The invention provides a signal processing system, for transferring analog signals from a probe to a remote processing unit. The system comprises a first ASIC at a probe, which is adapted to receive an analog probe signal. The first ASIC comprises an asynchronous sigma-delta modulator, wherein the asynchronous sigma-delta modulator is adapted to: receive the analog probe signal; and output a binary bit-stream. The system further comprises a second ASIC at the remote processing unit, adapted to receive the binary bit-stream. The asynchronous may further include a time gain function circuit, the first ASIC may further comprise a multiplexer, the second ASIC may further comprise a time-to-digital converter. The time to digital converter may be a pipelined time-to-digital converter.