Final Exam Review Flashcards
1
Q
What are the 3 types of microphones?
A
Electret
Dynamic
Carbon
2
Q
Which of the microphones require an amplifier and why?
A
Electret and Dynamic
They only produce mV outputs that need to be amplified to match carbon mics
3
Q
How does the electret microphone work?
A
sound = diaphragm vibration = distance btwn diaphragm and plate = electric signals
capacitance change
4
Q
How does the dynamic microphone work?
A
A diaphragm moves a magnet/coil which creates a current
Electromagnetic effects
5
Q
How does the carbon microphone work?
A
sound = carbon compressed by diaphragm = resistance change = current flow
6
Q
What are the 3 parts of a jack?
A
Tip, Ring, Ground/Barrel
7
Q
Which part of the jack is the PTT and what does it do?
A
The tip
When PTT is activated, tip is grounded which then we go from Rx to Tx
8
Q
Which part of the jack is the audio?
A
The Ring which has a DCV supplied from radio
9
Q
Which part of the jack is common to the PTT and audio?
A
The ground
10
Q
Which mics require a bias voltage to operate and where does the voltage come from?
A
All mics require a bias voltage, they come from the radio itself
11
Q
Aircraft microphones require a bias voltage of?
A
9V
12
Q
Microphone impedance is what?
A
150ohms AC
13
Q
Typical output voltage of microphones are what?
A
1Vrms
14
Q
Headphone output impedance is?
A
500-600ohms
15
Q
Speaker impedance is?
A
3.2 or 8 ohms
16
Q
For power conversions what are the decibels?
A
3dB(2x) and 10dB(10x)
17
Q
For voltage conversions what are the decibels?
A
6dB(2x) and 20dB(10x)
18
Q
What is the reference level for dBm units?
A
1mW
19
Q
What is the reference level for dBw?
A
1W
20
Q
If an amplifier has a gain of 26dB and input voltage is 1mV what is the output voltage?
A
20mV
21
Q
A transmitter has 3 stages with gains of 13dB, 20dB, and 3dB (total 36dB) if 2mW is input power what is the output power?
A
8W
22
Q
If a signal generator attenuator is set to minus 20dBm what output power is sent?
A
0.01mW
23
Q
Ground stations are identified during radios communications by?
A
Airport name and station type, ie Toronto tower.
24
Q
What is the spoken word for distress?
A
Mayday
25
What is the spoken word for urgency?
Pan Pan
26
According to the radiotelephone operators guide Coordinated Universal time (UTC) is used to avoid confusion between different time zones. What is the accepted abbreviation for UTC?
Zulu time
27
What is the max output power for your radio license good for?
250W ERP
28
Who can get a radio license?
Anyone as long as they don't have a disability that prevents them from operating a radio
29
What is the message format?
Who you are talking
then: this is
then: your call sign'\
then: your message
then: OVER
30
The time 4:45am is expressed as?
0445
31
The time 6:37pm is expressed as?
1837
32
A "." is said as what?
Decimal
33
The word "HEAVY" is used to describe what?
An aircraft weighing more than 300,000lbs
34
If you need someone to repeat the message what do you say?
SAY AGAIN
35
How long should signal/radio checks last?
10s
36
On a signal/radio check, when someone responds "5 by 5" what does the first and second numbers mean?
the first number is the READABILITY
| the second number is the STRENGTH
37
When carrying out a VSWR test a forward power of 100W and reverse power of 1 watt is measured, what is the VSWR?
1.2:1
38
When carrying out a VSWR test a forward power of 100W and reverse power of 10 watt is measured, what is the VSWR?
2:1
39
What value of VSWR is the acceptable limit?
2:1
40
If the antenna transmission line (co-ax) is open circuit what VSWR or SWR would be measured?
5:1
41
When testing a transmission line with a TDR, what indication would a short in the line show as?
Downward deflection on trace
42
When testing a transmission line with a TDR, what indication would an open in the line show as?
Upward deflection on trace
43
When testing VSWR, if you put the Wattmeter at the ANT and it passes at the ANT but fails at the Comm, what is faulty?
Transmission Line/ Co-ax is faulty
44
When testing VSWR, if it fails at both the ANT and the Comm, what is faulty?
The Antenna
45
What are the frequencies that you test the VSWR on?
118MHz, 126.5MHz, 136.975Mhz
46
If the antenna transmission line (co-ax) is a perfect circuit what VSWR or SWR would be measured?
1:1
47
When testing a 121.5MHz ELT what time restriction must be observed?
First 5min after the hour
48
ELTs have an arrow on the case. For proper installation where should the arrow point?
Towards the direction of flight / front of aircraft
49
What advantage does the 406MHz ELT have over 121.5MHz ELT?
Gives more accurate position coordinates
50
ELT non-rechargeable batteries must be replaced after:
activation Unknown duration
on or before batt. replacement
after ELT used in emergency
when sum of all tx exceeds 1hr
51
Replacement of ELT batteries should be done?
When testing shows insufficient charge
52
When can you transmit using the 406.025MHz ELT?
Not allowed at any time
53
What are the restrictions on performing a self test tx on a 406MHz ELT and how many bursts are we looking for?
No restrictions, 1 burst
54
ELT rechargeable batteries must be recharged after:
```
activation Unknown duration
after ELT used in emergency
when sum of all tx exceeds 1hr
time intervals specified by manuf.
Immediately before ELT installed on airc.
```
55
What is the transmits power output used on the 121.5MHz ELT?
50-100mW
56
What is the transmits power output used on the 406MHz ELT?
5Watts
57
An ELT has to be inspected every?
1 year
58
What is the modulation used on the 121.5MHz ELT?
AM
59
What is the modulation used on the 406MHz ELT?
Phase/DPSK
60
What is the modulation type used on the 121.5MHz ELT?
Swept tone
61
What is the modulation type used on the 406MHz ELT?
Bi-phase
62
The 406 ELT transmits for ______ every _______
0.5s every 50s
63
The 121.5MHz ELT transmits:
Continuously/Repetitively
64
The 406 MHz ELT output consists of a ______ but pulse train
112(short) and 144(long)
65
The 121.5MHz ELT is modulated by a distinct down-sweeping audio tone varying between _______ at a rate of ______
1600-300Hz
| 3Hz
66
What frequency spacing is used for the HF comm?
100Hz
67
What is the purpose of the antenna coupler in an HF installation?
To compensate for incorrect antenna length
68
What is the purpose of the lightning arrester?
Protect the receiver
69
The clarifier has a frequency range of about?
+/- 200Hz
70
Civilian aircraft are restricted to use the ______ side band on HF transmissions?
Upper Sideband
71
What is the typical output power of an HF transmission?
150W PEP (100-400W PEP)
72
What is the purpose of the clarifier?
Changes the frequency of the carrier oscillator during Rx only
73
Where is clarifier located?
In the BFO
74
If the mic is keyed and we don't speak but there is still a power output what is happening?
Faulty, diode could be broken keeping it unbalanced
75
HF audio response/bandwidth is?
350Hz to 2500Hz
76
At 2MHz how much Hz does the clarifier supply?
| What about for 30MHz?
+/- 17MHz
| +/- 250Hz
77
On HF, how do you perform a sensitivity test in SSB?
Carrier only (no modulation) at 1kHz above the Rx selected freq.
78
VHF frequency range is?
118MHz to 136.975MHz
79
VHF range is based on?
Altitude
80
VHF bandwidth is what?
5-10kHz
81
VHF channel spacing is what?
25kHz or 8.33kHz
82
What is the purpose of the limiters on VHF?
prevent modulation from going over 90%
83
Typical VHF comm power output?
20W
84
What is the VHF comm duty cycle?
4min off, 1min on
85
What is the purpose of the AGC?
Keep the volume approximately constant during signal strength variations at its input (maint. level within 3dB)
86
How do you test the AGC?
Done after the sensitivity test, 1kHz 30% mod, adjust generator output from 10uV to 20000uV, make sure no 3dB change
87
What controls the gain of the IF so that the proper voltage always comes out of the Detector?
AGC
88
What is squelch?
a unique circuit for comms, it keeps the audio nice and quiet unless we are receiving a signal
89
What do we use to monitor backup/carrier squelch?
AGC
90
Squelch operates at how many volts?
2uV (1kHz at 30%mod)
91
AGC operates at how many volts?
20uV (8kHz at 85%mod)
92
What does ACARS stand for?
Aircraft Communications Addressing and Reporting System
93
What is the last way to transmit ACARS if everything else has failed?
HF
94
ACARS transmits how man bits per second?
2.4k/s
95
What is the ACARS message format?
Preamble, Text, Block check
96
Why is a Low Pass Filter connected between the output of a transmitter and the antenna?
To reduce the possibility of transmitting harmonics
97
How many audio tones for SELCAL?
4 tones (2 tones sent at the same time)
98
How long are each bursts?
1s with a 0.2s pause then the other 1s
99
Each SELCAL pulse has a carrier that is modulated by how many %?
90%
100
How is the SELCAL decoder reset?
Reset by the PTT on transceiver
101
How does the pilot know what his SELCAL code is?
A placard on the windshield above the cowl
102
What is the proper sequence of a SELCAL code?
Cannot have a letter later in the alphabet come before earlier ones
103
What is the frequency of a SATCOM air to satellite transmission?
1500/1600MHz
104
What is the frequency of a SATCOM satellite to ground transmission?
4000/6000MHz
105
Where in the SATCOM system would you find an electro-mechanical Beam steering unit?
In a HIGH gain antenna system
106
Where in the SATCOM system would you find a conformal beam steering unit?
In a LOW gain antenna system
107
Operating the test switch or button on a VHF communication radio to verify serviceability actually tests:
The receiver from the IF amp to audio amp and the PSU
