----- Original Message ---- From: "EXT-McCleave, Howard R" <[EMAIL PROTECTED]> I was flying at about 50 feet of altitude along the tree line at the west end of the field when the plane did an immediate vertical dive into the ground with no possibility of recovery. When I walked out to get the trashed plane I found a gentlemen standing at the base of the trees with his transmitter on (not visible when the incident happened) doing a range check on the plane he had just crashed. A friend was walking back to the landing area with it. He explained as my Icon flew over his head he heard the servos "go nuts" and it went straight in. .. What do you think experts, is "swamping" a real phenomenon or did he have a lousy TX?? ======================================
Randy, when your signal is weak and there is an adjacent signal that is very strong, bad things can happen. Our receivers have little selectivity, of course, because they have little IF filtration, usually just a couple of 455 khz IF cans. It's not so much that an adjacent signal actually splatters into the passband; what is more likely is that a strong adjacent signal will depress the gain of the receiver on the desired frequency. There are various AGC techniques used by RC receivers, but most will be affected to some extent by strong adjacent signals. This effect is felt even in multi-thousand dollar ham receivers weighing 50 pounds, and obviously it's much more serious in a minimalist receiver like those in an RC plane. Your misfortune was that you were a long way from the plane, and he was right under it. The strength of his signal may have been 60 db or more above yours, which is the kind of thing that presents problems for much more elaborate receivers. This normally isn't the case, since usually all the flyers are standing together, and the signals reaching the plane are of similar strength. In that case, the desired signal still fills up the passband. His transmitter could have been working perfectly legally, right on its freq, no spurious radiation, and still caused such a thing. Sad but true. RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
