Ronja Twibright Labs

Duty cycle preemphasis test with Bertest



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Connect the device

Connect the Transmitter to Hertz and power supply.


Eye test

Note: for Inferno, you have to use B/W CCD camera or night shot camcorder instead of eyes because the light is invisible.

Switch Hertz between 1MHz and 10MHz. Repeat couple of times and look at the transmitter during that:

  • If the LED is shining more during 10MHz , then the preemphasis circuit is telling the LED to shine too long (test failed).
  • If the LED is shining less during 10MHz, then the LED is shining too short time (test failed).
  • If you cannot tell a difference, then the duty cycle preemphasis is set correctly (test passed).

Multimeter test

If the eye test passed and you have a photocell or large area photodiode, connect that to a multimeter set to suitable current range, and place it it over the TX LED and secure by some heavy enough object. Then repeat the same, but instead of eye use the multimeter. The higher current, the more the LED is shining.

An expected information missing here?