As New Horizon's signal is so weak, probability exists of errors in detected signal.
What error detection and correction codes are used in the signal? Is it known, what is the error rate in received signal?
Most ESA and NASA spacecraft have communications systems that are designed to the CCSDS (Consultative Committee for Space Data Systems) recommendations. For the TM coding there is a specific standard (CCSDS 101.0-B-4).
New Horizons uses the rate 1/6 Turbo Coding option, as described in this overview: New Horizons Spacecraft.