Broadcasters embrace PSIP potential
Large numbers of DTV broadcasters are implementing Program and System Information Protocol, or PSIP, in such a way that will permit electronic program guides (EPGs) and other viewer-friendly features.
Developed by the ATSC, PSIP is an integral part of DTV broadcasting and its use is mandatory. PSIP contains the information that lets receivers properly tune to the DTV channel and can contain additional information, such as major and minor channel numbers and even a master time reference.
However, some broadcasters are moving well beyond the minimum PSIP requirements, and both manufacturers and broadcasters are actively developing systems that will fully enable the EPG feature of PSIP.
Harris Corp. has been very successful with its FlexiCoder DTV encoder, which has a standard provision for a minimal version of static PSIP. But according to John DeLay, the director of DTV products for Harris, more than 400 broadcasters use the most advanced version of FlexiCoder's software, called PSIPplus Pro, which includes EPG capability.
"[PSIPplus Pro] supports every function, including caption description, and we have the ability to ingest and merge functions and talk to things like Encoda traffic systems, TMS services, Excel spreadsheets and other traffic systems," DeLay said.
Harris has a PSIP.com service that provides EPG services for broadcasters in a data form that is compatible with the company's PSIPplus Pro software.
"We go to Tribune Media Services, ingest the program guide services, build all the tables from the database and that is uploaded into the PSIP system," DeLay said.
There are many parts to PSIP, and some DTV receivers will not tune to a DTV signal if PSIP is completely missing. Therefore, most DTV encoders provide at least a minimal level of PSIP, often called "static PSIP," to handle the minimum amount of information necessary to ensure that the signal gets through.
Some broadcasters are pushing beyond the minimum and implementing EPGs on their DTV channels. Mark Aitken, director of advanced technology for Sinclair Broadcasting, said that the company is taking a corporate-wide approach.
"We have standardized on the Triveni Digital GuideBuilder [PSIP encoder] for all our stations, and we have 56 stations now on the air," Aitken said. "Some of our stations are doing EPG and we're working on a custom traffic management system that will seamlessly tie the traffic system into PSIP, including the EPG."
Sinclair is using Harmonic encoders on its DTV stations and Aitken said that, with Harmonic's assistance, there was minimal effort getting PSIP up and running.
"[We use] the Harmonic encoders with the THESYS management system," he said. "THESYS is really the multiplexed brains of their encoder product line and it allows you to stack up multiple encoders for multichannel operation."
Transmitting at least four blocks of the event information table (EIT) is required for DTV broadcasters. Since each block holds three hours of programming information, these four required blocks of EIT information require encoding PSIP with 12 hours of programming information.
PSIP vendors can optionally extend the number of EIT blocks, giving broadcasters up to 16 days worth of programming information that can be transmitted in the EIT portion of PSIP. In addition to the EIT, PSIP also supports the extended text table (ETT), which can hold descriptive information about upcoming programs. It is this optional information that Sinclair and other broadcasters are beginning to implement in their PSIP signals.
Broadcasters who decide to go with a low-cost, low-power DTV plant have some options for delivering EPG in their PSIP stream. KTech builds an all-inclusive DTV transmitter, which includes a DTV encoder with a static PSIP generator that provides the mandatory four blocks of EIT information.
"A lot of [customers] don't even know about it," said Romeo Castillo, the director of sales for KTech. "Our PSIP generator has a friendly, front-panel control for this information."
There are several DTV encoder manufacturers and each has options available to provide either enhanced EIT information, ETT information or will interface with a third-party PSIP encoder such as the Triveni Digital GuideBuilder.
Although DTV requires at least minimal information that could be used for an EPG, Aitken thinks that there is a reason to exceed the minimum. A comprehensive EPG is one way to stand out from the crowd when viewers first turn on their new DTV receivers.
"[Sinclair's] long-term vision is to be able to have a fully automated approach to programming and an EPG," he said. "It provides a competitive advantage."
Bob Kovacs is the former Technology Editor for TV Tech and editor of Government Video. He is a long-time video engineer and writer, who now works as a video producer for a government agency. In 2020, Kovacs won several awards as the editor and co-producer of the short film "Rendezvous."
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