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MJM-631E CD Jitter Meter
* End of sales


This MJM-631E can measure the time jitter in the 3T component of EFM modulated signals of CD players and other devices.
It separates and extracts 3T components in EFM signals, measures the jitter quantity in real time, and displays the measuring results by the meter, and LCD display.
Its T/V conversion system ensures high-speed measurement.
By resetting the judging value, whether the measuring results are acceptable (GO) or not (NO) can be displayed by LED.


The 3T jitter quantity in EFM signals can be directly read by the meter and LCD display.
The jitter quantity is displayed by the standard deviation (Sigma).
Since the jitter quantity is measured by the T/V conversion system, the jitter fluctuation quantity can be read continuously.
The measured jitter quantity is compared with its preset value to be able to judge whether it is acceptable (GO) or not (NO).
Measurement can be done at either falling or rising polarity of the 3T signal.
Owing to its improvements in the compensation circuit for the period, stable measurement can be done to asymmetric signals.
This unit can be remote-controlled by control signals.
This unit is a compact and lightweight jitter meter.


 Input section
Input signal EFM signal (eye pattern)
Clock frequency 4.3218MHz
Input level range 0.1Vp-p to 5Vp-p
Input impedance Approx. 1MΩ

 Measuring section
Measuring range 2.5T (578ns) to 3.4T (787ns)
Pulse width compensation range 694ns±100ns or over
Indicating system Sigma indication system
Range 30ns and 60ns full scale
Measuring accuracy
• Meter display ±3% of full scale
• Digital display ±(2% of reading +3 digits)
Min. resolution; 0.1ns
Measuring signal polarity Either positive or negative polarity is selectable
Residual jitter Less than 2ns
Judgment function To set from 0 to 60ns by the panel preset function

 Output section
MONITOR ±5% of input signal (open end)
Output impedance 50Ω ±10%
RECORDER Each range meter full scale 1VDC ±3% (open end)
Output impedance 600Ω ±10%
REMOTE Functions other than FUNCTION on the panel can be controlled from the exterior.
A judgment output function is provided.

Operating temperature range 0ºC to +40ºC
Power requirements AC100/120 to 220/240V, 5VA
Dimensions Approx. 240 (W)×154 (H)×137 (D) mm
Weight Approx. 1.95kg

* Specifications are subject to change without notice.


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