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Equipment
Computer:
The
computer used to provide the feeds is an AMD Sempron 2600+, running at
1.83 GHz. The computer runs 24
hrs a day and its only function is to run the software that permits the
feeds to operate. There are four Uniden scanners connected to four audio
cards.
Three of the four scanners are also connected to the
computer via serial ports. This permits software to generate the Alpha
Tags that are available on all the feeds except for the Toronto Centre Air Traffic feed.
Scanners:
All
manufactured by Uniden
Police scanner BCD996T Digital
capable
Fire & Ambulance BCT15
Waterloo Control Tower BC898T
Toronto Centre Air Traffic BC350C
Software:
Simplecast - Audio interface
from scanner
Serproxy and TalkgroupMonitor - Permit "Tags" to be inserted into the
audio stream accessing the scanner information via a serial interface
Icecast - Acts as a server interface to the internet for stream
delivery to listeners.
Audio Cards:
Four. Any
inexpensive PCI audio card is all that is needed for each feed. These
are Ebay items, usually coming from China. Typically the cards cost $3
and the shipping is $5.
Antenna Multicoupler:
This powered splitter is
plugged into a household outlet, and lets me split a single antenna feed
to the four scanners. Another Ebay item. Cost me 25 cents, but shipping
was $17.00. Reception quality actually increased after splitting.
The System
The four scanners are all
connected to the same antenna in my attic through the Antenna
Multicoupler.
When a requested frequency
become active in a scanner, two things happen at the same time:
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The
scanner audio is sent to one of the audio cards. The audio
from the scanner is processed in the computer by Simplecast.
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The
scanner sends the frequency information matching the audio to the
computer, and it is recognized by the programs Serproxy and
TalkgroupMonitor through one of the serial COM ports. Within
these programs, the frequencies are matched with the text that will
be
displayed in Winamp.
For
example, if the frequency information of 126.00 is received by
TalkgroupMonitor, it knows to match 126.00 with
the text "Waterloo
Tower".
The audio
from Simplecast and the matched text from TalkgroupMonitor
is then sent to the server software Icecast. Icecast
will deliver the audio and text (for Winamp) over the internet to any
audio program on a listeners' computer.
If the
listener does not use Winamp then only the audio is delivered. If Winamp
is used, the text of the agency being heard will be displayed at the
same time. There is sometimes a very minor lag in time between the audio and
the text display in Winamp if the listener has a slower computer, or if
there are numerous listeners accessing the server Icecast. I have
set the maximum number of listeners at any one time to 25 so as not to
overload the computer, but if I see that number being approached at some
time I'll raise it, and see what happens. I don't really know what is the
maximum number before there is deterioration in the system.
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