atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services T1's, CSU's and DSU's need information regarding LBO

Hi I am a t1 tester and we had issue on turning up a point to point t1 ckt. Now we are able to loo up csu on a end however not able to loop up csu on z end. we are able to run all bert patterns to the hard loop on the z end. The lec is ATT we had att dispatch out twice and came clean on both times. After extensive troubleshooting it was found that LBO settings were not correct due to which we were not able to loop up csu and csu was incrementing errors. The setting should be around -7.5db

My question is what is that setting they are talking about. need more info on LBO

LBO is the Line Build Out setting on the Multiplexor. Typically if the CSU is from 0-133 feet (40 meters) from the mux then a low level of amplification is required. If the CSU is farther away then a greater degree of amplification is required.

All the muxes I worked with broke it down into the following groups: 0-133, 133-266, 266-399, 399-533 and 533-655. As you can see the amplification ran in 40 meter increments, up to 200 meters. Any farther then that and additional amplification equipment was required.


Sam

Assuming that there is a smartjack at the Z end and assuming that the hard loop was put on at the RJ: There are specifications as too how close two devices can be to each other. If you are using a HDSL smartjack, the receive level of the pulses at the smartjack customer side is approx 0Dbm. If the CSU is to close to the smartjack the hot level of the pulses from the smartjack will be unreadable to the CSU. Therefore you "Build Out the Line" by introducing loss between the two devices. the settings are usually 0,-7.5,-15,-22.5 DB.

Settings of 0-133, 133-266, 266-399, 399-533 and 533-655 usually refer to the equalization of all frequences present in the signal. Due to the fact that a digital pulse is a complex waveform of analog frequencies the pulse can degrade over distance because of copper impairmrnts such as attenuation and capacitive reactice to name a few.

By setting the equalizer to match the distance range between the two devices you are insuring that all frequencies making up the pulse will arrive together making the pulse readable to the next device. It will not be "distorted". Please lookup "Envelope Delay" and "Delay Distortion"