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Engineers, can you help this OTA viewer?

Letter to the editor:

Hi Brad:

Remember me? I wrote a few articles for BE way back in 1999 and 2000 for you - mainly regarding the topic of high definition.

I am writing to you now to ask you to put my complaint in your letters to the editor section.

I am having a BIG problem with KDFW Fox 4 in Dallas, TX - DTV Channel 35.1 remapped to 4.1. KDFW Fox 4.1 introduced mobile services to their broadcast bitstream sometime around the end of January of this year. Ever since that happened I have had audio dropouts constantly in my OTA reception of KDFW Fox 4.1.

These audio dropouts occur every 1 to 2 seconds, and last for about 10 to 15 frames. I have sent emails to KDFW Fox 4 about this problem. Mark Harris of KDFW Fox 4.1 has responded to my complaints by stating that I have an "older" ATSC receiver in my HDTV and that is what is causing the audio dropouts.

I am having a really hard time accepting that explanation. I own a Sony XBR 970 34-inch 16X9 tube HDTV with a valid ATSC receiver that I purchased in April of 2006.

When the mobile services are inserted into the KDFW Fox 4.1 broadcast bitstream I experience the audio drop outs. When the mobile services are removed my OTA DTV reception of KDFW Fox 4.1 is fine.

I have been watching OTA DTV in Dallas/Ft. Worth for over 12 years. I was one of the first people to purchase and use a digital television in Dallas/Ft. Worth starting in August of 2000. My first set was the RCA 38-inch 16X9 tube HDTV. Yes it was a 300 plus pound TV that required me to build a custom stand to support it. It provided GREAT HDTV images for six years before I replaced it with the Sony so that I could obtain an HDMI input for my Sharp Blu-Ray player.

I also took the time to install a Radio Shack antenna on my roof pointed - "line of site"- towards Cedar Hill where most of the TV transmitters are located in Dallas/Ft. Worth. This antenna is even grounded by an 8 foot grounding rod I pounded into the turf myself.

I have NEVER had any DTV OTA reception issues until my audio drop out problems with KDFW Fox 4.1. Four other DTV stations now offer mobile services in Dallas/Ft. Worth - NBC 5.1, WFAA 8.1, CBS 11.1, and Channel 68.1. I have NO problems receiving these 4 DTV channels. The folks at KDFW Fox 4.1 refuse to tell me why they can't offer mobile services without screwing up my OTA DTV reception while these other 4 DTV channels in Dallas/Ft. Worth can.

Brad: Please invite the engineering department at KDFW Fox 4.1 to explain why they can't offer mobile services without screwing OTA viewers while other DTV stations in Dallas/Ft. Worth can do so...

Best Regards, Tim Werner

HD/SD Broadcast Television Video Editor/Colorist Member ATAS: Academy of Television Arts and Sciences - Television Motion Picture Editors Peer Group

Broadcast Engineering magazine editor responds: I called the engineering department at KDFW and got a recording, basically saying, "Leave a message". I did leave a detailed message outlining who I was and that I had a viewer complaint and wanted to talk with someone about it. I invited the station to provide a response that could accompany this viewer's letter. Concluding, I invited someone from the station to call me to discuss the issue.

It has now been more than a month and the KDFW engineering department has not responded to my inquiry.

Whether or not the staff at KDFW understands the actual cause of Mr Werner's reception is but a small part of the larger dilemma. The core issue is whether or not the station's management and engineers care enough about their viewers to at least try to understand why the station's signal may be the only one in the DFW area where a mobile DTV stream is causing OTA reception errors. (In a follow-up note, Mr. Werner is told the station, has sent "...a sample of their broadcast signal to Sony, and has told me that they are waiting to hear back from them."

Hey, I've got no dog in this hunt, but I feel for Mr. Werner and his attempt to solve what appears to be a one-station problem.

But to WDFW's defense, if the station's broadcast chain is performing correctly then the mobile DTV system has no chance of being widely implemented. What station GM in her right mind is going to risk damaging the audio of OTA broadcast feeds with mobile?

I invite other Broadcast Engineering readers to offer their thoughts here on why adding a mobile DTV data stream could cause OTA audio problems. Perhaps, we can help resolve this viewer's reception problem.

Update June 8 from KDFW engineer Mark


We have been in contact with Sony and they are currently looking to send an Engineer to Dallas in the next couple weeks to review our situation.

They have asked if it's possible to come to your home to play back sample RF streams into your TV to study the problem.

If you're okay with this please let me know what days of the week work best for you and if you are planning to be away for any length of time during the remainder of June.

Thanks Mark

Editor comment:

This is an interesting dilemma to follow as other stations may be experiencing similar issues and not know it. Stay tuned and if you have suggestions for a resolution, serve them up.