Summary of How LoRa Modulation really works - long range communication using chirps

00:00:00 - 00:25:00

This video discusses how LoRa modulation works and how it can be used to communicate over long distances without interference. The key innovation in LoRa is the use of a mathematical trick that allows for the efficient performance of similarity checks.

• 00:00:00 Lora is a new communication standard designed for low power long range communication. Laura uses chirps as the basis for each symbol, and it is complicated by attenuation and distortion, among other factors.
• 00:05:00 In LoRa modulation, a chirp waveform is used to encode information. The waveform is based on an exponential function, which gives rise to a complex sinusoidal wave. The argument of the exponential function contains the symbol number s, which varies between 0 and 127. The chirp waveform is used to transmit symbols at different frequencies, with the symbol duration t and the sample duration ts. The bandwidth limit is the maximum number of symbols that can be sent in a given time. Each value of s results in a different waveform. The receiver uses a correlation-based algorithm to determine which symbol was sent.
• 00:10:00 LoRa modulation is a way of transmitting data over long distances using chirps. The similarity check is performed by multiplying a received waveform by its complex conjugate, and summing the results. The receiver synchronizes to the incoming preamble using the preamble's frequency, and then performs a similarity check. If the two waveforms look similar, the receiver can estimate the sent symbols. The complexity of the receiver is reduced by separating the plus k term and bringing it out into its own exponential term.
• 00:15:00 The video discusses how LoRa modulation works and how it can be used tosend long-range messages without interference. Itshows how the receiver can demodulate signals below thenoise floor, even at low signal-to-noise ratios.
• 00:20:00 This video explains how LoRa modulation really works - long range communication using chirps. By adding noise to the chirps, the noise is multiplied and then used to calculate correlations as a function of s and for a symbol of 33, a big peak is expected at 33 or 34. This can be compared to theoretical values plotted earlier, and with a spreading factor of 12, 2 to the power of 12 possible symbols are generated. However, with a noise power of 23, the noise is much higher than the signal power, so there is likely to be some errors.
• 00:25:00 In this video, the author discusses how LoRa modulation works and how it can be used to communicate over long distances without interference. They explain that the best way to think about LoRa is as an extremely efficient correlation-based system, which is able to detect and identify an incoming symbol even in very noisy environments. The author also highlights the key innovation in LoRa, which is the use of a mathematical trick that allows for the efficient performance of similarity checks.