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Wed Nov 18 21:02:00 UTC 2009


rates, preferably at the mountaintop digipeater site, or at a home station,
to where other home and mobile stations are aware of ALL APRS activity in
their area, and the blend makes it transparent for any user to access this
data, and include some filtering or adjusting of path selection and other
variables.

We continue our discussions on the nwaprssig reflector, and have it included
in our list of presentations for the September 10th NWAPRS Summer Gathering,
more info for which can be found on the http://www.nwaprs.info web site.
Many thanks to Bob (K7OFT) and Scott (N7FSP) for their assistance in
preparing this message for discussion.

Regret I won't be able to attend the TAPR DCC in Portland at the end of
September, but wanted to get this out there now in hopes there will be some
discussions on it here in the sigs and at DCC.

David K7GPS
Lead Coordinator NWAPRS
Home QTH Spokane
Sunning by the pool in Tucson

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<span style=3D"BORDER-COLLAPSE: collapse; FONT-FAMILY: arial, sans-serif; F=
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<div>Hi all APRS and NWAPRS enthusiasts:</div>
<div>=A0</div>
<div>Within the NWAPRS region a couple groups of hams have been developing =
alternate APRS networks on 9600bd with great success. The project started b=
ecause the saturation of APRS activity on the primary freq, 144.39 at 1200b=
d, particularly around the Puget Sound region and Seattle. If you&#39;d tun=
e into the 144.39 freq you&#39;ll rarely hear a quiet moment, and we suspec=
t upwards of 50% of the packet activity never gets through due to collision=
s of u/i packets. I suppose this is happening in other larger metro areas a=
round the country and with our overseas friends.</div>

<div><br>The desire for further optimization sparked experimentation of 960=
0bd APRS on both UHF and VHF frequencies. Success was found on both bands, =
but one draw back on UHF was locating a common freq that could be expanded =
out of the Puget Sound region. We still haven&#39;t discovered that common =
freq that will work everywhere as we have on VHF, but we continue experimen=
ting on 440.800Mhz under the direction of Bob (K7OFT) in Seattle. A typical=
 WIDEn-N digi on 9600bd employs a Kenwood TM-D700 in some locations, or an =
Icom IC-207 and Kantronics KPC-9612 in others. Bob continues APRS developme=
nt on=A0220Mhz around the Seattle area as well. Bob (K7OFT)=A0has proven AP=
RS at 9600bd is a viable alternative to the crowded 1200bd activity on 144.=
39Mhz, but also notes that while the D700 can DIGIPEAT in APRS Packet mode,=
 it does so with a limited set of commands. The D700 internal=A0TNC is=A0no=
t fully compatible with what we want to do within the compatibility require=
ments.=A0The D700 is just about the=A0only rig we can use if we stay on 144=
.350 and 144.390MHz.=A0The reason is because the D700 turns off the receive=
r opposite of the band you are transmitting on.=A0So if you transmit on 144=
.350 then the receiver on 144.390MHz is shut off, and vice-versa.=A0Otherwi=
se the front end of the listening receiver could suffer damage because the =
40Khz=A0may be=A0too close to not cause problems. In Bob&#39;s experimentat=
ion,=A0we believe that the only way we can get around the limited commands =
problem is to use Digi_ned at the digi site.=A0Bob (K7OFT)=A0also notes we =
should be looking for an easy solution to passing messages and one-liners t=
o and from the primary and alternate frequencies.<br>
</div>
<div>From early analysis we=A0discovered a new problem of sharing data with=
in the two environments in what later evolved into the topic of this report=
, BLENDED APRS DEVELOPMENT.=A0 At our planning meeting for the NWAPRS Summe=
r Gathering Scott (N7FSP), brought up &quot;Blended APRS Networks&quot; to =
allow the sharing of APRS information across the various networks in the ar=
ea so that users were able to better share information between networks wit=
hout the use of the Internet. Simply put, we haven&#39;t discovered an easy=
 way to implement the crossband sharing of data specific to a mountaintop W=
IDEn-N digipeater. Our work continues.</div>

<div><br>In steps Scott (N7FSP), and Casey (KJ7XE), who both have interest =
and most importantly, mountaintop access, where development of a VHF 9600bd=
 experiment could continue. Scott settled on 144.35Mhz as it appears widely=
 under-utilized across the spectrum. The real &quot;jewel&quot; in this dev=
elopment was the reduction in implementation cost by combining a Kenwood TM=
-D700 and external Kantronics KPC-3 to come up with one &quot;easy&quot; di=
gipeater package resulting in 1200bd and 9600bd APRS on VHF with no need fo=
r another (UHF) antenna, feed line or coax, or other ancillary equipment ne=
eded to install a separate UHF radio at the remote location. The Kenwood D7=
00 is configured to digipeat APRS on the radio&#39;s A band on 144.35Mhz an=
d internal TNC at 9600bd, while the B band is tuned to 144.39Mhz and uses a=
n external KPC-3 set at 1200bd. The cost savings is better than two separat=
e radio systems at the mountaintop, and upgrading a typical VHF radio plus =
KPC-3 digipeater is easy; just replace the radio with a Kenwood TM-D700 and=
 you&#39;re in business on two freqs, one at 1200bd and the other 9600bd. T=
he XTAL/CRYSTL digipeater is the FIRST true &quot;Double Sided Digi&quot; (=
quote to K7MCR) that we know of.</div>

<div><br>OK, so we have lots of room for growth at the 9600bd environment, =
which means more data can be pumped to the users on 9600bd. We&#39;re still=
 working out exactly what we want to expand with, but for the most part the=
re&#39;s room for those 10 second trackers or club announcements and flood =
closure warnings or whatever.</div>

<div><br>Now comes the problem we&#39;re attempting to resolve now, with ou=
r BLENDED APRS DEVELOPMENT project. As it exists now, two mobile travelers,=
 one on the primary freq 144.39Mhz at 1200bd, and the other on the secondar=
y freq 144.35Mhz or 440.800Mhz at 9600bd, both driving down I-5 equipped wi=
th Kenwood TM-D710 radios and AvMap G5 GPSs, neither will know of each othe=
r&#39;s presence unless they&#39;re both communicating on a common voice fr=
equency. A nearby home station, typically setup for the primary freq, will =
only see the one station unless his APRS application, typically UI-View, is=
 also pulling data from the APRS-IS. Many don&#39;t, relying only on the RF=
 picture plotted on their screen. Another nearby home station, new and impr=
oved, but monitoring only the secondary freq with a 96kb-only TNC, will see=
 only the one station unless his APRS application is also pulling data from=
 the APRS-IS. A third home station, pulling only the APRS-IS feed, may see =
both stations while the fourth home station, with deeper pockets, has UI-Vi=
ew running on his computer connected to a KPC-9612 and two radios, one on 1=
44.35Mhz or 440.800Mhz and the other 144.39Mhz.</div>

<div><br>From this comes our goal of blending the various APRS frequencies =
and baud rates, preferably at the mountaintop digipeater site, or at a home=
 station, to where other home and mobile stations are aware of ALL APRS act=
ivity in their area, and the blend makes it transparent for any user to acc=
ess this data, and include some filtering or adjusting of path selection an=
d other variables.</div>

<div><br>We continue our discussions on the nwaprssig reflector, and have i=
t included in our list of presentations for the September 10th NWAPRS Summe=
r Gathering, more info for which can be found on the <a href=3D"http://www.=
nwaprs.info/" target=3D"_blank">http://www.nwaprs.info</a> web site. Many t=
hanks to Bob (K7OFT) and Scott (N7FSP) for their assistance in preparing th=
is message for discussion.</div>

<div>=A0</div>
<div>Regret I won&#39;t be able to attend the TAPR DCC in Portland at the e=
nd of September, but wanted to get this out there now in hopes there will b=
e some discussions on it here in the sigs and at DCC.</div>
<div><br>David K7GPS<br>Lead Coordinator NWAPRS<br>Home QTH Spokane<br>Sunn=
ing by the pool in Tucson</div></span>

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