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Improve RWC Reception?

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MFD4305

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I need to begin with a disclaimer: I am proficient at programming my vintage BCD-996T with FreeScan; both are great products! But I have no expertise in understanding trunked radio systems, what [negatively] affects the clarity of scanner reception, or band plans for Uniden scanners.

That said, I have read in several threads that reception of the RWC simulcast transmissions may be negatively influenced by reception from several towers at once. In my experience, the quality of reception of traffic on Simulcast A and Simulcast B varies widely even though I don't move my scanner [I use the set-back extending antenna].

Sorry for the long-winded preface. The questions are: is there good evidence to support the suggestion I read elsewhere that entering a band plan for the RWC system might improve reception, even though all necessary information should be transmitted by the Control Channel? And if a band plan might reduce multipath interference, what would it be for the RWC system?

Thanks for any thoughts and advice.
 

AZScanner

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I don't see how a bandplan is going to help with this issue. The bandplan just tells the scanner where to tune the voice channels which, as you stated, comes automatically in the control channel on the RWC anyway. When you factor in simulcast distortion, that affects the voice decoding capability, not necessarily the control channel data (it might affect that too, but not enough to matter). So an updated band plan will just help if the control channel data itself is getting corrupted (maybe) but it will do nothing to help you with voice decoding. I've played around with just about every setting available on my old dinosaur BC796D and nothing helps. The problem is in the design of the scanner itself - once the signal has been FM demodulated, it becomes nearly impossible to compensate properly for LSM distortion.

So far, the only tried and true method has been a directional antenna (such as a Yagi antenna) and/or positioning the scanner so that it only receives a signal from one simulcast tower. I'm hoping the new Unidens help with this issue but until they start arriving here in AZ, no one knows for sure (except maybe a beta tester or two, and they aren't allowed to say).

-AZ
 

KB7MIB

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At this point in time, only a directional antenna aimed at the site that gives you the best reception (which may not necessarily be the closest site, depending on what is beyond the closest site in that same direction) is your best bet to improve reception of the RWC and other simulcast systems like it around the country, unless you're lucky enough to live in the shadow of one site, and interference from other sites is negligble.
The second best idea, is to purchase a commercial/professional grade radio, which is built to better standards than a consumer grade scanner, and (have it) program(med) for receive only.
 

MFD4305

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Thanks!

Well, thanks for the replies. It's obvious that I shouldn't speculate about things I don't really understand. As a directional antenna isn't feasible at present, I'll just have to put up with inconsistent and often lousy reception on Simulcast A and -B.
 

KB7MIB

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If possible, try relocating your scanner to a different location. Whether it's just across the room, or to a different room altogether. I don't know if it'll help or not, but it may be worth trying.
 

AZScanner

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Well, thanks for the replies. It's obvious that I shouldn't speculate about things I don't really understand. As a directional antenna isn't feasible at present, I'll just have to put up with inconsistent and often lousy reception on Simulcast A and -B.
Depending on what part of town you live in, you might be able to monitor a different simulcast site and get better results. I'm located close to Tempe, so Simulcast F actually works best for me, and carries many of the same talkgroups I would normally monitor from A or B, plus others not normally heard on A or B such as Scottsdale, Chandler and Tempe PD.

-AZ
 

desert-cheetah

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I've actually found that while listening in my office building, if I turn the squelch all the way to the right (open?), I can get better reception on both RWC and TWRC, but I'm on the third floor of a 3 story building on the Salt River-Pima Reservation so YMMV. I'm really hoping the new Uniden scanners will decode them better and I'm anxiously awaiting AZScanner's report. :D
 

KB7MIB

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Turning the squelch all the way to the right, or clockwise, tightens it up, making it less receptive to weaker signals.
Turning it to the left, or counterclockwise, opens it up, letting you catch weaker signals. (And in conventional mode, turning it to the left let's you hear the squelch "rushing" sound or noise. You won't hear it on a trunked system, however.)
 

GB1952

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RECEPTION

I HAVE THE 6 ELEMENT GOLD YAGI FROM ANTENNA FARM WITH HIGH DB AND IT PICKS UP TOWERS FROM 360o around the antenna very well.
 

KB8TZX

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Okay, this may not work for a commercially made scanner due to lack of particular receiver controls, but here is what is showing some (modest) promise on my end. I decided to home brew a Yagi-like contraption out of 22 gauge solid wire (with the jacket on it), scotch tape and an empty paper towel tube. (I asked in another thread about dealing with the simulcast multipath issues and the use of a Yagi. With no budget but time to try ridiculous things, I figured I would experiment).

I cut the wire to proper length for each element, taped them to the side of the paper towel tube and insert the mini mag-mount that came with my RTL-SDR device in a hole in the driven element position. Each element was placed at proper Yagi spacing and made as straight as practical.

I placed the contraption over the (admittedly improper length) "driven element" of the mini mag mount vertical and, after manually adjusting the receiver gain down (with the AGC disabled, of course) gave it a slow turn while it was listening for the Simulcast G sites.

I only did this to the control receiver (I am running to receivers, both cheapy SDR) but... in doing so, I am now achieving very reliable data from the control channel. Whereas it used to be marginal at best, more usually very unreliable, it now is showing a very solid hold while decoding the control data.

I think I'm going to give it a try with the voice channel receiver next... when I run through the next roll of paper towels. ;) I will be sure to report back if it has the intended results, as the next step will be a trip to a hardware outlet for more reliable supplies.
 

AZScanner

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Definitely add to your shopping list a BNC adapter so you can connect a real antenna to the dongle. I ended up going to Fry's electronics and buying a BNC jack that I mounted on a simple plastic project box and I connected it up to the dongle by snipping off the ridiculously weak antenna they come with and connecting the remaining cable to the jack. This allowed me to put the RS-800MHz antenna on it instead which GREATLY improved reception. I just checked my feed, it's currently working (although not as well as I would like - need to tweak the ppm settings again it sounds like) so if you want an example of what you can expect reception-wise from one of these, give it a listen.

-AZ
 
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