I’ve experimented a bit more with parity checking balanced ternary values. As mentioned in an earlier post, the behavior is quite similar to binary parity checking. But the fact that each trit is capable of arriving incorrectly in two different ways (either incremented or decremented) causes some interesting effects.
Let’s say that a 9-trit word is transmitted, along with a single parity trit. This gives us 10 trits on the receiving end. We’ll call the original 9 trits ‘data trits’, the transmitted parity trit is the ‘parity trit’ and the calculated check trit on the receiving side will be called the ‘check trit’. If all 10 transmitted trits are received without any alteration, the check trit will be a 0. If one of the data trits is incremented, the check trit is a +. If one of the data trits is decremented, then the check trit is a -. However, if the parity trit itself is altered during transmission, the result is the opposite. If the parity trit is incremented, the check trit is a -. If the parity trit is decremented, the check trit is a +.
This phenomena is interesting, but not useful by itself since you don’t know which type of error caused the check trit to be non-zero. It may be of use in arrangements using multiple parity trits such as SECDED (Single Error Correction, Double Error Detection) schemes.