**4.2 Radar hardware overview**

In the transmitter unit of the radar system, a 'saw-tooth' voltage sequence is generated by the 'saw-tooth' generator. It is used to control a VCO to generate a frequency modulated radio frequency (RF) signal. The receiver channel, with the help of the beam forming array, receives the signal reflected by obstructions. The fundamental frequency output from VCO is connected to the transmit antenna array and halved frequency output. Signals received from the antenna array are mixed with the transmitted signal in the sub-harmonic mixer. The intermediate frequency (IF) signal obtained from the mixer is then amplified by the variable gain amplifier (VGA) and filtered by a band-pass filter (BPF). These two components are controlled by the radars electronic control unit (ECU) unit, which also communicates with the PC host via the USB interface [27–30]. The photograph of the manufactured FMCW radar unit is shown in **Figure 3**.
