In this paper design and implementing process of a compact, low-cost and user-friendly probe signal generator for pulse radars and constant wave radars based on software-defined radio (SDR) are presented [1]. In his research the author uses the Universal Software Radio Peripheral (USRP) as SDR developed by the National Instruments [2]. Proposed device was designed for a wide range of the radar systems, however, the first tests were held in conjunction with the synthetic aperture radar in the continuous wave mode [3], [4]. This application required a base band up to 40MHz, which after amplification in analog front-end x24 gave the band of 960 MHz on the output transmitting antenna, providing a range resolution of about 15cm.