[TenTec] cw creation

Wed Apr 27 17:13:46 EDT 2005

A PRF of 363 ?

73 Jeff kb2m AOS-270

----- Original Message ----- 
From: "James Duffer" <dufferjames at hotmail.com>
To: <tentec at contesting.com>
Sent: Wednesday, April 27, 2005 11:59 AM
Subject: Re: [TenTec] cw creation


> 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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>
>
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