Despite all the limitations, the first tests with W8BYA were quite promising. The path typically had significant QSB but we were actually able to exchange some very noisy pictures! This may not look like much, but it is actually very encouraging for a 200 Km path with an ancient 3-element yagi perched on the back of some chairs!

Within a short time I had replaced the old yagi with a stacked pair of M2 halos. The gain was about the same as the yagi, but the pattern was now omnidirectional! About this time it became evident that my new VHF SSB installation was having some problems. There was distinct distortion of the SSTV signal (chroma or color ghosting) which suggested the possibility of RF feedback. Since I had never had the problem on HF, it seemed possible that 2 meter RF might be getting into the DSP-"innards" of my precious Argonaut V. Sure enough, substituting my ICOM IC707 for the Ten Tec rig solved the problem!

As long as we had significant SNR limitations, good old FAX480 turned out to be one of the better modes for weak-signal work. Noise has less visual impact on the grayscale images and you get about 4-times the resolution with about the same transmission time as a Scottie 1 image. This is an example of a FAX480 image from W8BYA under pretty typical conditions.

Digital Images

The path between Gedas' station and mine always has some noise, be it light or heavy. Early on we resolved to check out the utility of trying Digital SSTV (RDFT). Basically, digital image transmission/reception is all or nothing - a "perfect" image or no image at all! It should be an ideal mode in the presence of moderate noise and there is always the option of increasing redundancy levels to cope with higher noise levels. The image above was one of our first tests. The image certainly has compression artifacts, but noise is not an issue!

This surrealist output from a fractal program is a striking example of what can be achieved with digital transmission. Our long-term goal is to evaluate optimum levels of redundancy and to quantify the relative advantages of analog vs. digital formats under varying conditions. Right now, with default redundancy (~20%), 80-120 second images succeed about 50% of the time.