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<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=796545708-24082004>Does
Packet require the tone shift from 1200 to 2200 to occur at a zero crossing ?
</SPAN></FONT></DIV>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV align=left class=OutlookMessageHeader dir=ltr><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B>
aprssig-bounces@lists.tapr.org [mailto:aprssig-bounces@lists.tapr.org]<B>On
Behalf Of </B>scott@opentrac.org<BR><B>Sent:</B> Tuesday, 24 August 2004 4:50
PM<BR><B>To:</B> 'TAPR APRS Mailing List'<BR><B>Subject:</B> RE: [aprssig]
APRS tone encode question<BR><BR></DIV></FONT>
<DIV><SPAN class=125224306-24082004><FONT color=#0000ff face=Arial size=2>I do
all of my schematics and board layouts in Eagle PCB, by
Cadsoft. The library system is awful, but I've gotten used to it,
and it's a good program overall. Hard to beat what it does for the
price.</FONT></SPAN></DIV>
<DIV><SPAN class=125224306-24082004><FONT color=#0000ff face=Arial
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=125224306-24082004><FONT color=#0000ff face=Arial size=2>I
find it's often quicker to sketch out a schematic, generate a board layout,
and etch and drill the board than it would be to build the same circuit on a
protoboard. I just did one today that worked right on the first try,
despite me reversing the top and bottom layers. It's a small board (2.5"
by 3") that serves as a carrier for a surface mount OpenTracker, and provides
APP power connectors (in and out), a power MOSFET for radio power control,
radio connector, serial connector, and RJ11 connector for a 1-wire weather
station. The firmware needs some debugging, but it makes for a very
compact, low-power (8 ma @ 12 volts) weather station. (Power consumption
is down to about 4 ma for some test boards and firmware, but it still needs
work.)</FONT></SPAN></DIV>
<DIV><SPAN class=125224306-24082004><FONT color=#0000ff face=Arial
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=125224306-24082004><FONT color=#0000ff face=Arial
size=2>Scott</FONT></SPAN></DIV>
<DIV><SPAN class=125224306-24082004><FONT color=#0000ff face=Arial
size=2>N1VG</FONT></SPAN></DIV>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV align=left class=OutlookMessageHeader dir=ltr><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B>
aprssig-bounces@lists.tapr.org [mailto:aprssig-bounces@lists.tapr.org]<B>On
Behalf Of </B>Marsh Jas III<BR><B>Sent:</B> Monday, August 23, 2004 8:38
PM<BR><B>To:</B> TAPR APRS Mailing List<BR><B>Subject:</B> RE: [aprssig]
APRS tone encode question<BR><BR></FONT></DIV>
<DIV>Hi Scott:</DIV>
<DIV> </DIV>
<DIV>What program program did you use to make your schematic? It looks
neat.</DIV>
<DIV> </DIV>
<DIV>Tnx. </DIV>
<DIV> </DIV>
<DIV>Jim. w9nje<BR><BR><B><I>scott@opentrac.org</I></B> wrote:</DIV>
<BLOCKQUOTE class=replbq
style="BORDER-LEFT: #1010ff 2px solid; MARGIN-LEFT: 5px; PADDING-LEFT: 5px">The
schematic is here: http://n1vg.net/opentracker/ot1_schematic.png.
The<BR>PWM waveform comes from pin 13 (timer channel 0) of the MCU. The
output is<BR>a 57.6 KHz square wave with the duty cycle determined by the
sine wave<BR>lookup table. The PWM frequency and its harmonics are far
enough out of the<BR>audio passband to not be a
problem.<BR><BR>Scott<BR>N1VG<BR><BR>-----Original Message-----<BR>From:
Andrew Rich [mailto:vk4tec@tech-software.net]<BR>Sent: Monday, August 23,
2004 1:46 PM<BR>To: scott@opentrac.org; 'TAPR APRS Mailing List'; 'TAPR
PIC Development<BR>Special Interest Group'<BR>Subject: RE: [aprssig] APRS
tone encode question<BR><BR><BR>Scott how do you get this waveform ? RC
?<BR><BR><BR>-----Original Message-----<BR>From: Scott Miller
[mailto:scott@3xf.com]On Behalf Of scott@opentrac.org<BR>Sent: Tuesday, 24
August 2004 4:17 AM<BR>To: vk4tec@tech-software.net; 'TAPR APRS Mailing
List'; 'TAPR PIC<BR>Development Special Interest Group'<BR>Subject: RE:
[aprssig] APRS tone encode question<BR><BR><BR>Yeah, I'd expect 16 levels.
Haven't had a chance to look at my TT3 to see<BR>what it's actually
doing.<BR><BR>Here's a snapshot of an OpenTracker's output. Steps aren't
really visible<BR>on this
'scope...<BR><BR>http://n1vg.net/opentracker/images/waveform.jpg<BR><BR>The
OpenTracker uses PWM for D/A. In AFSK mode it uses 4 bits
resolution,<BR>and in BPSK mode it's 8. Works pretty well. I'll have to do
a comparison<BR>of the output waveforms of the TT3, OpenTracker, and MX614
sometime. For<BR>audio stuff, Yoshimasa Electronic's RAL package is great.
It's got a nice<BR>oscilloscope and FFT analyzer display, plus a signal
generator and assorted<BR>other
features.<BR><BR>Scott<BR>N1VG<BR><BR>-----Original Message-----<BR>From:
aprssig-bounces@lists.tapr.org<BR>[mailto:aprssig-bounces@lists.tapr.org]On
Behalf Of Andrew Rich<BR>Sent: Monday, August 23, 2004 2:40 AM<BR>To: TAPR
APRS Special Interest Group; TAPR PIC Development Special<BR>Interest
Group<BR>Subject: [aprssig] APRS tone encode question<BR><BR><BR>I threw
the tinytrak audio onto a CRO and compared it to a sine wave from a<BR>sig
gen.<BR><BR>How come a DAC ladder network of 4 resistors only produces 8
steps ?<BR><BR>Should it not end up being 16 steps
?<BR><BR>0000<BR>0001<BR>0010<BR>0011<BR>0100<BR>0101<BR>0110<BR>0111<BR>1000<BR>1001<BR>1010<BR>1011<BR>1100<BR>1101<BR>1110<BR>1111<BR><BR>image<BR><BR>http://www.tech-software.net/139_3935.JPG<BR><BR><BR>_______________________________________________<BR>aprssig
mailing
list<BR>aprssig@lists.tapr.org<BR>https://lists.tapr.org/cgi-bin/mailman/listinfo/aprssig<BR><BR><BR><BR><BR><BR>_______________________________________________<BR>aprssig
mailing
list<BR>aprssig@lists.tapr.org<BR>https://lists.tapr.org/cgi-bin/mailman/listinfo/aprssig<BR></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BODY></HTML>