During a range test I noticed that not all transmissions were detected when I was close to the receiver but as I moved further away, the detection rate improved significantly. Whats going on?
The problem is caused by a severe echo situation. VEMCO receivers reject echoes by implementation of a Blanking Interval, the idea being that after detection of a pulse, the receiver ignores all potential pulse detections until this period of time has passed. As long as echoes arriving after the Blanking Interval are below the receiver’s threshold, everything is fine, and due to the conservative approach we take, this is almost always the case. However, in certain situations, it is not. If that happens, the extra pulses result in a failure to properly decode the code sequence and, consequently, there is an apparent loss of signal. So if you were using a tracking receiver such as the VR100, you would hear a stronger signal as expected at short range but the receiver would not always successfully decode it.
