Engineering Commons^™

Comments On A Proposed Change For Eurodocsis Specifications, Ron D. Katznelson

Ron D. Katznelson

This submission provides support and explanations to the recommendation that specifications adopted for European applications of CableLabs’® Downstream RF Interface specifications (“DRFI”) should be maintained in accordance with the existing North American DRFI. It contains responses to a proposed changes offered by European proponents. This note addresses the in-channel (Active Output Channel) return loss requirements and the ‘Other Channels’ spurious and noise requirements.

The Case Against A Proposed Relaxation Of Out-Of-Band Noise And Spurious Specifications For Docsis Edge-Qam Rf Devices, Ron D. Katznelson

Ron D. Katznelson

This submission supported Broadband Innovations' (BI) opposition to relaxing the Out-of-Band Noise and Spurious specifications in QAM downstream transmission of Edge-QAM (“EQAM”) devices. The specifications relaxation was proposed by a consortium of equipment vendors who called it the Joint Proposal for Self-Aggregate noise and spurious (“JPSA”). This note explains why the adoption of the JPSA would strip CATV systems from having sufficient operational noise and interference margins.

Post submission note: Despite the overwhelming majority of the Working Group's acceptance and recommendation of the JPSA, CableLabs' Technical Board voted to accept BI's proposal and to reject the JPSA.

Catv Modulator Return Loss Effects On Headend Combining Isolation, Ron D. Katznelson

Ron D. Katznelson

This note addresses the impact of broadband return loss of frequency agile modulators when combined through headend combining networks. In particular, the effect of less-than-ideal output return loss values are examined and it is shown that even under the worst case conditions, a broadband return loss of 10 dB produces only small reductions in isolation that still permit cable operators to meet their headend combining specifications.