End of line resistors
- Thread starter Pitt123
- Start date
- Status
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
100914-1600 EST
Pitt123:
Try calling it a terminating resistor.
See if this site helps explain what happens:
http://web.cecs.pdx.edu/~greenwd/xmsnLine_notes.pdf
If the reflection components die out quickly enough relative to when you need to sample the data, than a perfect match at the far end may not be the best choice because it reduces the low frequency output voltage. The die out time is determined by cable length.
A cable I have measured has a propagation delay of about 1.5 microseconds per 1000 ft, 7.92 microseconds/mile, and a velocity of 126,000 miles/second. The velocity of light is about 186,000 miles per second. So the signal propagation velocity in my cable is about 126/186 = 68% the speed of light.
.
Pitt123:
Try calling it a terminating resistor.
See if this site helps explain what happens:
http://web.cecs.pdx.edu/~greenwd/xmsnLine_notes.pdf
If the reflection components die out quickly enough relative to when you need to sample the data, than a perfect match at the far end may not be the best choice because it reduces the low frequency output voltage. The die out time is determined by cable length.
A cable I have measured has a propagation delay of about 1.5 microseconds per 1000 ft, 7.92 microseconds/mile, and a velocity of 126,000 miles/second. The velocity of light is about 186,000 miles per second. So the signal propagation velocity in my cable is about 126/186 = 68% the speed of light.
.
- Status