BCD436HP/BCD536HP: P25 Phase 2 Scanning Issue

[sfd745]

I have run into an odd issue with my BCD436HP trying to scan the Biddeford, ME P25 phase 2 800 mhz system.

I will preface this with I have tried configuring the TRS using Sentenel, ProScan and Butel ARC to no avail. All the right service types are enabled and I have verified the control channels.

I have a favorite's list set up just for the Biddeford system. I imported the system first using Sentenel and the RR database. Sitting in the next town over, we hear the radio traffic clear as day on a G5, but my radio sits silent. I then tried importing the system through Butel ARC and the RR database, still with no avail. I then went in and manually built the system using all three software programs. Still no bueno.

I have other P25 TRS systems, both phase 1 and phase 2 programmed in the radio and have zero problems with them. I am obviously missing something, but I need a clear set of eyes. Do any of you have a theory on what I am doing wrong?

Thanks,

Higgy

 

[jtwalker]

It appears to be simulcast, so my first guess would be simulcast distortion.

 

[dave3825]

There are many factors involved with simulcast. That's why some simulcast systems don't come in great and others do. All depends what variables are in your favor. And now that there are no leaves on the trees, just another variable in the mix that's either going to help performance, or hinder and hurt it.

 

[tvengr]

It doesn't matter which software program is used when dealing with simulcast distortion. The BCD436HP is not designed to properly decode simulcast sites. If you look at the license (WRMY624), you will see that the one site listed in the database actually consists of 3 subsites using the same 4 frequencies, all transmitting at the same time on the same frequency. The signals from the 3 subsites arrive at your scanner at slightly different times which degrades the scanner's ability to properly decode the control channel. That results in missed transmissions, dropouts, and garbled audio. In some cases, the scanner is not able to decode the control channel at all and will not be able to receive the system. Whether you are able to receive the system or not will depend upon your location in relation to the subsites. Turning on the attenuator may reduce the number of subsites received and improve control channel decoding. When dealing with simulcast, less signal is more. A directional antenna pointed at one of the subsites may help, but that is not practical in a mobile situation. You will find that as you drive around, the scanner will work properly in some locations and not in others. If you are very close to one of the subsites, it can override the out of phase interference from the other subsites. The G5 is designed to receive simulcast sites. The Uniden SDS100 handheld and SDS200 base/mobile are the only scanners specifically designed to receive simulcast sites.

 

[mc48]

Are you receiving data? If not turn the squelch down and see if that helps.

 

[rr60]

It doesn't matter which software program is used when dealing with simulcast distortion. The BCD436HP is not designed to properly decode simulcast sites. If you look at the license (WRMY624), you will see that the one site listed in the database actually consists of 3 subsites using the same 4 frequencies, all transmitting at the same time on the same frequency. The signals from the 3 subsites arrive at your scanner at slightly different times which degrades the scanner's ability to properly decode the control channel. That results in missed transmissions, dropouts, and garbled audio. In some cases, the scanner is not able to decode the control channel at all and will not be able to receive the system. Whether you are able to receive the system or not will depend upon your location in relation to the subsites. Turning on the attenuator may reduce the number of subsites received and improve control channel decoding. When dealing with simulcast, less signal is more. A directional antenna pointed at one of the subsites may help, but that is not practical in a mobile situation. You will find that as you drive around, the scanner will work properly in some locations and not in others. If you are very close to one of the subsites, it can override the out of phase interference from the other subsites. The G5 is designed to receive simulcast sites. The Uniden SDS100 handheld and SDS200 base/mobile are the only scanners specifically designed to receive simulcast sites.

 

[Harold]

Simulcast Distortion. The exact reason the SDS series were developed.

 

[Rq17954z]

I have a bcd 436 hp , I do get simulcast distortion. I have found some methods that make it manageable for me. For the system closest to me best signal I find the stock rubber ducky antenna works Best almost no distortion. Two other p 25 systems further away I will sometimes have it stop on the system But will hear nothing just see p25 in the lower corner. I bought a moonraker discone antenna that made the two further away systems good but caused more simulcast distortion with the local station. Since I can move the moonraker I can move it and can find spots in my house that it will work for all 3 systems. If I had put a discone on the roof think I wouldn't be able to do the same thing!

 

[Ubbe]

I bought a moonraker discone antenna that made the two further away systems good but caused more simulcast distortion with the local station.

You can set the scanners attenuation per site. If that discone made the signal 20dB stronger for the distant systems then the scanners own 20dB attenuator enabled for the local system could bring it down to a level where you only receive the most dominate transmitter in the local system.

I recommend to use an external variable attenuator to allow for an exact level where a simulcast system can be received the best with a non simulcast scanner. ScannerMaster sells one type that can be used.

/Ubbe

 

[Rq17954z]

Thanks, never touched the attenuator guess I know what that will help with!!!