[digitalradio] Hellschreiber Path Simulations
All, It's interesting to see how the various Hellschreiber modes print in the noise. There is a noticeable difference in contrast and character definition which is likely to affect the overall readability over HF. The disparity seems more apparent on-air than it does under the controlled environment of the path simulator. The image below (see link) illustrates the different characteristics of each mode after being subjected to the same level of white noise over a simulated channel. This is purely a sensitivity test - it does not show the affect of HF distortion. Hellschreiber comparison - http://www14.zippyshare.com/v/42533726/file.html Click image to enlarge. Test Software: IZ8BLY's Hellscreiber Path Simulation: White Noise -6db SNR Tony -K2MO
Re: [digitalradio] Hellschreiber Path Simulations
All, I received a couple of emails regarding the size of the Hellschreiber comparison image - the link below should make it easier to see. http://www14.zippyshare.com/v/42533726/file.html - click on the image to enlarge. Tony -K2MO On 7/29/2010 5:01 PM, Tony wrote: All, It's interesting to see how the various Hellschreiber modes print in the noise. There is a noticeable difference in contrast and character definition which is likely to affect the overall readability over HF. The disparity seems more apparent on-air than it does under the controlled environment of the path simulator. The image below (see link) illustrates the different characteristics of each mode after being subjected to the same level of white noise over a simulated channel. This is purely a sensitivity test - it does not show the affect of HF distortion. Hellschreiber comparison - http://www14.zippyshare.com/v/42533726/file.html Click image to enlarge. Test Software: IZ8BLY's Hellscreiber Path Simulation: White Noise -6db SNR Tony -K2MO __ Information from ESET NOD32 Antivirus, version of virus signature database 5324 (20100729) __ The message was checked by ESET NOD32 Antivirus. http://www.eset.com
[digitalradio] Hellschreiber Path Simulations [1 Attachment]
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
