| 摘要 |
A device 10 for determining the number of discrete events represented by an input signal is provided. The input signal may for example comprise pulses representing photons arriving at a detector. The device comprises a plurality, n, of comparator circuits 14 for reading the signal. For each comparator circuit from i=1 to i=n, the ith comparator circuit has a corresponding threshold value which the amplitude of a pulse representing i discrete events will exceed, but which the amplitude of a pulse representing i-1 discrete events will not exceed. Each comparator circuit is arranged to output a first value when the input signal exceeds its threshold value and a second value when the input signal is less than its threshold value. The device includes a counter 16 for counting the number of outputs of the first value that have been output by the plurality of comparator circuits. |
