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        <h1>iBlog</h1>

        <h2>04/16/2024</h2>
        <p>16/04/2024   LORA GPS Transmitter/Receivers<br><br>

Raspberry Pi 4 Model B - 8 GB RAM PID: 4564<br>
SBC (single board computer)<br>
sudo apt-get update (update list of available packages)<br>
sudo apt-get upgrade (update all software)<br>
sudo apt autoremove (remove packages/software that isn’t required)<br><br>

Adafruit LoRa Radio Bonnet with OLED - RFM95W @ 915MHz - RadioFruit PID: 4074<br>

Adafruit Feather 32u4 RFM95 LoRa Radio- 868 or 915 MHz - RadioFruit PID: 3078<br>
SDR (software defined radio)<br>
SX1276 LoRa® based module<br>

TFT FeatherWing - 2.4" 320x240 Touchscreen for all Feathers PID: 3315<br>

GPS<br>

Adafruit Ultimate GPS Breakout - 66 channel w/10 Hz updates - Version 3 PID: 746<br>
Firmware version AXN_2.51_3339_17112000,0004,16165,1.0*56<br>

NMEA (National Marine Electronics Association) to decimal degrees<br>
DDMM.MMMM<br>
(D)DD+(MM.MMMM/60)<br>
+4708.9380N<br>
47+(08.9380/60) = 47.1490<br>
-9331.1494W<br>
-93+(-31.1494/60) = 93.5192 //be careful of the negative sign<br>
+47.1490N -93.5192W<br>

LoRa Math<br><br>

A byte = 8 bits<br><br>

LoRaWAN protocol adds at least 13 bytes to the application payload<br><br>

Note that all the combinations of spreading factors and bandwidth are not orthogonal<br><br>

Spreading Factor (SF): Determines how much the signal is spread out in time. Higher SF means more spreading, which increases robustness but lowers data rate.<br><br>

Modulation: Refers to how digital data is encoded onto the signal. In LoRa, it's done through a technique called chirp spread spectrum (CSS), where the signal's frequency changes over time.<br><br>

chirps represent the frequency variation over time, and chips represent the basic unit of time used for encoding digital data<br><br>

Data Rate (DR) = BW / (2^SF)<br>
-   DR is the data rate in bits per second (bps)<br>
-   BW is the bandwidth in Hertz (Hz) LoRa has three bandwidths (125kHz (125,000 Hz), 250kHz (250,000 Hz), & 500kHz (500,000 Hz))<br>
-   SF is the spreading factor, which is a unitless value typically ranging from 7 to 12<br>

Chirp rate = BW*(Symbol rate)<br>

Chirp rate = BW* BW / (2^SF)<br>

symbol length in bits=2^sf<br>

Number of symbols = (payload size in bytes*8)/(symbol length in bits)<br>

In LoRa modulation, each chip is 1 bit<br>
</p>

<p>\[Maximum Payload Size = \frac{Symbol Rate * Bandwidth}{2^{sf}} - Overhead\]</p><br><br>

<a href="https://www.semtech.com/design-support/lora-calculator">https://www.semtech.com/design-support/lora-calculator</a>
*Firefox work well<br><br>

Chirp: Imagine a sound going up or down in pitch steadily. That's like a chirp. In LoRa, this chirp is used to send information.<br><br>

Chip: Think of a chip as a small piece of time. In LoRa, we divide time into tiny pieces called chips to send data. Each chip can represent either a 0 or a 1 in the digital signal.<br><br>

<a href="https://www.airspayce.com/mikem/arduino/RadioHead/classRH__RF95.html#a9b402c77236b0dfe3ec68e953faa02dd">https://www.airspayce.com/mikem/arduino/RadioHead/classRH__RF95.html#a9b402c77236b0dfe3ec68e953faa02dd</a> <br><br>

Calculate link budget<br><br>

Used ChatGPT for help with code<br><br>

Antenna analyzer <br><br>

Github access tokens to use git with raspberry pi</p>


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