P25 antenna... waste of money?

[ryradio]

I am using a Uniden 996P2 with the stock antenna. I am 6 miles from 1 of 3 towers for a 700mhz P25 simulcast. Im probably within range of the other towers as well but I cannot tell for sure if that has been an issue with distortion. I would guess 10-15 miles to the other two locations.

Do you think I would see an improvement using an antenna specifically for a 800mhz or am I wasting money?

 

[jim202]

I am using a Uniden 996P2 with the stock antenna. I am 6 miles from 1 of 3 towers for a 700mhz P25 simulcast. Im probably within range of the other towers as well but I cannot tell for sure if that has been an issue with distortion. I would guess 10-15 miles to the other two locations.

Do you think I would see an improvement using an antenna specifically for a 800mhz or am I wasting money?

Let me state this as has been pointed out in many post on this site. If the system your trying to listen to is a "simulcast system" then you will probably have problems trying to listen to it unless you can reduce the signals from all but the closest tower. Trying to do this will take a directional antenna and probably some attenuation of the incoming signal.

With that said, you haven't provided enough information to provide a good answer to your question. It would help to provide the information on just what system your trying to listen to. Then providing your location would also help.

 

[ryradio]

hi thanks for the response... I did read about using a yagi on these systems but since I am close (6 miles) to a tower I hae been reluctant to throw money and time at this. However, I am also not sure if I am hearing all the chatter or if the very little distortion I get on some transmissions is an issue of the simulcast overlapping.

I also read about reducing the signal on simulcast systems but when I tried that for kicks, by applying global attenuation to my scanner, the full 5 bars I was getting on my scanner reduced to 2 and I lost the signal.

I am in St. John Indiana, trying to monitor Lake County Public Safety Trunking System, Countywide, Indiana - Scanner Frequencies

I know fairly certain I am 6 miles from one tower.... I am unclear on where the other simulcast towers are located.

Is there a way to tell from the RR database where each tower is located?

 

[cmdrwill]

No such thing as a P25 Antenna. Or Digital antenna either.

P25 IS a mode of FM modulation, and antennas do not care what the modulation is, they just pick up radio signals. Now the antenna needs to be tuned for a particular radio frequency band, like 800 mHz.

 

[jbantennaman]

No such thing as a P25 Antenna. Or Digital antenna either.

P25 IS a mode of FM modulation, and antennas do not care what the modulation is, they just pick up radio signals. Now the antenna needs to be tuned for a particular radio frequency band, like 800 mHz.

+ 1 on your reply, you hit the nail on the head.
An antenna is just an electrostatically charged device.
There is no such thing as having too good of an antenna.

I would bet that a state wide system uses some type of cell arrangement - much like cellular telephone, where the frequency's are spaced far enough apart that with a marginally good antenna that you would only hear the closes tower.

At 700 Mhz, the leaves in the trees would attenuate the strength of the signal 8 months out of the year.
The walls in your house and low E glass in the windows would block or attenuate most of the signal available inside of the house.
I'm not even sure that a 5 watt handheld or a 40 watt mobile would talk 15 miles where I live.
That is the reason why the state police here went back to the 155 Mhz bandplan for simplex communications. Also the reason why they abandoned Open Sky..

 

[ryradio]

Are the towers locations listed in a database here or elsewhere? I thought i had seen repeaters listed by longitude/latitude somewhere but i cant find it now.

 

[budevans]

hi thanks for the response... I did read about using a yagi on these systems but since I am close (6 miles) to a tower I hae been reluctant to throw money and time at this. However, I am also not sure if I am hearing all the chatter or if the very little distortion I get on some transmissions is an issue of the simulcast overlapping.

I also read about reducing the signal on simulcast systems but when I tried that for kicks, by applying global attenuation to my scanner, the full 5 bars I was getting on my scanner reduced to 2 and I lost the signal.

I am in St. John Indiana, trying to monitor Lake County Public Safety Trunking System, Countywide, Indiana - Scanner Frequencies

I know fairly certain I am 6 miles from one tower.... I am unclear on where the other simulcast towers are located.

Is there a way to tell from the RR database where each tower is located?

ryradio,

To find the tower locations, Click on the link you posted for the Lake County Public Trunking system. Your browser should take to that web page. Next look at the System Frequencies area on the page.

Click on Countywide Simulcast. Next, Click on the FCC license WQVX462. Your browser will be directed to a web page with the tower locations, addresses and a map showing them.

What jim202 posted is absolutely correct. A directional antenna is the best option when trying to solve a Simulcast issue. Note: You do not need a big or expensive antenna. In the case of Simulcast less is more. There are table top Directional TV antenna's that cost in the $10 to $20 dollar range that may work for you. But, there are no guarantees every location is different.

Just as an FYI, I know that a Directional table top TV antenna can work. I own one. My friends refer to it as my PMY (Poor Mans Yagi). The antenna cost just $10 plus I bought a BNC adapter for $1 to connect to my scanner. The antenna is about 1 foot tall with a weighted base and three foot coax cable. I went from barely being able to copy maybe 30% of the transmissions. To copying crystal clear transmissions 85% of the time with the remaining 15% being just slightly choppy sounding. A huge improvement.

It all comes down to trial an error. Hopefully you'll find a solution that works for you.

 

[ryradio]

thanks for the info bud.

Now I know that there is one location listed 2.5 miles to my south and another, which I assume is the main location, 6 miles to the west.

The same frequencies, including the control channel I am monitoring, is listed on the FCC listing for both locations.

There are also 3 more tower locations located approx. 13 miles to the north. But I suppose the 2 close ones are the ones to be concerned with.

I do get a bit a distortion, but I figured that was normal. However, I am also not 100 percent positive I am getting all transmissions, there are some channels that I think 'should' have traffic on them but do not.

Do you think I have an issue?

 

[Metrofire31]

Antenna

ryradio,

To find the tower locations, Click on the link you posted for the Lake County Public Trunking system. Your browser should take to that web page. Next look at the System Frequencies area on the page.

Click on Countywide Simulcast. Next, Click on the FCC license WQVX462. Your browser will be directed to a web page with the tower locations, addresses and a map showing them.

What jim202 posted is absolutely correct. A directional antenna is the best option when trying to solve a Simulcast issue. Note: You do not need a big or expensive antenna. In the case of Simulcast less is more. There are table top Directional TV antenna's that cost in the $10 to $20 dollar range that may work for you. But, there are no guarantees every location is different.

Just as an FYI, I know that a Directional table top TV antenna can work. I own one. My friends refer to it as my PMY (Poor Mans Yagi). The antenna cost just $10 plus I bought a BNC adapter for $1 to connect to my scanner. The antenna is about 1 foot tall with a weighted base and three foot coax cable. I went from barely being able to copy maybe 30% of the transmissions. To copying crystal clear transmissions 85% of the time with the remaining 15% being just slightly choppy sounding. A huge improvement.

It all comes down to trial an error. Hopefully you'll find a solution that works for you.

Could you share the ordering information on the "Directional table top TV antenna" you use?

 

[budevans]

Could you share the ordering information on the "Directional table top TV antenna" you use?

Sure, I purchased the antenna from Micro Center. Back when I purchased it, the antenna was listed as a Supersonic SC-602. Back then it was also available at Targets and Walmarts.

When I checked today, I see the exact same antenna for sale at Micro Center with a new name. Here's the Micro Center link: Naxa Electronics High Powered Amplified Antenna Suitable for HDTV and ATSC Digital Television NAA-309 - Micro Center

Micro Center also carries the BNC adapter that I needed. The antenna rotates in any direction and also rotate from horizontal to vertical.

 

[budevans]

thanks for the info bud.

Now I know that there is one location listed 2.5 miles to my south and another, which I assume is the main location, 6 miles to the west.

The same frequencies, including the control channel I am monitoring, is listed on the FCC listing for both locations.

There are also 3 more tower locations located approx. 13 miles to the north. But I suppose the 2 close ones are the ones to be concerned with.

I do get a bit a distortion, but I figured that was normal. However, I am also not 100 percent positive I am getting all transmissions, there are some channels that I think 'should' have traffic on them but do not.

Do you think I have an issue?

The system is a Simulcast site. Which means all of the Towers in the System act as one. They carry the exact same traffic on the exact same frequencies. So, you should be hearing everything carried on that system.

At this point, you could try pointing your antenna in different directions. Note, not necessarily at the closest towers. You may just have to experiment and see what you get.

 

[RFI-EMI-GUY]

Speaking of simulcast, I have a 70's vintage DENON stereo receiver. On the rear are two jacks to connect the horizontal and vertical channels of an oscilloscope so that a listener in an urban area (one with the $$$ to buy this receiver and a scope) could adjust the antenna for minimum multipath, the Kenwood KC-6060 and Mackintosh MI-2 were scopes sold for such purpose.

This link describes the connections:

Adding Tuner Multipath Outputs

Instructions for the Mackintosh MI-2

http://akdatabase.org/AKview/albums/userpics/10004/MI2 Owners.pdf

My point is that for difficult simulcast reception, one could rig up an analog receiver to drive a scope and then adjust a directional antenna for best response. I am not sure how this would display on the digital modes. Something like this may be more valuable than the analyze mode in the Uniden BCD536HP which seems slow to respond to BER changes.