User:0864867/Week 3
Quarter 9 is all about introductions about the topic Radiation and all of this information is found here.
Contents
Radiation
I did a research on understanding Radiation in forms of AM/FM and Hertz
You can read it here:
▪ WHAT ARE HERTZ?
Hertz is the amount of oscilation per second, it is the unit of frequency. The name comes from Heinrich Rudolf Hertz, he was the first one to provide proof of the existence of electromagnetic waves at around 1865. At around 1960 it was made official by the CGPM that frequency was now called Hertz. Before this frequency was expressed as ‘cycles per second’, such as ‘kilocycles’ & ‘megacycles’.
In the illustration above you can see how Hertz work. 1 Hz is 1 oscilation per second, 5 Hz is five oscilations per second, and so on.
Hertz has many multiples. Radiowaves are mostly expressed in kHz, MHz or GHz. 1000 Hz = 1 kHz 1000 kHz = 1 MHz 1000 MHz = 1 GHz Etc.
Radiations like long-wave infrared light is mostly defined by terahertz radiation. Higher frequencies like Gamma-rays is mostly measured in exahertz.
▪ AM / AMPLITUDE MODULATION
In order to make sure you can send a message by radio, one has to modilate the signal. These modilations exists of different bandwiths which we can sense as different sounds in order to hear voices or music. Radio signals exists of a carrier, a standard wave which sounds monotone. This standard wave can be modulated in with to create a series of different sounds, in this way we can hear voices over far distance travelled by invisible waves in the sky. Amplitude in Dutch means: Omvang.
AM = Modulating the with of a wave
▪ FM / FREQUENCY MODULATION
Another way to modilate waves is by FM, or frequency modilation. This way of modilation works different from AM. Whenever you change the voltage of the carrier (where AM has a constant amount of voltage), different frequencies occur. The amount by which the signal varies is important, this is known as the deviation. The deviation’s unit is mostly written in kHz. So if the deviation is -/+ 5 kHz, the carrier moves up and down by 5 kHz. Broadcasts use these FM deviations, such as 103.3 FM (Q-music), to broadcast their music on.
FM = Modilating the length of a wave
▪ AM & FM
Ofcourse, these phenomena can also be combined. For broadcasting music, you need a certain frequency to broadcast your music to (such as 103.3 FM) and on that frequency you can modulate the amplitude by sending sounds into the carrier. These sounds are then transmitted to your speakers when you tune in on that certain frequency.
RTL-SDR
▪ WHAT IS IT?
RTL-SDR is a cheap software defined radio scanner. It's hardware comes in an antenna and dongle with which you are able to scan the radiowaves in the air around you. In this way you can listen to sounds and people talking over radio.
This device is to be plugged in in your computer/laptop. Together with SDR-Sharp (waterfall-software) you can go search for signals, listen to them and capture them.
