[Ronja] Vacuum tube in Ronja preamplifier

J.D. Bakker jdb at lartmaker.nl
Mon Oct 15 14:02:17 BST 2007


>  >Fibre optic system doesn't have ambient light from the sun with 
>the associated
>>strong noise source.
>
>Indeed, but if the *sun* dominates, then receiver noise factor is not a big
>deal ?

Sun noise doesn't necessarily dominate, see

http://www.pointless.net/pipermail/ronja/2006-August/009130.html
http://www.pointless.net/pipermail/ronja/2006-August/009132.html

ie: daytime sun-induced shot noise is equivalent to ~ -43dBm.

>Then only fix is filtering / optical screening to lower sun optical noise,
>is that not so?

That would be a good plan. I still hope to find the time to 
experiment with gel filters such as are used by theater lightning 
technicians.

Point remains that the current front-end is noisier and less 
sensitive than necessary; IMHO a change of architecture (active 
transimpedance amp versus the resistor that's used now) helps more 
that going for a hard-to-get vacuum tube would.

JDB.
-- 
LART. 250 MIPS under one Watt. Free hardware design files.
http://www.lartmaker.nl/




More information about the Ronja mailing list