[UK-CONTEST] IOTA Logging Advice Please

[G3WGV at aol.com]

In a message dated 14/11/2003 10:08:48 GMT Standard Time, 
G3SVL at manyoaks.co.uk writes:
Forgot to mention in my last posting that I have seen RF problems on long 
ethernet cables. Specifically it was connecting two tents approx 50m apart 
on VHF FD for packet cluster access. The ethernet cable was troubled by 
350W of 2m. We fitted WiFi boards at both ends - they worked and were RF 
immune.

I didn't have the courage to try WiFi for IOTA this year but have played 
with it here between two machines. So it could be that WiFi is more RF 
resilient than a long twisted pair ethernet cable.  Anyone out there had 
any experience with WiFi in RF rich environments?


Of LANs and Wirelesses and things...

UTP is, IMO, a menace to Amateur Radio in anything longer than about 3m 
lengths.  It relies upon the balanced pair posessing common mode rejection, which 
in turn is totally dependent on the accuracy with which the pairs are twisted.  
Otherwise, it's basically another antenna, with all its EMC susceptibilities 
in both directions.

At D68C we used 10Base2 (UR43-like coax to us radio types) and by and large 
this worked well, though we did get some sprogs on 30m, which we fixed by 
burying the cable a few inches underground.  We also occasionally had the LAN drop 
out, which we attributed to lots of QRO transmissions all coming together at 
the same time.  These days 10Base2 is becoming tricky to implement as suitable 
terminating hubs, NICs, etc are getting hard to source.

For 3B9C it seemed to me that WiFi was the way to go, so as the DXpedition 
technology guy, I started experimenting.  So far I have been completely unable 
to detect any EMC troubles in either direction.  Once you get it set up 
properly, the LAN is stable and, more or less, works just like a wired LAN.  It may 
also help with good RF engineeering practice, because the LAN no longer creates 
an electrical connection between the stations.

WiFi is becoming extremely cheap now.  I obtained very satisfactory CardBus 
NICs at £15.99 + VAT and the associated access point can be bought for under 
£50.  It seems that it is hardly worth using wired LAN any more!  Right now, 
here in the shack, I have 16 (yes 16!) PCs all connected together via a wireless 
LAN, as the testbed for 3B9C.  I can detect no trace of noise in my station RX 
(at least none that I can attribute to the LAN) and I am unable to cause the 
LAN distress with the maximum amount (ahem) of power that I am able to muster 
on bands from 160m to 2m.  Conclusion... I think it'll work just fine, but 
I'll be able to tell you for sure after 3B9C!

73, John
G3WGV
http://fsdxa.com/3b9c 
http://g3wgv.com