I have increase the requested steps to 10 Hz total
There are 12 steps in the message
Only 8 discreet steps are present
The total pattern does not achieve the 10Hz expected
Each step will be 0.833Hz
The shift achieved is around 6Hz
8 steps times 0.833 equals 6.666Hz
How did you increase the requested steps to 10Hz total? The FSK (Hz) size parameter is ignored here. In the custom message mode, the size of each step is always 0.5Hz. So if you have 12 steps, it should go from 0 to 5.5Hz always.?
I believe that the observations of only 8 steps being apparent on 3.5MHz are just a feature of the settings you are using in your spectral analysis program. If you changed the settings or used a different program I think that you would see the 12 steps correctly. I think at the settings you have, the resolution of the spectral analysis is limited to a "bucket" size of more than 0.5Hz, which mean you can't observe all the 12 steps accurately.?
Anyway I don't think we need to lose any more sleep over this stuff. I think I understand the problem adequately now. Regardless of whether it is there on 3.5MHz or not, it clearly arises as you go up in frequency and at 10m the steps are much too inaccurate or non-existent. I don't need any more experimental observations now, I think the experiments to date have been extremely helpful.?
Many thanks to Eddie and all those of you who have provided the observations. Now I have to just change the part of the code which calculates the DDS tuning word.?
