CATV Archives

5 02, 2009

DOCSIS and Cable Modems – How it works :: Upstream RF

Mia Colabrese2021-08-17T13:29:04-04:00February 5th, 2009|

Cable modems use RF (radio frequency) signals to transport data over hybrid-fiber coax (HFC) networks according to the DOCSIS® specification. This blog will discuss the finer points extracted from the DOCSIS specification related to how cable modems communicate with the headend Cable Modem Termination System (CMTS), allowing two-way transport of Ethernet traffic over a cable TV network. There are currently three major revisions and one sub-revision of the DOCSIS specification; DOCSIS 1.0, 1.1, 2.0 and 3.0. With each major revision came significant changes to the cable modem upstream specification because the upstream has typically been the bottleneck in terms of data through-put rates as will be discussed.

2 02, 2009

DOCSIS and Cable Modems – How it works :: Advanced RF

Mia Colabrese2021-08-17T13:36:52-04:00February 2nd, 2009|

In high speed data communications, the industry has evolved and implemented complex modulation schemes which vary a signals voltage (amplitude), phase, and frequency in order to transmit more data, faster. The following will cover these methods in order to describe how Quadrature Amplitude Modulation (QAM) works in DOCSIS communications. We live in an analog world. Sure, [...]

29 01, 2009

DOCSIS and Cable Modems – How it works :: RF Fundamentals

Mia Colabrese2021-08-17T09:58:12-04:00January 29th, 2009|

Most of us are quite comfortable with changing the dial on our FM radios. Don't like what's on Soft 95.1 FM, then change the frequency (Kenneth) to 102.5 FM for some classic rock. What you have actually done is changed the RF (radio frequency) tuner in your car stereo from a lower frequency of 95.1 MHz to a higher frequency of 102.5 MHz where there was a different station playing. The fact that two different stations were playing...

27 01, 2009

DOCSIS and Cable Modems – How it works :: Introduction

Mia Colabrese2021-08-26T08:28:17-04:00January 27th, 2009|

Over the past several years of training people on troubleshooting DOCSIS® networks and explaining how DOCSIS cable modems and CMTSs work, I have been asked numerous times - "Why don't you write a book on this?" You see, there is no definitive book, guide or manual that explains the Data-over-Cable Service Interface Specification (DOCSIS) other than the several hundred page specification...

22 01, 2009

Boxee TV – Next Generation Television

Mia Colabrese2009-01-22T01:25:57-05:00January 22nd, 2009|

Though I have dabbled in numerous Internet on-demand offerings, Boxee (http://www.boxee.tv/) appears to be the most promising offering of emerging technologies to enter the market. Boxee aggregates all of the existing online IPTV web portals and makes them available in one user-friendly interface for Apple (Mac), Linux and now Windows. It provides everything from...