Hi folks,
I think I found out what the unit is. I am taking measurements on a T1 circuit. The meter measures "dBSx," but I can find no description of the unit. However, when I look at the T1 specifications, they use a unit called dBdsx, which is defined as dBdsx(Vpp)=20*log(Vpp/6 V), where 6 V is the nominal peak-to-peak level of a T1 signal. It appears that a number of the meter manufacturers truncate the official unit, dBdsx, to dBSx, dBS, or dBx to make everything fit on their screens.
Thanks for the help.
Mark