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Program Clock Reference
Probably the most important item in the television transport stream is the Program Clock Reference (PCR). The entire ATSC system relies on correct timing of the creation and reception of all the elements in the transport stream. In a somewhat similar fashion, we had the same thing in NTSC with Vertical and Horizontal sync.
The encoder has an internal clock operating at 27 MHz which the various elements are locked to. A sample of this clock, called the PCR is inserted in the stream every 100ms and is used to lock the clock located in the customers receiver.
If the PCR time stamp does not occur when the receiver expects it “PCR jitter” can occur. This often happens anytime you multiplex streams....and the more services you are multiplexing into a stream the harder it is to keep the spacing for PCR accurate. Not only can this happen in the station encoder but also during re-endcoding at a cable head in.
While encoding and re-encoding PCR jitter can be created because of packet respacing. This can lead to underflow or overflow in the receiver buffers. The more services in the stream sometimes can make it more difficult for the PCR to remain in the correct location.
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ABA 80th Anniversary Tour
Across the state this year, the ABA has been celebrating the wonderful partnerships between broadcasters and community stakeholders, PLUS inducted legendary broadcasters into our Hall of Fame.
So far ABA has hosted receptions at 8 different cities around the state. The final stop on the tour will in Birmingham on November 18th.
The Birmingham reception will be held at Ross Bridge Resort in Birmingham.
Register here for the Birmingham reception.
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FCC Inspections
Yes Virgina, the FCC can and will inspect broadcast operations to ensure complete compliance with Commission Rules and Regulation.
One recent inspection dealt with a group of stations not monitoring the correct sources with their EAS decoder.
11.52(d)(1): “EAS Participants must comply with the following requirements: With respect to monitoring for EAS messages that are formatted in accordance with the EAS Protocol, EAS Participants must monitor two EAS sources.
The monitoring assignments of each broadcast station and cable system and wireless cable system are specified in the State EAS Plan and FCC Mapbook. They are developed in accordance with FCC monitoring priorities.”
If for technical reasons you are unable to monitor the correct sources, stations are required notify the State Emergency Communications Committee (SECC) for alternate monitoring sources.
In addition, the stations were not maintaining a “Station Log” correctly.
73.1820(a): “Entries must be made in the station log either manually by a person designated by the licensee who is in actual charge of the transmitting apparatus, or by automatic devices meeting the requirements of paragraph (b) of this section .
(b) All Stations: An entry of each test and activation of the Emergency Alert System (EAS) pursuant to the requirement of [47 CFR § 11, et seq.] and the EAS Operating Handbook.
(c): “The chief operator is responsible for completion of the following duties specified in this paragraph below. When these duties are delegated to other persons, the chief operator shall maintain supervisory oversight sufficient to know that each requirement has been fulfilled in a timely and correct manner.
Review of the station records at least once each week to determine if required entries are being made correctly. Additionally, verification must be made that the station has been operated as required by the rules or the station authorization. Upon completion of the review, the chief operator or his designee must date and sign the log, initiate any corrective action which may be necessary, and advise the station licensee of any condition which is repetitive.”
If you have any question about EAS compliance contact your state’s SECC or State Broadcasters Association. In Alabama email the SECC.
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