The MJM-631C is designed for measuring the time jitter in the 3T component of the EFM modulated signal of CD Players and other devices. It extracts the 3T component of the EFM signal and measures the jitter in real time. It also indicates GO or NO-GO with lamps according to preset GO/NO-GO threshold values and displays the results on the meter.
In addition, measurements at high speed are possible since the T/V conversion method is employed.


1. The 3T jitter of the EFM signal can be read directly form the meter.

2. The jitter value is indicated in standard deviation (SIGMA mode).

3. Changes in the jitter can be read continuously, due to the T/V conversion method of measurement.

4. A GO/NO-GO result is indicated in relation to a preset jitter threshold value.

5. The polarity of the 3T measurement can be selected (Positive-going or Negative-going ).

6. Improvements in the compensation circuit for the period have resulted in highly stable operation when the signal

    is in the asymmetrical condition.

7. A jitter output connector enables the jitter waveform to be observed on an oscilloscope.

8. A remote control function is provided.


Input Section
Input Signal EFM signal (eye-pattern)  Clock frequency  4.3218MHz
Level Range  0.1Vp-p to 5Vp-p
Input Impedance  Approx. 1M Ohm
Jitter Measurements
Measurement Range  2.5T (578nsec) to 3.4T (787nsec)
Pulse Compensating Range  (Asymmetric variable range) 694nsec 100nsec
Meter Indication Mode  SIGMA (Standard deviation) mode
Meter Range  30nsec and 60nsec of full scale
Meter Readout Accuracy  3% of full scale
Polarity of Input  Signal Positive or Negative, selectable
Residual Jitter  Less than 2nsec
Judgment Function  Possible to preset the GO/NO-GO threshold value
Output Section
MONITOR output  5% of input level at open circuit
Output impedance  Approx. 75 Ohm
JITTER output  1Vp-p 10% of full scale at open
Circuit output impedance  Approx. 600 Ohm
RECORDER output  1V DC 5% of full scale at open circuit
Output impedance  Approx. 600 Ohm
Remote Control Function A remote control operation is available
General Date
Operating Temperature  0ºC to 40ºC
Power Requirements  100, 115, 215, 230V AC 10%, 50/60Hz
Power Consumption  Approx. 20VA
Dimensions & Weight  Approx. 150(W) 220(H) 325(D)mm, 4.2 kg

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