Patent ID: 8310940

Claim:
A method of testing an upstream DOCSIS channel with a test signal transmitted within mini-slots allocated for contention transmission or data PDUs during normal operation of a cable modem in transmission to a CMTS comprising: a) generating the test signal with a testing device including a cable modem; b) sending a request signal to the CMTS using the cable modem for as many mini-slots in the DOCSIS upstream channel as required to send the test signal; c) receiving a map PDU from the CMTS with details of a map, within which is a data grant for the mini-slots requested in step b); d) transmitting the test signal in the mini-slots granted by the CMTS; e) receiving the test signal at a test signal collection unit; and f) performing tests using the test signal; wherein the test signal comprises a preamble, a message, and a test pattern wherein the preamble comprises a reference sequence, and a plurality of ID slots, each ID slot for storage of a test sequence indicative of the identification of the testing device; and wherein step e) includes identifying the test device by autocorrelating the test sequence in the ID slots with the reference sequence.