We recently experienced a total loss of WGN America HD program audio on our downlink monitoring system. Master Control (MC) operator confirmed audio was present at the output of the MC plant. Operator replaced the primary audio processing chain (Linear Acoustics processing, Nielsen and Arbitron watermarking, AES audio de-embedder and Dolby DP-569 AC-3 encoder) with an identical secondary chain switched into the primary D9050 encoder. Program audio did not return. Even though the PNC did not indicate any alarms/faults, the backup D9050 was then placed on air using the PNC. Program audio immediately returned. We then switched back to the primary audio processing chain - program audio remained. The now off line primary D9050 was power cycled - PNC alarmed appropriately. After reboot, audio was present and decodable from the 9050 ASI output. This unit was left in standby mode for 48 hours while output was monitored through a stand alone ASI decoder and audio QC system with no further audio loss occurring. Encoder was then placed back into primary operation. No further problems have occurred.
Marc Drazin
Director of Engineering
WGN TV - WGN America - CLTV - Antenna TV - This TV
Chicago
Tuesday 10 December, 2013
FURTHER UPDATE – and some interesting findings.
I went to revert the test receiver back to 3.96 and the earlier FPGA code this morning to reconfirm that the receiver still functioned properly.
In doing so from the Web GUI – I discovered that the unit was using the new App code V4.00, but the updated FPGA code WAS NOT LOADED. Specifically the receiver was still using FPGA code R00.00.04vu – not the newer R00.00.05az. I left the App code at V4.00, and forced FPGA code R00.00.05az to load via the GUI. After the requisite reboot – I rechecked and the unit reported that both V4.00 and R00.00.05az were loaded. Initial testing back in our test bed found that the cue trigger outputs WERE firing as expected – following the various DPI Events and DTMF tone sequences properly.
Testing continues. I have asked TAC if this is typical behavior for a "non PNC initiated" application and FPGA upgrade.
Marc Drazin
Chicago
