Author Topic: New feed: technical questions  (Read 5231 times)

Offline Metlik

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New feed: technical questions
« on: January 28, 2013, 10:58:17 AM »
Hello!
I have a plans to provide feed from Riga (EVRA) and investigating the possibilities to do it. My idea is to make a three feeds: Riga tower, Approach and CTAF. I'm listening these frequencies at home now (I'm living close to airport), but I'll try to install the equipment on GA airfield hangar, which is 2 nm away from international airport.
Is it possible to spent not more than 500 EUR for that? I'm located in Europe and lot of web-shops with cheap equipment in USA is unavailable for me.
I need your advise for technical part: from my point of view there will be one antenna and three separated radioscanners. I'm thinking about Bearcat/Uniden BC-350A. At home I'm using self-maded antenna L/4, but for mentioned installation I will buy a new antenna.
About computer: I'm thinking about Raspberry Pi, but I saw on forum, that there is a problems with audio from several sources simultaneously. In case of unable to use the Raspberry I can find some old PC under Win or Linux, but I think that Raspberry will be better option, because in the hangar sometimes is quite low temperatures (for example now is -12C). 
So, I believe my idea is more or less clear for you and you could suggest me something:
-antenna - what is the best option to buy and where? I mean the best price/quality ratio.
-PC - which one? How to provide several audio channels - just several audio cards will be enough? what about Raspberry Pi?
-one antenna and several scanners - I will need a multicoupler, which is quite expensive and is over allowed budget. Can I connect scanners without it? at least for the first time?
Thank you for help in advance!



Offline stealth71

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Re: New feed: technical questions
« Reply #1 on: January 28, 2013, 04:13:05 PM »
I can help with a few things. First, the Bearcat 350 and 355 series are great scanners. I just upgraded my feed to the 355 and am very happy with the results. As for the antenna, the Arrow GP126 is really good, but not sure if its widely available over there. Very good price, built like a tank, excellent performance. That's all I can help you with at the moment, I'm sure others will help on the other topics.

Offline dave

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Re: New feed: technical questions
« Reply #2 on: January 29, 2013, 12:27:03 AM »
Hello!
I have a plans to provide feed from Riga (EVRA) and investigating the possibilities to do it. My idea is to make a three feeds: Riga tower, Approach and CTAF. I'm listening these frequencies at home now (I'm living close to airport), but I'll try to install the equipment on GA airfield hangar, which is 2 nm away from international airport.
Is it possible to spent not more than 500 EUR for that? I'm located in Europe and lot of web-shops with cheap equipment in USA is unavailable for me.
I need your advise for technical part: from my point of view there will be one antenna and three separated radioscanners. I'm thinking about Bearcat/Uniden BC-350A. At home I'm using self-maded antenna L/4, but for mentioned installation I will buy a new antenna.
About computer: I'm thinking about Raspberry Pi, but I saw on forum, that there is a problems with audio from several sources simultaneously. In case of unable to use the Raspberry I can find some old PC under Win or Linux, but I think that Raspberry will be better option, because in the hangar sometimes is quite low temperatures (for example now is -12C). 
So, I believe my idea is more or less clear for you and you could suggest me something:
-antenna - what is the best option to buy and where? I mean the best price/quality ratio.
-PC - which one? How to provide several audio channels - just several audio cards will be enough? what about Raspberry Pi?
-one antenna and several scanners - I will need a multicoupler, which is quite expensive and is over allowed budget. Can I connect scanners without it? at least for the first time?
Thank you for help in advance!

Welcome and we look forward to your feeds.

Some notes:

1) We are running some Raspberry Pi's in production.  Still doing some testing on running multiple sound cards.  There are some issues and hopefully we'll resolve them.  Lots of variables.  A better alternative is a Sheevaplug or variants.  More rugged - and known to work well with multiple sound cards.  Have many of these in the field.  If you can run an old PC with Linux that will work great.  Many of those in the field as well.  Several audio cards gets messy.  If you can find one, an M-Audio Delta 1010LT is really the best way to go.  It is a PCI sound card that has 8 inputs available under Linux.  The chipset is well supported on most versions of Linux.

2) Hopefully someone can chime in with a good source in Europe for a reasonably priced ground plane antenna.  Everything I have seen is overpriced.

3) with one antenna and a few scanners you will want an RF power splitter, probably a 4-way for your application.  If you can, get one that is a 50-ohm unit.  But to save money you won't lose a lot by using a 75-ohm unit, and they are widely available and inexpensive since they're a common component in TV systems.  But don't split the antenna without a decent power splitter - the main issue you will have is lack of isolation between the antenna ports on the scanners - and LO signals and the like will start leaking around your setup, and worse.

Hope this all helps...let us know if you have more questions.


Offline Metlik

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Re: New feed: technical questions
« Reply #3 on: January 29, 2013, 09:34:48 AM »
Thank you for your answers!

Seems that is not so easy to connect three audio feeds to a single computer? I found the M-Audio Delta 1010LT at my hometown, but price is unfit into my budget at this moment. Maybe there is possible to use standard PCI or USB -sound card with "line-in, mic 1, mic 2" inputs? What you'll suggest as an easiest way for three audio feeds?

Dave, do you have a separated forum threat about audio-issues for Raspberry Pi?