[Laser] RE : Re: Crab Pulsar : Ultimate optical DX ?

[Garnier Yves]

Tim,
Thank you for your very interesting infos:
The Barn Door drive or Scotch Mount principle could be
used with strong frames for heavy devices.
The equatorial table principle for Dobson telescope
could be also used:  
http://members.tripod.com/denverastro/dsdfile/dspfile.htm
Your 3 Hz GPS synchronized EME experiment success will
depend your detector sensitivity, the total
integration time available and your moon target
tracking quality for TX and RX.
Because the very low pulse rate, a low capacitance
photodiode K3PGP RX used like a charge sensitive
amplifier could be nearly as sensitive an APD RX.
This RX diagram could be a good choice:
http://picasaweb.google.fr/F1AVYopto/A1TECHNOSHFEtLASER#5288642173309702290
The use of the HAMAMATSU S5973 photodiode and the
associated precise FETs types are mandatory because
with this schematic, FET's Idss ratio and input
capacitances are critical.
I am going to evaluate its real sensitivity in a few
days.
This 1 GHz PIN photodiode is rather low cost and its 2
pF capacitance at 0V with 3 Gohms Rshunt could be
optimal.
Thank you for ideas and help.
Yves F1AVY  

--- Tim Toast <toasty256 at yahoo.com> a écrit :

> Hi all
> 
> A very interesting report Yves. That is ultimate DX
> and weak signal for sure. I had been reading about
> some things recently that might be some help for
> this and other celestial experiments like EME. 
> 
> One is an alternative to high priced, clock driven,
> equatorial mountings: The Barn Door drive or Scotch
> Mount. It can allow you to track objects for up to
> an hour before resetting depending on the design. 
>
http://www.google.com/search?hl=en&q="barn+door"+mount&btnG=Search
> 
> And another is a simple and cheap way to stabilize
> any crystal oscillator:
> http://www.setileague.org/askdr/xtaloven.htm 
> http://www.qsl.net/k0lr/SW-RX/sw-rx.htm
> 
> I wanted to let you know i am working on getting the
> equipment together to try that 3 Hz GPS synchronized
> EME experiment this spring hopefully. I will also be
> trying on other non-synchronized frequencies as well
> probably.
> http://www.aladal.net/toast/gps_1.jpg
> 
> good luck with all the experiments
> and Happy new year to all!
> 
> 
> 
> ````````````````````````
> Yves wrote:
> 
> Hello all.
> You will find at the bottom of page:
>
http://f1avyopto.wifeo.com/comptes-rendus-et-liens.php
> a first report about tests in the 450 THz band :-))
> !
> Although initial results suggest some hopes there is
> still much to do ...
> Happy new year 2009!
> Yves F1AVY
> http://f1avyopto.wifeo.com
> 
> 
> Tim Toast
> http://www.aladal.net/toast/exp.html
> 
> 
> 
>       
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Yves F1AVY
http://f1avyopto.wifeo.com