One of the cisco documents recommend length of V.35 cable versus transmission speed. This document also refers to a graph published in EIA422 standard which gives further details. Can any one provide this graph ? Also some practical recommendations about this subject is welcome.
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V.35 cable length
- Thread starter rsmadhava
- Start date
It's a question of attenuation or the degrading of the signal over the length of the cable thats at issue. RS232 has dealt with this for years which is why the 25 foot range has been stretched by using better cable and better connections. By the same token, if the source of the signal is weak, then it will not matter how good of a cable you have as I found out once with a cheapo RS232 PC card 
Always buy quality cables when this is a critical piece of the design. Cheap cables may not follow the complete standard by using all the wires listed even if they are not "used", the quality of wire could be poor and the same goes for the connectors.
Here is Cisco's paper on V.35/RS449
You can see in the charts that length will degrade the signal unless you drop the speed of the data at the same time. They also give the assumptions of the cable.. 24AWG wire and 100ohms of resistance. This gets back to good wire vs. cheapo wire. One of the most important measurements is this one:
Nominal capacitance: 15.5 picofarads per foot
This is where you pay the bucks for the ultra low capacitance cable to stretch out the cable run at speed.
See this link for the details:
MikeS
Find me at
"Take advantage of the enemy's unreadiness, make your way by unexpected routes, and attack unguarded spots."
Sun Tzu
Always buy quality cables when this is a critical piece of the design. Cheap cables may not follow the complete standard by using all the wires listed even if they are not "used", the quality of wire could be poor and the same goes for the connectors.
Here is Cisco's paper on V.35/RS449
You can see in the charts that length will degrade the signal unless you drop the speed of the data at the same time. They also give the assumptions of the cable.. 24AWG wire and 100ohms of resistance. This gets back to good wire vs. cheapo wire. One of the most important measurements is this one:
Nominal capacitance: 15.5 picofarads per foot
This is where you pay the bucks for the ultra low capacitance cable to stretch out the cable run at speed.
See this link for the details:
MikeS
Find me at
"Take advantage of the enemy's unreadiness, make your way by unexpected routes, and attack unguarded spots."
Sun Tzu
- Thread starter
- #3
clocking = data speed
lower clock, lower data rate and gte more distance
Find me at
"Take advantage of the enemy's unreadiness, make your way by unexpected routes, and attack unguarded spots."
Sun Tzu
lower clock, lower data rate and gte more distance
Find me at
"Take advantage of the enemy's unreadiness, make your way by unexpected routes, and attack unguarded spots."
Sun Tzu
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