The modulation type associated with this downstream RF
channel. See the associated conformance object for write
conditions an limitations. See the DOCSIS specification
for specifics on the modulation profiles implied by qam64
qam256 and qam1024.
qam64, qam256 and qam1024 are various modulation schemes
often used in digital cable and cable modem applications.
The numbers 64/256/1024 in qam represent constellation
points, which is the measurement of qam transmission
capability, the higher the number, higher the bits that
can be transmitted.