Design of Beidou integrated communication and navigation module with RDSS TX notch filter
A Beidou integrated communication and navigation module which supports positioning and short message communication functions is designed in this paper. A Bandpass filter with notched band is designed for the first-stage filtering of RNSS receiver front-end, which can effectively suppress the strong interference signal coupled from RDSS TX. The first-stage filter of RDSS receiver front-end adopts a low-pass filter to suppress the interference of 5 G mobile communication system, two-stage amplification and two-stage bandpass filter to improve the sensitivity of receiver. The one-stage amplification and two-stage filter are used in RDSS TX channel to amplify the modulation signal. The module area of 26 × 30 mm can be obtained by using RF SoC chips to realize the frequency conversion and baseband process. The independent power supply of RF channel, ground plane isolation island and independent shield technology are adopted to suppress PCB crosstalk. The measured results show that the RDSS can simultaneously acquire 8 beams, with a maximum CNR of 57 dB, a transmit power of 37.42 dBm, and a communication success rate of 97.2%. During RDSS transmission, the number of visible satellites acquired by the RNSS receiver decreases by 2, and the CNR attenuates by 3 dB. However, the positioning performance which has 44.25 s cold start time, 2.3 s hot start time and 4.6 m positioning accuracy is not affected.