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Old 07-29-2014, 11:32 PM
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Question PRO-652 and Frederick County Fire

Hi! New user here. My old analog scanner finally dies and I wanted to purchase a digital unit in anticipation of Carroll County going digital and to listen to Frederick County Fire. Bought a RS PRO-652 and had no problem loading Carroll through RadioReference download. However, have tried everything to receive Frederick County without success. I can load control channel and it populates other frequencies and the scanner seems to be scanning the system as I get a SS reading. However no audio what so ever. Downloading from RadioRef also did not work. Will FC ever work with the PRO-652 or should I return it? And if so, what would be recommended replacement?

Thanks for any input/suggestions.
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Old 07-31-2014, 8:28 PM
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You didn't say much here about what antenna you're using. The 652 is too new to be sure about this, but it seems that it's somewhat less sensitive than its PRO-197 brother.

I'd look at that first (along with the coax from the antenna to scanner) before thinking about returning it...Mike
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Old 07-31-2014, 10:18 PM
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Thanks for the info. I believe it is a reception problem, not a scanner problem. Seems I'm in one of the Mt. Airy blackholes for Frederick reception!

I have tried just about every rubber duck antenna I have as well as a 2M/440 whip on a mesh ground plane in the attic. My plan is to put the scanner in the car and drive into Frederick County and see what I can receive. If that proves the scanner is working, I'll have to work on rigging some sort of 800 ground plane outside.
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Old 08-01-2014, 12:01 PM
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With wavelengths this short, you should try moving the radio around in the home. Height helps! You may find a sweet spot that way

Testing with a 2m/440 antenna (even assuming it might work on a harmonic) or a duckie is not going to work well, as you've already discovered. Building a 800 Mhz antenna - even putting that in the highest part of your attic - is going to be a better performer. Heck you might even try a J-Pole - at frequencies this high, the antenna will be positively tiny - and the small amount of gain might be beneficial in getting out of the 'hole'

GL...Mike
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Old 08-01-2014, 1:00 PM
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The Frederick site is a simulcast LSM site. The GRE/RS radios, new or old, do not work well to receive the LSM sites. You can experiment with little to no antenna or attenuation to cut down on the mutli tower reception..

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Old 08-01-2014, 2:42 PM
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When I was in Mt Airy last summer parked at the Mt Airy carnival grounds just off Rt 27, I couldn't pick up anything on my PSR800. I agree, it's almost certainly the digital simulcast problem your seeing.
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Old 08-01-2014, 5:21 PM
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Here's our article on simulcast distortion from our wiki..

Simulcast digital distortion - The RadioReference Wiki

Mike
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Old 08-03-2014, 9:24 PM
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Today I put the scanner in the car and drove from Mt. Airy towards Frederick on 144. Just outside town I began to receive FC Fire. At the New Market Food Lion, the radio was working perfectly! Seems like there is an electromagnetic "door" at the county line!

Interestingly this evening, when a thunderstorm came through, the scanner was picking up FC. Must have been some ducting going on.

Another question for the group. What Phase of Project 25 is Carroll changing over to, if it is Phase II, the PRO-652 will be useless.
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Old 08-04-2014, 9:10 AM
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Quote:
Originally Posted by KD3MW View Post
Another question for the group. What Phase of Project 25 is Carroll changing over to, if it is Phase II, the PRO-652 will be useless.
Probably a phase 2 system - but I'd expect them them to start as Phase 1 - but we'll see.
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Old 08-06-2014, 11:30 AM
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Quote:
Originally Posted by KD3MW View Post
Today I put the scanner in the car and drove from Mt. Airy towards Frederick on 144. Just outside town I began to receive FC Fire. At the New Market Food Lion, the radio was working perfectly! Seems like there is an electromagnetic "door" at the county line!
More likely one of two things happened here;

a. You were receiving signals from only a single tower, avoiding the issues with simulcast distortion -or-
b. Frederick county's system concentrates its signals within the county using antenna orientation. Other jurisdictions - the city of Philadelphia comes to mind - do this as well

Nevertheless your issue appears to be at least partially resolved...Mike
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Old 09-01-2014, 11:48 AM
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Quote:
Originally Posted by ka3jjz View Post
More likely one of two things happened here;

a. You were receiving signals from only a single tower, avoiding the issues with simulcast distortion -or-
b. Frederick county's system concentrates its signals within the county using antenna orientation. Other jurisdictions - the city of Philadelphia comes to mind - do this as well

Nevertheless your issue appears to be at least partially resolved...Mike
The ridge Mt. Airy (I-70@ county line) sits upon gives unimpeded line of sight access to multiple sites across a wide range of distances, including New Market (5mi), Vernon(13 mi), Hill St (15mi), Mar Lu (19mi), Gambrill (20 mi), and even Bridgeport (22mi) and Tower Rd(25 mi) can be heard from that distance. To receive LSM the scanner has to be able to sort out the traffic that arrives with between 25 microseconds and 125 microseconds of delay spread. In short, the scanner can't handle the time delay between valid signals it is receiving when trying to render the audio.

Its not a black hole (too little signal) its too much signal, with too much delay, from too many places. Radios can handle it. Scanners can't. Use less antenna, not more.

http://www.fedeng.com/whatsnew/artic...res_(4-14).pdf includes a pretty to the point explanation.
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Old 09-14-2014, 6:56 PM
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Quote:
Originally Posted by KD3MW View Post
Today I put the scanner in the car and drove from Mt. Airy towards Frederick on 144. Just outside town I began to receive FC Fire. At the New Market Food Lion, the radio was working perfectly! Seems like there is an electromagnetic "door" at the county line!

Interestingly this evening, when a thunderstorm came through, the scanner was picking up FC. Must have been some ducting going on.
The Prince George's County Phase II system is like that. on 495 between exits 29 and 28, little to no signal, cross New Hampshire Ave (ext 28) and the county line and BLAM! they come in like gang busters. Same going the other way, cross NH Ave heading west and the signal goes out like a light switch going off.

That wasn't ducting occurring. The winds aloft were pushing the signals with them!

JK
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Old 09-14-2014, 7:28 PM
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Quote:
Originally Posted by KD3MW View Post
Hi! New user here. My old analog scanner finally dies and I wanted to purchase a digital unit in anticipation of Carroll County going digital and to listen to Frederick County Fire. Bought a RS PRO-652 and had no problem loading Carroll through RadioReference download. However, have tried everything to receive Frederick County without success. I can load control channel and it populates other frequencies and the scanner seems to be scanning the system as I get a SS reading. However no audio what so ever. Downloading from RadioRef also did not work. Will FC ever work with the PRO-652 or should I return it? And if so, what would be recommended replacement?

Thanks for any input/suggestions.
I live is strasburg va at the junction of intertstate 66 and interstate 81 and copy frederick county,md on
my scanner on my dresser on 153.845 if all else fails use that freq. My antenna is a square of # 18 wire on my wall total length is 300 inches because i use it for low band from 30.45 up to 45.00mhz. I used the same one in the air force on my wall for 39.50 in Louisiana but u can find the total length in inches 12060/freq or of each of the 4 sides for your use using the formula 3015/freq Feed the antenna by cutting one of the sides and hook ur coax to it. i used the right side and cut it half way up and ran the coax with a bnc to my scanner. I tried hooking the center of the coax to the wire going up and the shiels to the piece going down the difference wasnt very much. For higher freq or stronger signals i am sure the antenna that came with ur scanner might work. I did notice for 453 Mhz the 6 inches on top of my scanner works better and doesnt degrade my low band freq like 33.86 ans 39.34 and 39.26 and etc


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