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@gmail.com>
>Reply-To: "Martin, AA6E" <martin.ewing@gmail.com>,Discussion of Ten-Tec
>Equipment <tentec@contesting.com>
>To: Steve Baron - KB3MM <SteveBaron@starlinx.com>,Discussion of Ten-Tec
>Equipment <tentec@contesting.com>
>Subject: Re: [TenTec] cw creation
>Date: Wed, 27 Apr 2005 11:39:43 -0400
>
>On 6/26/06, Steve Baron - KB3MM <SteveBaron@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@gmail.com
>http://blog.aa6e.net
>_______________________________________________
>TenTec mailing list
>TenTec@contesting.com
>http://lists.contesting.com/mailman/listinfo/tentec
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|