freq meter vs. spectrum analyzer for sweeping

[Michael H. Warfield]

On Wed, Jul 11, 2001 at 08:29:02AM -0700, A. Melon wrote:
> bob said:

> >You need a spectrum analyzer, which shows you signal strength vs.
> >frequency.
> >
> >And you need to worry about intermittent ('burst') bugs.
> >
> >And WTF is an 'infinity' transmitter?

>   Umm, all the stuff being sold for counter surveillance are frequency
> counters of one sort or another.  
>    Infinity transmitter? I guess you don't know much about bugs
> if you don't know that -- try a web search on the term.

	Amusing...  And from what I can tell from the descriptions of the
two types I saw, if you are looking for it with a frequency meter, grid
dip oscilator, specturm analyzer, RF meters, or whatever, then you are
barking up the wrong tree.  Both of what I saw worked through the phone
lines (one using the existing phone line and one using an additional
phone line) and would not be emitting RF.  Are you think of a third type
that activates over the phone but transmitts on RF (Why?  If it transmitts
RF, why not activate it with RF and avoid the need for the telephone
call in, entirely?) or were you just not thinking?  I suppose that one
might be led to the false conclusion that because someone put the word
"transmitter" in the name that it must transmit RF.  The mouthpiece of
a telephone handset is also called a transmitter and doesn't emit a spec
of RF.

	BTW...  A voltmeter across tip and ring should detect the one type
while the other type requires the installation of an additional phone line
and wouldn't ring your phone.  The former (single line) would also interfer
with normal operation of the phone.  Get a "call and hang-up", hang up,
count to twenty, pick up, draw down a dial tone (which could, in theory
be faked - classical modem callback trick) and call someone else,
preferably someone with calling line ID who can verify your phone number
(to avoid stupid loopthrough systems - another classic "man in the middle
trick).  The former also does not work well with ESS switches because
it depends on "calling party disconnect" to hold the line open, which
ESS will not do.  The later (the two line system) was specifically
advertised as working within ESS systems without requiring modification
to the ESS system (obviously to work around the "called party disconnect").

	From the desciptions I have seen for the "classic" ring-up single
line infinity transmitter, it seems to be little more than the "classic"
diode-bridge to hold a line off-hook where the calling party can still
hear the called party phones after the called party hangs up.  Lame...
No transmitter, and you just have to install the bridge and controller
anywhere on the POTS pair between the SLC and any of the phones, even
outside the house on the drop line.  If you have a few thousand feet
of copper loop between you and the SLC, it doesn't even need to be in
your subdivision.  Nothing needs to be installed in the house at all to
make that work.  It's still lame and easy to detect (line voltage
siting at off-hook voltage) and even a "busy line" detector you can get at
Radio Shack (lits up to indicate when another extension is off hook)
should detect it.  But NOT with an RF detector.  :-)  Also wouldn't work
with ISDN phones.

	As far as ring and hang up goes...  We average about 2 of those
per day, always from "out of area" and always tracks down to these moronic
auto telemarketing boxes that overdial the number of operators.  If you
answer the phone and say "hello" and the autodialer doesn't have a free
operator to had you off to, it hangs up the phone.  Been discussions to
make these illegal (since they don't give you an opportunity to tell them
to add you to their "do not call list" they already violate FCC rules in
theory) and to make the use of "out of area" CLID indicators by telemarketers
illegal for the same reasons.  I happen to know people who work for a
company that designs and manufactures those devices.  Some of these
clowns configure them for dialing as many as 10 times as many numbers
as people handling the calls.  That way if you only get 1 out of 10
answering the phone, all your operators stay pretty much busy.  If you
get more than one out of ten answering the phone, you generate a lot
of "call-and-hangup" calls.  But you (the telemarketer) don't care about
them because they can't identify you and they can't tell you to never
call back and the extra calls don't interrupt your dinner.

	Mike
-- 
 Michael H. Warfield    |  (770) 985-6132   |  mhw at WittsEnd.com
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