1A Flashcards
The HF band extends from
3MHz - 30MHz
HF is vulnerable to what three things?
weather, atmospheric disturbances, and the time of day.
We characterize an AM radio wave as having what three things?
an amplitude, a frequency, and a wavelength
This is the magnitude of change in the height of the radio wave. This is the amount of power introduced to the signal.
Amplitude
This is the number of cycles completed by a periodic quantity in a unit of time.
Frequency
This is the distance over which the wave’s shape repeats. It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests or troughs.
Wavelength
Frequency and wavelength have an ___ relationship.
inverse
The symbol for wavelength is…?
Greek letter lambda (λ)
What is the formula for wavelength?
the speed of light divided by the frequency of the signal
The following describes what?
How radio waves move in free space and over the surface of the earth.
The study of radio wave propagation
Radio waves passing through different environments experience what five things?
reflection, refraction, polarization, diffraction, and absorption
Ground waves travel at or near the…?
earth’s surface
___ allows these wave to propagate beyond the horizon, traveling as surface waves which follow the contour of the earth. This allows
mediumwave and longwave broadcasting stations to have coverage areas beyond the horizon out to hundreds of miles.
Diffraction
What two frequencies communication systems can communicate over most of the earth and with submarines hundreds of feet underwater?
Very Low Frequency (VLF) and Extremely Low Frequency (ELF)
This refers to radio waves that travel in a straight line from the transmitting antenna to the receiving antenna.
Line of Sight (LOS)
True or False: LOS requires a cleared sight path?
False - as lower frequency radio waves can pass through buildings, foliage, and other obstructions.
What is the only propagation method possible at frequencies above 30MHz?
LOS
On the surface of the earth, LOS propagation is limited by the visual horizon to about…?
64km (40 miles)
By using ___ to transmit beams of microwaves, point-to-point microwave relay links transmit telephone and television signals over long distances up to the visual horizon.
parabolic dish antennas
What can communicate with satellites and spacecraft billions of miles from earth?
Ground stations
Skywave propagation is also called what?
Skip propagation
The ionosphere is the region of the atmosphere that extends from about ___ miles above the earth’s surface.
30-250 miles
The ionosphere has several layers of electrically charged gas atoms called…?
Ions
The ion arrangement is dependent to some degree upon what? Due to this, the conditions change as the time of day changes.
The Sun
When does the F layer breaks up into two layers (F1 and F2)?
during the daylight hours
The D, E, and F layers are all responsible for HF long haul communications, but the F layer allows communications to take place beyond an estimated…?
1,500 miles
What is the AM broadcast band frequency range?
530kHz to 1700kHz
During the daytime lower frequencies typically return to earth somewhere between ___ miles away. At night, the ionosphere thins, and refracted signals may return to earth as far as several thousand miles away.
20-500 miles
Operating at the high end of the frequency range, the transmitted signal may return to earth anywhere from ___ miles away during the daytime, but at night, the signal may pierce through the ionosphere and not return.
300 to 5,000
___ combines two or more frequencies (i.e., the RF carrier wave & the user data/intelligence wave) across a nonlinear device to produce new frequencies. AM is accomplished by this process.
Heterodyning
In heterodyning, the sum frequency is also known as the ___; the difference frequency is also known as the ___.
upper sideband (USB)
lower sideband (LSB)
A 10MHz RF carrier signal that is amplitude modulated with a 3kHz intelligence signal will generate two sidebands: what is the USB and what is the LSB?
9.997 MHz LSB
10.003 MHz USB
During heterodyning, the carrier signal’s amplitude is modified to match the instantaneous amplitude changes of the modulating signal. This modified signal is called what?
Composite Signal
True or False - Another aspect of AM is that both sidebands contain the same information so they do not have to both be transmitted.
False - Another aspect of AM is that both the sidebands are transmitted even though they contain the same information.
The sidebands occupy from ___ to a maximum of ___ on each side of the center frequency for a maximum total bandwidth of 6000Hz (6kHz).
300Hz to a maximum of 3,000Hz
Another important concept of AM is the distribution of the power between the carrier and the sidebands. The carrier consumes ___ of the total power produced while the sidebands take up ___.
carrier - two thirds
sidebands - one sixth each
Transmitting and receiving radios must be on the same ___ to communicate.
sideband
What are the seven advantages of SSB?
Spectrum Conversation
Power Efficiency
Effective Gain in Transmit
Effective Gain in Receive
Total Effective Gain
Peak Envelope Power
Better Signal to Noise Ratio
This refers to decreasing the bandwidth of each channel in a radio system. This creates more channels in the overall radio spectrum.
Spectrum conservation
The HF communications normal spectrum range is 3MHz – 30MHz. However, the AN/PRC-160 Harris radio used in this module extends this slightly to…?
1.5MHz to 29.9999 MHz (extended from the lower end)
In what two ways is SSB more power efficient than AM?
- Available power is concentrated in the one utilized sideband.
- Power output is only developed when carrier is modulated with intelligence (data or voice).
Why is an SSB transmitter more efficient than an AM transmitter?
Because it can concentrate almost all-available power into a single sideband
SSB receivers have an advantage over AM receivers because of…?
the smaller bandwidth
The Total Effective Gain is simply what?
Adding the effective gain in transmit and the effective gain in receive.
Every 3dB does what to power?
Doubles or Halves the power
This is the transmitter’s averaged power output during one RF cycle (a sample) at the highest crest of the modulation envelope.
Peak Envelope Power (PEP)
When you “key” the radio, we measure zero watts at the antenna until what?
someone starts talking or we send data to it
Power output depends on __ input because sidebands are only developed when this occurs.
modulation
Modulation only occurs when…?
there is intelligence that needs to be applied to the signal
The AN/PRC-160 has three different configurations. What are they?
They are the manpack, vehicular, and base-station configurations.
What does the “AN/PRC” in AN/PRC-160(V) stand for?
Army Navy Portable Radio Communications
The manpack consists of an OE-505 ___ antenna, flexible base, antenna bag, and base adaptor.
whip
We generally use the manpack radio for short-range/groundwave transmissions in the ___ maximum range.
20-watt
The radio is mounted on the center console or dashboard of a vehicle such as a High Mobility Multipurpose Wheeled Vehicle (HMMWV.) These are also commonly called?
Humvee
The ___ is the most advanced military Type-1 encryption HF radio available today, setting the standard for reliable, long-range HF communication on the battlefield.
AN/PRC-160
This radio provides operators with ___ secure voice and data communications, even in the harshest conditions.
Type1
The AN/PRC-160 provides continuous coverage in the ___ frequency range and has been deployed by US and coalition forces enabling them to stay connected where LOS communications are not an option.
1.5MHz to 59.999MHz
Identify the controls and indicators of the radio. What is #1?
Ground Post - provides a grounding point for connecting an RF ground reference to the radio.
Identify the controls and indicators of the radio. What is #2?
J3 Data - provides a connection for DTE data and auxiliary audio
Identify the controls and indicators of the radio. What is #11?
J10 Battery - Battery connector
Identify the controls and indicators of the radio. What is #12?
J9 Accessory - Provides connection for an external power amplifier.
Identify the controls and indicators of the radio. What is #13?
HUB - Provides access to the Hold Up Battery (HUB)
Identify the controls and indicators of the radio. What is #3?
J7 HF/VHF ANT - Provides a 50-ohm antenna port for either a BNC connector or a whip antenna.
Identify the controls and indicators of the radio. What is #4?
J2 GPS - Provides a connection for the remote Global Positioning System (GPS) antenna
Identify the controls and indicators of the radio. What is #5?
LCD Display - Displays operational and programming screens.
Identify the controls and indicators of the radio. What is #6?
Keypad - provides user access to operating and programming functions.
Identify the controls and indicators of the radio. What is #7?
J4 KDU - provides connection for external Keypad Display Unit (KDU)
Identify the controls and indicators of the radio. What is #8?
Function Switch
Identify the controls and indicators of the radio. What is #9?
J1 Audio - provides a connection for an audio handset which uses a six-pin connector
Identify the controls and indicators of the radio. What is #10?
J5 USB - provides connection for Universal Serial Bus (USB)
Before operating the AN/PRC-160, you must program the presets, nets, keys, etc. This is done using what?
Communications Planning Application (CPA)
The CPA is very useful when…?
You need to program multiple radios. You program the CPA once and then proceed to download load the programming to as many radios as necessary.
What does HUB stand for?
Hold Up Battery
This applies a constant voltage to the radio memory circuits, such as communications plan and encryption key circuits
HUB
To maximize the HUB life, place the radio function switch in the ___ position and remove the HUB when storing the AN/PRC-160.
OFF
What can occur if you replace the HUB incorrectly?
you can lose the radio’s programming
What allows the memory circuits to retain data while the radio is off?
HUB
You can perform some simple configurations using the radio front panel keys, but you must use the CPA to program what?
3G and 3G+ networks
The stake grounding kit provided in the manpack is used for what purpose?
when setting the manpack on the ground for better operation of the radio
What does the acronym ALE stand for?
Automatic Link Establishment
This alleviates the need for radio operators to manually check frequencies to adjust for changes in the ionosphere (atmospheric conditions), time of day, or interference.
ALE
The radio determines the best HF channels between itself and other radios on the same network based on a scoring system called…?
Link Quality Analysis (LQA)
When not transmitting, the AN/PRC-160 is doing what?
scanning through its assigned frequencies listening for calls
This is a LQA technique that sends a one-way message on all channels in the channel group.
Sounding
This is an LQA technique that involves two-way messages sent between two stations.
Exchange
Target stations establish channel rankings based on received signal quality by receiving the sounding signal but do not send a responding signal. Why is this?
This is done to ensure security of their location
Channel rankings are established based on…?
received signal quality
During a call, the radios measure and exchange link quality information; however, the call may not link on the best channel if ___ have changed since the last LQA.
propagation conditions
What are the two modes of ALE?
3G and 3G+
In 3G, it requires Time of Day (TOD) and operates on channels…?
100 to 162
Channels in this mode range from 1 to 62.
3G+
What is the transmit power for HF on the AN/PRC-160?
20 watts
What is the transmit power for VHF on the AN/PRC-160?
10 watts
What is the bandwidth for the AN/PRC-160?
3 to 24kHz
The AN/PRC-160 utilizes VULOS when operating from __ to __ MHz using frequency modulation.
30 to 59.9999 MHz
ALE enables radios to call and automatically link over the best HF channel. ALE systems use ___ to determine the best channel for communication between two stations, taking the guesswork out of the operator’s hands.
Link Quality Analysis Data (LQA)
What does 3GIP stand for?
Third Generation Internet Protocol
Wideband Hopping is set in one of two ways - name both of them.
Frequency Bonds - defines upper and lower frequency bounds within which the radio will hop frequencies
Exclusion Bonds - defines frequency bounds which
Which frequency hopping mode is this referring to?
“The operator would give the radio a center frequency designed in multiples of 5kHz. The radio, using a predefined bandwidth, would hop frequencies above and below this center frequency (Fc.)
Narrowband Hopping
Which frequency hop type is this referring to?
“Enables the operator to specify frequencies to be used during hopping.”
List Hopping
True or False: Manual synchronization requires re-syncing every six hours while the radio is on, and more frequently if the radio is powered down.
True
Broadcast Synchronization is also known as what?
Passive Sync
Which statement is TRANSEC and which is COMSEC?
- Concerned with preventing signal detection and jamming of transmissions and minimizing the likelihood of information being recovered by an enemy.
- Maintains security by using scrambling or cryptographic techniques to make information unintelligible.
- TRANSEC
- COMSEC
When discussing TRANSEC, there are two methods radios use to secure their traffic:
- Low Probability of Detection (LPD): Techniques for minimizing transmitted signal detection.
- Low Probability of Intercept (LPI): Techniques for minimizing transmitted signal interception.
This is A.K.A. “radio silence,” radios refrain from transmitting to reduce the probability of a transmitter being located.
Emissions Control (EMCON)
ANDVT, TSVCIS/TSV, and KG-84 are all examples of what?
Type 1 NSA Encryption Standards
What does PMI stand for?
Preventative Maintenance Inspection
What does CSM stand for?
Communications Service Monitor
The range of the Spectrum Analyzer is…?
100kHz to 1.0GHz
When planning for which HF frequencies to use, keep in mind these three basic rules:
- Time of day - this determines the min and max usable frequencies between two points and determines the FOT.
- Surface Wave Absorption - terrain absorbs surface waves and the effect increases with frequency.
- Line-of-Sight - VHF and frequencies higher are better suited for LOS communications.
What does NVIS stand for?
Near Vertical Incidence Skywave
True or False: NVIS frequencies are high by default because higher frequencies produce higher take-off angles.
False - NVIS frequencies are LOW by default because lower frequencies produce higher take off angles.
The following describes which of these options - Skip Zone, Skip Distance or Hops?
“When HF signals refract back toward the Earth and are reflected upward at the same angle.”
Hops
This HF sky wave propagation modelling tool predicts radio performance by using real world data to simulate the effects of seasons, solar weather, geographic location and time of day.
Voice of America Coverage Analysis Program (VOACAP)
A fresh HUB is good for ___ without the main battery attached
one year (2-4)
The AN/PRC-160 Supports Frequency Modulation (FM) from __MHz to __ MHz
30 MHz to 59.9999 MHz
Fixed frequency mode of operation is supported from ___ MHz to ___ MHz
1.5 MHz to 59.9999 MHz
With its high-speed wideband waveform, the AN/PRC-160(V) transmits data in bandwidths from…?
3 kHz to 24 kHz
The PR/ANC-160 provides __ watts HF and __ watts VHF.
20 watts HF
10 watts VHF
