Saddle Point Approximation for the Error Probability in PAM Systems with Intersymbol Interference

An easily computed, closed form expression in terms of the saddle point location is used to approximate the error probability, and tight bounds are derived. For the Chebyshev pulse with 10 interferers, the approximation was within 1% for error Probabilities
<10^{-6}
. With 80 interferers, upperbound/lower bound was about 1.1 at SNR = 16 dB.