CBT Broadcast Systems & Equipment 3 — Questions and Answers
Question 1: What is the key advantage of using fiber optic cable over coaxial cable for signal transport in large broadcast facilities?
- Lower cost per foot
- Immunity to electromagnetic interference and much longer distance capability (Correct answer)
- Easier termination and repair in the field
- Higher impedance matching with broadcast equipment
Correct answer: Immunity to electromagnetic interference and much longer distance capability
Fiber optic cable is immune to EMI/RFI and supports signal transport over kilometers without amplification, making it ideal for large facilities and outside broadcasts.
Question 2: In digital broadcast systems, what is the purpose of a serializer/deserializer (SerDes)?
- To encrypt the video signal for secure transmission
- To convert parallel data to serial form for transmission and back to parallel at the receiver (Correct answer)
- To serialize multiple audio channels into a single stream
- To convert SDI signals to HDMI format
Correct answer: To convert parallel data to serial form for transmission and back to parallel at the receiver
A SerDes chip converts parallel data (multiple bits simultaneously) into a serial bitstream for efficient single-cable transmission, then reverses the process at the destination.
Question 3: What is the primary difference between SDI and HD-SDI?
- SDI uses fiber while HD-SDI uses copper
- HD-SDI operates at a higher bit rate (1.485 Gb/s) to carry high-definition video (Correct answer)
- SDI supports embedded audio while HD-SDI does not
- HD-SDI requires 110-ohm termination instead of 75 ohms
Correct answer: HD-SDI operates at a higher bit rate (1.485 Gb/s) to carry high-definition video
SD-SDI operates at 270 Mb/s for standard definition, while HD-SDI runs at 1.485 Gb/s (SMPTE 292M) to accommodate the greater bandwidth of HD video.
Question 4: What function does a test signal generator serve during broadcast equipment alignment?
- It generates encrypted test patterns for secure facility testing
- It produces known reference signals like color bars or tone for calibrating equipment (Correct answer)
- It simulates satellite uplink conditions for testing transmitters
- It generates SCTE-35 cue tones for ad insertion testing
Correct answer: It produces known reference signals like color bars or tone for calibrating equipment
Test signal generators produce standardized reference signals (color bars, multiburst, tone) used to align, calibrate, and verify broadcast equipment to specification.
Question 5: In broadcast audio, what is the function of a mix-minus feed?
- An audio mix with the low frequencies removed
- A program mix sent to a contributor with their own audio removed to prevent feedback (Correct answer)
- A backup audio path used when the primary mix fails
- A mono downmix of a stereo program for narrowcast applications
Correct answer: A program mix sent to a contributor with their own audio removed to prevent feedback
A mix-minus is the program audio mix minus the recipient's own contribution, preventing echo or feedback when the feed is returned to them.
Question 6: What is the standard reference level for professional broadcast audio in the United States?
- +4 dBu nominal operating level (Correct answer)
- 0 dBFS peak level only
- -10 dBV consumer level
- +8 dBu peak program level
Correct answer: +4 dBu nominal operating level
Professional broadcast audio in the US uses +4 dBu as the nominal operating level, providing headroom above the noise floor and below the clipping point.
Question 7: What is the purpose of a loudness meter (such as one measuring LKFS/LUFS) in broadcast audio?
- To measure the peak amplitude of individual audio samples
- To measure perceived loudness over time to ensure compliance with broadcast loudness standards (Correct answer)
- To detect clipping and distortion in the audio signal chain
- To compare left and right channel levels for stereo balance
Correct answer: To measure perceived loudness over time to ensure compliance with broadcast loudness standards
Loudness meters using ITU-R BS.1770 algorithms measure integrated loudness (LKFS/LUFS) over time to ensure compliance with standards like ATSC A/85 in the US.
CBT Broadcast Systems & Equipment 3
What is the key advantage of using fiber optic cable over coaxial cable for signal transport in large broadcast facilities?