Original article from: Rob Dennis 
 Reposted by Moderator HAM_TECH,for use of the FIDO HAM_TECH echo.
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Author: Rob,VE3SJN
Subj:   DF'ing a Jammer,some Hints,Kinks & Tips
Revised: Dec. 1997
Part 1 of 3
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
 We have all at one time or another run into a button-pusher on a local FM
repeater. This `twit' takes great delight in cancelling an auto-patch,dumping
a tone or carrier on a conversation,and generally being a pain in the butt.
 This Q and A file was put together about 5 years ago as a guide to nailing a
few of our more infamous twits here in the Ottawa-Hull area.
 Take it as it is,a bare bones hint,kink and tips check-book to nail that
pesky twerp or at least give him a severe case of the shakes after you find
him,her or it.
-------------------------------
 First ask yourself some general questions about the jammer and he/she/it's
jamming "habits". Most,and darn near ALL jammers have a set pattern if you 
ay
close attention to their activities.
1) Is the time of day the jamming occurs the same or does it change with the
different days of the week ?
 (ie:local drive time,evenings/mornings/latenight/weekends/foul weather ?)
 [HINT: the jammer may work shift-work hours,and play aournd those hours]
2) Does the jammer target only SPECIFIC people,or random ?
  (He/she/it has a `hate-on' for certain,specific people. You can use this
later on for `baiting' the jammer.)
3a) Can you or anyone else hear it on the repeater's input,or inputs if it 
as
multi-band,full-duplex capabilities?
 (helps narrow it down into a rough area,and see if he/she/it is only on one
band or can do more than one band on full-duplex systems)
3b) Does he/she/it knock out certain stations from a repeater and not others
when jamming away?
 (depending on who gets blocked you can get an idea of what area the signal 
s
coming from by knowing where those blocked out stations are.)
 EXAMPLE:
 Jammer comes on while stations east of a rptr. are talking to those to the
west and south of the repeater site.
 Jammer blocks out the south station,yet any west or east one comes right 
ver
the signal into the repeater,but the western one just barely makes it in over
the jamming signal.
 Knowing that info will place he/she/it probably north and west of the 
tation
to the south of the repeater's location,yet south of the western station that
just makes it over the signal.
4) If you can hear the jammer on the input does it sound like it is a mobile
(antenna flutter from motion) or base (solid signal,background house noises)
or a weak HT (noisey and stable)?
 (listening carefully to the signal can tell you things about its source)
5) Is he/she/it only using 144 or does he/she/it have 440,220 or 6m ?
 (helps to `know thine enemy' if they only bother one band or side of a rptr.
they may only have a mono-band radio to jam with,or they may do most of their
talking on another band other than the one they jam.)
6) Does he/she/it jam the same repeaters in a certain sequence every time or
at random on random repeaters?
 (they may make a habit of jamming in the same pattern all the time as they
programmed the radio's memories that way!! BELIEVE IT!)
7) Does the jammer target specific club repeaters/nets/groups,individuals?
 (once again a pattern to be followed )
8) Is it happening mainly during winter snowstorms/rainstorms or at night ?
 (less chance that someone may be out looking for them then...NOT!!)
--> NOTE: This is `jammer's delight' weather as no-one may be that willing to
go out in a blizzard or thunderstorm to go nail them. I've been there and so
have the jammers.
9) Do you have 3 or more people with beams who can take bearings on the
signal ? (poor man's triangulation method)
10) Is there a co-ordinated effort to catch he/she/it?
 (If there isn't START ONE using people who can keep their mouths SHUT if
any information is derived from your efforts. )
11) Does everyone complain,moan and groan or hit their REVerse button to see
if they are at all close to the source?
 (at least a rough area to start in helps more than a `guess-timate')
 Answering these questions can help set-up a pattern to the jamming and help
you nail them. Most important is a well-kept logging of the jamming time and
days of the week and the specific stations jammed.
 A month of logging can tell you a lot about a jammer's habits and favourite
targets he/she/it likes to annoy and give you a base to work from when you do
go out to track them down.
 If they seem to work shifts and jam at odd times over a month,you may be 
ble
to predict when they are going to be active and go hunting for them then.
 You may also begin to see a set pattern to what route through the area they
are driving if the jammer is a mobile station.
 [HINT: Most people drive the same route home and to work every day.]
----------------------------
Now for baiting the jammer:
 This is assuming you have a rough area to start tracking in for the jammer's
location and are ready to go if they show up to `play around'.
1) Can you get 2 or 3 of his/her/it's favourite `targets' to co-operate and
lay a trap the jammer can't resist playing with ?
 (most if not all victims will agree to do anything to nail the rotten little
S.O.B. if they get half a chance at them.)
2) Can the `bait' keep a conversation going long enough to get the jammer all
`riled up' by ignoring them no matter what they do ?
==>TIP: Have two of the jammer's favourite targets talking to each other both
on the `phone AND the repeater at the same time!  (old 11m trick!)
 (ignoring the jammer only makes them jam more often if they see it is having
no effect on those they're jamming,and gives you a chance to get a good track
or bearing on them.)
3) Can you get the local FCC or DOC/IOC field office or local police force
made aware of what you are about to do and get some help from them ?
 If you catch a jammer red-handed it may help to have someone along with the
proper authority to shut them down then and there and lay some charges.
 As jamming of any type is a federal offence under both the Canadian Radio
Act and the FCC regulations you may be lucky and get a local,State,Federal or
Provincial police force to help you when it comes time to ID the jammer.
 (it can also help your case if the police have been having problems of their
own on -their- radio systems around the same time as the jammer is active.)
4) If you can't get any `official' department presence get the trustee/owner
of the repeater being jammed to come along as a witness and to file any 
ormal
complaints with the FCC or DOC/IOC later.
   Have all the `hunters' as willing and ready court-witnesses against the
jammer if the case ever goes into court.
5) With the advent of home-video it may even be a good idea to video-tape any
of the signals as recieved on a radio parked in right front of a jammer's
suspected location with no visible antenna connections on the radio.
   And if you are REAL LUCKY you may get a video of the culprits themselves
through a window from across the street.
----------------------------
Tracking A Jammer:
 Methods can and do vary depending on the terrain you have to go under,over 
r
through to get a bearing on the signal you are after.
 Short of a full-blown Doppler on the mobile to play with here are some ways
that may sound strange at first but odd enough they WORK.
1) Tracking a signal starting in a rough area close to the source:
  PLEASE obey any and all rules of the road,don't go driving around like your
out to try for the INDY500.
  The driver does the driving and the co-pilot does the tracking,PERIOD.
  Simple tools to carry along for hunting:
 -4 element 2m beam
 -1/4 wave magnetic-mount antenna
 -PL-259 and/or BNC connector with 2 inch length of wire soldered into the
center pin of the connector,insulated from the connector's ground-side.
 (this depends on the radio you are using.)
 -an ordinary paper-clip
 -an up-to-date city map (helps if you know where the heck you are)
 -LOTS OF PATIENCE!!!
--- GoldED 2.42.G1219
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