-=> On 03-01-98  12:23, John Stanley said to Ivy Iverson,<=-
-=>"About RFI...,"<=-
-=> Wednesday, 25 February 1998 22:22:00, Ivy Iverson wrote to John Stanley
 
 JS> Greetings Ivy!
 
Hi again, John;
 
 JS> > Cheap junk...
 JS> Could be right there!
 
{Grin}
 
 II> 2) FILTERING: Get some ferrite doughnuts and run ALL leads into/out of
 JS> The controllers have the beads on as standard.
 
Well, at least they spent a COUPLE of pennies on filtering... possibly
because it was tearing up nearby TV's.   :-/
 
 JS> However, I did find a TX signal on 27.145MHz which is one of 5
 JS> frequencies dedicated for radio controlled cars.  I did located a
 JS> signal which was changing in pitch and sounded like botton press
 JS> signatures, this could have been controller codes from a radi
 JS> controlled vehicle but they tend to change pitches rather than big step
 JS> bursts.
 
It could be a proportional controller, such as throttle or steering for
a toy car (or a joystick).  There are many ways of encoding proportional
controlers, and one is by changing a frequency.  Remember the old remote
control TVs that used ultrasonic tones rather than infra-red or radio
signals, (and you could activate them by jangling a ring of keys)?  Those
tones were detected by a frequency discrimnator just like used in an FM
radio, (though a much lower frequency - just above hearing).  A positive
output activated one function, and a negative voltage activated a
different function.  If they had sensed the voltage level and polarity
instead of just the polarity, they would have had a proportional
controller.
 
I suggest that you check for 27.145 when he has the thing turned on, then
have him turn it off and see if the signal is still there.  Does he have
a wireless (not hard-wired) joystick or other controller with it?  It
could also be a wireless computer mouse or any of a dozen other kinds of
remote-control devices.  Or it could be an internal frequency of the
playstation, used by it's microprocessor.  (Yes, it is a computer, and
computers are FAMOUS as noise generators!)
 
 JS> If this is the TX of the Playstaion then there will be nothing
 JS> I can do about it as it shouldn't be TXing on that frequency anyway.
 
Suggestion: Keep an exact log of ALL your transmissions, and have the
owner of "the thing" keep a log of EXACTLY when he gets the QRM,
(Synchronize watches/clocks).  Then compare the logs.  That will quickly
tell if you or someone/thing else is the culpret.
 
 II> Another 10 feet wouldn't make a noticable difference.
 JS> Well, it's a good excuse to get the antenna a little higher! :)
 
 JS> Thankyou for the advice.
 
My pleasure.  Good luck!
 
 JS> I am going to get him to bring the *thing*
 JS> round here to see if it has anything to do with location.
 
Unlikely, but possible.
 
 JS> 73, 51 to you and your family
 
(My "family" consists of 2 cats, a next-door neighbor and a bunch of
friends from both Hamming and my BBS).   :-}
 
73 DE KB9QPM
   Ivy
 
 
 
... HAM (n) 3. Acronym for Help Another Member.
 
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