Hi all, Was going over my NAQP notes this weekend. I have two basic RTTY radio configuration questions. My Yaesu FT-950 has two pre-amp settings. On phone I typically only engage these on the quieter
RF preamps improve noise floor but reduces the large signal capability of a receiver (a.k.a. overloading). On the lower bands, 30m and lower, the sky noise is usually way over the noise floor of any
Michael, Sounds good! 3Khz or 6Khz setting is about the same on the 950. And try to use as little preamp as you can manage. If signals on the bands are weak anyway, then it's not much problem anyway.
-- ORIGINAL MESSAGE --(may be snipped) REPLY: I read this in the ARRL handbook 50 years ago and it still holds true today: With the antenna disconnected, observe the background noise level. With any
Actually with RTTY the AGC setting should be slow. The reason for this is the best decoders decode each tone separately and make use of the signal amplitude and measured noise over time. They compare
-- ORIGINAL MESSAGE --(may be snipped) REPLY: There seem to be mixed opinions on AGC speed for RTTY. If the AGC is set to slow, that means the overall receiver gain is relatively constant over time a
If you are willing to manually ride the RF/IF gain controls, "AGC off" is best. As David G3YYD has pointed out, you need the "gains" of the Mark and Space tones to be perfectly equal. Under poor SNR
I see Chen got into this one before me. Chen and I both design and make available RTTY decoders. The internal workings of those decoders for best performance requires that the AGC does not change the
What about AGC turned off? I found that turning off AGC in RTTY mode has improved print for me, especially on 80 meters. I started doing that only on 80 meters but now do it on all bands. Someone onc
Oops. I see Chen has already addressed this. Sorry... What about AGC turned off? I found that turning off AGC in RTTY mode has improved print for me, especially on 80 meters. I started doing that onl
Well, this is all very interesting. Thanks to David and Chen for enlightening me. Your recommendation is something I would never have guessed, but of course I don't write RTTY demodulator software. I
Very interesting indeed. Some of us have stuck with operating methods that were best practice 30 years ago, forgetting that we are using 21st century decoders. I have been trying different AGC settin
My preferred way of operating is to disable AGC for everything but "ear-saving". I will always, at the very least, turn RF gain down so that band noise is not loud. I will always engage one or two st
Just like with filter bandwidths and AGC, there is also a cold, hard, objective way to set the RF gain. Please allow me to explain. This is long. If you just want a monkey-see-monkey-do directions, j
Thank you all for the discussion on AGC. I disabled AGC and adjusted RF gain and signal decoding improved significantly! TU ! 73, Hoop K9QJS _______________________________________________ RTTY maili
I have not had the opportunity to be near enough to my radio to do this, but I plan to. Enlightening! Thanks from me, too! -- Peter Laws | N5UWY | plaws plaws net | Travel by Train! _________________
This thread has definitely been saved to disk! Learned so much here. I'm glad I asked. :D -- /*/-=[Michael / KT5MR]-=/*/ _______________________________________________ RTTY mailing list RTTY@contest
When I posted the following, I did not supply the justification why you want to adjust the noise floor for a largest acceptable SNR loss. After all, you could even adjust the receiver gain so that th