This paper presents a study of the possibility of improving the performance of the radar stations that use Linear Frequency Modulation (LFM) using signals pairs, uplink and downlink, to get rid of the negative interference signals, with the use of packet filters opposite narrow area dedicated to measuring the goal. The output of these packet filters is connected to subtractor circuit, so the reflected signals from fixed objects (negative interference) excite filters have the same arrangement leading to subtracting it, and the reflected signals from a moving target will vary its frequency value of the offset Doppler "fd" and thus excite different filters arranged to pass through the subtraction circuit without being deleted.