[aprssig] Re: NWS CAE

wes at ai4px.com wes at ai4px.com
Sun Sep 23 12:54:59 CDT 2007

Guys, here's the link to the schematic for that audio mixer box.


On 9/22/07, Wes Johnston, AI4PX <wes at ai4px.com> wrote:
> Well, we attended a meeting at the NWS office in Columbia SC today.  They
> have a PC running VMWare which allows them to run xastir under windows along
> with AGWPE sound card software.  The PC has two sound cards, and that's 4
> channels of audio.  What to do with 4 channels of audio?  Monitor 4 voice
> repeaters for mic-e packets of course.  They have three 2m only mobile rigs
> and a tm-d700.  We set it up so that 1/2 of the D700 is data on 144.39, and
> the other 1/2 is monitoring a 70cm voice repeater.  The data 1/2 of the d700
> is connected to the PC with a serial cable.
> Here's where it gets good.  W4CWG has made a REALLY nice audio mixer for
> them.  This mixer allows a pass thru for the 4 audio lines from the radio
> speakers thru to the line level inputs via audio transformers (a la psk31
> interface).  The speaker outputs are paired so that each one goes to the tip
> or ring of a stereo 1/8" jack, which in turn plugs into the line input on
> the PC's sound cards.  This is a 4 mono into 2 stereo arrangement.
> The 4 channels of audio are available individually via headphone jacks on
> the front of the box, but they also feed two 4 channel mixer busses (bus a
> and bus b).  You can mix audio from any of the 4 sources into bus A and/or
> bus B, and there are head phone jacks for each bus.  Additionally, there is
> a headphone jack for both busses and a speaker jack around back.  All of
> this allows any combination of 1 thru 4 operators present to mix-match
> listening to audio from any combination of the 4 radios.  With headphones on
> each operator, they can all work in close proximity to each other.  Ohh and
> there are also LEDs on top of each column in the mixer to let us see which
> radio has active audio.
> W4CWG has said he'll provide a PDF with a schematic in it to me by email.
> When I get it I'll post on a web site somewhere.
> They also have mounted a big screen LCD over the ham station that the
> meteorologists can control to allow us to see their nice sat images and
> radar. With xastir, we can also overlay the ridge radar over the positions
> of spotters running aprs (or spotters that we have created and plotted on
> the map ourselves).   We will also be able to put our xastir image on the
> big LCD for the meteorologists to see.  There is also a printer on the ham
> table so if a weather warning is issued, we can see it right away when
> running the skywarn net.
> Thanks to Gale, KC4PL for creating the VMware image that they use (it's bomb
> proof since if they screw it up, they can simply copy the VMware file back
> from the DVD).
> And thanks to Steve K9NWS for seeing this project thru...
> wow!
> Wes
> --
> In theory there is no difference between practice and theory.

In theory there is no difference between practice and theory.

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