[aprssig] Maryland X-band Voice Alert

[Robert Bruninga]

A new Crossband APRS Voice Alert system went up in Annapolis Md
today.

Mobiles  can make a call on 445.925 T100 and their call will
come out from the WB4APR-1 repeater site on 144.39 T100 as voice
alert.  This way, instead of only being able to call Voice Alert
mobiles within 3 to 5 miles on simplex, one can call them
anywhere in the county.

The CALLER using this system must say something like this
"WB4APR Crossband Voice Alert, listening on 147.075".  This is
because, the monitoring mobile will not normally know how to
respond.  By announcing a repeater that covers the area of this
voice-alert call, then communications can be established.

We used an ALINCO 605 radio set for cross band repeat.  As an
aside, to my knowledge, you can not force it to be an only
UHF==>VHF cross band, it always works both ways.  So in order to
prevent the UHF xmtr from always being keyed by any VA mobile in
range (packets), we set the VHF side to operate with a 600 KHz
offset.  SO in effect, the VHF side is listening on 144.99 also
with T100 (which is 144.39 +600)... Easy to upt in a memory for
quick access.

In most cases, talk-back-to-UHF is not desired.  The real
objective is as above, to have the Voice-Alert CALLER always
announce his repeater where he is listening.

P.S.  This ALINCO survived 22 VDC for YEARS!  Found this old
X-band radio sitting unused in the repeater tower when we went
to install the 6 meter APRS system.  This old radio was on
146.55 and 445.95 from some project years ago.   So we tried it
and it sounded horrendous with HUMMMMMmmmmm.  Anyway, when we
downloaded a manual to figure out how to reprogram it for APRS
Voice Alert, we swapped out the power supply too, and now it
works great...  Tested the ASTRON P.S and the regulator was shot
AND that radio has been runnning on 22 volts for many YEARS!  On
TX, it came down to about 17 volts with 3 volts of ripple.

Bottom line... The ALINCO 605... What a solid brick to survive!

Bob, Wb4APR


> -----Original Message-----
> From: aprssig-bounces at tapr.org 
> [mailto:aprssig-bounces at tapr.org] On Behalf Of Bob Bruninga 
> Sent: Saturday, August 08, 2009 12:05 AM
> To: aprssig at tapr.org
> Subject: [aprssig] Maryland, NoVa Voice Alert
> 
> For Central Maryland and Northern Virginia: 
> 
> The WN3R crossband Regional APRS Voice Alert repeater is on 
> the air from Fredrick Mountain for testing.   
> 
> The CALLER uses 445.925 T100 TX/RX and his call must contain 
> something like "Crossband Regional Voice Alert, WB4APR 
> listening on 146.52 TONE 100". 
> 
> This comes out on 144.39 T100 Voice alert to ALL APRS voice 
> alert mobiles in the region.  For the mobile to get back to 
> the caller, the mobile must respond on 146.52 with tone 100 
> which then comes back to the caller on 445.925. 
> 
> So once everyone understands how this works, then it will be 
> ideal if all Voice Alert mobiles program T100 into their 
> 146.52 channel for ease of use. 
> 
> As with all use of Voice Alert, the only objective is to make 
> the call and then immediately QSY to a chosen repeater.  In 
> this case, the caller COULD also make a one-way call such as: 
> "Crossband Regional Voice Alert, Wb4APR Listening on the 
> 147.300 repeater".  In this case, no 146.52 call back is
expected. 
> 
> I'm out of the footprint from my haunts, so I am announcing 
> it here so that those over closer to the Fredrick Mountain 
> can give it a try. 
> 
> Use i springly, but be thinking of how we can use this new
asset. 
> 
> Bob, WB4APR 
> 
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