[time-nuts] Measuring receiver...
steve heidmann
steveheidmann at yahoo.com
Wed Jun 22 14:11:26 EDT 2016
Don't forget the Digikey !!
--------------------------------------------
On Wed, 6/22/16, Richard W. Solomon <w1ksz at earthlink.net> wrote:
Subject: Re: [time-nuts] Measuring receiver...
To: "'Discussion of precise time and frequency measurement'" <time-nuts at febo.com>
Date: Wednesday, June 22, 2016, 9:20 AM
Back before Iambic
Paddles and Computer Keyers, the Vibroplex Bug
(or some copy cat version) was the key of
choice.
You could ID
Operators by what they called ..."swing"... , the
spacing between Dots and Dashes.
73, Dick, W1KSZ
-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces at febo.com]
On Behalf Of William H. Fite
Sent:
Wednesday, June 22, 2016 6:54 AM
To:
Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Measuring
receiver...
I was a newbie
at the very tail end of commercial telegraphy but the old
guys spoke of operators who "sent with an accent"
and one apparently memorable employee who
"stammered."
On Wednesday, June 22, 2016, Bob Camp <kb8tq at n1k.org>
wrote:
> Hi
>
> Based on what I have
read, at least at the start of WWII, the
> recognition was all done by ear. The
operator rather than the
> transmitter
was the key. The gear to do much else simply was not out
> in the field.
>
> Bob
>
>
> > On Jun 21, 2016,
at 9:01 PM, William H. Fite <omniryx at gmail.com
> <javascript:;>> wrote:
> >
> > In the days
of my misspent youth, I worked as a telegrapher (one of
> > the very last) for a Norwegian
shipping line. We sent and received
>
> both Norwegian and English though few of us were
bilingual. Between
> > ships and
shore stations, there were about forty of us and we all
> > could recognize each other's
"fists" with near-perfect accuracy.
> > This is not difficult, gentlemen, and
does not require any esoteric signal analysis.
> Transmitters
> >
would be a different story.
> >
> > Bill KJ4SLP
>
>
> >
> >
> > On Tuesday, June 21, 2016, John
Ackermann N8UR <jra at febo.com
> <javascript:;>> wrote:
> >
> >>
I've seen references that at least by the latter part of
WW2
> oscillographs
>
>> were being used to identify transmitters and/or
ops. It should be
> possible
> >> to deduce chirp, rise time, fall
time of signals, all of which
>
characterize
> >> the transmitter,
as well as element spacing and other
>
>> characteristics
> that
> >> help identify the operator, from
oscilloscope snapshots of the
>
demodulated
> >> audio at various
sweep speeds.
> >>
> >>
> >>>
On Jun 21, 2016, at 7:02 PM, Alan Melia <alan.melia at btinternet.com
> <javascript:;>
>
>> <javascript:;>> wrote:
> >>>
>
>>> TX "fingerprinting" in WWII
> >>> You seem to be forgetting
that there were very few of the
>
>>> sophisticated
> >>
digital timing systems were available 75 years ago. Traffic
> >> analysis was started early in
1938 or even before. By 1939 we knew
>
>> all the nets used
> in
> >> Europe and had "Y" ( a
corruption of WI, Wireless Intercept
>
>> )operators monitoring the nets. Many of these were
amateurs and
> >> they were
> allocated to
> >>
specific nets and followed them around as they moved. They
became
> >> very familiar with the
"accents" of operators on their nets, and
> >> particularly before 1939 security
procedures were very lax and "chatting"
> >> common-place.....but it was all
aural.
> >>>
> >>> I suspect serious transmitter
parameter logging was not done
>
>>> before the
> >> cold
war when spectrum analysers, or at least pan-adapters became
> >> more readily available. To
keep a little OnTopic .....you would
>
>> have
> difficulty
> >> doing this with a BC-221.!! :-))
A crystal clock of this period was
>
>> at least one fully utilised 6foot 19inch rack
(there is one at
> >>
Grenwich.)
> >>> Alan
> >>> G3NYK
>
>>>
> >>>
> >>> Alan
>
>>> G3NYK
> >>>
> >>> ----- Original Message -----
From: "jimlux" <jimlux at earthlink.net
> <javascript:;>
>
>> <javascript:;>>
>
>>> To: <time-nuts at febo.com
<javascript:;> <javascript:;>>
> >>> Sent: Tuesday, June 21, 2016
10:02 PM
> >>> Subject: Re:
[time-nuts] Measuring receiver...
>
>>>
> >>>
> >>>>> On 6/21/16 11:28 AM,
Brooke Clarke wrote:
>
>>>>> Hi:
>
>>>>>
>
>>>>> During W.W.II there were secret methods
of "fingerprinting"
>
>>>>> radio transmitters and separately the
operators.
> >>>>> I
suspect the transmitter fingerprinting involved things
like
> frequency
>
>>>>> accuracy, stability, CW rise and decay
time, &Etc. For the
>
>>>>> operator
> >>
some
> >>>>> from of
statistics on the timings associated with sending Morse
Code.
> >>>>> But. . . I
haven't seen any papers describing this. Can anyone
> point
>
>>>>> me to a paper on this?
> >>>> For "human
controlled" stuff, e.g. recognizing someone's
"fist",
> >> there's
a huge literature out there on biometric identification
> >> looking
>
at
> >> things like keyboard and
mouse click timing - the timing
>
>> requirements
> are
> >> pretty slack, and hardly
time-nuts level, unless you're looking to
> >> do it with mechanical devices
constructed from spare twigs and
>
>> strands of
> kelp.
> >>>>
>
>>>> There have been a variety of schemes for
recognizing individual
>
>>>> radios
> >> by
looking at the frequency vs time as they start up. Likewise,
> >> it's
>
pretty
> >> easy to distinguish
radar magnetrons from each other. Not a lot of
> papers
> >> about
this, but you'll see it in advertising literature, or
> occasionally in
>
>> conference pubs (although I can't think of any
off hand). There
> >> was
someone selling a repeater access control system that was
based
> >> on the transmitter
fingerprint.
> >>>>
> >>>> But the real reason why
you don't see any publications is that
> >>>> this
>
>> stuff is pretty classic signals intelligence
(SIGINT or MASINT) and
> >> it
> is
> >> still
being used, and is all classified. You're not relying on
> >> Betty the receiver operator
to recognize the characteristic chirp
>
>> as the agent's radio is keyed, it's all
done by computer now, but
> >> the
basic idea is the same. And as with most of this stuff,
the
> >> basics are well known,
but
> the
> >>
practical details are not, or, at least, are the proprietary
secret
> sauce
>
>> in any practical system. (In a significant
understatement, Dixon,
> >> in
"Spread Spectrum Systems" makes some comment about
how synch
> acquisition is
> >> the difficult part and won't
be described in the book)
>
>>>>
> >>>> You
might look at the unclassified proceedings of conferences
> >>>> like
> >> MILCOM and find something.
Googling with MASINT might also help.
>
>>>>
> >>>>
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> >>>>
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> >>>
> >>>
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> >
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