[Laser] Lunar Eclipse #3

[Art]

Sounds good Tim!!!

I so wish we had a capability to listen from a remote island or a 
boat at least 500 miles off shore!!!!

Someone on a cold island rather than a warm one would have much 
cleaner air and less chance of hearing terrestrial 'qrm'.

Anyway, I look forward to reading the results.

Regards,

Art


>Hi all
>The lunar eclipse is coming up fast...
>
>  Wednesday evening Feb 20th in the US or Feb 21 in the
>early morning hours for people in western Europe. I hope
>all who can will turn their receiver-scopes toward the moon
>and listen for the 120/360 Hz or 100/300Hz signals from
>across the pond. If possible make recordings in .wav
>format. This time it looks like both sides should have an
>equal chance to hear the streetlight buzzes.
>http://www.aladal.net/toast/eclipse.html#feb21
>
>When Yves, F1AVY heard the US 120 Hz signal last year, only
>a narrow strip of the US east coast was visible to him via
>the moon. This time the whole US will be visible as will
>most of western Europe.
>
>Since i have a rather noisey sound card and some local
>interference here, i thought - just for fun - i would try
>to transmit something during the darkest parts of the
>eclipse -  from about 3:00 UT to 3:51 UT (feb 21) 9 to
>9:51pm CST feb 20th.
>I will be blasting away with my xenon strobe transmitter on
>7.126 Hz and 7.629 Hz (DFCW). The strobe will have a
>1-wattsecond energy (1 joule) with a pulse width somewhere
>between 100 and 1000 microseconds - for a peak power of
>1000 to 10,000 watts. At 7 Hz pulse rates, average power
>will be about 7 watts. This is a modified camera strobe
>tube about 3 x 10mm in size, used with an F1.5 lens of
>330mm focal length.
>http://www.aladal.net/toast/optics.html
>It has a beam width of about 0.5 x 1.5 degrees. Just right
>for illuminating the whole moon with the narrow vertical
>and about three moonwidths in the long horizontal
>dimension. I am using a two crystal TTL oscillator with a
>CMOS divider chain to generate the two frequencies for
>triggering the strobe. see image:
>http://www.aladal.net/toast/lexse.jpg
>
>Robert Laszlo, OM1LD has volunteered to listen with a very
>sensitive PMT which will be used with a filter for 400 -
>480nm in the blue. The peak continuum and lines in the blue
>parts of the xenon spectrum are in that range, so those are
>the best wavelengths i assume for his PMT tube.
>Xenon has even stronger lines in the NIR between 800 and
>1000nm making for the best responce from ordinary silicon
>photodiodes or APD's. The highest signal to noise may be in
>the blue though since most of the interfering light during
>the eclipse is reddish.
>I choose the 7 Hz frequency based on Yves' experiments with
>a variable rate strobe some time ago. It appeared there was
>a 'sweet spot' or shoulder of around 7 Hz where higher
>pulse rates had lower amplitudes. So that's really two
>'sweet spots' - the natural responce of silicon photodiodes
>in the NIR to xenon's peak lines and the special 'odd'
>effect of low frequencies with the K3PGP receivers.
>Not that any of that is enough for my signal to be heard by
>anyone, but i do not know it will not work (yet). I figure
>though about half the power my strobe tube generates will
>be captured by my lens and sent moonward. I would have to
>have a fresnel with a faster F ratio to get much more out
>of it.
>
>I don't have a call sign but i will send a DFCW600? signal
>on 7.629 Hz and 7.126 Hz (0.503 Hz shift).
>Starting at 3:00 UT on 7.629 Hz, I will transmit for 10
>minutes then switch to 7.126 for 10 minutes then back again
>etc... so it will look like a 50/50 square-wave test
>pattern.
>
>3ut-------_______-------_______-------_______4ut
>
>...so there is time for about 5 frequency steps over the 51
>minutes of eclipse totality. I hope that is long enough on
>one frequency to be detected :) I could be better off just
>transmitting an unmodulated carrier on one of the
>frequencies.
>
>so good luck and happy eclipse watching!
>
>http://www.aladal.net/toast/moon.html
>
>(TST = toast)
>-___-
>
>
>
> 
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