P25 Digital Decode

[DJ88]

Does anyone know if distance and signal strength have anything to do with a digital scanner's ability to decode digital signals? The reason I ask is because I live in northern Ocean County New Jersey use a Uniden BCD996T with an outside discone antenna, and I'm having trouble receiving the Coast Guard New York VHF Repeater, 164.9125 (P25 Digital). I don't know exactly where the repeater is located, but I do know I am quite a distance away from it wherever it is. Often times I get the buzzing (motorboat sound) and when I can receive it, it's broken up and the voice is hard to understand. It kind of sounds like space aliens talking. I receive other P25 systems okay, the farthest one being about 20 mies away. Any input would be appreciated. Thanks.

 

[rdale]

Absolutely...

 

[fineshot1]

Does anyone know if distance and signal strength have anything to do with a digital scanner's ability to decode digital signals? The reason I ask is because I live in northern Ocean County New Jersey use a Uniden BCD996T with an outside discone antenna, and I'm having trouble receiving the Coast Guard New York VHF Repeater, 164.9125 (P25 Digital). I don't know exactly where the repeater is located, but I do know I am quite a distance away from it wherever it is. Often times I get the buzzing (motorboat sound) and when I can receive it, it's broken up and the voice is hard to understand. It kind of sounds like space aliens talking. I receive other P25 systems okay, the farthest one being about 20 mies away. Any input would be appreciated. Thanks.

Yes Ken - If you have low signal strength and are on the fringe of reception you can experience this type of rx problem on P25 systems. In P25 the audio is converted to and transmitted as data. The more noise on the rx'ed signal translates into a higher BER (bit error rate) on the data being decoded into audio. Once the BER reaches a certain threshold ( i think its about 3 or 4 % errors ) the data errors can not be corrected and the digital sound ( sometimes referred to as "R2D2" or "going digital" ) is a result.

 

[DJ88]

Thanks guys.

 

[kb1ipd]

Does anyone know if distance and signal strength have anything to do with a digital scanner's ability to decode digital signals? The reason I ask is because I live in northern Ocean County New Jersey use a Uniden BCD996T with an outside discone antenna, and I'm having trouble receiving the Coast Guard New York VHF Repeater, 164.9125 (P25 Digital). I don't know exactly where the repeater is located, but I do know I am quite a distance away from it wherever it is. Often times I get the buzzing (motorboat sound) and when I can receive it, it's broken up and the voice is hard to understand. It kind of sounds like space aliens talking. I receive other P25 systems okay, the farthest one being about 20 mies away. Any input would be appreciated. Thanks.

So I am assuming that you're getting the signal consistently but the signal is too weak or too noisy to properly decode? You could try going to a higher gain antenna and that would likely help. The fact that you're already using an outdoor antenna means that you'd probably need to go the next step and get a directional antenna which, of course, is going to be a bit more involved than the omnidirectional discone, as it will only work with certain frequency ranges well and also if you want to get different stations you'd need a rotator.

You could try a preamp to give it a little extra boost especially if it's going through a long run of cable. Don't expect a preamp to be magic or anything, but if you're right on the edge it may be enough and it would likely be the simplest way to go.