Question

1. Explain the basic principles of radio frequency transmissions.

2. Describe the different types of modulation techniques.

3. Explain how frequency and wavelength relate to one another.

4. Describe 5 different behaviors that radio waves exhibit.

Answer 1

Basic Principles of Radio Communication

Frequency

A Frequency forms the bottom of any radio communication. Radio’s work - at a really basic level - by emitting magnetism waves that have totally different oscillation frequencies. By calibration, to a frequency, the radio is in a position to receive and transmit on the desired frequency.

Channels

A Channel could be a preprogrammed channel on a radio device that enables for fast change to preprogrammed networks. Examples are that Channel one could be tuned to fifty and Channel a pair of could be tuned to fifty-one. By change between Channel one and Channel, a pair of the user are going to be able to modification between fifty and fifty-one quicker than writing within the frequency.

Network

A defined use of a given Frequency that's utilized by a group of Callsigns to speak with one and alternative for a chosen purpose. as an example, you may have a commanding web for communication of High level orders to execution components or a fires web for communication with Artillery or military unit components.

Radio

A Radio is associate degree electronic Transceiver that enables for the RX and TX of communications of 1 or a lot of such frequencies.And the sorts are SCOM Rated,LCOM Rated,AVCOM Rated.

Transmission

A Transmission could be a burst of communication sent from one callsign to a different on a Frequency. A transmission happens on a frequency and contains the sender and meant recipient in aboard a corresponding finish word - either “Over” or “Out” however ne'er each.

Message:

A Message is that the contents of a transmission that conveys explicit parts of data.

Call Sign:

A Callsign could be a keyword designed to unambiguously establish a manipulator on a Network. Callsigns conjointly offer accrued OPSEC within the event that communications are compromised as they mask the identity or capabilities of a component.


Modulation techniques:


Analog Modulation

In analog modulation, the analog signal is employed as a carrier signal that modulates the message signal or information signal. the overall operate curved waves is shown within the figure below, in which, 3 parameters will be altered to induce modulation – they're amplitude, frequency and phase; therefore, the kinds of analog modulation are:

Amplitude Modulation

Amplitude modulation was developed within the starting of the twentieth century. it absolutely was the earliest modulation technique wont to transmit voice by radio. this sort of modulation technique is employed in transmission. during this modulation, the amplitude of the carrier signal varies in accordance with the message signal, and alternative factors like section and frequency stay constant.

Frequency Modulation

In this form of modulation, the frequency of the carrier signal varies in accordance with the message signal, and alternative parameters like amplitude and section stay constant. FM is employed in several applications like radio detection and ranging, radio and measure, seismal prospecting and watching newborns for seizures via electroencephalogram, etc.

Phase Modulation

In this form of modulation, the section of the carrier signal varies in accordance with the message signal. once the section of the signal is modified, then it affects the frequency. So, for this reason, this modulation is additionally coming below the FM.

Digital Modulation

For higher quality and economical communication, digital modulation technique is used. the most benefits of the digital modulation over analog modulation embrace offered information measure, high noise immunity, and permissible power. In digital modulation, a message signal is born-again from analog to the digital message, then modulated by employing radio radiation. The radio radiation is switched on and off to form pulses such the signal is modulated. almost like the analog, during this system, the kind of the digital modulation is determined by the variation of the radio radiation parameters like amplitude, section, and frequency.


frequency and wavelength relation:


A wavelength is a distance between 2 identical peaks Crest or Troughs during a wave.

A wave could be a continuation pattern of traveling energy for eg. Light, sound etc.

Frequency describes the amount of repetitions/Cycles per unit time.In the spectrum there are many various styles of waves with varied frequencies and wavelengths.

Any magnetism wave's frequency increased by its wavelength equals the speed of sunshine

Frequency (f) × Wavelength (λ)= Speed of light(c)

We can use this relationship to calculate the wavelength or frequency of any electromagnetic radiation if we have the opposite measuring. simply divide the speed of sunshine by whichever measuring you have got then you have the opposite.

Frequency = Speed of sunshine / Wavelength

Higher the frequency, shorter are going to be the Wavelength.

Lower the frequency, Longer is going to be the Wavelength.





The behavior of radio waves in different media.

Radio waves are subject to the influence of the environment in which they are propagated.

When a radio wave leaves the boundary of one medium and enters another, the wave changes direction.

Three things can occur when a wave passes from one medium to another:

(1) Some of the energy can be reflected back into the initial medium.

(2) Some of the energy may be transmitted into the second medium where it may continue at

a different velocity.

(3) Some of the energy may be absorbed by the medium.

Refraction:

Changes: direction, wavelength, speed, amplitude (unless total refraction, within which case not)
Constant: frequency/period, phase

Reflection:

Changes: direction, phase, amplitude (unless total reflection, within which case not)
Constant: wavelength, frequency/period, speed
The unrefracted element of the wave is mirrored, and the other way around.

Diffraction:

Changes: Direction, section, amplitude
Constant: wavelength, frequency/period, speed