Broadband Sonobuoy Uplink

Today, sonobuoy sensor data is sent to a surface transceiver via a data tether and broadcast on an analog uplink to an airborne collection platform loitering above the sonobuoy field. This legacy uplink is ripe for modernization. The NATO SG90 standard employs a spectrally inefficient Continuous Phase Frequency Shift Keying (CPFSK) signaling format that offers just 0.85 bps/Hz. In the congested 136 ¢ 170 MHz Very High Frequency (VHF) band, this limits uplink data rates to just 320 kbps over 375 kHz channels. Compare that to modern satellite communications (SATCOM) uplinks which offer 3 bps/Hz or more. In this SBIR, Caliola will design, demonstrate, and productize a modernized uplink for ASW sonobuoys. By combining bandwidth efficient modulation, capacity-approaching forward error correction (FEC), and advanced data compression, our design will achieve a spectral efficiency of at least 2.67 bps/Hz, thereby supporting 1 Mbps or more over a 375 kHz VHF channel. Our design will also scale to support multi-carrier, spectrally discontiguous operation. If spectrum is scarce, this would allow a Mbps+ uplink to be spread over three 125 kHz channels; if spectrum is plentiful, then multi-Mbps operation can be supported.