[aprssig] *** APRS TNC Test CD Now Available ***
dave at emv.co.uk
Tue Oct 31 03:13:08 CST 2006
Downloaded it last night, all 500MEG+ zip file, two hours over 2MEG DSL
(I know, overheads etc) but not a problem.
Burnt it to a CD this morning, just to check, then had a quick listen
with mk1 ear-ole, just to check the disk burnt OK.
The track numbering is a bit odd. Track 1 is very short and blank,
track two announces itself as "Track One" , track 3 announcement is
"Track Two" and so on....
The "De-emphasised" audio is "very" muffled, compared to what comes out
of the rig speaker jacks hear in the UK. I'm not aware of any US/EU
differences in Ham FM radio charactersisics, but I suspect some TNC's
will struggle with the "De-emphasised" tracks, where as they will work
just fine with a real FM radio speaker jack feed. I have a collection
of TNC-220's, none have a problem with radio speaker feeds, so long as
you load the radio with say a 10r resistor, and that's more like keeping
the radio's speaker output chip bias point in the right place.
The "Non de-emphasised" audio examples are as expected very "bright" to
say the least.
I was playing it on a true audio CD player (a 10 year old discman) into
'phones, with all the audio enhancements turned off, just a flat
response, as near as. I'll feed it to a TNC tonight, and see what
happens. Let you know.
Overall, a nice idea, well done that man...
> -----Original Message-----
> From: Stephen H. Smith [mailto:wa8lmf2 at aol.com]
> Sent: Monday, October 30, 2006 7:18 AM
> To: TAPR APRS Mailing List
> Subject: [aprssig] *** APRS TNC Test CD Now Available ***
> *** APRS TNC Test CD Now Available ***
> I have produced a CD containing signals for testing and
> comparing the performance of different packet TNCs, and
> radios that might be used with these TNCs. The recordings of
> live off-the-air APRS activity are also useful for
> demonstrations in locations where live signals aren't
> available, such as a basement conference room.
> This disk is a "CD-Plus" combination disk that contains
> CD-ROM data files viewable on a computer, and standard CD
> audio files playable on any normal home or car audio CD
> player, boombox or DiskMan.
> The audio files could also be played on an old CD-ROM drive
> standalone, without a computer, by connecting the TNC under
> test to the drive's front panel earphone jack, or to the
> 4-pin analog audio jack on the drive's rear panel. (A CD-ROM
> drive normally doesn't need computer support to play audio
> CDs. A drive with a front panel volume control and
> track-select button is preferred.)
> Playing back standard CD audio rather than CD-ROM .wav or
> .aiff audio data files avoids the timing errors and incorrect
> playback sample rates that often accompany low-cost
> software-based PC sound systems (i.e.
> motherboard AC97-based systems).
> Details on the disk, links for downloading the 530MB image
> file for creating this CD, and a link for purchasing a
> ready-made CD, are located on my website at:
> Scott, N1VG, of OpenTrac fame ( http://opentrac.org ) is
> handling the sale of recorded disks on his Argentdata
> e-commerce site, and has also graciously volunteered to host
> the large downloadable CD image files on his server.
> About The Tracks
> ---- Track 1 is an off-the-air recording of 40 minutes of activity on
> 144.39 MHz in Los Angeles, California, during the afternoon
> rush hour at about 5:00 PM when the channel is totally
> saturated to several hundred percent of the Aloha threshold.
> It contains a variety of over- and
> under- deviated signals, packet collisions, rapid-fire
> packets with practically no pause between them, raw NMEA
> string trackers, TinyTraks, clueless idiots using CW ID on
> packet, etc. All periods of dead air over about 1 second have
> been edited out so that 40 minutes of real-life activity have
> been compressed to 25 minutes on the CD.
> This track is intended to be played back directly into TNCs
> to compare the performance of various TNCs "under fire" in
> the real world . The rapid pace of the packets should be a
> good test of the ability of buffers in TNCs and associated
> applications to hand a rapid flow of data without overrunning.
> ---- Track 2 is identical to Track 3 except that a precise
> 6db-per-octave/20db-per-decade de-emphasis between 300 and
> 3000 Hz has been applied to simulate the typical de-emphasis
> found at the volume control or speaker output of the typical
> land-mobile receiver. This can used to evaluate the relative
> performance of TNCs in handling raw non-deemphasized
> discriminator audio vs de-emphasized speaker audio. The
> effectiveness of jumper-selected equalization networks
> available inside some TNCs can also be tested. This track was
> created by applying the graphic equalizer filter in Adobe
> Audition set to simulate the standard EIA land-mobile radio
> de-emphasis curve.
> ---- Track 3 is a recording of a Kenwood D700 transceiver
> sending a Mic-E position report, taken from the wideband
> low-distortion discriminator output of an IFR1500 service
> monitor. This recording of a single packet was then copied
> and pasted repeatedly in the Adobe Audition audio editor. The
> result is 20 bursts each minute, for 5 minutes, for a total
> of 100 absolutely identical packets.
> This track is intended to modulate an RF signal generator.
> Connect the CD player to the external modulation input of a
> generator, and set the playback level so that the data bursts
> deviate the generator about 3.5 KHz. Connect a radio's
> receive audio output to the TNC under test.
> Connect the RF generator to the radio's antenna input. While
> the recording is playing, gradually decrease the generator RF
> output level until the TNC starts failing to decode. Since
> the recording contains exactly 100 bursts, counting the
> number of successful decodes can directly indicate the
> percent success rate at various RF carrier levels.
> Possible uses of this track:
> 1) Compare different TNCs connected to the same radio.
> 2) Connect the same TNC to different radios to compare the
> weak-signal data performance of various receivers.
> 3) Evaluate the relative receive performance of audio
> taken from the
> radio's speaker versus audio taken from dedicated "data" or "packet"
> jacks or outputs. (De-emphasis and audio bandwidth may be
> different at these two sources.)
> --- Track 4 is an off-air recording of 25 minutes of a single mobile
> D700 beaconing every 12 seconds (maximum beacon rate) on a
> quiet channel
> (no other stations) while driving around the San Gabriel
> Valley area of
> Los Angeles. The signals were monitored in Pasadena,
> California. Most of
> the drive test course was 8-10 miles from the fixed station,
> far enough
> away from the monitoring fixed station to create some mobile flutter,
> multipath and loss of quieting. In several stretches, several
> packets are audible on the recording but failed to decode
> with the AGW
> packet engine.
> Again, this recording was taken from the non-de-emphasized direct
> discriminator output of a Yaesu FT-1500b via the 6-pin mini-din data
> This track is intended to be played back directly into TNCs
> under test.
> An APRS application running on a computer attached to the TNC should
> create a realistic moving object.
> The three following tracks are for TNC alignment rather than testing.
> They are intended to evaluate TNC demodulator tolerance to
> tone "skew"
> (unequal levels of the 1200 and 2200 Hz tones).
> ---- Track 5 is a direct recording of one minute of a KPC3+
> TNC in the
> CAL mode sending the alternating 1/0 test pattern (i.e. alternating
> between 1200 and 2200 Hz tones) with both tones at the same amplitude.
> ---- Track 6 is the same recording with a precise 6 dB/octave 20
> dB/decade DE-emphasis applied as in Track 3 above.
> ---- Track 7 is the same recording with a mirror-image precise 6
> dB/octave 20 dB/decade PRE-emphasis applied.
> Stephen H. Smith wa8lmf (at) aol.com
> EchoLink Node: 14400 [Think bottom of the 2M band]
> Home Page: http://wa8lmf.com --OR-- http://wa8lmf.net
> NEW! TNC Test CD
> JavAPRS Filter Port 14580 Guide
> UI-View Misc Notes and FAQ
> "APRS 101" Explanation of APRS Path Selection & Digipeating
> Updated "Rev G" APRS http://wa8lmf.net/aprs
> Symbols Set for UI-View,
> UIpoint and APRSplus:
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