Frequency Accuracy
How closely the clock’s output frequency agrees with its nominal frequency under stated conditions.
Accuracy describes an offset from the intended frequency. Stability describes changes in frequency over time or with operating conditions; the two are separate specifications.
Frequency Accuracy — External Clock
For an External Clock, frequency accuracy indicates how close its reference or clock output is to the specified rate. A smaller tolerance means a closer stated agreement with that rate under the conditions given.
Values are often expressed in parts per million or parts per billion: 1 ppm equals 1,000 ppb. Read the tolerance with qualifications such as temperature, calibration or accuracy at shipment. A figure specified at shipment does not by itself describe later ageing.
Compare accuracy figures on the same basis and retain any stated upper limit. Do not substitute a temperature-stability or annual-drift figure. High frequency accuracy alone does not establish low phase noise, compatible electrical outputs or an audible improvement in a connected audio system.