These contest
recordings provide a great way to listen and learn, warm up your ears for
the next contest, and listen to what your signal sounded like at K5ZD!
Live Audio (only available during contest)
During some of the serious contest operations from K5ZD, we will enable
live audio streaming direct from the headphones. Click on the link below any time during the
contest to listen in on what conditions the operator is experiencing.
To listen, you will need software capable of receiving streaming
MP3 broadcasts (e.g., Winamp, Media Player, Real Player, iTunes,
etc.) Note: Some users have reported slow start-up on no response
using Microsoft Windows Media Player. I recommend using Real
Player.
If you get disconnected, click on the link again to restart.
This experiment in real-time contest audio is made possible through
the resources of www.liveatc.net, a
site for aviation enthusiasts that provides
streaming of live Air Traffic Control (ATC) radio traffic from around
the world.
How it Works
There have been a lot of questions about how the
streaming is being done.
The system uses MP3 streaming via a network of Icecast2 (www.icecast.org)
servers (running on Linux, & FreeBSD, but Icecast2 runs fine on Windows,
too).
The whole system is based on replicated unicast:
broadcaster -> central Icecast2-->slave servers->listeners (k5zd) server
Listeners connect to the central Icecast2 server, which runs a custom
instance of Icecast running on a special port for load balancing. The
listener is then redirected to one of the replicated (slave) servers.
The slave server then "pulls" the requested stream from the central
Icecast2 server (i.e., only the requested streams are replicated).
It's proven to be a very reliable system.
It all boils down to having access to bandwidth. CPU/RAM requirements are
minimal since Icecast has a pretty small memory footprint and CPU loading.
All the encoding is done on the broadcaster end - Icecast is just "passing
the stream."
The system is currently limited to about 1,000 listeners, mainly to conserve
bandwidth, but it is scalable to thousands of simultaneous users. Best of
all it's
standards-based so any client software capable of receiving MP3 audio
streams can tune in.
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Copyright 2000-2008 by Randy Thompson, K5ZD
E-mail to k5zd@k5zd.com
