COMNAV Flashcards
Who discovered electromagnetic spectrum?
SIR WILLIAM HERSCHEL
In what year did Sir William Herschel discovered electromagnetic spectrum?
1800
Sir William Herschel used what to separate sunlight into its rainbow of colors.
GLASS PRISM
It is not visible to naked eye.
INFRARED LIGHT
He discovered the UV or ultraviolet light.
JOHANN WILHELM RITTER
He developed the Infrared Light.
JAMES CLERK MAXWELL
In what year did infrared light discovered?
1867
What did Heinrich Hertz discovered?
RADIO WAVES
In what year did Heinrich Hertz discovered the radio waves?
1887
Who invented the X-Ray?
WILHELM CONRAD RONTGEN
X-ray result when a sudden accident happen in experimenting with what?
VACUUM TUBES
First called in X-ray
X-RADIATION
RONTGEN RAYS
What did Paul Villard discovered?
GAMMA RAYS
Who proposed the name of gamma rays?
ERNEST RUTHERFORD
It transmit the radio signal.
TRANSMITTER
It received the radio signal or radio wave.
RECEIVER
It is the energy that travels and spreads out as it goes.
RADIATION
Electromagnetic spectrum is the result and composed of what?
VIBRATION
OSCILLATION
They are the combination of EM.
MAGNETIC FIELD
ELECTRIC FIELD
It is invisible to the human eye.
RADIO WAVE
What is the relationship between the frequency and wavelength?
INVERSELY PROPORTIONAL
HIGH FREQUENCY = SHORT WAVELENGTH
LOW FREQUENCY = LONG WAVELENGTH
HIGH FREQUENCY = SHORT WAVELENGTH
LOW FREQUENCY = LONG WAVELENGTH
It describes as a SERIES OF ENERGY waves composed of oscillating electric and magnetic fields.
NON-IONIZING RADIATION
It is a FORM OF ENERGY that acts by removing electrons from atoms and molecules
IONIZING RADIATION
It refers to types of radiation carries enough energy to ionize atoms.
IONIZING RADIATION
It refers to types of radiation that do not carry enough energy to ionize atoms.
NON-IONIZING RADIATION
Extremely Low Frequency
3Hz to 30Hz
USED IN SEISMIC ACTIVITIES & VOLCANIC ACTIVITIES
Very Low Frequency
SPAN FROM 3KHz to 30KHz
USED IN SUBMARINE & TIME RADIO STATION
Other term for low frequency
GROUND WAVES
Low Frequency
RANGE OF 30KHz TO 300KHz
USED IN LONG DISTANCE COMMUNICATION & AMATEUR RADIO OPERATORS
It is one of the most important sources of information transfer when other kind of communication sources fails during some situations.
AMATEUR RADIO OPERTORS
It is one of the most popular frequency bands since the beginning of wireless radio transmission in the early nineteenth century
MEDIUM FREQUENCY
Range of Medium Frequency
RANGE OF 300 KHz to 3 MHz
It has been widely using in AM radio transmission, navigation systems for ships and aircraft, emergency distress signals, cost guards and other experimental applications.
MEDIUM FREQUENCY
High frequency is also known as?
SHORT WAVE
Range of high frequency
3MHz AND 30MHz
It also gets reflected by earth’s ionosphere and it is one of the suitable band for long distance communication.
HIGH FREQUENCY
It is mostly used by aviation industry, near field communication (NFC), government systems, amateur radio operators and weather broadcasting stations.
HIGH FREQUENCY
It is one of the most commonly used bands which has an operating range from 30 MHz to 300 MHz.
VERY HIGH FREQUENCY
It is widely used in analog TV broadcasting since it has started few decades back.
VERY HIGH FREQUENCY
They using frequency between 118 MHz to 137 MHz to communicate.
AIR TRAFFIC CONTROLLER AND PILOT
It usually affected by big terrains but suitable for short distance communication.
VERY HIGH FREQUENCY
It is the most important frequency bands for modern wireless communication systems.
ULTRA HIGH FREQUENCY
It begins from 300 MHz to 3 GHz and extremely complicated to design and implement the system.
ULTRA HIGH FREQUENCY
It has many sub frequency bands, some are restricted and assigned only for particular applications.
ULTRA HIGH FREQUENCY
It is used in GPS navigation systems, satellites, pagers, Wi-Fi, Bluetooth, television broadcasting, and most importantly GSM, CDMA and LTE mobile transmission.
ULTRA HIGH FREQUENCY
It is in the range of 3 GHz to 30 GHz.
SUPER HIGH FREQUENCY
It can only operate in line-of-sight path since any obstruction in between the transmitter and receiving station will break the communication.
SUPER HIGH FREQUENCY
It is commonly used in point-to-point communication, satellite systems, digital TV broadcasting in Ku band (DTH service – direct to home), Wi-Fi (5GHz channel), microwave ovens and mobile networks.
SUPER HIGH FREQUENCY
What are suitable between transmitter and antenna due to higher losses of usual RF cables?
WAVEGUIDES
It is extremely hard in SHF band due to its smaller wavelength and complexity.
SYSTEM DESIGN
It is the highest in RF frequency spectrum which range between 30 GHz and 300 GHz.
EXTREMELY HIGH FREQUENCY
It is only used in advanced communication systems due to its complex nature and line of sight requirement.
EXTREMELY HIGH FREQUENCY
It is used in radio astronomy and remote sensing (weather analysis).
EXTREMELY HIGH FREQUENCY
It is suggested to use for high-speed internet systems like 5G technology for future transmission networks due to large bandwidth availability.
EXTREMELY HIGH FREQUENCY
The distance between successive crests of a wave.
WAVELENGTH
Wave cycles passing a given point in a given period of time
FREQUENCY
Measured between the crest and the mid-point of a wave
AMPLITUDE
Two common ways or method to put information in a radio wave
A.M. (AMPLITUDE MODULATION)
F.M. (FREQUENCY MODULATION)
In this method, the information is put into a radio wave by varying the amplitude.
AMPLITUDE MODULATION
The amplitude is kept constant, it is the frequency that is varied.
FREQUENCY MODULATION
It is associated with the PHENOMENA that occur when a wave travels between transmitter and receiver.
RADIO WAVE PROPAGATION
It is a characteristic of electromagnetic radiation in which two stations can only transmit and receive data signals when they’re in DIRECT VIEW of each other with no obstacles in between.
LINE-OF-SIGHT
two common examples of LoS communication
SATELLITE
MICROWAVE TRANSMISSION
It is a term used to describe radio transmission across a path that is PARTIALLY OBSTRUCTED.
NON-LINE-OF-SIGHT
Other term for non line of sight
NEAR-LINE-OF-SIGHT
It is a term often used in radio communications to describe a radio channel or link where there is no visual line of sight (LOS) between the transmitting antenna and the receiving antenna.
NON-LINE-OF-SIGHT
It is also known as surface wave propagation.
GROUND WAVE PROPAGATION
The radio waves transmit by passing through the semi-conductive surface of the earth
GROUND WAVE PROPAGATION
This mode of propagation requires vertically polarized waves as the horizontally
polarized waves in this case will get absorbed by the earth.
GROUND WAVE PROPAGATION
Ground wave propagation’s frequency range
30kHz TO 3MHz
This type of wave propagation makes use of the upper atmospheric layer i.e., the ionosphere to transmit the radio waves.
SKY WAVE PROPAGATION
Sky wave propagation is also known as?
IONOSPHERIC WAVE PROPAGATION
Here the signals radiated by an antenna
BENT BACK towards the earth by getting refracted from the WHAT?
IONOSPHERIC LAYER
It is also called direct wave propagation and offers a line-of-sight communication.
SPACE WAVE PROPAGATION
Here the signal from the transmitting antenna PROPAGATES in a straight line towards the receiving antenna.
SPACE WAVE PROPAGATION
The transmission of a signal between transmitter and receiver is achieved in the tropospheric
region of the atmosphere.
SPACE WAVE PROPAGATION
The space wave propagation is sometimes referred as?
TROPOSPHERIC WAVE PROPAGATION
It is sometimes called forward scatter propagation or scatter propagation and is suitable for VHF, UHF and microwaves.
TROSPOPHERIC SCATTER PROPAGATION
The waves propagate through forward scattering due to the irregularities of the troposphere. This propagation technique uses the properties of the troposphere. This mode offers reliable communication between 160 km to 1600 km.
TROSPOPHERIC SCATTER PROPAGATION
Tropospheric scatterknown as?
TROPOSCATTER
It is a method of transmitting and receivingmicrowave radiosignals over considerable distances – often up to 300km.
TROPOSPHERIC SCATTER
This method of propagation uses the tropospheric scatter phenomenon, where radio waves at particular frequencies are randomly scattered as they pass through the upper layers of thetroposphere(hence troposcatter).
TROSPOPHERIC SCATTER PROPAGATION
It occurs when a plane wave meets a plane object that is large relative to the
wavelength of the signal.
REFLECTION
In such cases the wave is reflected with minimal distortion and WITHOUT ANY CHANGES in velocity.
BOUNCE
REFLECTION
It occurs when a wave moves from one medium into another in which it travels at a different speed.
DISTRIBUTED
REFRACTION
The effect is similar to that experienced by a beam of light when it encounters a glass prism.
DISTRIBUTED
REFRACTION
It occurs when a wave meets an edge which has dimensions that are large relative to the wavelength of the signal.
DIFFRACTION
It occurs when a wave encounters one or more objects in its path having a size that is a fraction of the wavelength of the signal
SCATTERING
It s the lowest layer of our atmosphere.
TROPOSPHERE
It extends upward to about 10 km (6.2 miles or about 33,000 feet) above sea level.
TROPOSPHERE
The infamous ozone layer is found
within this layer of atmosphere.
STRATOSPHERE
about 50 km (31 miles) above the ground.
STRATOSPHERE
It extends upward to a height of about 85 km (53
miles) above our planet
MESOSPHERE
The coldest temperatures in Earth’s atmosphere, about -90° C (-130° F), are found near the top of this layer.
MESOSPHERE
The air is far too thin to breathe in this layer of the atmosphere.
MESOSPHERE
High-energy X-rays and UV radiation from the Sun are absorbed in this atmosphere layer, raising its temperature to hundreds or at times thousands of degrees.
THERMOSPHERE
It can be found anywhere between 500 and 1,000 km (311 to 621 miles) above the ground.
THERMOSPHERE
The aurora, the Northern Lights and Southern
Lights, occur in the thermosphere.
THE AURORA, THE NORTHERN LIGHTS AND SOUTHERN LIGHTS, OCCUR IN THE THERMOSPHERE.
It is the uppermost layer of our atmosphere.
EXOSPHERE
It also consider to be the actual “final frontier” of Earth’s gaseous envelope.
EXOSPHERE
It somewhere between 100,000 km (62,000
miles) and 190,000 km (120,000 miles) above the surface of Earth.
EXOSPHERE
The latter value is about halfway to the Moon.
EXOSPHERE
It is a series of regions in parts of the mesosphere and thermosphere where high-energy radiation from the Sun has knocked electrons loose from their parent atoms and molecules.
IONOSPHERE
The electrically charged atoms and molecules that are formed in this way are CALLED?
IONS
It giving the ionosphere its name and endowing this region with some special properties.
IONS
It is the distance over the Earth’s surface between the point where a radio signal is transmitted, and the point where it is received having travelled to the ionosphere and been refracted back by the ionosphere.
SKIP DISTANCE
It s a region where a radio transmission can not be received.
SKIP ZONE
Other term for Skip Zone
DEAD ZONE
SILENT ZONE
It is a condition that occurs when the same signal arrives at a TV receiver at two different times; the reflected signal travels farther and is WEAKER THAN the direct signal, resulting in double image.
GHOSTING
