The use of complex signals in the radar

As was shown in Lecture 6.2., Instead of a short probing signal, you can use a long, lower power, followed by "restoring" the power at the receiver. In this case, the range is not reduced. In this lecture, this option is considered in more detail by the example of pulsed radar with FCM.

  Often, instead of correlometers, multiple lateral delay lines are used. The example of the figure shows such a delay line by 5 code points. FCM code is presented in the form of a parcel of 5 code elements with a total duration of t _and    and the length of the code element   t _{el .}

  On the delay line, the reflected signal is shifted by 1 code element and added to the common bus with a positive or negative polarity. As a result of the addition, a narrow signal peak and side lobes are obtained. Its duration is equal to the duration of the code element, and the amplitude increases in the number of elements of the code parcel. A positive feature of the PCM method is the possibility of using modern digital processing technology.

  From the example it is clear that the receiver is much more complicated. Therefore, this method is used when a large pulse power is required from the transmitter, which cannot be achieved with existing microwave devices.

  Along with FKM, a linearly frequency-modulated sounding signal is often used.

When receiving the "compression" of the reflected signal is done in an analog way on the dispersive ultrasonic delay line DULZ. At the same time, approximately the same results are obtained as with FCM.