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ZL3AI > APRDIG 02.11.06 05:35l 243 Lines 10105 Bytes #999 (0) @ WW
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From: ZL3AI@ZL2BAU.#87.NZL.OC
To : APRDIG@WW
Today's Topics:
1. RS GPS (Ron)
2. Some followup comments on the TNC Test CD (Stephen H. Smith)
3. *** TNC Test CD Update - Mirror Server Now Available ***(Stephen H. Smith)
4. RE: *** TNC Test CD Update - Mirror Server Now Available ***
(scott_at_opentrac.org)
5. RE: *** TNC Test CD Update - Mirror Server Now Available ***
(Christopher T. Day)
6. Re: *** TNC Test CD Update - Mirror Server Now Available ***
(Stephen H. Smith)
7. RE: *** TNC Test CD Update - Mirror Server Now Available ***
(scott_at_opentrac.org)
8. Mobile/Tracker TX power (Robert Bruninga)
9. RE: *** TNC Test CD Update - Mirror Server Now Available ***
(Christopher T. Day)
10. RE: *** TNC Test CD Update - Mirror Server Now Available ***
(scott_at_opentrac.org)
11. Re: *** TNC Test CD Update - Mirror Server Now Available ***
(Robbie, wa9inf)
12. Re: *** TNC Test CD Update - Mirror Server Now Available ***
(Stephen H. Smith)
13. Re: *** TNC Test CD Update - Mirror Server Now Available ***
(John Habbinga)
14. Re: *** TNC Test CD Update - Mirror Server Now Available ***
(Robbie, wa9inf)
15. RE: *** TNC Test CD Update - Mirror Server Now Available ***
(scott_at_opentrac.org)
16. Re: *** TNC Test CD Update - Mirror Server Now Available ***
(Stephen H. Smith)
17. Re: *** TNC Test CD Update - Mirror Server Now Available ***
(Robbie, wa9inf)
18. RE: *** TNC Test CD Update - Mirror Server Now Available ***
(Christopher T. Day)
19. RE: *** APRS TNC Test CD Now Available *** (Dave Baxter)
20. Re: *** APRS TNC Test CD Now Available *** Updated Info
(Stephen H. Smith)
21. Re: *** TNC Test CD Update - Mirror Server Now Available ***
(Stephen Brown Jr)
22. Re: *** TNC Test CD Update - Mirror Server Now Available ***
(Gregg Wonderly)
23. RE: *** TNC Test CD Update - Mirror Server Now Available ***
(scott_at_opentrac.org)
24. RE: Re: *** APRS TNC Test CD Now Available *** Updated Info
(Christopher T. Day)
25. Re: *** TNC Test CD Update - Mirror Server Now Available ***
(Robbie, wa9inf)
26. Service monitors (scott_at_opentrac.org)
27. Re: *** TNC Test CD Update - Mirror Server Now Available ***
(Gregg Wonderly)
28. Re: *** TNC Test CD Update - Mirror Server Now Available ***
(Steve Huston)
29. RE: *** TNC Test CD Update - Mirror Server Now Available ***
(scott_at_opentrac.org)
----------------------------------------------------------------------
Message: 1
Date: Mon, 30 Oct 2006 17:10:21 -0500
From: "Ron" <rgilson_at_adelphia.net>
Subject: [aprssig] RS GPS
I have been using a Radio Shack GPS with a D700. I used a separate 12VDC
with a 7805 regulator. Can I just use the car battery for both the D700
and the GPS??? With the internal bridge in the GPS will using a common
battery cause any problems??? Thanks.
Ron
WA2WWK-9
------------------------------
Message: 2
Date: Mon, 30 Oct 2006 14:14:11 -0800
From: "Stephen H. Smith" <wa8lmf2_at_aol.com>
Subject: [aprssig] Some followup comments on the TNC Test CD
I received a question about the use of Tracks 1 and 2 on the TNC Test CD
>Stephen,
>
>Is track 2 the best way to test a TNC for typical audio, or would data
>recorded from an actual radio speaker jack be a better? I'm
>interested in learning more about the audio that most users would
>present to a TNC, which would not be from the discriminator.
>
>Thanks,
The majority of users take de-emphasized audio from the speaker of a radio
for use with their TNCs because it's the easy thing to do, but this has
many dis-advantages.
1) The level varies, obviously, depending on the volume control setting.
2) The audio de-emphasis curve in many radios is implemented incorrectly
and varies wildly from the EIA standard. (Some radio designs apply
excessive amounts of audio high-frequency rolloff (de-emphasis) in the RX
audio power amp in an effort to attenuate popping noise and make the radio
sound "quieter".) A TNC connected to such "mangled" audio will perform
less than ideally.
3) The speaker audio is usually squelched which can add many milliseconds
of delay to the start of decoding, forcing other users to increase the TXD
time to compensate.
4) A de-emphasized speaker-audio-type connection absolutely WON'T WORK
for 9600 baud operation.
Users have been inhibited from using the direct discriminator connection
due to the need to make connections inside the radio. However, many modern
radios now have the 6-pin mini-DIN "data" or "packet" connector on their
rear panels which provides easy access to the raw discriminator audio.
In this case, the discriminator connection will overcome the problems
above.
Details on the signals available at the 6-pin mini-DIN connector are in
this PDF on my website:
http://wa8lmf.net/msicinfo/MiniDIN6-Packet.pdf
VARIOUS FACTS
* Traditionally, 1200 baud packet has been assumed to have TX pre-emphasis
due to users inserting their TX audio tones into the mic jack, and
de-emphasis at the other end due to being taken off the speaker, In other
words the 2200 Hz high tone has nearly twice the deviation on-the-air than
the 1200 Hz low tone, due to the transmitter mic audio pre-emphasis.
(You can see this by putting a TT or KPC3 in the CAL mode and selecting one
tone at a time while observing the resulting deviation on a service
monitor. Typically the high tone will be set to yield about 3.5 to 4.0 KHz
dev. The low tone will then produce about 2.5 to 3.0 Khz or so.).
* 9600 baud operation is intrinsically transmitted "flat" since it uses
direct FSK of the carrier (rather than audio tones), achieved by applying
DC-coupled logic-level signals directly to the transmitter modulator,
bypassing the mic amp and pre-emphasis entirely..
* The Kantronics TNCs provide jumper-selectable equalization (de-emphasis)
inside the box. You can disable the de-emphasis if you use
already-demphasized audio from the speaker, or enable de-emphasis if you
use raw discriminator audio.
* The Kenwood D700 and TH-D7 transmit the two tones at EXACTLY THE SAME
deviation. (Their internal TNCs are connected DIRECTLY to their TX
modulator and RX discriminator, bypassing the TX mic channel with it's
pre-emph and RX audio channel with it's DE-emphasis.)
* PLL-based decoders (such as the TNC2 and clones) are very intolerant of
the low tone being higher level than the high tone. They must see the high
tone at a level equal to or higher than the low tone. When you have
reverse "twist", i.e. low tone at higher level than the high tone, they
often fail to lock up and decode. Tuned-filter and zero-crossing-detect
TNC demodulators are much less affected by this de-emphasis issue than PLL
types. However, the de-emphasis (or lack therof) does also create phase
shift that will cause the zero-crossings to be slightly advanced or
retarded from their correct point in time.
* If the RX de-emphasis curve on another radio is a little bit excessive,
packets received from Kenwoods will arrive at the attached TNC with the low
tone far LOUDER than the high tone. This can cause the attached TNC to fail
to decode bursts from Kenwoods.
The bottom line of this intractable mess is that some users (mostly Kenwood
owners) transmit "FLAT" while others transmit "PRE-emphasized". Ideally
the receiving TNC has to somehow accommodate both. The best compromise is
to split the difference. Take the receive audio from the discriminator,
and apply just a very slight amount of de-emphasis at the TNC input.
Or provide for a slight amount of optional (jumper-selectable)
high-frequency BOOST at the TNC input to accommodate users that connect to
the radio speaker output.
On my CD, track one emulates receive via raw discriminator, while track two
emulates de-emphasized receive via speaker or earphone jack. **TNC
developers are encourage to use both tracks alternately to optimize their
TNC performance to tolerate BOTH flat AND de-emphasized audio. **
To make the other tracks (recorded "flat" straight off the discriminator)
simulate speaker audio, you will have to connect a de-emphasis network
between the CD player and the TNC.
Assuming the CD player has a low output impedance ( 1K or less, which is
typical of consumer audio devices) and the TNC under test has a high input
impedance (disable any jumpers that select a 600 ohm input Z), then a
simple RC network can do the job. Connect a 100K resistor in series
between the CD player out and the TNC input. Shunt the TNC input to ground
with a 750 pF capacitor. Or use a 47K resistor and a .0015 uF capacitor.
Approximate this value by paralleling a .001 and a .0005 uF cap.) Either of
these two networks will approximate the standard 75 microsecond de-emphasis
network.
--
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! JavAPRS Filter Port 14580 Guide
http://wa8lmf.net/aprs/JAVaprsFilters.htm
UI-View Misc Notes and FAQ
http://wa8lmf.net/aprs/UIview_Notes.htm
"APRS 101" Explanation of APRS Path Selection & Digipeating
http://wa8lmf.net/DigiPaths
Updated "Rev G" APRS http://wa8lmf.net/aprs
Symbols Set for UI-View,
UIpoint and APRSplus:
------------------------------
Message: 3
Date: Mon, 30 Oct 2006 14:42:26 -0800
From: "Stephen H. Smith" <wa8lmf2_at_aol.com>
Subject: [aprssig] *** TNC Test CD Update - Mirror Server Now
Available ***
*** TNC Test CD Update - Mirror Server Now Available ***
John EI7IG of http://ireland.aprs2.net has offered to mirror the two
CD image files on his server located in Europe.
The two new download links have been added to
http://wa8lmf.net/TNCtest/getfile.htm
BTW, Scotts server for the original links has been pounded for 30 GB of
downloads in the first 12 hours after my announcement!
--
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
------------------------------
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