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The 8-VSB exam has 51 questions and runs 3 hours.
These 10 free 8-VSB questions are organized by exam domain, so you can see how each part of the Certified 8-VSB Specialist blueprint is tested. Reveal the answer and explanation under each question.
After a remultiplexer replacement, one service has normal video but no audio. Its PAT entry leads to a valid PMT, which identifies AC-3 audio on PID 0x0042. No packets use that PID. The intended audio is present and decodes correctly when PID 0x0043 is selected manually. Other services are unaffected. Which correction addresses the demonstrated fault?
Correct answer: B - Make the PMT's audio entry identify the emitted AC-3 stream on 0x0043.
A fixed-rate 8-VSB multiplex carries 19.392658 Mb/s. Existing non-null traffic occupies 18.550 Mb/s, including all of its transport overhead. A proposed service needs 0.700 Mb/s of video, 0.128 Mb/s of AC-3 audio, and 0.060 Mb/s of additional packetization and signaling overhead. These are steady allocations, not averages of variable-rate peaks. With the existing services unchanged, which launch assessment is correct?
Correct answer: D - It exceeds capacity by approximately 0.045 Mb/s; reduce allocations before launch.
A promo and the program following it both measure -24 LKFS before AC-3 encoding. The promo carries a raw dialnorm value of 31; the program carries 24. A reference decoder applies dialogue normalization, with dynamic-range compression disabled and no other gain changes. Which diagnosis also corrects the inaccurate loudness metadata?
Correct answer: A - The promo plays 7 dB louder; set its dialnorm to 24.
During football coverage, close-ups are clean but crowd shots break into blocks. A local decode of the MPEG-2 encoder output reproduces the defects; the uncompressed source and transport integrity checks are clean. Encoder telemetry shows much coarser quantization during the affected scenes, and the multiplex has unused bitrate. Which adjustment best addresses this limitation?
Correct answer: C - Increase the video allocation and let the encoder use finer quantization.
A channel rebrand changes the short_name in the current TVCT. The revised table has a valid CRC and is transmitted every 200 ms, but its version_number remains 12. Receivers that rescan show the new name; some receivers already tuned to the service retain the old name. The MGT still announces TVCT version 12. What is the appropriate on-air correction?
Correct answer: C - Advance the TVCT version to 13 and update the corresponding MGT announcement.
Virtual channels 6.1 and 6.2 play the correct news and weather services, respectively, but their program listings are exchanged. The verified TVCT assignments are news source_id 0x0101 and weather source_id 0x0102. Captured EIT sections attach news events to 0x0102 and weather events to 0x0101. Program numbers, PAT/PMT mappings, and event start times are correct. Which association must be repaired?
Correct answer: B - The EIT source_id links to their intended virtual channels.
A vendor demonstrates an AC-3 complete main audio service encoded at 48 kHz and 640 kb/s. It decodes successfully, and the vendor cites A/52 codec capability as proof that the setting is suitable for conventional ATSC terrestrial emission. The purchase specification requires compliance with A/53 Part 5:2014. Which finding belongs in the acceptance review?
Correct answer: A - The bitrate exceeds Part 5's 448 kb/s limit for a complete main service.
At a receive site near several high-power transmitters, an 8-VSB receiver shows strong signal strength but intermittent decoding failures. Inserting a calibrated 10 dB attenuator directly ahead of its tuner lowers the desired-signal reading, raises MER from 21 dB to 31 dB, and eliminates uncorrectable packets. The antenna and cable are unchanged, and repeating the test gives the same result. What does this response most strongly indicate?
Correct answer: D - Receiver front-end overload from excessive input signals.
Short impulse-noise bursts leave clusters of erroneous bytes at an 8-VSB receiver's trellis-decoder output. Why can the byte interleaver/deinterleaver pair improve Reed-Solomon recovery without adding parity?
Correct answer: B - Deinterleaving distributes the burst's errors among multiple Reed-Solomon codewords.
Following a transmitter power-supply fault, a remote OFF command reduces indicated RF output to zero. A qualified technician is preparing for internal maintenance in the high-voltage compartment, not energized troubleshooting. The supply contains energy-storage capacitors. What must be established before the equipment can be treated as deenergized for that work?
Correct answer: A - Energy sources are isolated and locked out, stored energy is controlled, and absence of voltage is verified.
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