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Author Topic: zlc_slc Feed  (Read 11117 times)
bbrasmussen
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« on: October 01, 2012, 02:26:22 AM »

Here's a picture of the Raspberry Pi fed ZLC Feed.  The primary receiver is a Uniden BC350C.  For the zlc_slc2 feed I have a BCT7 scanner (not shown) and the BCT8 scanner.  The other 2 are just part of my monitoring shack.  The Sony Air-8 was my first real air band receiver back in the mid 80's.  I also have a Sporty's JD-100 receiver.  Both do reasonably well in monitoring.  They are a bit more steamy than the newer receivers, but their simplicity is nice.  I've found that my newer Uniden 346XT which was primarily built for 800 MHz trunked radio system reception is nearly deaf as a post in the VHF air band with the stock antenna and no filtering, even when sitting at the airport.  The JD-100 or the Sony are nice for both home and portable monitoring.

The most important part of the setup which is not shown is the antenna, feedline, etc.  I will try to post some pictures later, but currently I have a Glen Martin 8' rooftop tower with various antennas including HF and VHF/UHF antennas.  The ZLC feed is currently using an 11 element 2m yagi.  It's not perfectly cut for the air band, but it's close enough that the gain from the yagi more than makes up for any loss for the elements being slightly small for the air band. (And the free price was right!)  That is fed to into that shack with 50' of LMR 400 low loss coax.  I've found that since I'm so close to the city, that commercial FM signals are a problem, so I run the signal through an HPN 30118 combined notch filter ( http://www.liveatc.net/forums/listener-forum/i-need-a-filter-for-my-scanner/msg44582/ ) which really improves the signal.  The filter feeds a 4 port Stridsberg Multicoupler which I use to share the one antenna signal with my various receivers.

Another fun part of the project was setting up a Raspberry Pi, an ARM/GNU Linux box, to run the feed.  It's about 5 Watts to run, so it's nice to be able to have something small and economical to run the feed.  

It's more fun to spend money on fancy receivers with lots of bells and whistles, but the biggest bang for the buck comes from the less-exciting things that get the signal out of the air and into the radio.  I'm glad to be a new feeder and am enjoying sharing a great marriage of two hobbies - aviation and radio.
« Last Edit: October 01, 2012, 02:29:46 AM by bbrasmussen » Logged

nontexan
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« Reply #1 on: November 07, 2012, 12:01:16 AM »

Great setup.
What are you using for sound input to the Raspberry Pi? I am assuming that you used a USB audio input, in which case, if you are using multiple identical USB sound adapters, how have you determined which input is which?

Thanks,

Andy

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bbrasmussen
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« Reply #2 on: November 07, 2012, 11:33:40 PM »

Great setup.
What are you using for sound input to the Raspberry Pi? I am assuming that you used a USB audio input, in which case, if you are using multiple identical USB sound adapters, how have you determined which input is which?

Thanks.  I am using a HDE 7.1 Channel USB External Sound Card Audio Adapter.  I have also used a Syba SD-CM-UAUD USB Stereo Audio Adapter with good results.  They both show up as Generic USB Audio devices.  To determine which card is which in Linux I type arecord -l and it will list the available recording devices.

I have had and still have audio issues with crosstalk and distortion with getting the audio into the Raspberry Pi.  Despite having an adequate power source (greater than 1.5 amps), I can't plug the USB sound cards directly into the RPi. I got a 7 port powered USB hub (only $4.50) online and use it to plug the sound card into.  I found that the USB hub works fine without being externally powered. 

I'm still trying to fix my crosstalk/audio bleed issues.  If I plug a second USB sound card into the RPi I get very loud bleed through from the audio of the second sound card into the first.  I've tried multiple combinations of cables, ground loop isolators, and radios among other things, but haven't had any luck fixing it yet.  If anyone has suggestions, I'd be much appreciative.  For now I have the second feed running on a second computer.
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SQWK7700
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« Reply #3 on: November 09, 2012, 03:17:09 AM »

Geez, that Sony brings back memories. I would have given my left arm for one of those as a kid interested in radio Wink

73's
Darrin
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bbrasmussen
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« Reply #4 on: November 09, 2012, 06:13:09 PM »

Geez, that Sony brings back memories. I would have given my left arm for one of those as a kid interested in radio Wink

73's
Darrin

I know what you mean. I lucky as a 10 year old when I got got that radio. I loved to take it out in the back yard and watch planes fly by as I listened. I dragged my poor parents out to the airport many times with that radio in tow so I could get a better look at the action.  I think all that got me hooked on the 2 greatest hobbies ever - radio and airplanes.

It's still working just fine all these years later.  The audio on it is very nice. The JD-100 is a little steamy compared to the Air-8.  Of course it only has 10 memory channels per mode(AM, FM, PSB, and AIR), but other than that it's a great radio.

73,
Brandon
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bbrasmussen
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« Reply #5 on: April 06, 2014, 03:06:53 AM »

I need to add some new pictures since the KSLC feeds have grown. I just moved the kslc_app and kslc_gnd feeds to a Raspberry Pi from RadioFeed for better stability.

Thanks to those people who posted their tips on how to get multiple feeds running on one Raspberry Pi. It took some tweaking of antenna cables, audio cables, and audio levels, but I think I have it sounding ok.
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