[Laser] Field Day 2004

[laser@mailman.qth.net]

I have tried to absorb the comments by Andy K0SM and Bob K3DJC about Field 
day demonstrations.  It is not clear but I think that each is relating to my 
question about the Field Day rules if an MCW is considered CW for contacts.  
Unfortunately, I do not see the connection.  


Maybe I'm dense, but what I read of the rules, there are three allowable 
contacts: voice, CW, and digital.  It clearly states that ALL voice contacts are 
equivalent, so a voice contact via laser does not distinguish between AM, PWM, 
PPM, subcarrier FM, or digitized voice.  I would probably extend that so far 
as to include synthesized voice.  CW is clearly identified as something 
distinct from voice or digital.  The rules also lump all digital contacts together.  
ATV, SSTV, and others are identified for bonus points as non-traditional 
modes, but I do not see in the rules where they count as contacts for points.  
There also seems to be minimum distance (if I remember, it is derived from VHF/UHF 
contest rules, and is 1 kilometer) though I am not sure if the minimum 
distance applies to bonus demonstrations as well as contacts for score.

Anyway, I want to try to make the laser score the best that I can (It would 
help if I could get more people interested in building equipment.)  A CW 
contact at HF is turning on and off the transmitter for the dits and dahs.  Most 
laser CW contacts are turned on and off at an audio frequency, which are started 
and stopped for the dits and dahs, which is the HF equivalent to keying a code 
practice oscillator into the mike of a SSB rig.  I am not sure that the rules 
would treat the two as equivalent.  I could compare MCW to the high speed 
spark gap rotors used on some stations almost a century ago, but I am not sure 
that makes it any clearer.



CW transmitted by a laser, when detected does not give an audio tone, unless 
you have some sort of optical mixer (to act as a BFO).  That is why we usually 
modulate the laser at an audio tone and send MCW.    Otherwise we would have 
to create a synthetic audio.


>>>>>>  I know the W6's have been using 2m FM handhelds as the 
subcarrier-->>>>>>>>

Andy,  the W6's you refer to, are they modulating the laser beam with a 2M 
subcarrier, or are they frequency modulating a subcarrier at 40KHz on the 
transmit side and then on the receive side up-converting the signal to use 2M HT for 
part of the IF chain and detection?



 
Well I though someone might have done this before.   Thanks for the ideas.


James
N5GUI


--- StripMime Report -- processed MIME parts ---
multipart/alternative
  text/plain (text body -- kept)
  text/html
The reason this message is shown is because the post was in HTML
or had an attachment.  Attachments are not allowed.  To learn how
to post in Plain-Text go to: http://www.expita.com/nomime.html  ---