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Title: Utilizing JANUS for Very High Frequency Underwater Acoustic Modem
JANUS is a physical layer communication standard for underwater acoustic communications published by North Atlantic Treaty Organization (NATO) in 2017. Instead of the nominal frequency band of 9440 – 13600 Hz specified in the standard, we adopt the JANUS packet for a high frequency band spanning from 96 kHz to 134 kHz. We also add cargo packets in the same frequency band using JANUS fast mode with a symbol rate of 23 ksps. Experiments were conducted in a swimming pool and the JANUS 3.0.5 Matlab version of the example receiver program was used to process the JANUS packets. We found that the example receiver program uses many fix(), round() and floor() functions which lead to synchronization errors. After modifying the simple rx code and fixing the error, our JANUS decoding results show that the adopted JANUS fast mode successfully achieves carrier and frame synchronization in all cases despite some bit errors remaining in the JANUS packet in severe multipath scenarios.
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