RSSI level testing

For the source code implementation, Visual Studio Code was used with the Pymakr extension installed.
For the communication tests, two Fipy modules were used, one designated as the Transmitter and the other as the Receiver.
At the receiver, to determine the thresholds regarding the level/quality of the received signal RSSI, the RGB LED provided with the Fipy module was used for indication. Additionally, for some measurements, serial communication was also used to determine the absolute values of RSSI.
The source code used for the transmitter Tx is:

       # main.py -- put your code here!
       # code for the LoRa Tx Fipy module

       import pycom
       import time

       pycom.heartbeat(False)

       time.sleep(1)

       pycom.rgbled(0x7f0000)
       time.sleep(1)
       pycom.rgbled(0x7f7f00)
       time.sleep(1)
       pycom.rgbled(0xff00)
       time.sleep(1)
       #############################
       from network import LoRa
       import socket
       import time
       import ubinascii
       time.sleep(1.0)

       lora = LoRa(mode=LoRa.LORA, region=LoRa.EU868, frequency=868000000) # note that the frequency variable must be the same at the receiver
       s = socket.socket(socket.AF_LORA, socket.SOCK_RAW)
       s.setblocking(False)

       while True: # running infinitely
           s.send('Ping') # sending the message
           
           pycom.rgbled(0xFF0000) # programming the RGB LED for the color Red
           time.sleep(1) # pause for one second
           pycom.rgbled(0x7f7f00)  # programming the RGB LED for the color Olive 
           time.sleep(1) # pause for one second
           pycom.rgbled(0x00FF00) # programming the RGB LED for the color Green
           time.sleep(1) # pause for one second
       #############################

The source code for the receiver Rx is:

       # main.py -- put your code here!
       # code for the LoRa Rx Fipy module

       from network import LoRa
       import socket
       import time
       import pycom

       # A region corresponding to our location where we use the module will be chosen
       # Asia = LoRa.AS923
       # Australia = LoRa.AU915
       # Europe = LoRa.EU868
       # United States = LoRa.US915
       lora = LoRa(mode=LoRa.LORA, region=LoRa.EU868, frequency= 868000000)
       s = socket.socket(socket.AF_LORA, socket.SOCK_RAW)
       s.setblocking(False)
       pycom.heartbeat(False)

       while True:
       if s.recv(64) == b'Ping':

       status=lora.stats()
       rssi = status.rssi
       snr = status.snr
       # print(lora.stats())
       print("RSSI= %s" %rssi)
       print("SNR= %s" %snr)

       int_rssi=int(rssi)
       if int_rssi >=-71:
       pycom.rgbled(0x00FF00) # Green LED
       elif int_rssi <=-71 and int_rssi >=-120:
       pycom.rgbled(0x000FF0) # Blue LED
       elif int_rssi <= -121:
       pycom.rgbled(0xFF0000) # Red LED
       int_rssi=0 # initialize the RSSI value

To connect via Wi-Fi using the FTP protocol, the connection to the Wi-Fi router will be established using the boot.py file:

 boot.py -- run on boot-up
import machine
import os

uart = machine.UART(0, 115200) # Delete the line if serial port is not desired
os.dupterm(uart) # Delete the line if terminal at the serial port is not desired

if machine.reset_cause() != machine.SOFT_RESET:
from network import WLAN

# We establish which wireless network we are connecting to; if it does not connect, it will switch to the default AP mode 
known_nets = [('SSID', 'parola')] 

wl = WLAN()

original_ssid = wl.ssid()
original_auth = wl.auth()

wl.mode(WLAN.STA)

available_nets = wl.scan()
nets = frozenset([e.ssid for e in available_nets])

known_nets_names = frozenset([e[0] for e in known_nets])
net_to_use = list(nets & known_nets_names)

try:
net_to_use = net_to_use[0]
pwd = dict(known_nets)[net_to_use]
sec = [e.sec for e in available_nets if e.ssid == net_to_use][0]
wl.connect(net_to_use, (sec, pwd), timeout=10000) # The waiting time for connection (ms)
except:
wl.init(mode=WLAN.AP, ssid=original_ssid, auth=original_auth, channel=6, antenna=WLAN.INT_ANT)

Initially, the RSSI values were measured with the transmitter and receiver close together, achieving perfect values for RSSI=0, as shown in the figure below:

Modules prepared for field measurement

RSSI level=0 for nearby modules, as above

For efficiency, it is useful to use a car:

Field measurements

No.	Distance [km]	RSSI [dBm]	Receiver antenna type	Transmitter antenna type	Screenshot
1	2.2	-115	Yagi-Uda isolated boom	Stick
2	2.2	-115	Yagi-Uda metal boom	Stick
3	2.2	-121	Stick	Stick
4	2.9	-127	Yagi-Uda isolated boom	Stick
5	2.9	-	Stick	Stick	No reception

The tests were conducted under the following conditions:

• The heights of the antennas above ground were approximately 1.8 m;
• The tests were conducted within a municipality with blocks and other quite tall buildings;
• Tests 1-3 are conducted in a direction with more houses than blocks up to the municipal limit;

• Tests 4-5 are conducted in a direction with more blocks and tall buildings.

  The conclusion is that at reception, a high-gain antenna makes a difference, and long distances or lower consumption can be achieved, depending on what is desired. The Yagi-Uda antennas with 12 elements are those found here . The antenna with an isolated boom is less noisy than the one with an aluminum boom but is less durable over time in inclement weather.