I've been out of the field for awhile, but every DS3 I've done was coax. Usually brought in on fiber to an OCx Mux and dropped to DS3 level for transmission via 75 Ohm coax. Loopbacks were normally programmed at the edge devices.
So here's my question(s):
1.Is the hard loop (which is in fact done with a 75 Ohm coax patch cable) being done to test the edge devices?
2. Have there been developments that changed the DS3 media to something other than coax?
Richard S. King, RCDD/LAN/OSP
TKG Consulting Engineers, Inc.