This reports the configured external clock rate for DSX1, T1, and E1 timing cards, expressed as a multiple of 8KHz ranging from 1 to 255. Because this rate must match what the upstream timing source is actually providing, a value that doesn't correspond to the expected reference frequency, such as a standard T1 timing rate, would explain synchronization or clock-slip problems that aren't obviously clock down but are instead a rate mismatch. For example, cardExternalClockRate reporting 193 (193 times 8KHz, about 1.544MHz) confirms the card expects a standard T1-rate timing reference, so a mismatched upstream feed at a different rate would need reconfiguring here.