用51单片机进行电机转速的测定，显示到屏幕上-Carried out with 51 single-chip motor speed measurement, indicating that the screen

we present a new space–time block code for timeand frequency-selective (doubly-selective) channels. It can be interpreted as the extension of the Alamouti code to doubly-selective channels, and relies on a joint time–frequency reversal of the trans