"you went digital...repeat your traffic..."

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mrova

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Help me understand why this is. Listening to state police, on a conventional frequency, the officer's transmission occasionally starts making weird sounds and dispatch will call back for them saying, "you went digital, repeat their traffic." Again, that's on a conventional channel and it has occurred while using my sportcat 180 and the psr 500.

Then, on occasion, when listening to the local police, who are digital, and on the psr 500, the exact same thing happens, and the dispatch there says the same thing.

So, why does a conventional channel "go digital" and why does a digital channel/frequency, that is not encrypted, also "go digital." It's not a distraction nor annoyance, I'm just wondering why/how that happens. Seems to me that could be a terribly dangerous thing if it happen at just the right inconvenient moment.

sv
 

jehm1212

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I assume you are referring to STARS. I too have heard the same thing all too often from VSP dispatchers. The reason that they sound digital when listening is that the receiving site which is listening to the unit transmitting is getting a weak signal from the radio. On an analog system, you would hear static. On a digital system, you hear R2D2. The reason that you also hear it on the conventional channels is because those are just a simulcast of the corresponding STARS talkgroup (ie. you hear what the system hears).
 

JoeyC

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"Going digital" is the same thing as in the old analog days "10-9 you were 10-1" i.e "Repeat, you were unreadable".

This is a lame explanation, but should probably suffice.

With digital the reception is either ON or OFF.
In analog, there are varying levels of signal strength that are readable up until a very weak signal where it becomes difficult to make out voice.
Same thing in digital only as the signal weakens the radio compensates for the loss in quality by averaging (sort of) the remaining usable data. When the amount of BAD signal data exceeds the GOOD, at a certain point the radio cannot compensate to make a usable sounding voice and you will hear garbling and all the other junk that is associated with digital, all in full quieting.
 

rvawatch

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I assume you are referring to STARS. I too have heard the same thing all too often from VSP dispatchers. The reason that they sound digital when listening is that the receiving site which is listening to the unit transmitting is getting a weak signal from the radio. On an analog system, you would hear static. On a digital system, you hear R2D2. The reason that you also hear it on the conventional channels is because those are just a simulcast of the corresponding STARS talkgroup (ie. you hear what the system hears).
ditto. just goes to show that even thousand dollar radios don't work 100% of the time.
 

troymail

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I have some folks in my area currently undergoing acceptance testing for a digital upgrade... Yesterday, for the first time, I heard one of the testers refer to the digital garbling as "static" which I found pretty interesting.

The funny thing is that when a receiver says "I couldn't copy - you went digital" the transmitter could really come back and say "So what's the problem? I thought we were digital?".... :lol:

I think the correct term should be "garbled".
 

LEH

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In Division Five, VSP calls it "robotic."

That is why I do not believe anyone who says his scanner is 100% on STARS.
Could it be the scanner is doing 100%, but STARS isn't? If STARS is messing up and I hear the garbage, then the scanner is fine.

But overall, I'd agree, I miss a lot on STARS either with my 500 or my 396.
 

Don_Burke

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Could it be the scanner is doing 100%, but STARS isn't? If STARS is messing up and I hear the garbage, then the scanner is fine.
True enough, but how would a scanner listener know?

It could also be that the system is working fine, but both receivers got confused.
 

mrova

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You're right about "garbled." That might be the better word to use. The expanations make sense. I would just hate to be scanning when there's an emergency that the officer is dealing with, needs help right away, and his transmission gets garbled. It does appear to be more frequent and troublesome with and for the state police (STARS?) and rarely occurs with the local police.
sv
 

LEH

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Even though STARS is VHF-HI (less line of sight), the system also has a larger area to cover with more possibilities for interference.

We may not hear the drop offs as much on local systems, but they do occur, with sometimes fatal results. Several larger departments have been reported with complaints about the slow or garbled 'new' systems. I believe it was Philadelphia who lost a couple of firemen due to a 'communications' breakdown on their digital system.

Don, we'd better quit before we're accused of being garbled. :D
 

troymail

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You're right about "garbled." That might be the better word to use. The expanations make sense. I would just hate to be scanning when there's an emergency that the officer is dealing with, needs help right away, and his transmission gets garbled. It does appear to be more frequent and troublesome with and for the state police (STARS?) and rarely occurs with the local police.
sv
There's ALOT of discussion about this issue in the emergency services sector--- folks would rather get a partial static filled message than none at all... several major cities have been through this and it's been all over the news but eventually dies down.. not sure if that means the problems were eventually fixed or people just started living with it....
 

LEH

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... it's been all over the news but eventually dies down.. not sure if that means the problems were eventually fixed or people just started living with it....
What has probably happened is the 'media' no longer considers it 'newsworthy' and has stopped reporting on it. They'll get involved the next time a police officer or fireman dies because they couldn't communicate.
 
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Our fire department guys have made it VERY clear that they would rather hear static filled tx's than nothing. This is why despite our city investing in the most expensive p25 system in America (so I am told), our FD still insists on using the old VHF analog radios for fire fire fighting. Also, when wearing breathing apparatus, digital doesn't always work too well for whatever reasons, and it picks up background noise (plenty of that in a fireground), and does strange things that analog doesn't do, from what I am told.

There is no room for "working the bugs out" when you are fighting a structure fire. Even a cop, if he falls victim to digital radio problems, still has a gun, and a taser to hold the wolves at bay for a short time if needed. When a firefighter gets trapped in a fast burning structure, there is little he can do but pray help comes quickly, and that radio is just too important.

PFD is currently working on the development of vehicular repeaters so that they drive around with little repeaters on their engines and LT's, and and don't have to be at the mercy of the simulcast sites.

Financially, it is an utter fiasco, in my view. Our city, like many these days is facing a budget shortfall, and after spending all this money to end up where we are is a shame. The current PFD VHF approach is considered by some experts to be the model for how fireground coms should be done, so changing to digital is painful.
 
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