Back Channel

July 21, 2012

See also Back Haul and Back Path

CIMM DEFINITION: A return path connection that can be used by a Set-Top Box to communicate with the cable headend; Can be used to communicate to cable headend or the service provider. It applies to asymmetric data connections and is the slower of the two data paths in the connection.

2: “A communication channel that can be used by a Set-Top Box to communicate with the cable headend or other devices. Also known as Back Haul. A term used to describe the technology which provides the infrastructure for electronic traffic traveling from the subscriber to the platform company.” (Source: Nielsen)

3: “Term commonly used to describe the action of sending data back to a host server over a phone wire or cable pipe.” (Source:

NOTE – Many other types of homes (with the exception of digital Set-Top Box homes) do not have backchannels. Satellite homes receive back signals from landline phone lines which vary from home to home.

NOTE – Available bandwidth on the return path is severely limited within the existing digital cable environment, and exceeding bandwidth limits can be catastrophic —i.e., STB reboots, network downtime. Motorola systems are limited to a raw bitrate of 256 Kbps per node (i.e., 500 to 1500 STBs), much of which is consumed by the system itself, VOD session management, IPG interaction, interactive application processing, etc.,  Also, communication on this return path is limited to UDP, which does not guarantee delivery of information from STB to the back-end, and generates additional bandwidth usage by applications to confirm delivery and resend lost data. Cisco systems provide slightly more return path bandwidth and support TCP (i.e., guaranteed delivery of data), but typically reserve more return path bandwidth for system and resident application (e.g., SARA) use. Collecting STB measurement data with low Latency is a complex task, especially for census data. Load on the back channel is an issue in downloading STB data. (Source: FourthWall Media)

NOTE – From Mediapost TV Board article by Weisler, Feb09- A way to get data back to the operator. Cable systems have a back channel but satellite operators can only send data back via the phone lines. Since not all satellite Set-Top Boxes  connect to phone lines, this must be taken into account when receiving Set-Top Box data from satellite homes. Kantar Media Audiences says there is no significant difference in the satellite homes with and without the back channel. Rentrak says boxes are connected in different ways – some need to back channel to get scheduling data, others connect via broadband. It all varies by operator. More examination may be in order.