[aprssig] APRS station on voice repeater - how to monitor

[Robert Bruninga]

>>Seems like one of our local aprs users has forgotten to 
>>switch off the TNC while on one of the local 2m repeaters. 
>>I've tried in vain to monitor with Winpack and Hyperterm 
>>to see what the station is..... even tried monitoring
>>via the input.

This is exactly why Signal Strength Signal location was built 
into APRS.  SImply call up the PHG display which will display
the radio range of all APRS stations, then look at all those
stations who's PHG circle overlaps the PHG circle of the
voice repeater.  Those are your candidates.

Then send out a BULLETIN on APRS that says, LISTEN
on XXXX (the repeater input frequency) and report if
you hear the packet.  If so, enter an APRS DFS report
(DF Signal Strength Report).

Boom, done.  Now you will have the over lapping signal
contrours from all that data and can easily narrow it
down to the one station whos PHG signal contour
intersects with those who report a DFS and heard the
signal.  And it cannot be any of the stations who's PHG
circles intersect any of the 0-DFS reports (of not hearing it) 

Slam-dunk. Done.

But, unfortunately, you have to eliminate most of the UIview
stations, since most of them do not transmit their PHG 
signal contours (because it is not built in),  and they also do 
not have a DFS signal reporting function so that others can 
plot their data either.  Of course, a UIview station CAN 
manuallly enter his PHG data into his position packet and
he can manually format  a DFS report if he reads the spec 
and looks at how to do it and types in the exact byte structure.  

To see how we used this technique on the last stuck
signal in our area, see:

http://www.ew.usna.edu/~bruninga/dfing.html

Oh, to make a DFS report, replace your PHG string
with a DFS string and change the power byte to a
signal report byte on the scale of 0 to 9.  That's
all there is to it...  Your antena height and gain
is the same in both the PHG and DFS reports.

GOod luck.
de WB4APR, Bob