[OZAPRS] FW: [Fwd: 70 cm APRS frequencies]

[Andrew Rich]

conversley, has 6m FM ever been tested ?



----------------------------------------------------------------------
Andrew Rich (VK4TEC)





>From: Bob Bruninga <bruninga at usna.edu>
>Reply-To: ozaprs at marconi.ics.mq.edu.au
>To: vk3jfk at amsat.org, <ozaprs at marconi.ics.mq.edu.au>
>CC: vk2-aprs at yahoogroups.com, Robert Bruninga <bruninga at usna.edu>,

>bewhite at tpg.com.au
>Subject: RE: [OZAPRS] FW: [Fwd: 70 cm APRS frequencies]
>Date: Thu, 20 Nov 2003 18:29:50 -0500 (EST)
>
>On Wed, 19 Nov 2003, Richard Hoskin wrote:
>
> > When this subject came up a year or two ago John Martin/Peter
Hallgarten
> > suggested we use 439.100Mhz for a National UHF APRS frequency but due
to
> > the other issues the WIA never ratified this in the band plan.
>
>WB4APR's 2 cents for what its worth...
>
>1) APRS is a SINGLE frequency tactical system for end users.  There is no
>need or desire (in general) for other than one freq.  Everyone wants and
>needs to be "where the local action is"...  (If everyone is not on the
>same channel, then everyone is not seeing the same tactical information)
>and you dont have a real-time tactical system...
>
>2) UHF for single UI mobile packets is MUCH WORSE than VHF due to
>triple the mobile flutter rate and 9 dB worse path loss dipole to dipole
>and 7 dB worse modem detection...
>
>3) APRS needs  UHF backbones to tie the long haul packets between end
>users on local LANS operating on the single national frequency.  These
>cross links and backbones CANNOT all operate on a common UHF frequency
>(hence, there is no need for a "common APRS UHF frequency))...
>
>4) Mobiles (think Kenwooods and HAM-HUDS) have NO NEED for LOTS of
>incoming megabytes of positions from anywhere but their local area.  They
>cannnot display it and the driver cannot ABSORB IT.  THus there is NO
NEED
>for UHF or 9600 baud to imporve the SPAM rate to mobiles...
>
>5) CONVERSLY, those with full displays and PC's are usually fixed.  THey
>DO WANT TO SEE lots of stuff.  But they are FIXED and LOCAL and so they
>have no problem "remembering" their local UHF backbone or LINK.  Again,
>there is no need for a common (mutually interferring) high speed UHF
>backbone frequency.  For best integration, it is desired that all high
>speed UHF feeds use DIFFERENT channels to completely avoid the mutual
>interfere3ce and to give dedicated full time access.
>
>So my conclusion after looking at this for YEARS, is that there is just
no
>need for a single coordinated UHF APRS channel.  But there is a need for
>EVERY local APRS lan to coordinate a LOCAL UHF channel (different from
>their 4 neighboring LANS) to feed high speed data to the LAN...
>
>Just my two cents...
>de WB4APR, Bob
>
>
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