[TenTec] cw creation

Wed Apr 27 11:59:39 EDT 2005

Thanks for the research Martin.

I am a retired FAA type that worked at a long range radar (ARSR-1D) that fed 
the Memphis Center (ARTCC).  The method that the radar generated a signal 
was kinda like CW.  A magnetron was keyed with a pulse (dit) at about 363 
pulses per second (high speed dits hi).  Of course this keying was a very 
high pulse of shaped negative voltage about 2 microseconds wide applied to a 
magnetrons cathode.  A pulse forming network shapped this pulse.  During 
this pulse, the magnetron a "cross field device" went into oscillation at a 
frequency in the "L" band that was determined by its cavity.  Now we have a 
pulse consisting of RF energy.  Again kinda like CW with  rapd short   dits. 
  Of course this was a "P" type of modulation not A type but still very 
similar.  And of course CW does have sidebands, determined by the rate and 
shape of the dit/dah    (duh).

I of course with my CW sending do not have to worry about generating a wide 
bandwidth as my speed is slow enough to be safe!

73 to all, de wd4air

>From: "Martin, AA6E" <martin.ewing at gmail.com>
>Reply-To: "Martin, AA6E" <martin.ewing at gmail.com>,Discussion of Ten-Tec 
>Equipment <tentec at contesting.com>
>To: Steve Baron - KB3MM <SteveBaron at starlinx.com>,Discussion of Ten-Tec 
>Equipment <tentec at contesting.com>
>Subject: Re: [TenTec] cw creation
>Date: Wed, 27 Apr 2005 11:39:43 -0400
>
>On 6/26/06, Steve Baron - KB3MM <SteveBaron at starlinx.com> wrote:
> > How does the FCC define CW?
> >
>Having nothing better to do, I went to the FCC website to read up on
>Part 97 and what they say about CW.  The relevant sections are 97.3
>which refer back to 2.201 and 2.202.  Some excerpts are at the end.
>Classical amateur CW  might be 100HA1A, specifying 100 Hz bandwidth,
>or simply A1A. The ARRL FCC Rule Book has some useful material, too.
>
>It seems that the FCC is interested in the signal that shows up on the
>air and not how it is generated.  Fair enough.  Everything we have
>been talking about in this forum is A1A, I believe.   Some generation
>methods (like tones into a poor SSB rig) are worse than others.  FCC
>requires signal purity to observe good engineering practices, or words
>to that effect, and that may rule out the KWM-1 technique nowadays.
>The DSP method (e.g., Orion = TenTec content!) can be as perfect as
>you're willing to pay for.
>
>As the Rule Book (8th ed.) explains, it would be possible to narrow
>the "100 Hz" DSB spectrum of an A1A signal by eliminating one sideband
>(50 Hz) and suppressing the carrier.  (However you make it, CW does
>have a carrier and sidebands just like a voice signal.*)  I wonder if
>anyone has ever done it, and whether a half-width carrier-less CW (or
>psk31?) signal would be decodeable after HF propagation.  You'd need
>really tight frequency and passband control.
>
>73, Martin AA6E
>
>*A carrier?  What about between characters?  Yes, mathematically the
>carrier is still there -- even after you turn your rig off.  Of
>course, there are also very low freq sidebands that conveniently
>cancel out the voltage...  So your rig had better be very very linear
>or it won't be safe to shut off the power!  Don't lose sleep over it.
>;-)
>================================
>97.3(c)
>    (1) CW. International Morse code telegraphy emissions having
>designators with A, C, H, J or R as the first symbol; 1 as the second
>symbol; A or B as the third symbol; and emissions J2A and J2B.
>
>2.201
>(c) 1st symbol
>
>(2) Emission in which the main carrier is amplitude-modulated
>  (including cases where sub-carriers are angle-modulated):..........
>   --Double-sideband.................................................   A
>   --Single-sideband, full carrier...................................   H
>   --Single-sideband, reduced or variable level carrier..............   R
>   --Single-sideband, suppressed carrier.............................   J
>...
>   --Vestigial sideband..............................................   C
>...
>
>(d) Second Symbol--nature of signal(s) modulating the main carrier:
>
>...
>  (2) A single channel containing quantized or digital information      1
>  without the use of a modulating sub-carrier, excluding time-
>  division muliplex..................................................
>  (3) A single channel containing quantized or digital information      2
>  with the use of a modulating sub-carrier, excluding time-division
>  multiplex..........................................................
>...
>
>     (e) Third Symbol--type of information to be transmitted:\2\
>---------------------------------------------------------------------------
>
>     \2\ In this context the word ``information'' does not include
>information of a constant, unvarying nature such as is provided by
>standard frequency emissions, continuous wave and pulse radars, etc.
>
>...
>  (2) Telegraphy--for aural reception................................   A
>  (3) Telegraphy--for automatic reception............................   B
>
>(Also see 2.202 for the bandwidth designators which precede the
>emission type designation.)
>==========================================
>
>--
>martin.ewing at gmail.com
>http://blog.aa6e.net
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