[aprssig] PIC processor for APRS info for D-STAR mobiles?

Pete Loveall AE5PL Lists hamlists at ametx.com
Mon Jul 7 13:57:54 EDT 2008

> -----Original Message-----
> From: Robert Bruninga
> Sent: Monday, July 07, 2008 12:37 PM
> To: 'TAPR APRS Mailing List'
> Subject: Re: [aprssig] PIC processor for APRS info for D-STAR mobiles?
> But that is an important point of this discussion.  How does the
> local D-STAR mobile position data, get back to the local
> surrounding APRS users?  Sure it gets to the APRS-IS and the
> world, but it should more importantly be injected into the local
> APRS channel directly on RF...  APRS is a local RF system (which
> just happens to have global visibility)...

Again, that is called an IGate.

> OK, so that is the function I was after.  It takes the local
> D-STAR mobile data and gets it to local APRS RF channel?  If so,
> that's good.  That's half the funciton I am after.

Rich's SmartDigi -gates- (read "IGate") D-PRS from D-STAR to AX.25 using -third party- APRS packet format (again, very important distinction between the D-STAR transport and the AX.25 transport).

> > It is not.  It is called an IGate and performs
> > exactly as such.  Because it is a voice medium,
> > it should not be viewed as a data medium and bulk
> > gating to a D-STAR channel will interfere with
> > voice communications.
> Which gets us back to square one.  The last paragraph of the
> Introduction in your paper says that the "bridge can also pass
> APRS packets via the D-STAR DV low-speed channel in TNC-2
> format."  It is the display of those local APRS packets that I
> want to enable for the D-STAR mobile operator via GPS, or HAMHUD
> or any others simple displays...

Correct: TNC2 format encapsulated in the GPS-A form (CRC, etc.).  If those packets are gated from APRS-IS, they will be in 3rd-party format.

> No, I am confused since I want to use this bidirectionality of
> the D-PRS  translation to send limited local APRS position and
> other information to the D-STAR mobiles for display.  It seems
> that to fit in the narrow confines of this DV low-speed channel
> that there has to be some kind of filtering or metering to
> restrict this information only to APRS packets of immediate
> local value to the D-STAR mobile operator.

There is no DV low-speed channel.  Please read my other post comparing your original Mic-E design and D-STAR.  That should clear this up for you.

> I have.  I cannot find any mention in that paper about what
> kinds of APRS packets will be translated by D-PRS back to the
> D-STAR mobile via the low rate DV channel.  It is the nature of
> those packets, how are they filtered to contain only local
> information, and how we are going to display them that I am
> interested in.

That's because D-PRS does not limit what is gated.  It is simply an encapsulation/translation specification.  It does not limit what is transported.  Fortunately, IGates do limit that.

> Good, so therefore any D-PRS translated APRS packets that get
> sent back out to the D-STAR mobiles via the DV low rate channel
> will all be able to display this information.

You consistently use this term "DV low rate channel".  Understand that there is no "DV low rate channel" (ref: recent post on this SIG).  There is only the DV bit stream.  This is an extremely important concept that you are apparently overlooking in your zeal to make this a data channel.

> But why not?  You have made D-PRS bidirectional so that it can
> send APRS information back to the D-STAR users on that DV low
> rate channel.  It seems like all we need to do is figure out the
> filtering mechanism so that this channel (via the add-on PIC
> processors, and map display GPS's and HAMHUDS) can send back
> only immediate local APRS information that the mobile user
> should see on his GPS map and his HAMHUD or other PIC derived
> display...

Please read my post demonstrating the basic comparison of D-PRS/D-STAR and your Mic-E concept.  If you are still confused, please contact me offline and I will try to explain that comparison.

> I am sorry you read my efforts as demeaning.  They are not.
> They are trying to see what we can do to display the local APRS
> information to the D-STAR mobile operator.  It seems all the
> pieces are there:

Your words have been demeaning.  No matter how "honorable" your intentions are, if they are presented in a demeaning manner you turn away those people you most want to work with you.  Please leave this alone on the SIG as the damage has already been done.  If you want to discuss with me privately (and keep it private) about possible future communications with vendors regarding D-PRS, you are always welcome to correspond -privately-.

While your intentions are well understood by everyone on this SIG, your approach and lack of understanding of the D-STAR DV medium has remained a primary obstacle to communicating what D-PRS is and how it plays within the D-STAR and APRS worlds.  At this point, I ask that you read my other post and correspond with me off-list regarding this subject (where it should have stayed in the first place).  As for other people with questions, comments, etc. about D-PRS, I will be happy to discuss it here or privately.


Pete Loveall AE5PL
pete at ae5pl dot net

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