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--- exploring_lora [2018/09/27 17:00] – [2. Theoretical Study] samer
+++ exploring_lora [2018/09/29 12:59] – [3.1. Modifying the Radio Parameters] samer
@@ Line 28: / Line 28: @@
 Download the following software on your PC:
-  * RadioHead: The Packet Radio library for embedded microprocessors can be downloaded from [[http://www.airspayce.com/mikem/arduino/RadioHead/]] or from this [[http://www.airspayce.com/mikem/arduino/RadioHead/RadioHead-1.86.zip|direct link]].
+  * RadioHead: The Packet Radio library for embedded microprocessors can be downloaded from [[https://github.com/samerlahoud/RadioHead]].
   * Arduino IDE: Specific OS versions can be downloaded from [[https://www.arduino.cc/en/Main/Software]].
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 Note well the location of the library folder on your computer. In the following, you will be required to modify source files located in this folder.
 </WRAP>
 ==== -. Installation ====
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 ==== -. Modifying the Radio Parameters ====
-Start by setting the central frequency of your LoRa modules according to the following table:
+Download the {{ :sketch-1819.zip | basic sketches}} that implement a simple LoRa communication between the two modules: a client module and a server module. Open the sketches with Arduino IDE. Make sure to choose the correct ''Board'' and ''Port'' in the ''Tools'' menu.
+Take a look at the source code in ''rf95_client.ino'' and ''rf95_server.ino''. Particularly, the ''setup'' function configures the radio parameters of your LoRa devices:
+  * Central frequency (freq)
+  * Spreading Factor (SF)
+  * Bandwidth (Bw)
+  * Coding Rate (CR)
+  * Transmit power (Pow)
+<code c++>
+rf95.setFrequency(frequency);
+// Setup Power,dBm
+rf95.setTxPower(13);
+// Setup Spreading Factor (6 ~ 12)
+rf95.setSpreadingFactor(7);
+// Setup BandWidth, option: 7800,10400,15600,20800,31250,41700,62500,125000,250000,500000
+//Lower BandWidth for longer distance.
+rf95.setSignalBandwidth(125000);
+// Setup Coding Rate:5(4/5),6(4/6),7(4/7),8(4/8)
+rf95.setCodingRate4(5);
+</code>
+In order to reduce collisions, configure the central frequency of your LoRa modules as indicated below:
 ^  Group Number  ^   Frequency     ^
@@ Line 84: / Line 109: @@
 |       12       |      868.9      |
-For this, open the ''RH_RF95.cpp'' file located in the ''RadioHead'' folder and change the frequency using the following command:
-<file cpp RH_RF95.cpp>
-setFrequency(86X.Y);
-</file>
-The typical configuration for LoRa modules consists of 125 kHz sub-channels, a coding rate of 4/5, and a spreading factor equal to 7. You can modify the radio parameters by selecting one of the three available configurations:
-  * Bw125Cr45Sf128
-  * Bw125Cr48Sf4096
-  * Bw31_25Cr48Sf512
-Radio configuration is applied in ''RH_RF95.cpp'' as in the following example:
-<file cpp RH_RF95.cpp>
-setModemConfig(Bw125Cr45Sf128);
-</file>
 ==== -. Running Basic Sketches ====
-Download the {{ :sketch-1819.zip | basic sketches}} that implement a simple LoRa communication between the two modules. Open the sketches with Arduino IDE, compile and upload on the two arduino modules, respectively. On the serial interfaces, you should obtain similar results as in Fig. 2 and Fig. 3. The client sends periodically a short message and towards the server. The server outputs the RSSI (received power in dBm) for each received message.
+Now you can compile and upload the client and server sketches on the two arduino modules, respectively. On the serial interfaces, you should obtain similar results as in Fig. 2 and Fig. 3. The client sends periodically a short message towards the server. The server outputs the RSSI (received power in dBm) for each received message.
 [{{ :client-iotlab1.png?direct&600 ||Figure 2. Client serial monitor}}]
 [{{ :server-iotlab1.png?direct&600 ||Figure 3. Server serial monitor}}]
-In the remainder of this lab, you will conduct measurements to validate the obtained theoretical receiver sensitivity.
 ===== -. Performance Evaluation =====
 In the following, you will design and implement a set of scenarios that enable to evaluate the performance of the LoRa modulation. As you will deal with scientific assessment, you are required to use scientific tools to show the results. You have the choice between [[http://www.gnuplot.info | gnuplot]], [[https://matplotlib.org/index.html#|matplotlib]] with Python, and MATLAB. Take some time to become familiar with one of these software as you will be required to use them in different occasions of your academic programme.