Engineering Commons^™

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.

The Technical Requirements For Multichannel Qam Rf Modulators, Ron D. Katznelson

Ron D. Katznelson

This paper addresses the technical requirements and implications for multichannel QAM RF modulators and upconverters and the factors that affect their proposed RF specifications. RF output power levels per channel, adjacent channel noise and broadband noise levels of such a class of multichannel modulators will be discussed. A spectral noise specification mask that is equivalent to that obtained from a combination of multiple identical masks of a standard single channel noise specifications based on power addition will be presented. The power back-off required for maintaining the proposed distortion mask levels as a function of the number of adjacent channels supported …

A Case For Including Harmonic Distortion Components In Docsis’ Rf Specifications For Non Aggregating Spurious Components, Ron D. Katznelson

Ron D. Katznelson

This note is submitted in support of a change in DOCSIS specifications for spurious performance. It shows that the impact of a proposed change is negligible and that the advantages far outweigh the perceived disadvantages of adopting such a change.

Delivering On The 256 Qam Promise, Ron D. Katznelson

Ron D. Katznelson

The accumulation of degradation factors in the downstream channels is reviewed with focus on headend/hub transmission-related noise aggregation due to a plurality of downstream Quadrature Amplitude Modulation (QAM) transmitters and upconverters. Substantial increase in the number of QAM transmitters based on frequency agile upconverters is expected. Unlike fixed channel upconverters, these do not have narrow band filters at their output, consequently imparting appreciable levels of broadband noise on the network when several such units are combined. Based on these factors and other noise contributions, it is shown that additional impairments due to fluctuations associated with composite distortion terms on the …

Specifying And Measuring Aggregate Broadband Noise Of Catv Modulators And Upconverters, Steven I. Rubin, Andre Basovich, Brani Petrovic, Ron D. Katznelson

Ron D. Katznelson

This paper discusses the practical limitations and the subtle assumptions that must be incorporated into the specifications and measurements of Aggregate Broadband Noise of CATV upconverters and digital QAM transmitters. Considerations that govern the accuracy and measurement dynamic range required for such Aggregate Broadband Noise measures are identified. Novel methods involving the separation of the Aggregate Broadband Noise measure into its composites, namely, modulated distortion noise components and other broadband noise components are discussed. Optimal ways in which such measurement techniques have been automated to enable rapid and efficient evaluation of transmitter devices are also presented along with examples of …

Statistical Properties Of Composite Distortions In Hfc Systems And Their Effects On Digital Channels, Ron D. Katznelson

Ron D. Katznelson

The statistical properties of Composite Triple Beat (CTB) and Composite Second Order (CSO) distortion terms associated with the analog channels carried on Hybrid Fiber Coax (HFC) are presented. Both simulation and measurement results show that such distortion components falling on individual channels have amplitude Probability Density Function that is nearly Rayleigh distributed (having a Standard Deviation of 5.7 dB). It is shown that both CTB and CSO components have peak envelope power fluctuations that exceed their average (measured) power levels by more than 15 dB. The temporal statistical properties of these distortion components demonstrate peak envelope power fluctuations with characteristic …