What is the resolution/accuracy of the IFR ATC-601 Mode S Altitude data?
The UF4 test, displays Mode S altitude data to a resolution of 25ft. The IFR ATC-601 has no tolerance associated with the display of altitude data, as the data is converted to digital format prior to transmission from the air data computer to the Mode S transponder. The IFR ATC-601 just displays the digital data, as downlinked from the Mode S transponder. The important tolerance is that of the barometric test equipment used to stimulate the air data computer.
