training sequence codes is a part of Air interface burst, MS knows training sequence code, so in particular part of burst MS knows what should be received, so in case of signal degradation in Air interface MS adjust it’s own digital filter such way that it reconstruct received signal to training sequence code, so degraded incoming signal reconstructed to receive correct sequence, so all other information bits also cerrectly received even in case if high bit error ration in Air interface (if bit error ration < 12.8 % then every simbol 100% reconstructed) Alex http://www.dx200.biz