Assertion: radar's frequency | /r/HasProperty | vhf maritime channels
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text: AIS transceivers use two different frequencies, VHF maritime channels 87B (161.975 MHz) and 88B (162.025 MHz), and use 9.6 kbit/s Gaussian minimum shift keying (GMSK) modulation over 25 kHz channels using the High-level Data Link Control (HDLC) packet protocol.