Podcast
Questions and Answers
What degree does the signal detected by receiver R1 lead the reference signal?
What degree does the signal detected by receiver R1 lead the reference signal?
- 90°
- 180°
- 270° (correct)
- 360°
How does the signal detected by receiver R2 differ from that of receiver R1?
How does the signal detected by receiver R2 differ from that of receiver R1?
- It is a lower frequency signal.
- It leads the reference signal by 270°.
- It lacks variability.
- It leads the reference signal by 180°. (correct)
What is assumed about the distance from the antenna array to the aircraft receivers?
What is assumed about the distance from the antenna array to the aircraft receivers?
- It is equal to the diameter of the array.
- It is significantly smaller than the diameter of the array.
- It is significantly larger than the diameter of the array. (correct)
- It varies depending on the aircraft type.
What is the rotational direction of antenna A with respect to antenna M?
What is the rotational direction of antenna A with respect to antenna M?
What is the primary type of signal that the DVOR station initially radiates from the northernmost point of the array?
What is the primary type of signal that the DVOR station initially radiates from the northernmost point of the array?
What does the vector representation in Figure 2-5 illustrate?
What does the vector representation in Figure 2-5 illustrate?
Which receivers are specifically illustrated in the context of a DVOR station?
Which receivers are specifically illustrated in the context of a DVOR station?
What phase relationship is observed as the antenna array commutes?
What phase relationship is observed as the antenna array commutes?
What is the relationship between distance and time for RF signals as they propagate?
What is the relationship between distance and time for RF signals as they propagate?
Which antenna produces a lower Doppler shifted frequency compared to the fundamental frequency?
Which antenna produces a lower Doppler shifted frequency compared to the fundamental frequency?
What effect does the counterclockwise rotation of sideband radiating elements have on signal frequency?
What effect does the counterclockwise rotation of sideband radiating elements have on signal frequency?
How is frequency defined in the context of signal propagation?
How is frequency defined in the context of signal propagation?
What happens to the frequency produced by the eastern antenna?
What happens to the frequency produced by the eastern antenna?
What measurement is utilized to determine the separation of wave fronts from antennas?
What measurement is utilized to determine the separation of wave fronts from antennas?
Which antennas produce no frequency shift according to the given information?
Which antennas produce no frequency shift according to the given information?
What is the significance of the measurement distance d1 and d2 in the context?
What is the significance of the measurement distance d1 and d2 in the context?
What is the phase relationship between the detected FM signal and the reference AM signal for aircraft receiver D?
What is the phase relationship between the detected FM signal and the reference AM signal for aircraft receiver D?
At what bearing does aircraft receiver C detect the variable FM signal leading the reference by 180°?
At what bearing does aircraft receiver C detect the variable FM signal leading the reference by 180°?
Which combination of antennas results in no Doppler shift being present?
Which combination of antennas results in no Doppler shift being present?
How much time separates the emissions of RF energy from antennas #12 and #13 during the counterclockwise rotation?
How much time separates the emissions of RF energy from antennas #12 and #13 during the counterclockwise rotation?
What is the angular relationship between the detected FM signal of receiver B and its reference signal?
What is the angular relationship between the detected FM signal of receiver B and its reference signal?
What type of signal does aircraft receiver A detect that is identical across all receivers?
What type of signal does aircraft receiver A detect that is identical across all receivers?
What phenomenon is described as being most pronounced when the West and East antennas are radiating?
What phenomenon is described as being most pronounced when the West and East antennas are radiating?
What does the variable FM subcarrier detected in aircraft receiver A serve to represent?
What does the variable FM subcarrier detected in aircraft receiver A serve to represent?
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Study Notes
RF Energy and Antenna Operation
- Antenna #37 starts radiating RF energy 1/1440 of a second after antenna #12 and #13.
- The separation of wave fronts from these antennas is defined as distance d2, with d1 observed to be greater than d2.
- Signal propagation relates distance separation to time; frequency (f) is the reciprocal of time (1/t).
Doppler Shift Mechanism
- The western antenna produces a Doppler-shifted frequency of 9480 Hz (9960 Hz - 480 Hz).
- The eastern antenna shifts frequency to 10440 Hz (9960 Hz + 480 Hz).
- Northern and southern antennas do not produce frequency shifts.
Aircraft Receiver Detection
- Aircraft receiver A detects a 30 Hz FM subcarrier and outputs a 30 Hz reference signal identical to other receivers (B, C, D).
- Aircraft receiver D, at a 90° bearing, leads the reference signal by 90°; C leads by 180° at a 180° bearing; B leads by 270° at a 270° bearing.
- Aircraft receiver A at 0° has signals in phase.
Azimuth-Dependent FM Generation
- The azimuth-dependent FM generation is reliant on the configuration of antennas around the DVOR station.
- Antenna A rotates counterclockwise around a reference antenna M, impacting the variable signal detection by receivers R1 and R2.
Array Commutation and Phase Relationships
- After a quarter cycle of commutation, the antenna returns to its northern position, repeating the cycle.
- The distances from antennas A (sideband) and M (reference) to aircraft receivers are assumed substantially larger than the array's diameter.
- At the start of antenna operation, the upper sideband signal is emitted, but the lower sideband is similar in characteristics.
Visual Illustrations
- Figures referenced illustrate the instantaneous direction of RF sources, received signals, and vector representations of phase relationships at various positions in relation to the DVOR station.
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