I received several responses to my question in last week's RF Report concerning PSIP
and channel numbers for broadcast TV stations on digital cable systems.
I've seen cases where DTV sets display major and minor numbers that don't match anything the broadcaster is sending in his PSIP when hooked directly to a cable TV outlet without using a set-top box. Program guides aren't displayed either. Hooked up to an antenna, the same DTV sets work fine and display all the broadcasters’ PSIP data.
Many broadcasters, especially UHF stations, brand their station with both their over-the-air cable channel and the analog cable channel number. Some identify the digital cable channel number as well. This works fine, as long as the viewer is using a cable company set-top box.
As more viewers discover they can plug their new HDTV into the cable jack and get not only all of their analog channels but many digital channels, including local HDTV stations at no extra change, cable companies and TV stations are likely to receive calls from viewers frustrated by odd major/minor channel numbers assigned by cable companies or generated by default in the DTV set when no specific PSIP information such as the station call letters, name, or program name are present.
Some of the readers indicated that their cable system was correctly sending the local broadcast station PSIP data, at least the major and minor channel numbers, to DTV receivers without set-top boxes. Comcast in Portland, Ore., is doing a great job. Everett Helm, CPBE and Director of Engineering for RF Systems at Oregon Public Broadcasting, said he can punch in 10-1 on his ClearQAM set and get his station's main DTV channel, as expected. A viewer using Comcast's San Francisco system said PSIP data is very inconsistent, noting ABC's and PBS's flagship channels, 7.1 and 9.1, are not available in the clear and return a “not-authorized” message on both of his new Sony DTVs. He said other channels were viewable, with varying levels of PSIP data and no EPG.
Art Allison, director of Advanced Engineering in the NAB Science and Technology Division, wrote to remind me that FCC rules require cable companies to carry PSIP data for the primary channel when it is present. The cable PSIP rules are in 47 CFR Sections 76.602(b) and 76.640(b)(1)(iv) (You can access the latest FCC rules at no charge on the Internet using e-CFR
from GPO Access.)
Carrying broadcaster PSIP data requires some compromises by cable companies. For example, as Allison points out, a channel can carry only one broadcaster. It could carry multiple program streams from the same station and could possibly carry cable channels that aren't in the clear that are listed only in the channel guide used by set-top boxes. He commented that putting only one broadcaster on a channel would allow the channel to carry the correct TSID data.
I'm interested in receiving readers' comments on this. If there is enough interest in the topic, I'll pull some data from other industry experts and cover it in detail in a future RF Technology
column in TV Technology
. Please include the name of your cable system and the DTV receiver you are using along with the PSIP data that is making it through. If the channel numbers don't match, please include three or four DTV cable channel numbers and the stations real major/minor channel number.
Read all of the latest RF Report here