ET2021 X.21 Circuit Tester Specification

Power: Off/On
Input: Hi-Z or 110ohms
Control: Sets condition of pins 3-10 to either on/off
Transmit: Continuous 1's or 0's PRP15 test pattern inverted as per ITU recommendations for 2.048Mb/s PCM systems PRO15 (215-1)
Inject Errors: Single errors /2 errors per sec
Error Count/Reset/Clock Speed: Sets the display options for the LCD display, Reset also resets the lost sync to be used.
Set Speed: Selects the appropriate clock speed to be output by the testers. Speeds (kb/s) 64, 128, 256, 512, 1024, 2048.
DCE/Tester: Sets the clock source to be used

Low Battery (flashing): <30 mins power remaining
IND: Displays the status of the indicate signal (pins 5-12), Red = OFF, Green = ON
DATA: Red = '1', Green = '0'
PRP Sync: Green = OK, Red = Inverted Data
LOST: Indicates a loss of synchronisation has occurred during a test cycle which may result in large error bursts.
DCE: Indicates status of clock signal; Green= clock phasing correct, Red= Clock phasing out of tolerance/inverted

Inactive display shows a '_' sign
BERT test running: alternating '_' and '.' signs
Overflow indicated by flashing most sig. '1'
Error display range 0000 to 9999Frequency display range: 1Khz - 2048Khz (accuracy 0.5Khz)