• Effective immediately we will be deleting, without notice, any negative threads or posts that deal with the use of encryption and streaming of scanner audio.

    We've noticed a huge increase in rants and negative posts that revolve around agencies going to encryption due to the broadcasting of scanner audio on the internet. It's now worn out and continues to be the same recycled rants. These rants hijack the threads and derail the conversation. They no longer have a place anywhere on this forum other than in the designated threads in the Rants forum in the Tavern.

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Dpl?

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Thorny41587

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Why is it that when I am listening to business uses or FRS for that matter that are using DPL it cuts out when the person talks to loud or there is too much backround noise? My Police Dept., Fire and EMS is on a DPL and this never happens with them.
 

cristisphoto

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Duuuh!!!!!

X1536 said:
Why is it that when I am listening to business uses or FRS for that matter that are using DPL it cuts out when the person talks to loud or there is too much backround noise? My Police Dept., Fire and EMS is on a DPL and this never happens with them.
ME thinks that's because
A
FRS is a cheaper technology hence the applications USUALLY arn't life and death ops
wheras
B PD fire etc uses more EXPENSIVE tech
ya know Motorola MA/Coms etc..
Hence I really doubt if Motorola want to be suued out of bussiness and name, rep etc
cause they failed to make their PL tones dependable for etc etc PD, Fire...
You get what you pay fo, PERIOD....
ANyways
I think it's all common sense
I mean do the math FRS/GMRS two ways are around $40. average ,maybe more depending on brand, features etc
whereas Motorola, millions for one city.....:roll:
and it's billed to you Taxpayer...:twisted:
and most of he costs are just because they CAN charge it and the city /county will pay it as it IS a need indeed lol
Yes, they could really charge cheaper, but ya know how that goes lol

Anyways,
Regards,
Crista
 

2112

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X1536 said:
Why is it that when I am listening to business uses or FRS for that matter that are using DPL it cuts out when the person talks to loud or there is too much backround noise? My Police Dept., Fire and EMS is on a DPL and this never happens with them.
In the thread that you started titled "156.7":

http://www.radioreference.com/forums/showthread.php?t=42370

I posted a link with more info about DCS (or DPL as Motorola calls it) that may contain some answers for you on this. Did you read it?

You'll note in the article that transmitters must have proper low frequency response before they can properly employ DCS. It also says "A poor low frequency response in the transmitter or receiver... <snip> ...may seriously degrade a wide band signal containing multiple frequency components." Voice transmissions contain multiple frequency components. If you add background noise, the transmissions contain even more frequency components.

Now, rude as Crista is with her "Duuuh!!!!!"... there is some truth to what she's said: You get what you pay for. The biz-band and FRS radios are generally cheaper than their public-safety bretheren... and therefore are not as likely to have the proper low-frequency response. That doesn't matter to the manufacturer, who markets the such radios under terms like "privacy" and "more channels" (I never could figure out how tones/DCS gave more "channels", but then again, the marketing departments of these firms depend on the target market to be ignorant). Using DCS in an FRS radio gives them an opportunity to give both "even more privacy" and/or "even more channels", even if it sounds like garbage. So, they'll continue this marketing scheme, without improving the radios themselves.

Public safety radios, on the other hand, are very expensive, and the extra money spent on them buys a better radio all-around. They have the proper low-freq response to properly implement DCS, which is why you don't hear crappy transmissions when they're used.
 

cristisphoto

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Soory Being rude wasn't my intention.....

Sorry I didnt mean to come off as ruuude lol
Maybe I should have come up with a better choice of title...

Buut thank you for your reply and thread I too learned sumtrhin new,,,

Warm regards,
Crista
 

Napalm

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Clark Co., Ind.
Anyone notice when you're using DCS/DPL, you can actually hear the low frequency "warbling", even when you're on a DCS enabled radio?

Maybe it's just the Yaecomwood equipment that I'm using that's at fault, but you'd have thought it would be filtered out in the same way CTCSS/PL is.
 

kb2vxa

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Hi all,

To expound a bit on what CR said, professional and Amateur tranceivers employ high pass audio filtering at 300Hz to keep the voice frequencies and "sub band" PL region separate and low pass at 3KHz to keep the modulation index within proscribed limits. DPL follows the same scheme but like the man said this is not so with cheaply made equipment that doesn't have to meet such rigid standards, this raises manufacturing costs considerably. This includes scanners which is why you often hear the PL in the background and strange sounds from DPL when you use a hi-fi type of speaker or headphone. This is why the transmitter may not be at fault but rather the receiver, I have yet to figure out if one of the "hot" AP25 transmitters in the area or my scanner is at fault when loud audio coupled with high background noise makes the voice sound like it's under water.

Napalm, the simple solution is to use a speaker tailored for the voice range like those lovely Motorola Slim Line types that I use on all my communications gear, they vastly improve readability too.
 

rescuecomm

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Location
Travelers Rest, SC
Dpl

I have noticed that my Uniden 898 does the same thing when our EMS dispatch is sending two tone sequential pages and I have it set for PL decode. The scanner takes off and I hear the tones only on the one in the back bedroom that does not have PL. I don't know why Motorola has the paging tones set so loud. The GMRS/FRS stuff is operating on less than normal deviation (10khz channels?) if they are bubble pack radios and the tones may be crowded out by excessive mic volume. As spoken, the more expensive public safety radios had limiters to prevent such a thing.

Bob
 

cristisphoto

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kb2vxa said:
Hi all,

To expound a bit on what CR said, professional and Amateur tranceivers employ high pass audio filtering at 300Hz to keep the voice frequencies and "sub band" PL region separate and low pass at 3KHz to keep the modulation index within proscribed limits. DPL follows the same scheme but like the man said this is not so with cheaply made equipment that doesn't have to meet such rigid standards, this raises manufacturing costs considerably. This includes scanners which is why you often hear the PL in the background and strange sounds from DPL when you use a hi-fi type of speaker or headphone. This is why the transmitter may not be at fault but rather the receiver, I have yet to figure out if one of the "hot" AP25 transmitters in the area or my scanner is at fault when loud audio coupled with high background noise makes the voice sound like it's under water.

Napalm, the simple solution is to use a speaker tailored for the voice range like those lovely Motorola Slim Line types that I use on all my communications gear, they vastly improve readability too.
Thank You lol
Yeah ya get what you pay for
its why you can go into Rastshck and pay 40 bucks for those FRS/GMRS two ways
Wheres it in the millions for a city based TRS...:roll:

Regrads,
Crista
 

kb2vxa

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Hi Rescue and all,

"...the tones may be crowded out by excessive mic volume. As spoken, the more expensive public safety radios had limiters to prevent such a thing."

Actually the limiter will excaserbate the problem. The tone being set for 20% modulation and the remaining 80% for voice if the voice is excessive the limiter will hammer down the overall modulation to a point where the tone all but disappears. I have noticed this effect on Amateur repeaters because of the audio processing in the controller, users with hot mics tend to chop in and out until someone tells them to back off. Another thing that happens is the signal deviates outside the receiver's passband causing the same effect.

Please note that transmit limiters are the subject, receive limiters serve another purpose altogether and are not the source of the problem, they have no effect on the modulation.

On the other hand pagers having no need for PL aren't affected which is why your scanner with PL decode drops out while the one without doesn't. You could try widening the passband for that channel if it's not set to FM to begin with or remove the PL decode if other stations on the frequency aren't a problem. Then again you could read my tag line. (;->)
 
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