[aprssig] Mobile Digipeating

Jim Alles kb3tbx at gmail.com
Sat Sep 17 10:51:51 CDT 2011

Besides, we really aren't talking about mobile digipeating.  That is not
recommended for APRS, either.

I would call it a re-locatable digipeater, others might use the term
portable.   It is temporary, fixed use.

On Sat, Sep 17, 2011 at 8:53 AM, Lynn W. Deffenbaugh (Mr) <
ldeffenb at homeside.to> wrote:

> A digipeater is not a dual-frequency repeater, but a receive and
> re-transmit on a single frequency.  There is no pre-registration required in
> the United States that I'm aware of.
> Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32
> On 9/17/2011 8:32 AM, Dr. John wrote:
>> Mobile repeaters in the amateur environment is not authorized. As
>> repeaters need to be registered at a fixed position
>> Dr. John Gregory /W3ATE-8
>> ------------------------------**--------------------
>> From: "Tom Russo" <russo at bogodyn.org>
>> Sent: Saturday, September 17, 2011 1:02 AM
>> To: "TAPR APRS Mailing List" <aprssig at tapr.org>
>> Subject: Re: [aprssig] Mobile Digipeating
>> On Fri, Sep 16, 2011 at 10:34:30PM -0600, we recorded a bogon-computron
>>> collision of the <dnchls at gmail.com> flavor, containing:
>>>> I am in search and rescue and use APRS so others can keep track of me.
>>> You're in good company.
>>> I
>>>> live in New Mexico where we have many digipeaters on mountain tops, but
>>>> we
>>>> still have many dead zones.
>>> I've been watching your tracks.  I'm not sure the dead zones are as dead
>>> as
>>> all that.  Still, there are some notable places where there are searches
>>> and
>>> that have spots where you can't be heard.
>>> I have a YAESU VX-8DR ht that I carry with me
>>>> both when practicing and on actual searches. I am considering buying a
>>>> Kenwood TM-D710A. I would like to use the 710 in my mobile as a
>>>> digipeater
>>>> to either get back to search base on a search or to a mountain digi when
>>>> I'm
>>>> practicing so my family can know where I'm at on APRS.fi. I would
>>>> typically
>>>> be within a couple of miles from my truck when I transmitted an APRS
>>>> signal
>>>> from my ht. How much power does the 710 transmit when in digipeater
>>>> mode?
>>> It transmits with the same power that you have set for its own APRS
>>> transmissions.
>>> Would this be a situation where using a mobile would be useful?
>>>> Presently,
>>>> it just doesn't seem I have the punch I need when using the ht.
>>> It would help if your truck is generally within range of your handheld,
>>> the
>>> truck is in a good place where it is getting digipeated, and you don't
>>> have
>>> terrain in between you and the truck that prevents the truck from hearing
>>> you.
>>> In this case you could use your truck's callsign as the first hop in your
>>> digi path, and WIDE2-2 next in the path.  That'd let your truck beacon
>>> you
>>> with more ooomph.
>>> The downside of this is that if you wind up in a spot where your truck's
>>> radio can't hear you, you won't get anywhere even if a WIDE can hear you,
>>> because they won't premptively digipeat before your truck.
>>> It's unfortunate that Yaesu chose not to implement "Proportional Pathing"
>>> in the
>>> VX-8*R series radios.  The VX-8R lets you set 8 paths, but rather than
>>> cycling through them, it simply concatenates them for every transmission.
>>> I'm
>>> unfamiliar with the VX-8DR, maybe it does have proportional pathing.
>>>  With
>>> proportional pathing, you can set multiple digi paths, but rather than
>>> using
>>> them all at once, it cycles through them for each transmission.  Then you
>>> could have "TRUCK,WIDE2-2" for every third transmission,
>>> "WIDE1-1,WIDE2-2" for every third transmission, and "WIDE2-2" for every
>>> third.
>>> That would take care of making sure that at least SOME of your packets
>>> get
>>> to a wide digi --- either directly, or through your truck, or through a
>>> fill-in.
>>> Unfortunately, the people I know both in SAR and amateur radio have never
>>>> played with mobile digipeaters and are pretty clueless on the matter.
>>> Clueless?  I don't think that's a fair statement.
>>> To date, most SAR activities in the state have managed without pressing
>>> need
>>> for mobile digis.  NM SAR Support's comms trailer does have a TNC
>>> programmed
>>> to digi WIDE1-1, so if your path is WIDE1-1, WIDE2-2 (which is OK in NM
>>> for
>>> low-powered stations and ONLY low-powered stations... there was a big
>>> discussion on that subject recently, and you should check the archives
>>> about it, I won't open that can of worms again), then the comms trailer
>>> in
>>> base will serve as a fill-in digi if needed.  We also have a portable
>>> digi we
>>> can place in the search area when necessary.  It is rarely necessary, but
>>> it
>>> does get deployed now and then.
>>> You should also set your D710 to do TEMPn-N digipeating, but I'm sure
>>> Bob B. will pipe in here quickly about that one.  Right now, very few
>>> people
>>> in the SAR community have their radios set up for it, so counting on the
>>> availability of TEMPn-N on searches is not a safe bet just yet.  But if
>>> you
>>> set your own truck to do TEMPn-N, then when you know you aren't reaching
>>> a wide with your handheld on a search, and you know you can hear your
>>> truck,
>>> you can tinker with your path to use TEMPn-N for a while to be sure of
>>> getting
>>> out.  You'd use "TEMP1-1,WIDE2-2" in that case, and as long as your truck
>>> can hear you you're good.
>>> One thing you should NOT do is set your truck to digipeat WIDEn-N as if
>>> it
>>> were permanent infrastructure.  Some folks in NMSAR did do that for a
>>> while
>>> and it was a terrible mistake --- it meant that ALL traffic heard by the
>>> incident comms trailer was getting digipeated if it had any wide hops
>>> left.
>>> That meant the APRS radio in the trailer was transmitting all the time,
>>> and
>>> desensing lots of nearby voice radios every few seconds.
>>> --
>>> Tom Russo    KM5VY   SAR502   DM64ux
>>> http://www.swcp.com/~russo/
>>> Tijeras, NM  QRPL#1592 K2#398  SOC#236 http://kevan.org/brain.cgi?**
>>> DDTNM <http://kevan.org/brain.cgi?DDTNM>
>>> "One man alone can be pretty dumb sometimes, but for real bona fide
>>> stupidity, there ain't nothin' can beat teamwork." - Edward Abbey
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