniden rep, suggested setting the squelch to 0 when receiving a simulcast trunked system. Also, turn off digital audio AGC. The AGC action can increase garbled audio problems.

 

[jbspeed79]

Thanks for the input. I’ll give her a shot

 

[tvengr]

You can also try changing the length and orientation of the back of scanner antenna. You may be able to obtain more signal from your closest tower and decrease the interference from the other towers. A directional antenna often helps. What is your city so that I can take a look at the tower locations in relation to your location? Which agencies do you monitor?

 

[jbspeed79]

For this scanner I just scan one system digital p25. My location is the red dot with the nearest tower at 1pm. It’s mountainous here in 12992 Clinton county NY so not all flat terrain. Thanks

 

[tvengr]

The red dot appears to be about equidistant between towers 3 & 1. If you use the cigarette lighter cable which comes with the scanner and drive toward one of the towers, the signal will probably go in and out and you will have good reception when you get close to the tower. If you see NFM on the scanner display, it is unable to properly decode the control channel.

 

[jbspeed79]

Right now the signal is good. But it’s not alwasy like that. I tried the attenuator but lost the signal completely so had to turn it off. I’ll wait till the other agencies start using it especially southern departments and than check signal strength. Just throwing this info out there. We have determined the scanner is not appropriate for my needs. Thanks

 

[jbspeed79]

Southern department transmission. Got a little garbled there because the signal not the greatest.

 

[werinshades]

Unfortunately, someday I’ll be able to purchase the SDS 200 but I cannot at this moment

As you've figured out, you're experiencing simulcast distortion. Until you can get the SDS200, don't beat your head against the wall trying to figure it out, it's just not going to get much better.

 

[tvengr]

Southern department transmission. Got a little garbled there because the signal not the greatest.

With the trunked system, it doesn't make a difference if the talkgroup is in the north or south. Signal strength has nothing to do with it. The entire county is carried on every subsite in the system. If only the south is distorted, they must still be using conventional frequencies which are patched to the trunked system until they move. Here is a FreeSCAN file for you to try. It has only county Fire and EMS. Pressing 1 on the scanner keypad will toggle the system on and off. The PDF file will answer all of your questions about using quick keys. Save the attached zipped file to your computer and extract. Open the extracted file with FreeSCAN and Upload Programming.

 

[tvengr]

Please attach your FreeSCAN programming file so that I can take a look at it and check for problems. You will need to zip the file to be able to attach it. Click on Attach files and open the zipped file. Give my file a try in the previous post and see how it works.

 

[jbspeed79]

With the trunked system, it doesn't make a difference if the talkgroup is in the north or south. Signal strength has nothing to do with it. The entire county is carried on every subsite in the system. If only the south is distorted, they must still be using conventional frequencies which are patched to the trunked system until they move. Here is a FreeSCAN file for you to try. It has only county Fire and EMS. Pressing 1 on the scanner keypad will toggle the system on and off. The PDF file will answer all of your questions about using quick keys. Save the attached zipped file to your computer and extract. Open the extracted file with FreeSCAN and Upload Programming.

I have uploaded the file to the scanner. I will monitor both systems and see what I find out.