1. Analog Operating Modes

2. Continuous Wave (CW) Morse code Narrow bandwidth
Constant amplitude and frequency
Morse code (no more requirements to learn for the 3 levels of licenses in the U.S.)
Narrow bandwidth of less than 250 Hz
One of most reliable forms of communication
Unmodulated single carrier turned on and off at different rates
Key interrupts signal
Only mode allowed in mode-restricted sub-bands 50.0 MHz to 50.1 MHz and MHz to MHz

3. Amplitude Modulation (AM)
Two sidebands and a carrier
SSB more common than DSB
Two sidebands and a carrier
Carrier wave shown in second graph, amplitude changes by audio input
Information contained in the sidebands
Early mode for voice transmission by HAMs
Now only sometimes used in the 80 meter band (around 3.9 MHz)
SSB has many advantages over the DSB shown here
If you tune into the USB or LSB slightly away from the center frequency, carrier can sound like a continuous tone

4. Single Sideband (SSB) AM with suppressed carrier and sideband
Popular voice mode on HF
Like AM but with one sideband and the carrier suppressed
Half the bandwidth of AM
Occupy about 3 KHz of spectrum
Signal more focused in just one sideband
Therefore signal travels farther and is easier to copy
Mode of choice for HAMs on HF (between 10 and 80 meter bands)
Receiver still needs original carrier to decode signal
SSB receivers reinsert low-level carrier to accurately reproduce the original transmission sound
Convention to use USB above 10 MHz and LSB below 10 MHz

5. Frequency Modulation (FM)
Common voice mode on 2 meter band
High bandwidth
Common mode of voice transmission on 2 meter band and higher frequencies, though sometimes around 10 meters
Where most HAMs start
Higher frequencies have a lot of room for the higher bandwidth requirements of KHz
High bandwidth → high quality
High bandwidth and frequencies → shorter range and higher attenuation
Sidebands from changing frequencies
Also SSB for FM

6. Exam Questions

7. T1B09
Why should you not set your transmit frequency to be exactly at the edge of an amateur band or sub-band?
A. To allow for calibration error in the transmitter frequency display
B. So that modulation sidebands do not extend beyond the band edge
C. To allow for transmitter frequency drift
D. All of these choices are correct
Could be calibration error
Transmit frequency is center frequency, and as shown by AM and SSB visualizations, sidebands extend beyond the carrier frequency
Freq. drift: component aging, temperature, problems with crystal oscillator and voltage regulator

8. T1B09
Why should you not set your transmit frequency to be exactly at the edge of an amateur band or sub-band?
A. To allow for calibration error in the transmitter frequency display
B. So that modulation sidebands do not extend beyond the band edge
C. To allow for transmitter frequency drift
D. All of these choices are correct

9. T1B11
What emission modes are permitted in the mode-restricted sub-bands at 50.0 to MHz and to MHz?
A. CW only
B. CW and RTTY
C. SSB only
D. CW and SSB
See slide on CW

10. G2A04
Which mode is most commonly used for voice communications on the 17 and 12 meter bands?
A. Upper sideband
B. Lower sideband
C. Vestigial sideband
D. Double sideband
General class, not technician class question
c = λv 12 meter around 25 MHz and 17 meter around 18 MHz
Convention of LSB <10MHz and USB > 10MHz I mentioned on the SSB slide

11. Sources CW AM
SSB