Re: Fine Tuning Shifting

On 8/14/2024 3:35 PM, cyclintom wrote:

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Flunky just talks ahbout crap that he doesn't know about. Notice how he could not answer how you measure the length of a wire electronically? That's because he personally doesn't know how to use an oscilloscope. Which comes as no

Or, It could be because Jeff answered it as well as I could so I didn't feel it was worth commenting, but since you insist, here's how you test cable length with _out_ using dedicated TDR equipment:
- Connect a pulse generator, an oscilloscope, and the cable under test together with a T connector (Typically BNC, but adaptors may be required depending on the equipment.
- set up a pulse generator to single pulse, starting with a 1 nS width, 5 V P-P.
- Set up the scope to trigger on the single pulse from the generator, with the pulse from the generator being displayed at the extreme left of the display.
- Adjust the time base of the oscilloscope until the reflected pulse appears on the right side of the display while manually initiating the pulse on the generator.*
- Longer cable lengths may make the returned pulse not quite discernible. When the trigger pulse is no longer visible, increase the pulse width until it is visible, then begin adjusting the time base again until the reflected pules is visible (It may also be necessary to increase the pulse amplitude).
- Once the reflected pulse is visible, measure the distance between the trigger pulse and the reflected pulse on the scope as time delay (Hence the term Time Domain Reflectometry).
- PLug this delay into the propagation delay value for the cable under test, and do the math.
* setting up the generator to a repetitive pulse could prove problematic in that the trigger pulse period my be shorter than the propagation delay of the cable under test giving a confusing display. A competent technician could manage it, but given the bizarre and completely non-nonsensical method you described, it's well beyond your comprehension.