Hi, I am using a FT991A with integrated audio card in the radio.
If I see on my extract of the log, I recognize that not only I have the sporadic doubles. Also stations which received me. The frequency difference is mostly less than 20 Hz. Sometimes a double entry with same frequency. Here it could be that the signal was received in parallel via long way ?! From the log sometimes different other stations received me double with the same timestamp. I do not think that they have all issues with audio connection at the same time. So my hint is that it must be a reflection or equal. But a plane? What would be for example with a moving reflection zone? Maybe it would be helpful to analyze the database of wspr when and where such doubles are happened. But those database is to big to do this with excel ☹ 73 Roland, dk4rh -----Ursprüngliche Nachricht----- Von: Jim Brown <k...@audiosystemsgroup.com> Gesendet: Sonntag, 14. Juli 2019 09:33 An: wsjt-devel@lists.sourceforge.net Betreff: Re: [wsjt-devel] FT8 ghost signals On 7/13/2019 11:50 PM, roland.hartm...@web.de wrote: > If it is an issue on my receiving audio path, than all received > stations should be doubled. This is not happened. > > If it is an issue on my sending audio path, than all the other > stations who received my should be doubled. Those is also not happened. Roland, I use FT8 almost exclusively on 160M and 6M. My rig is an Elecraft K3. It is VERY common for WSJT-X to provide multiple decodes on 6M signals that are only moderately strong. When it's something like an aircraft reflection, the second decode will typically be 15-20 dB below the primary signal. When it's IMD in the other station's transmitter, they are usually symmetrical, can be 30 dB or more below the main signal. Because on both of these bands I am surrounded by very strong local signals, I run the RX audio slider (green bar, bottom left) as close as possible to clip without going red. The reason is simple -- the 16-bit system has a practical dynamic range of about 90 dB, those strong locals are often 30-40 dB over S9, and I'm trying to decode the weak stations down around S3 or S4. If you don't run those locals to the top of the A/D's dynamic range, those weaker stations you want to work will be below the range of A/D. I'm using a semi-pro audio audio card, the Tascam US-100, which has better than average audio characteristics. 73, Jim K9YC _______________________________________________ wsjt-devel mailing list wsjt-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/wsjt-devel _______________________________________________ wsjt-devel mailing list wsjt-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/wsjt-devel
