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Technical

More HD is coming. What, when and where is up to each region. Many area's need to work on "reclaiming" some spectrum which can be used for more HD launches. Reclaiming bandwidth can come from migrating an analog channel to digital, or re-optimizing a multiplex so that 3 HD channels can fit in the same space a regular analog channel would fit. Migrating HD from the normal 2:1 to a 3:1 mux would be unnoticed for most people since the channel mapping stayed the same, it was just the source that changed. Each analog channel slot can contain up to 12 (soon to be 15 with new grooming) SD digital channels. Many Comcast systems have over 2/3rds of their bandwidth dedicated to Analog channels. It is vital that these channels are migrated to digital for better resource allocation over the RF network.

With any channel launch or frequency change, there is a LONG drawn out process that must be followed. The FCC requires notice to be given for any channel changes or removals/repositions. Corporate must approve any channel change requests and then there is the marketing side with contracts, timing and advertising. For any MAJOR changes Comcast is required to give 30 days notice, and just getting that out can sometimes be troublesome. One way around a 30 day notice in a channel add would be a soft launch. A soft launch is when channels will appear 'out of the blue'. Usually a week or two later there will be an ad in your local paper saying that the channels will be available 30 days from now, but you can enjoy a 'free preview' today.

It's also because of this required notice, along with the mis-match of channel maps, channel locations, etc, between all the various systems throughout their history of acquisitions that you end up having the channels all over the place. Comcast tries to stick things where they can find room. A region may have 30+ channel lineups to handle each with it's own bandwidth limitations. Imagine playing a really hard game of Soduku. If you simply make a change to a multiplex in one area, it's likely to affect 30 other area's because they are pulling the video from the same multicast IP address. Everyone must be coordinated and on the same page. Adding/changing channels can be a very messy and tedious project.

Definitions:
Multiplex - communicates two or more signals over a common channel
Mux - Shorthand for Multiplex. 2:1 Mux means 2 signals are broadcast over a common channel. 3:1 means 3 signals are broadcast over a common channel, etc.
RF - Radio Frequency
SD - Standard Definition (up 480i resolution)
HD - High Definition (1280x720p or 1920x1080i resolution)
Multicast - addressing is a network technology for the delivery of information to a group of destinations simultaneously using the most efficient strategy to deliver the messages over each link of the network only once, creating copies only when the links to the multiple destinations split.
Bandwidth - The width, usually measured in hertz, of a frequency band; Of a signal, the width of the smallest frequency band within which the signal can fit; A measure of data flow rate in digital networks typically in bits per second; The capacity, energy or time required



by cypherstream See Profile edited by SpHeRe31459 See Profile
last modified: 2013-12-21 16:35:00

AnyRoom DVR is an offering by Comcast that allows recordings to be stored on a single host DVR (usually placed in the Family/Living Room) and then can be watched on a client set-top boxes (usually in a bedroom, kitchen, playroom, etc).

The boxes communicate in the house using a technology called Multimedia Over Coax Alliance or MoCA for short, this is the industry standard for multi-room DVR, used by all the major cable and satellite TV providers. The AnyRoom DVR allows the DVR recordings to be watched in any room using a compatible Set-top. For "classic" AnyRoom DVR service (boxes using the older i-Guide interface) client boxes cannot be used to program the DVR or schedule recordings but this can be done on the Comcast.net website or using their iPhone/Android apps. The new X1 platform does allow for scheduling and managing recordings from the secondary boxes. See the X1 FAQ for more information.

An initial installation by a Comcast technician is required for the AnyRoom DVR service. The technician will install a MoCA trap on the incoming line (the point of entry) to isolate the MoCA signals from the rest of the cable plant and the installer will then setup a compatible DVR and client boxes. The equipment that is currently offered works with HDTV and Standard Definition televisions sets. After the installation, any faulty equipment can usually be swapped out at a local office but the replacement equipment must be compatible (MoCA ready). The provisioning of the equipment is done remotely.

Additionally the inside wiring must be in good condition as MoCA operates in the higher frequencies in between and above all normal cable TV signals. Wiring should be RG6 or better. The installer will check levels and cabling issues before installation.

Thanks to IowaCowboy See Profile for the initial wording of this FAQ entry.



by SpHeRe31459 See Profile
last modified: 2013-07-17 13:05:43

The Master Headend or does their bit in aggregating and sending the video signals in MPEG format across the CRAN network. From the cran it goes to the various local headends via Multicast UDP through routers. Finally the local hub picks up the signal and converts it to RF to shoot out over the network. There is also a VOD server farm, which could reside in it's own building or in a regional headend depending on the local archetecture either built by Comcast, or inherited from acquisitions. VOD has been known to spread apart to other larger headends in the region for redundancy. There are various hubs spread out along the plant house the OOB communications equiptment and the VOD (and potentially SDV) edge qams.

There are digital controllers that address all of the set top boxes in the area's. For Scientific Atlanta sites there's a *NIX based server called the DNCS, while Motorola sites there is a server called the DAC. While DNCS's and DAC's pretty much do the exact same job, the way they do it on a SA plant vs Motorola plant are ENTIRELY different. Motorola tends to break things out a bit more with NC1500's, RPD's, etc.....While SA tends to centralize things a bit more within it's DNCS/Appserv setup.

Definitions:
Headend - The control center of a cable-television system, where incoming signals are amplified, converted, processed, and combined into a common cable for transmission to subscribers.
CRAN - Comcast's Reginal Area Network
Multicast - network technology for the delivery of information to a group of destinations simultaneously using the most efficient strategy to deliver the messages over each link of the network only once, creating copies only when the links to the multiple destinations split.
UDP - A communications protocol that is mostly used to send streamed material over a Network
VOD - Video On Demand
SDV - Switched Digital Video - A method of broadcasting only channels that are currently tuned, rather than every channel offered at once.
DNCS -Digital Network Control System
DAC - Digital Addressable Controller
SA - Scientific Atlanta (now owned by Cisco).
NC1500 - Motorola device that links application servers and set-tops using Internet Protocol (IP) to deliver data packets through the out-of-band data channel.
RPD - Motorola's Return Path Demodulator for interpreting commands from the Motorola Cable Box back to the Cable Headend.
OOB - Out of Band communication. Method used to program cable boxes remotely, while allowing their tuners to be on any channel.

by cypherstream See Profile
last modified: 2009-05-22 15:51:09

Although this list is not complete, here are the majority of the Muxes from Comcast Media Center. They are available on the CRAN network, and some of them are available via Satellite. For an explanation of CRAN and what it means for you, please see this entry courtesy of our friends in Comcast HSI: »Comcast High Speed Internet FAQ »What is CRAN?

A 3:1 HD mux means 3 HD channels in 1 38.8mbps QAM. Instead of dedicating 19.4mbps for one HD channel, it is varied depending on the channels on each QAM. As of late Comcast has modified their "muxes" in order to improve picture quality; they place 2 1080i channels and 1 720p channel together.

Mux 1 Starz East, HGTV, A&E
Mux 2 Food, SciFi, UniversalHD
Mux 3 Discovery, USA, NatGeo
Mux 4 HDTheater , Animal Planet, History
Mux 5 HBO East, Max East, TLC
Mux 7 AMC, Golf, CNN
Mux 8 Disney, ABC Family, Science
Mux 9 FX, Speed, Fox News
Mux 11 IFC HD, WE HD, Fuse HD
Mux 12 Encore HD, Fox Bsiness, Hallmark Movie Channel
Mux 14 Bravo, CNBC, QVC
Mux 15 MGM HD, ESPNews, Toon Disney
Mux 16 Lifetime Movies, Biography, Planet Green
Mux 17 E!, Travel, Cartoon
Mux 18 Starz Edge, Starz K&F, Starz Comedy
Mux 19 Spike, Lifetime, Nickelodeon
Mux 20 G4, Style, TV One

by cypherstream See Profile edited by sansri88 See Profile
last modified: 2009-02-13 17:01:47

QAM stands for Quadrature Amplitude Modulation. It's a modulation scheme that transmits data by changing the amplitude of two carrier waves. The two carrier waves are out of phase with each other by 90 degrees. Digital Cable uses QAM to transmit the majority of their signals. Two major QAM schemes are 64QAM and 256QAM. 64QAM contains data throughput around 28 mbps, where 256QAM has data throughput of 38.8 mbps.

If your TV has a QAM tuner, it has the ability to read this signal and display it. The cable company can encrypt the digital video carried in a QAM signal and this is commonly referred to as Encrypted QAM. To receive Encrypted QAM, you would require a device with a CableCARD slot or an official Comcast digital receiver.

A QAM tuner on a TV or DVD recorder does not 'map' the channels to the same location on the Comcast channel lineup card. A QAM tuner will display unencrypted channels on their physical location in relation to the frequency they are carried on.

Some areas are able to pass PSIP data along with local broadcasts. PSIP data is embedded in the digital information that tells your TV what channel number to display. For example, Channel 3 in HD may embed 3.1 in it's video stream. Your TV would be able to tune this by typing in 3-1. Each Comcast area is different, and some may not pass PSIP.

It's also recommend to force your TV or DVD recorder to rescan the QAM channel lineup from time to time. Additional channels may show up unencrypted or may have changed frequencies.

NOTE: Comcast does not guarantee channel availability through a QAM tuner. Comcast has been slowly encrypting all channels in many markets, if this is the case you will not be able to receive any channels without a set-top box. »customer.comcast.com/help-and-su···ryption/

If your looking for a QAM channel lineup, there is no official one from Comcast. You could try the SiliconDust HD-Home Run page. Enter your zip code at this following website:
»www.silicondust.com/hdhomerun/channels

Then choose "Comcast" from the pick list menu.

Feedback received on this FAQ entry:
  • Actually it provides both... you just have to select Comcast from the pull down because OTA shows up first

    2011-01-26 14:43:20

  • The link listed is for OTA information, and I think that is an important detail that is overlooked in this article since it has nothing to do with Comcast. Those that don't know the difference will be thoroughly confused.

    2010-04-22 21:47:37



by cypherstream See Profile edited by SpHeRe31459 See Profile
last modified: 2013-03-27 02:11:13

The June 12, 2009 digital transition will have absolutely NO EFFECT on your Comcast service! This date is a Government mandate that only affects over-the-air broadcasters. Cable systems are using their own private RF spectrum over fiber and coaxial cable. Comcast will do what they want with their spectrum when they want. Expect Comcast to take advantage of the situation by attracting new customers signing up to basic cable because their over the air antenna no longer works. Comcast will also take advantage to run additional outlets in homes where some rooms relied on rabbit ears while only the primary room had cable.

You may of heard of Comcast digital migration website seen here: http://comcastdigitalworld.com/ or »www.comcast.com/digitalnow It's true that digital signals are a much more efficient way of transmitting video. Remember, with every one analog channel removed, about twelve standard definition digital channels can be added. With the much higher bandwidth requirements of HDTV channels, each analog removed would allow a system to add three additional HD channels. The removal of analog channels can also be used to increase cable Internet service speeds and capacity, for every analog channel removed it gives back about 38Mbit/sec of speed to be used for Internet subscribers.

Because of the efficiency with the digital transmission, Comcast has also slowly been migrating channels from analog to digital. This has been done in phases throughout 2009-2012. As of early 2013, the vast majority of Comcast's systems have now been migrated to 100% digital.

For more see: »customer.comcast.com/help-and-su···igration



by cypherstream See Profile edited by SpHeRe31459 See Profile
last modified: 2013-12-21 16:35:39

In order to troubleshoot issues channels breaking up, turning to a black screen, or saying "This channel will be available shortly" you should check your signal strength. There are hidden diagnostic menus for most cable boxes that will let you find the signal strength.

For Motorola cable boxes:

There is extensive documentation on this over at the Motorola DVR Wikihow site:
»en.wikibooks.org/wiki/How_to_use···Strength

For Cisco/SA cable boxes:

Turn to the channel that is giving you issues and then follow the instructions below.

For newer Cisco branded cable boxes: Power off the box, Press down the power button on the cable box until the green light blinks twice, then press power button again.

All Other SA boxes: Power off the cable box, Press the OK/Select button and the Info button on the cable box at the same time.

Once the Message light on the front of the box starts to flash press the INFO button on the front.

You navigate the menus with the Vol +/- keys on the remote.

Choose the RF Status

The stats are color coded, amber signifies a borderline signal and red means there is a definite issue with the signal quality.

Click for full size


* CURRENT QAM refers to currently tuned video channel:
Level: Should be -12 to +15 dBmV for QAM256
S/N: Should be 33 dB (or more) for QAM256 [This is more important than level]
Seconds: How long channel has been tuned.
Corr Bytes: How many bytes were detected in error and corrected since first tuned
Uncor Blks: How many data blocks that failed parity check, but could not be corrected.
Errs Avg/Inst: Average and Instantaneous Bit (byte? block?) Error Rates.

When finished press the EXIT button on the front of the cable box.

Feedback received on this FAQ entry:
  • The acceptible ranges for some of the other items are provided in this post: http://www.dslreports.com/forum/r26152160-

    2014-03-04 10:45:03 (telcodad See Profile)



by SpHeRe31459 See Profile
last modified: 2013-05-23 21:01:30

Comcast may ask for the "Data ID" which is not technically the correct term. The Host ID is what Comcast calls the "Data ID", provide the phone rep the Host ID and Card ID and your CableCARD device should be easily activated over the phone.

by SpHeRe31459 See Profile