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On 10/22/2011 7:20 PM, Bob Bruninga wrote:
<blockquote cite="mid:201110222320.021445@mp6.usna.edu" type="cite">
<pre wrap="">What we really need is a PACKET ANALYZER software!
Mike Chesena, KA2ZEV suggested something like this.
I think it is a GREAT idea!
Do we have any DSP jockies that can write this code? Or probably most of it alreayd exists somewhere. But the self-calibration will be important so we are all comparing to the same orange.
Bob, WB4APR
_______________________________________________
</pre>
</blockquote>
<br>
You can achieve something close to this with three off-the-shelf
Windows applications together NOW, with no DSP code needing to be
written.<br>
<br>
1) The well-known AGW Packet Engine is a 300/1200/9600 baud KISS
TNC entirely in software that will run on most sound systems.
AGWpe has an internal "tuning aid" display that can create an audio
spectrum analyzer display, a waterfall (time domain spectrum
analyzer) display similar to most PSK programs, and perhaps most
importantly, a simple oscilloscope display that can clearly display
the relative level of the the 1200 and 2200 Hz tones (and the
relative level of different users' bursts). <br>
<br>
2) The companion freeware program "AGW Monitor" automatically
connects to AGWpe's TCP/IP output when started, with absolutely no
configuring or tweaking. It creates an on-screen display similar to
the MONITOR mode of most classic TNCs with the header information
(callsign, path, destination, etc on one line and the packet
payload on a second line. (Or alternatively, you can point any web
browser to localhost:8000 and view the same info via AGWpe's
built-in internal web server output, along with useful stats such as
a MHEARD list of stations that shows how many times each one has
been heard.) <br>
<br>
3) The third application (and second sound card app) is the
absolutely amazing Visual Analyser 2011. This *FREEWARE*
program, written by an Italian electrical engineering PhD candidate
at the University of Rome, emulates a whole stack of HP audio test
instruments in a single 5 MB exe file.<br>
. From the sound card record input(s), Visual Analyzer creates a
dual-trace audio scope with adjustable triggering, a dual-trace
audio spectrum analyzer, an audio frequency counter, an audio
voltmeter that can display in either millivolts, or dB similar to a
"VU" meter, a phase meter (if you have the same tone freq in both
channels) and a harmonic distortion meter. All these parameters can
display in separate windows at the same time from an audio input. <br>
. At the same time, it can create a dual-tone audio GENERATOR,
an audio sweep generator, a function generator (sine, square,
triangle,etc) or a pulse generator with fully configurable pulse
duration and repetition rate on the PLAYBACK (output side) of the
sound system, assuming that the sound card is capable of full duplex
operation. Finally with a few simple external circuit components,
the program can become a ZRLC bridge!<br>
<br>
The spectrum analyzer is capable of linear or log display on either
the X-axis (audio frequency) or Y-axis (amplitude). In the default,
mode, the Y-display is log (expressed in dB) and is limited only by
the dynamic range and noise floor of your sound card. Even a crap
bottom-of-the-line sound system should be able to display a 50 dB
dynamic range, and a GOOD one 90-110 dB. A zoom slider lets you
expand the display to a much smaller dB range on the Y-axis, to the
point where you can easily see tone skewing of only a dB or two, or
accurately measure the noise floor of a radio 20-30 dB below peak
deviation. By default, the spectrum display X-axis is a 3-decade 20
Hz to 20,000 Hz log presentation, but it can be switched to linear
and over a specified min and max range. For normal radio response
testing, I set the display to 200Hz-5000Hz linear. The
scope/analyzer has switchable custom high-pass and low-pass filters
that can keep low frequency components like PL or DCS from producing
"ripple" on the display of higher frequency tones, or to remove
hiss-induced "grass" from off-the-air monitoring of weak
signals. <br>
<br>
"Out of the box", the program displays relative values referenced to
the minimum and maximum counts of the sound card A-D converter. The
program has provisions for being calibrated against a known external
audio source with the results made permanent in a .ini file. The
Visual Analyzer scope and analyzer can then display absolute audio
millivolt and dBm values. <br>
<br>
I hacked a Bearcat 760 scanner and tapped the output of it's
discriminator, wiring it to the existing "Tape Recording output
mini-jack on the back panel . In turn, I attached the audio input of
my iMic external USB sound card (<a
href="http://wa8lmf.net/ham/imic.htm">Click Here for review of
this device on my web site</a>) to the Bearcat's discriminator,
and calibrated the pair with my IFR-1500 service monitor. Using
the external sound system lets me move the assembly from one PC to
another without having to re-calibrate it each time. [Note that
the 6-pin mini-DIN "DATA" or "PACKET" jack on many FM-capable radios
will provide the same kind of raw non-de-emphasized discriminator
output for these kinds of measurements.] The Bearcat/iMic pair
now serves as a quite usable deviation meter and signal monitor. <br>
<br>
Looping the sound card audio generator output back into one channel
of the sound card scope input lets you do very precise
lissajous-figure frequency measurements on received PL tones, DTMF
tones, TNC mark/space tones in CAL mode, etc fed into the other
sound card input channel.<br>
<br>
<br>
It is not too well known that since Windows XP, it is possible to
have more than one program accessing the sound system
simultaneously. I routinely run mmSSTV (analog SSTV), EasyPal
("digital" SSTV) and AGW Packet Engine off the same sound card at
the same time in my APRN (combined SSTV and APRS) setup. In a
similar manner, I run Visual Analyser (for a closeup view of the
wave forms) and AGWpe (to display the packet information)
simultaneously. About the only thing I can't measure exactly is
the TXD, but as you have pointed out, this can be easily guessed at
by ear. <br>
<br>
Download URLs:<br>
<br>
AGW Packet Engine (Free Version)<br>
<a class="moz-txt-link-rfc2396E" href="http://www.sv2agw.com/downloads/agwpe.zip"><http://www.sv2agw.com/downloads/agwpe.zip></a><br>
<br>
AGW Monitor Companion to AGWpe<br>
<a class="moz-txt-link-rfc2396E" href="http://www.sv2agw.com/downloads/AGWMonitor_new.zip"><http://www.sv2agw.com/downloads/AGWMonitor_new.zip></a><br>
<br>
Visual Analyzer 2011 Information<br>
<a class="moz-txt-link-rfc2396E" href="http://www.sillanumsoft.org/prod01.htm"><http://www.sillanumsoft.org/prod01.htm></a><br>
<br>
Visual Analyzer 2011 Download<br>
<a class="moz-txt-link-rfc2396E" href="http://www.sillanumsoft.org/download.htm"><http://www.sillanumsoft.org/download.htm></a><br>
<br>
<hr size="2" width="100%"><br>
--<br>
<br>
Stephen H. Smith wa8lmf (at) aol.com <br>
=== Now relocated from Pasadena, CA back to 8-land (East Lansing,
MI) ===<br>
Skype: WA8LMF<br>
Home Page: <a class="moz-txt-link-freetext" href="http://wa8lmf.net">http://wa8lmf.net</a><br>
<br>
===== Vista & Win7 Install Issues for UI-View and Precision
Mapping =====<br>
<a class="moz-txt-link-freetext" href="http://wa8lmf.net/aprs/UIview_Notes.htm#VistaWin7">http://wa8lmf.net/aprs/UIview_Notes.htm#VistaWin7</a><br>
<br>
*** HF APRS over PSK63 ***<br>
<a class="moz-txt-link-freetext" href="http://wa8lmf.net/APRS_PSK63/index.htm">http://wa8lmf.net/APRS_PSK63/index.htm</a><br>
<br>
"APRS 101" Explanation of APRS Path Selection & Digipeating <br>
<a class="moz-txt-link-freetext" href="http://wa8lmf.net/DigiPaths">http://wa8lmf.net/DigiPaths</a> <br>
<br>
<br>
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