On 7/17/2018 8:52 AM, turnbull wrote:
I agree but many people are suffering from wide FT8 signals from others with strong signals.
Part of this is perception rather than reality -- a failure to understand the waterfall display. Because the waterfall displays both signal strength and spectrum, a very strong signal may APPEAR to be broader than it really is. I have a half dozen or so neighbors running FT8 on 6M within about 15 miles, and all are running a power amp (mostly KPA500, but my closest neighbor, about 5 miles, runs 1.3kW. Most of us are running K3s. It's not uncommon for one of these signals to SEEM to occupy 500 Hz or more, the reality is that I often decode weak signals within that 500 Hz.
Another point. K1JT recommends setting audio level into the computer for an indicated 30 dB on the bar graph. I think this is part of the problem caused by strong signals taking over the AGC and greatly reducing the gain. If, for example, a local who's 30 dB over S9, reduces the RF gain by 30 dB, an S9 signal would be below the level of the sound card! I set audio level into the computer for the highest level that doesn't flash RED (indicating digital clip) on strong signals. My bar graph typically runs 50-60 dB. With this setting, even when AGC has reduce the gain by 30 dB or more, weak signals are still well above the "bottom" of the A/D converter, and are decoded just fine.
73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
