[time-nuts] Measuring receiver...

Don Latham djl at montana.com
Tue Jun 21 23:27:38 EDT 2016


Yes, very simple for people, very difficult for “machinery”. 
Don
> On Jun 21, 2016, at 7:01 PM, William H. Fite <omniryx at gmail.com> 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 <mailto:jra at febo.com>> 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:;>> 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:;>>
>>> To: <time-nuts at febo.com <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.
>>>> 
>>>> _______________________________________________
>>>> time-nuts mailing list -- time-nuts at febo.com <javascript:;>
>>>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>>> and follow the instructions there.
>>> 
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts at febo.com <javascript:;>
>>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>> 
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com <javascript:;>
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>> 
> 
> 
> -- 
> I am Pulse. Unbreakable.
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com <mailto:time-nuts at febo.com>
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts <https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts>
> and follow the instructions there.

Felix qui potuit rerum cognoscere causas.
Lucky is he who has been able to understand the causes of things.
Virgil
-------------------------------
"Noli sinere nothos te opprimere"

Dr. Don Latham, AJ7LL
Six Mile Systems LLC, 17850 Six Mile Road
Huson, MT, 59846
mailing address:  POBox 404
Frenchtown MT 59834-0404

VOX 406-626-4304
CEL 406-241-5093
Skype: buffler2
www.lightningforensics.com <http://www.lightningforensics.com/>
www.sixmilesystems.com <http://www.sixmilesystems.com/>


More information about the time-nuts mailing list