Changes in ATSC Standard to Affect AC-3

Beginning March 1, 2008, The ATSC Standard will require ISO-639 Language bytes within the AC-3 audio stream. In addition, it is suggested that the ISO-639 Language Descriptor remain for legacy devices. (2007 ATSC Standard A/53 Part 3, Sections 6.8.1 and 6.8.3)

If you use AC-3 audio encoding for your DTV transmissions, don’t forget to check your PSIP for compliance to the new requirement. If you don’t know how to check this yourself, you can contact your PSIP encoder manufacturer. Have your software release number ready, and they can tell you if your version supports this ATSC standard update.

If you do not have the latest software updates for your system, you may want to include that cost in next year’s budget. November and December are popular budgeting months around the country.


Several readers have written in about the TV Technology Audio Tip from Sept. 11, “Audio Hum: Causes and Solutions.” Their comments reflect concerns about the safety element involved with using two-prong to three-prong AC adaptors.

In response, it should be noted that a 3/2 prong AC adaptor should only be used on equipment that employs a “double insulated” design, such as wall-type power supplies typically found with low current devices.

In addition, only adaptors that ensure proper polarity should be used. It is also a good idea to use only GFCI breakers. Safety must be the number one priority.