&gt; You may say &quot;But nyquist says you can&#x27;t transmit or receive frequencies at more than 1&#x2F;2 the sample rate (40 MHz in this case). To a degree that is true. Some people thought it may be overtones, but what happens in reality something stranger happens. Everything you transmit is actually mirrored around 1&#x2F;2 the sample rate (40 MHz).<p>For anyone interested this is called aliasing.<p>If you&#x27;ve ever noticed wheels going backwards in racing or train footage, this is exactly what&#x27;s happening: the wheel&#x27;s angular velocity is above half the sampling rate (i.e. the camera&#x27;s FPS), producing a mirrored version which in turn appears to rotate backwards.