All, It's interesting to see how the various Hellschreiber modes print in the noise. Close examination reveals a noticeable difference in contrast and character definition that is likely to effect the overall readability over HF. The disparity seems more apparent on-air than it does with under the controlled environment of the path simulator - which is likely due to the the fact that the simulator is not capable of capturing all the finer details of the real HF channel.
The image below (see attached) illustrates the different print characteristics of each mode after being subjected to the same level of white noise over a simulated channel. It is purely a sensitivity test which does not show the effect of HF distortion. While it isn't a weak signal mode per se, Hellschreiber has proved to be very tolerant to just about anything the ionosphere can throw at it. Test Software: IZ8BLY's Hellscreiber Path Simulation: White Noise -6db SNR Tony -K2MO
