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  #21 (permalink)  
Old 04-05-2016, 6:09 PM
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I would aim it where it works the best.....
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Old 04-05-2016, 6:20 PM
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Quote:
Originally Posted by AnikF1R View Post
The distance from element to the rear of the can is the same length as the element, about 3.25". I'm running 100' of LMR-400 to a PAR FM trap then to my 436. The trap had more to do with my air band setup.
Thanks. I am building one ASAP. I'll report back on my results.

Chuck
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Old 04-05-2016, 7:16 PM
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Looking at a tower map it and your location NE aim is between the Golden Valley Tower and City Center- if you try monitoring MPLS 1-009 and Metro 1-001 and have similar signal results I would suspect you are on City Center, if they are noticeably different you are most likely picking up Golden Valley.
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Old 04-05-2016, 11:06 PM
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Quote:
Originally Posted by stmills View Post
Looking at a tower map it and your location NE aim is between the Golden Valley Tower and City Center- if you try monitoring MPLS 1-009 and Metro 1-001 and have similar signal results I would suspect you are on City Center, if they are noticeably different you are most likely picking up Golden Valley.
Is there a list of services that operate on MPLS 1-009 and Metro 1-001? I'm not quite sure what these two things represent.
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Old 04-05-2016, 11:28 PM
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1-009 is a system owned and managed by the City of Minneapolis. It is the primary site for all Minneapolis radios, 1-001 is the States metro site with towers in Minneapolis and St. Paul, primary site for MCTO buses and trains, MN Dot and other state agencies.
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Old 04-06-2016, 12:22 PM
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I've re-aimed at City Center, but, again, I get some breakup. I'm going to extend my can antenna by rolling up some aluminum flashing and sticking it in the open end.
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Old 04-06-2016, 9:22 PM
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The best direction is usually NOT to aim it at a tower, but to null out all but one tower. That may happen in a direction that is not directly at any particular tower.
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Old 04-06-2016, 10:42 PM
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Quote:
Originally Posted by Voyager View Post
The best direction is usually NOT to aim it at a tower, but to null out all but one tower. That may happen in a direction that is not directly at any particular tower.
That's most likely what I had when aimed NE. I guess I don't want to miss out on anything, but I don't want distortion either. Can't have it both ways unless I'm willing to have multiple scanners and antennas.
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Old 04-08-2016, 9:11 PM
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So this monstrosity, or beauty, whichever way you want to look at it, is pulling in...

Fire pages. That's it. And that's in the 150 MHz band. I'm aimed directly at City Center. Maybe something not sooooo long is in order
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Old 04-08-2016, 10:55 PM
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Looks like a beauty to me...

Is that ventilation duct?
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Old 04-08-2016, 11:11 PM
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Quote:
Originally Posted by Voyager View Post
Looks like a beauty to me...

Is that ventilation duct?
Ha! Yes, it's a sewer vent. You can't see them, but I drilled holes in the PVC pipe that holds up the antenna so that it still could function.

The aluminum "extender" is now sitting in the basement. I'm back to just the paint can. It worked the best.
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Old 04-09-2016, 9:09 AM
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Default Simulcast Distortion Buster

I am just curious if anybody here has experimented with using directional antennas inside their home with ARMER? An 800 MHz Yagi isn't really that big. Using it inside would make it easy to try it in different directions.

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The Digital Blues (or why does my local digital system sound like #$^?)
Posted on November 30, 2015 by Rich Carlson
So you bought that fancy new digital scanner and while it usually works great, sometimes on certain digital systems it doesn’t seem to sound right. Sometimes it just drops words or phrases but sometimes it drops the whole conversation.

You try moving the scanner around or connect to a better antenna and it doesn’t help or even gets worse. Before you throw the scanner against the wall in frustration read on:

We feel your pain! The problem isn’t you or in or the programming. It is called “Simulcast Digital Distortion” or more commonly “Bit Error”. Our friends at RadioReference have a great technical explanation of this in their Wiki at Simulcast digital distortion - The RadioReference Wiki

The 10 cent explanation of this is that you have signals from more than one tower arriving at your radio at ever-so-slightly different times. These signals compete with each other and tend to null each other out. This is why sometimes the radio will stop but you won’t hear any or part of it.

There are a couple things you can do to help get past this issue. If your radio has an attenuator function try that first. This reduces the signal and hopefully will force your radio to only be able to receive a single tower site. You can also try moving the antenna around the room to see if you can find a “sweet spot”. If you are using a telescoping antenna try adjusting it to different lengths or angles. Also try opening the squelch all the way. If all you are listening to is the digital system then this will not affect other channels.

If all of this fails then you may need to try a directional antenna. Commonly called “Yagi’s” these antennas will direct your reception in a single direction and hopefully force your radio to hear only a single tower.

This type of digital distortion usually is less prevalent with newer models of scanners and firmware updates usually reduce it as well. Make sure you have a current model scanner and that its firmware is up to date.
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Old 04-09-2016, 9:52 AM
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I have used a directional amplified TV antenna inside my house to pick up towers outside my normal range. I have only done as an experiment to see what I could pick up but never left it set up for general long term monitoring. I was successful picking up towers outside there plotted coverage areas doing this.
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Old 04-09-2016, 2:03 PM
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Quote:
Originally Posted by JASII View Post
I am just curious if anybody here has experimented with using directional antennas inside their home with ARMER?
Not specifically with ARMER, but the walls will cause reflections which could add to the multipath distortion.

Still, it could work. Try it.
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Old 04-10-2016, 12:01 PM
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Just thought I'd comment on the building of a Waveguide (Cantenna) antenna for 850mhz.

I live in Oakdale northeast of the 694/94/494 intersection and I have been fighting the multipath/simulcast issue here for over a year now. I started with the usual SDR dongle routines, bought a BCD396XT, and also found a PRO-96 at a garage sale. All of the above would give me a full strength signal but only about 0-70% decoding, and I have been trying all the known "tricks of the trade" without much luck. With the BCD396XT/800mhz rubber duck I could drive around the area and see 0% to 100% decoding.

I finally decided to go for max isolation and give a waveguide a go. I have seen folks building Cantennas for 800mhz but they sounded to me that they would be too small for that frequency. I looked around and followed up on the formulas and calculators ending up using Cantenna Waveguide . I found that at 850mhz a waveguide of 8.7" would be about as small as you could go so I decided to build one to specs using those popcorn tins you find at the store at Christmas time. Plug 0.850Ghz and a diameter of 224.67mm (8.845") into the calculator at the above URL and you will see the numbers I used to build mine. I used four tins so mine it 35.125 which is close to the Lg (Waveguide Wavelength) called for by the specs. It's a Biggie!!

So, Does it work?? ..... Sort of.

It is quite directional and when I had the BCD396XT plugged directly into it (hung from the probe BNC) I could find spots that would give me close to 90% decoding from inside my condo on the 3rd floor. I would get about the same using the SDR mounted directly and fed back to the computer via a powered USB cable. My 90% decoding comes with the Cantenna mounted on a stand about two feet off the floor and pointed at a inside wall that is about 1 inch from the open end. %-)

It's been a while since I have played with it because I have been using the URL for johnmoe1's scanner which if far greater that anything I have built. "Two Thumbs Up"... you did good.

Anyhow, I just thought I'd throw out what I have found about the Cantenna antenna.

George
WD0AKZ
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  #36 (permalink)  
Old 04-10-2016, 3:23 PM
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I sorta figured that my paint can, at around 6", is too small. I'm pretty happy with the can, though. I'll be keeping it. It's interesting to hear others' experiences with waveguide. Thanks George.
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Old 04-14-2016, 1:39 PM
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Now this is an interesting article. I will surely try this before spending any more money on antennas that might/might not work. Thanks for sharing this!
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Old 05-09-2016, 9:44 AM
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Love that paint can antenna. I tried something like that before. I used something smaller though (a soup can) which I assume was too small? Not sure, but I built the attached corner reflector and its the best that I've heard my scanner since I purchased it years ago. I live directly between two towers 2.5 miles in exact opposite directions. So I have the distortion blues, big time! But this made it probably 75-80% better. Still has its bad moments but I'm done, not touching a thing anymore. :-)
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Old 05-09-2016, 12:09 PM
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Quote:
Originally Posted by jcardani View Post
What a great idea for simulcast LSM reception!

BTW I like your user name! I put my first TVRO dish up in 1984 and watched many shows from CBC on the Anik birds! The great pre 1986/Captain Midnight days when mostly everything was free on satellite.
I remember the days of Shawn Kinney/Greensheet, Doug Dennert's Skystore [interesting snowmobile guy aka sat guy from Thief River Falls]. Oh, and of course I was a young punk, so I have to mention American XXXtasy later on.

I may have to give a cantenna a try and see how it works with the not-so-local simulcast. Too easy to pass up building one of those, and cheap!

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Old 05-10-2016, 10:12 AM
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Quote:
Originally Posted by WaveJam View Post
Love that paint can antenna. I tried something like that before. I used something smaller though (a soup can) which I assume was too small? Not sure, but I built the attached corner reflector and its the best that I've heard my scanner since I purchased it years ago. I live directly between two towers 2.5 miles in exact opposite directions. So I have the distortion blues, big time! But this made it probably 75-80% better. Still has its bad moments but I'm done, not touching a thing anymore. :-)
Here in the San Francisco Bay Area, on the EBRCS system, I had the same problem with simulcast distortion. I built a corner reflector too and it was the best solution I could find.
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