Conceptually, radar is very simple. It transmits radio waves and measures the time it takes for them to return via echo. However, in reality, there are many trade-offs to consider. For example, producing longer pulses gives you more energy and range, but limits how far you can see up close and also limits the system's ability to resolve objects that are close to each other. Pulse compression uses long transmissions that vary in frequency. Because we have information about the precise timing of the reflected energy, the reflected waves can be reconfigured to behave like shorter pulses. [Henrik] I didn't want to make things too easy, so I decided to build a pulse compression radar operating at 6 GHz.
To be fair, [Henrik] I'm no novice when it comes to radar. He created several more traditional devices using continuous wave architecture. However, this type of radar is used only in limited applications due to its inherent limitations. The new system can operate in continuous wave mode, but can also encode pulses using arbitrary waveforms.
Several design choices were made to save costs. For example, transmitter and receiver filtering has limitations. Additionally, the receiver is more of a direct conversion receiver than a superheterodyne. Signal processing is made significantly easier using his Zynq FPGA with a dual-core ARM CPU. These were expensive at regular retailers, but were available for about $17 from an online seller in China. The system may be able to boot Linux, but that's for the future. [Henrik].
At 6 GHz, everything gets harder. Wiring his PCB for DDR3 RAM is also difficult, but you can read how it was done in the original post. To say we were impressed with this work would be an understatement. You probably do too.
Radar has come a long way since World War II and is now installed in more places than you might think. I don't want to admit it, but I'm more likely to buy a ready-made radar module if necessary.