Power
Flashes while performing startup diagnostics internal to modem (after initial power-on or reset), and turns solid green when modem successfully completes diagnostics.

Receive
Flashes while scanning for downstream frequency, and turns solid green when modem has successfully acquired a downstream channel.

Send
Flashes while locating and ranging an upstream channel, and turns solid green when modem successfully ranges upstream channel.

Online
Flashes while requesting an IP address (DHCP), downloading the configuration file (TFTP), and getting network time (TOD). Turns solid green when modem has successfully completed DHCP/TFTP/TOD and activities noted above for Power, Receive, and Send.

Activity
Flashes when data is transmitted on the downstream or upstream connection. If there is no data traffic, the amber LED remains dark.
 

Downstream operating Range is -15 to +15dBmv.
Upstream operating range is +8 to +58dBmv