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Wave Theory

What is it?

  • A wave is a pattern of a signal, such as that generated by sound and light, that changes at regular intervals.

  • Radio waves are part of a larger group of waves classified all together as electromagnetic radiation.

  • This large group of waves is broken down into smaller groups based on their frequencies and wavelengths.

  • Frequency describes the number of waves that pass a fixed place in a given amount of time. 

  • So if the time it takes for a wave to pass is in 1/2 second, the frequency is 2 per second. 

  • Frequency is measured in Hz (hertz).

Frequency (f):

1 wave

1 wave

2 wave

3 wave

4 wave

Amplitude

1 cycle

1 oscillation

Low frequency radio wave

1 frequency per second.

High frequency radio wave

4 frequencies per second.

Wavelength: (λ)

  • the distance between successive crests of a wave especially points in a sound wave or electromagnetic wave.

  • A repeating pattern of traveling energy like light or sound.

  • Wavelengths are measured in:

  • kilometers

  • meters

  • millimeters

  • micrometers

  • nanometers

  • picometers 

  • femtometers 

Wavelength (λ)

Wavelength

A wavelength is a measure of distance between two identical peaks (high points) or troughs (low points) in a wave.

Frequency & Wavelength Relation:

  • Electromagnetic waves always travel at the same speed (299,792 km per second).

  • In the electromagnetic spectrum, there are many different types of waves with varying frequencies and wavelengths.

  • They are all related by one important equation: Any electromagnetic wave's frequency multiplied by its wavelength equals the speed of light.

FREQUENCY OF OSCILLATION x WAVELENGTH = SPEED OF LIGHT

  • We can use this relationship to figure out the wavelength or frequency of any electromagnetic wave if we have the other measurement.

  • Just divide the speed of light by whichever measurement you have and then you've got the other.

10^5

f

10^9

10^12

10^14

10^15

10^16

10^19

λ

10^3

Radio

10^-1

10^-3.5

10^-6

10^-6.5

10^-8

10^-11

Microwave

Infrared

Visible light

Ultraviolet

X-ray

Gamma rays

  • Radio waves are electromagnetic waves with the longest wavelength and lowest frequencies.

  • A radio receiver converts radio waves into sound waves that you can hear.

  • The radio spectrum is the part of the electromagnetic spectrum from 3 Hz to 3000 GHz.

  • The bandwidth of a radio signal is the difference between the upper and lower frequencies of the signal.

  • Below is an illustration of how electromagnetic radiation is broken down into groups. 

  • The electromagnetic (EM) spectrum is the range of all types of EM radiation.

  • Higher frequencies have shorter wavelengths, and signals with shorter wavelengths have more trouble penetrating obstacles like walls and floors.

FREQUENCY OF OSCILLATION

=

 SPEED OF LIGHT

WAVELENGTH ​

 SPEED OF LIGHT

WAVELENGTH ​

=

FREQUENCY OF OSCILLATION

A wavelength is a measure of distance between two identical peaks (high points) or troughs (low points) in a wave.

Spectrum

Radio Spectrum

f

3 kHz

30 kHz

300 kHz

3 MHz

30 MHz

300 MHz

3 GHz

30 GHz

VLF

LF

MF

HF

VHF

UHF

SHF

EHF

100 km

λ

10 km

1 km

100 m

10 m 

1 m

10 cm

1 cm

Mobile phone, Bluethooth, wireless LAN, GPS

1 mm

300 GHz

  • To prevent interference between different users, the generation and transmission of radio waves are strictly regulated by national laws, coordinated by an international body, the International Telecommunication Union (ITU).

  • Below is the mobile revolution in wireless telecommunication.

  • All of them refer to the technology used by the mobile carrier and device itself; they have different speeds and features that improve on the generation prior to it.

Wireless mobile telecommunications technology timeline

AMPS

​GSM

GPRS

EDGE

UMTS

LTE

1G
2G
2.5G
4G
3G
2.7G

1985

Bell Labs

1992

ETSI

1995

ETIS

2003

3GPP

2004

3GPP

2013

3GPP

  • Each of those generation here are have different modulation scheme, different technology. 

  • 1G (1st Generation): (voice)

  • This did not have data.

  • Only voice.

  • Developed by AMPS

  • 2G (2nd Generation): (digital voice + data)

  • GSM (Global System for Mobile), CDMA.

  • Developed by ETSI

  • 2.5G added dedicated digital data called GPRS (General Packet Radio Services ).

  • Data rate 54 kbps.

  • 2.75G EDGE(Enhanced Data rates for GSM Evolution).

  • Introduces 8PSK.

  • Datarate 170 kbps.

  • 3G (3rd Generation): (voice + data + video call )

  • UMTS (Universal Mobile Telecommunications System).

  • Developed by 3rd Generation Partnership Project(3GPP).

  • 3.5G, HSPA (High-Speed Packet Access), data rate 2mbps.

  • 3.75G, (HSPA+).

  • 4G (4th Generation): (digital + data + video call)

  • LTE (Long-Term Evolution).

  • Video conferencing.

  • 1Gbps for stationary.

Audible Frequency

  • A range of frequencies, characteristic of signals audible to the normal human ear.

  • The SI unit of audio frequency is the hertz (Hz). 

  • The generally accepted standard range of audible frequencies is 20 to 20,000 Hz.

  • Here are some notable voice produced:

  • 8.18 Frequency - Lowest organ note.

  • 32.70 Frequency - Lowest C on piano.

  • 85-180 Frequency - Average Male voice.

  • 165 to 255 Frequency - Typical adult Female voice.

  • 2093 - Highest note for flute.

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