It's one thing to detect the carrier wave another to demodulate the signal
The signals from Pioneers 10 and 11 were extremely hard to lock onto. The baud rate from those space craft was glacially slow (practically morse code) with the signal frequently repeated. The data hosed out from Huygens was at a fairly high baud rate. The radio telescopes saw the carrier and could detect the doppler shift due to Titan's winds. That's probably the best they can do.
Gary