Fine tuning P-25 digital sound???

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Blind_Shadow

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Dec 21, 2013
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Is there a way to fine tune the digital sound, scanner feed to where it is more able to listen to the feed better? Some times it is and then times dispatcher's can not hear the cars and vise versa. The sound is garbled or cut off and completely un-hearable. Is this how the digital is supposed to sound?

Some other county's have digital and are completely unable to make sense to each transmission. They are not encrypted, just very difficult to hear a complete transmission. That is not the case hear luckily. ( though I have not checked to see if those counties are on same type of digital system )

I am running xt scanners 396 and 996. Both have the same issues.

Thanks..
 

KD0TAZ

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Dec 26, 2010
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Kansas
It happens. There's nothing you can do about it, especially when you hear them asking for 10-9 because they 'went digital' - because that means its in the system, not your scanner. I hear that all the time on our P25 system.
 

jim202

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Mar 7, 2002
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New Orleans region
Digital systems are different from analog systems in that there is a very fine line between where the signal is strong enough to function and where it drops out. In an analog system, when you were near the end of your rope (signal near the edge of coverage), it would get noisy. This is not the case with a digital system. When your near the edge of coverage, it either works or it doesn't. The times when you hear the robotic dropout in the voice is the very edge where your going to go away and the radio system can't function any more..

Sometimes this is due to the type of system being used. You will hear this type of problem more in a simulcast system. The phasing between transmitters in the overlap zone can really cause problems. Sometimes this issue can be resolved by better engineering of the antennas and direction the antennas are pointed. Careful computer modeling can let you fix a system that is having these problems.

A system in point is the county of Mobile, AL. It just recently had the antennas replaced at a number of sites and point them in different directions than what the original antennas did. The indications are that there were improvements in system coverage. Then you could still have issues with individual radios. Some of the radios in use might have transmitter problems, antenna problems or poor batteries in the portables. Until the radios are singled out, you don't know where to point the finger.

Problems with radio systems and coverage are not easy things to just walk up and say this is the problem. It takes careful understanding of what is there, what condition the base radio equipment and antenna system are in and where the problem areas of coverage are. Then you go hit the computer and model the system. Many times it takes doing drive testing with recording equipment to monitor signal strength of the different control channels. This information is then plotted by each channel and you can then see what the coverage truly is. Then and only then can you start to have a hand on what the facts are. It may be a simple change in the system timing is required. On the other hand it may take a redesign of the antenna system and careful adjustment of the transmitter output power at the different tower sites. Many cases it takes a combination of all the above to bring the system to a fully usable condition.

These changes are not done overnight. It takes planning and time to line up the technical work and tower crews to do the work. When you do a change, many times it takes doing many of the tower sites at the same time. The radio system is going to be limited in capacity during the work as transmitters will be taken off the air to allow antenna work to take place.

The radio systems owner needs to admit there is a problem and work on a game plan to have this work done. It takes time to have the funding in place to pay for engineering work, new antennas, tower crews and the radio techs to be on hand to adjust the base radios. This is no one week of planning and the next week go do the work. It is also weather dependent so the tower crews can do the antenna work.
 
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