Analogue v Digital – Companding

Analogue FM wireless system use a compandor circuit in the signal chain to maintain dynamic range. A compander first compresses audio at the transmitter by a fixed compression ratio before RF modulation. At the receiver the signal is then expanded by the same ratio after demodulation. Companders help overcome the noise limits inherent in narrow bandwidth FM radio signals.

This analogue companding process can produce audible artifacts, including ‘pumping’ effects at low levels and garbled high-frequency transients. Some analogue wireless systems use digital companding circuits to address the limitations of analog companding, though these systems still transmit analogue audio. These “hybrid” systems send audio through an analog-to-digital converter and digital signal processing at the transmitter and receiver to address the limitations of analogue RF. Hybrid systems introduce >3 ms of latency, from transmitter to receiver. 

The all-digital topology of the A10 Digital Wireless System eliminates all companding. Audio is converted to a digital data stream at the transmitter and that digital data stream is received, without signal loss, at the receiver. The signal sent over an A10 Wireless link is not modulated audio, but bits. The end-to-end latency of the A10 Digital Wireless System is a category-leading 2 ms.