Free CBRE Practice Questions

Question 1

An FM feeder develops substantially higher insertion loss. At the same operating frequency, separate measurements show that the antenna's feed-point impedance has not changed, yet the VSWR measured at the transmitter now looks better. The improved transmitter-end reading is best explained by:

Accepted Answer

Additional attenuation of the reflected wave on its return through the feeder.

Answer

A reduction in antenna mismatch caused by the feeder's added resistance.

Answer

A change in antenna gain that reduces the power reflected toward the transmitter.

Answer

The lower power reaching the antenna has reduced its reflection coefficient.

Question 2

During an FM stereo encoder test, identical in-phase 1 kHz tones are applied at equal levels to the left and right inputs. The composite output contains the audio sum and a normal 19 kHz pilot, but no detectable difference-channel sidebands around 38 kHz. How should this result be interpreted?

Accepted Answer

Their absence is expected because equal in-phase inputs contain no L-R information.

Answer

The suppressed 38 kHz carrier must be restored to carry the stereo audio.

Answer

The encoder's difference-channel modulator has failed despite a working pilot.

Answer

The pilot is too low to generate sidebands from identical audio inputs.

Question 3

A full-power commercial FM station receives a valid Required Monthly Test at 10:10 a.m. The operator proposes relaying it during the 10:45 a.m. program break. Required CAP checks are complete, and the applicable EAS plan imposes no shorter relay interval. Is the proposed relay time permissible?

Accepted Answer

Yes. The relay would occur within the permitted 60-minute interval.

Answer

No. Every Required Monthly Test must interrupt programming immediately upon receipt.

Answer

No. The relay deadline is 15 minutes after receipt.

Answer

Yes. The monthly test can be relayed at any time that day.

Question 4

After a transmitter plate-supply fault, all identified energy sources are locked out and the prescribed discharge procedure is completed. A qualified engineer's correctly rated tester indicates zero volts on the 5 kV bus. The tester passed its known-live-source check before the measurement but fails that check immediately afterward. What is the status of the bus for repair work?

Accepted Answer

Deenergization is unverified; repeat the voltage test with proven working equipment.

Answer

It is deenergized; lockout and discharge establish a safe condition.

Answer

The zero reading remains valid because the tester passed its check before the measurement.

Answer

It can be treated as deenergized after waiting through another specified discharge interval.

Question 5

Clicks begin after an AES67 receiver is replaced. A capture shows continuous RTP sequence numbers and packets arriving before their playout deadlines. Network utilization is low. The sender follows the station's PTP grandmaster, but the new receiver reports a free-running media clock; both devices show the same NTP wall-clock time. What should be corrected before changing packet buffering?

Accepted Answer

Configure the receiver to lock to the station's PTP timing system.

Answer

Increase the receiver's playout delay to smooth out the continuing clock-rate difference.

Answer

Upgrade the switch port to increase available bandwidth.

Answer

Use 16-bit instead of 24-bit PCM to lower the packet payload.

Question 6

For a proposed FM antenna system, the design target is 25.0 kW ERP. The antenna gain in the specified polarization is 5.15 dBi, and the matched feeder has 2.0 dB insertion loss at the operating frequency. Ignoring other losses, approximately what transmitter output power will produce the specified ERP?

Accepted Answer

19.9 kW

Answer

12.1 kW

Answer

12.5 kW

Answer

31.5 kW

Question 7

After a stereo patch lead is replaced, a mono announcer's voice sounds normal when either output channel is monitored alone but nearly disappears in an L+R fold-down. Equal-level test signals arrive at the fold-down inputs with opposite polarity. The patching error most consistent with these findings is:

Accepted Answer

The two balanced signal conductors are reversed in one channel.

Answer

The left and right channel connectors have been interchanged.

Answer

The balanced signal conductors are reversed in both channels.

Answer

One channel's cable shield is open, with both signal conductors intact.

Question 8

A calibrated modulation monitor on a conventional monophonic AM station shows recurring negative peaks of 94% and positive peaks that never exceed 118%. Carrier power, audio quality, and occupied-spectrum measurements are satisfactory. How should these readings affect the station's modulation settings?

Accepted Answer

Retain the settings; both peak measurements are within the applicable limits.

Answer

Lower the positive-peak ceiling to 100% to comply with the AM modulation limit.

Answer

Reduce carrier power until the positive peaks indicate no more than 100% modulation.

Answer

Suspend transmission until the processor produces equal positive and negative peaks.

Question 9

Bench tests of a superheterodyne FM receiver show that the wanted 100.1 MHz signal and an unwanted 121.5 MHz signal both produce the same 10.7 MHz intermediate frequency. Where must additional frequency selectivity be placed to reject the unwanted signal before the two signals become indistinguishable?

Accepted Answer

At the RF input, where a preselector can reject the image before mixing.

Answer

In a narrower 10.7 MHz filter following the mixer.

Answer

In the amplitude limiter immediately before the FM detector.

Answer

In the recovered-audio low-pass filter following the detector.

Question 10

An HVAC contractor is scheduled to work alone for two hours on an FM-site roof. The contractor has no RF-safety training and cannot control or avoid the exposure. A qualified survey establishes continuous far-field exposure of 0.35 mW/cm² from the site's only RF source, operating at 100 MHz. Which assessment applies to the proposed work?

Accepted Answer

General-population limits apply; 0.35 mW/cm² exceeds the 0.2 mW/cm² limit.

Answer

Occupational limits apply because this is paid work; 0.35 mW/cm² is below 1.0 mW/cm².

Answer

General-population limits apply, but the exposure may be averaged over the full two-hour job.

Answer

Occupational limits apply once a site-access badge is issued.

Free CBRE Practice Questions

Domain 1: safety

Question 1

Question 2

Domain 2: problems: electronic and practical

Question 3

Question 4

Question 5

Question 6

Domain 3: operating practices

Question 7

Question 8

Domain 4: theory

Question 9

Question 10

That's 10 of 1,030