In 14.02 02/05/00 , hai scritto:
Friday (28 april) arround 22UT I had a good copy of Marco's 10mW signal,
both with Spectran and Spectogram.
Some screenshots can be found at my webpage :
http://www.qsl.net/on7yd/IK1ODO/ik1odo.htm
Although, based on the difference in bandwidth, Spectran was supposed to be
7.5dB better I had the impression that the difference in SNR between
Spectran and Spectogram was less.
Further I noticed that launching another application while running Spectran
caused a kind of 'frequency shift' (see screenshot at my webpage).
Alberto is working on this same problem, see his message.
Finaly I want to thank Marco for the beacon signal, it gave many hams the
opportunity to do some testing and proved what can be achieved with 10mW ERP.
At the risk of being 'greedy' I would suggest following to Marco : would it
be possible to have a series a characters at reduced power after the call ?
eg. : 'IK1ODO X Y Z' where IK1ODO is tranmitted at 10mW ERP, X at 5mW ERP,
Y at 2.5mW ERP and Z at 1.25mW ERP (of course any other 3 characters can be
used).
73, Rik ON7YD
Rik, I will take this seriously. What about writing a modified version of QRS
to command an attenuator and step power levels?
I may build a linear amplifier, of some 10W output, and reduce the power
in four steps of 5 dB (3W, 1W, 300 mW, 100 mW for instance).
The big problem is to have an automatic tuning. I started the beacon
on Thursday evening, then left home Friday, and it was raining; so I had to
raise the power, since the aerial current was down from the nominal.
The rain stopped on Saturday, and the antenna current rose to (probably)
+5 dB respect to Friday evening. I was not able to transmit a fixed power
level;
my station currently can't run unattended (in effect, my wife was attending
and checking for smoke, HI).
I returned home by Tuesday, and found the tuning of the variometer
completely different from Friday.
Thanks to all for the reports. I think we have to go on.
Well, Rik, what signal may we use to change the power levels ? go to
the parallel port, or use an UART on the serial ?
73 - Marco IK1ODO
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