LoRa/LoRaWAN tutorial 12: Modulation Types and Chirp Spread Spectrum

in this tutorial I will explain what the basic modulation types are and what chirp spread-spectrum is modulation means how analog or digital information are encoded onto a carrier signal when analog information are encoded onto a carrier signal three modulation types can be used amplitude modulation frequency modulation and phase modulation when digital information are encoded onto a carrier signal three modulation types can be used and platoons shift keying frequency shift keying and phase shift keying as mentioned earlier an eighth-note has a radio module this ratio module has a modulator which encodes information onto a carrier signal this modulated signal is transmitted and received by a gateway the Gateway also has a radio module this radio module has a demodulator which decodes the modulated signal and extracts the information the communication between the end node and Gateway is bi-directional which means the end node can send data to the Gateway but it can also receive data from the Gateway if a device can both transmit and receive signals this device is also called a transceiver Laura add nodes and gateways are transceivers now let's focus on modulating digital values on to a carrier signal in this example we have a digital message which we want to encode on this carrier signal there are three basic modulation types amplitude shift keying frequency shift keying and phase shift keying when we use amplitude shift keying only the amplitude changes as you can see the amplitude is here 3 and here the amplitude is 1/2 in this example if the amplitude is 3 then it represents a digital one and when the amplitude is one and a half it is a digital zero when we use frequency shift keying only the frequency changes the signal here has an higher frequency than the signal here this particular signal represents a digital one and this particular signal represents a digital zero and when we use phase shift keying only the phase changes as you can clearly see the phase of this signal is different than the phase of this signal for example when the signal has this phase it represents digital one and when the signal has this phase it represents digital zero besides the three basic modulation types there are many other modulation types laura is a propriety spread spectrum modulation scheme that is based on chirps spread spectrum modulation chirp spread spectrum is a spread spectrum technique that uses white belt linear frequency modulated chirp pulses to encode information let's focus on the words spread spectrum technique and chirp spread spectrum techniques are methods by which a signal is deliberately spread in the frequency domain for example a signal is transmitted in short bursts hopping between frequencies in absurd or random sequence this is already explained in tutorial 11 and the chirp often called a sweep signal is a tone in which the frequency increases or decreases with time if the frequency increases in time it is called an observe and when it decreases in time it is called a Down chirp here's an example of an object where the frequency increases in time another way to visualize it the lowest frequencies over here the highest frequencies over here the frequency increases in time when the maximum frequency is reached its jumps back to its lowest frequency and the process starts all over again this is the OP sure the down trip is the inverse of the object it starts with its highest frequency and the frequencies decreases with time and when the lowest frequency is reached its jumps back to its highest frequency and the process starts all over again these chirp signals are used as carrier signals where a message is encoded on here is an actual laura modulated signal this is the start of the message and here's the encoded message you can easily recognize the start of a message it is a number of observes followed by two down chirps here is not that Laura modulated signal example this is the start of the message a number of observes followed by two down chirps and here is the encoded message you thanks for watching I hope you enjoyed the video please hit the like button and don't forget to subscribe if you have questions leave your comments below I'll do my best to answer them

Channel: Mobilefish.com

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Keywords: LoRa/LoRaWAN tutorial 12 Modulation Types and Chirp Spread Spectrum, LoRa tutorial 12, LoRaWAN tutorial 12, LoRa, LoRaWAN, basic Modulation Types, Chirp Spread Spectrum, Amplitude Shift Keying, Frequency Shift Keying, Phase Shift Keying, spread spectrum modulation, CSS modulation, ASK modulation, FSK modulation, PSK modulation, LoRa sweep signal, LoRa up chirp, LoRa down chirp, LoRa modulated signal, chirp, sweep signal, LoRa carrier signal

Id: lg0eZWZFKiE

Length: 6min 2sec (362 seconds)

Published: Tue Oct 02 2018