Simple script that takes 10 samples of wifi signal quality and then calculates the average.

measure-wireless.sh

#!/usr/bin/env bash

wifi_interface="$(nmcli d | awk '$2 ~ /wifi/ {print $1}')"

description="${1:-${wifi_interface}}"

sudo true

samples=10
sequences=($(seq 1 ${samples}))

total_link=0
total_level=0

for index in "${sequences[@]}"
do
    # shellcheck disable=SC2016
    values=($(sudo awk '$1 ~ /'"${wifi_interface}"'/ {print $3" "$4}' /proc/net/wireless | sed 's/\.//g'))
    link="${values[0]}"
    level="${values[1]}"
    total_link=$((total_link+link))
    total_level=$((total_level+level))
    echo "Sample ${index}: ${description};${link};${level}"
    [[ "${index}" -lt "${samples}" ]] && sleep 10
done

average_link=$((total_link/samples))
average_level=$((total_level/samples))

echo ""
echo "Average:"
echo "${description};${average_link};${average_level}"