The inventive data conversion device is typically embodied as a modular unit including a PCBA and a frame that houses it. The PCBA includes a PCB and electronic components mounted thereon including a computer and one or more conventional conversion devices, viz., at least one conventional synchro-to-digital converter and/or at least one conventional digital-to-synchro converter. According to typical inventive synchro-to-digital conversion, analog synchro data (received from a synchro) is converted by the synchro-to-digital converter(s) to lower-level-format parallel-binary-angle digital synchro data, which in turn is converted by the computer to higher-level-format digital synchro data. According to typical inventive digital-to-synchro conversion, higher-level-format digital synchro data (received from a modern-day digital device/system/network) is converted by the computer to lower-level-format parallel-binary-angle digital synchro data, which in turn is converted by the digital-to-synchro converter(s) to analog synchro data.