GSM Scan Networks

This example prints out the IMEI number of the modem, then checks to see if it's connected to a carrier and prints out its signal strength. It also scans for all nearby networks.

Hardware Required

Arduino Board
Arduino + Telefonica GSM/GPRS Shield
SIM card enable for Data

Circuit

GSMShield ArduinoUno

image of the Arduino GSM Shield on top of an Arduino board

Code

First, import the GSM library

#include <GSM.h>

SIM cards may have a PIN number that enables their functionality. Define the PIN for your SIM. If your SIM has no PIN, you can leave it blank :

#define PINNUMBER ""

Initialize instances of the classes you're going to use. You're going to need the GSM, GSMScanner, and GSMModem classes.

GSM gsmAccess;

GSMScanner scannerNetworks;

GSMModem modemTest;

Create a variable to hold the IMEI number, and a status messages to send to the serial monitor:

String IMEI = "";

String errortext = "ERROR";

In setup, open a serial connection to the computer. After opening the connection, send a message to the Serial Monitor indicating the sketch has started. Call @scannerNetworks.begin()@@ to reset the modem.

void setup(){

  Serial.begin(9600);

  Serial.println("GSM networks scanner");

  scannerNetworks.begin();

Create a local variable to track the connection status. You'll use this to keep the sketch from starting until the SIM is connected to the network :

boolean notConnected = true;

Connect to the network by calling gsmAccess.begin(). It takes the SIM card's PIN as an argument. By placing this inside a while() loop, you can continually check the status of the connection. When the modem does connect, gsmAccess() will return GSM_READY. Use this as a flag to set the notConnected variable to true or false. Once connected, the remainder of setup will run.

while(notConnected)

  {

    if(gsmAccess.begin(PINNUMBER)==GSM_READY)

      notConnected = false;

    else

    {

      Serial.println("Not connected");

      delay(1000);

    }

  }

Get the IMEI of the modem with modemTest.getIMEI() and print it out to the serial monitor.

Serial.print("Modem IMEI: ");

  IMEI = modemTest.getIMEI();

  IMEI.replace("\n","");

  if(IMEI != NULL)

    Serial.println(IMEI);

In loop(), scan and print out all available networks. This may take some time

Serial.println("Scanning available networks. May take some seconds.");

  Serial.println(scannerNetworks.readNetworks());

Print out the current connected carrier, and the strength of the signal. Signal strength is on a scale of 0-31, where 0 is the lowest, and 31 is the highest. close the loop().

Serial.print("Current carrier: ");

  Serial.println(scannerNetworks.getCurrentCarrier());

  Serial.print("Signal Strength: ");

  Serial.print(scannerNetworks.getSignalStrength());

  Serial.println(" [0-31]");

Once your code is uploaded, open the serial monitor to see the status of the connection.

The complete sketch is below.


/*

 GSM Scan Networks

 This example prints out the IMEI number of the modem,

 then checks to see if it's connected to a carrier. If so,

 it prints the phone number associated with the card.

 Then it scans for nearby networks and prints out their signal strengths.

 Circuit:

 * GSM shield

 * SIM card

 Created 8 Mar 2012

 by Tom Igoe, implemented by Javier Carazo

 Modified 4 Feb 2013

 by Scott Fitzgerald

 http://www.arduino.cc/en/Tutorial/GSMToolsGsmScanNetworks

 This example code is part of the public domain

 */

// libraries
#include <GSM.h>

// PIN Number
#define PINNUMBER ""

// initialize the library instance

GSM gsmAccess;     // include a 'true' parameter to enable debugging

GSMScanner scannerNetworks;

GSMModem modemTest;

// Save data variables

String IMEI = "";

// serial monitor result messages

String errortext = "ERROR";

void setup() {

  // initialize serial communications and wait for port to open:

  Serial.begin(9600);

  while (!Serial) {

    ; // wait for serial port to connect. Needed for Leonardo only

  }

  Serial.println("GSM networks scanner");

  scannerNetworks.begin();

  // connection state

  bool notConnected = true;

  // Start GSM shield

  // If your SIM has PIN, pass it as a parameter of begin() in quotes

  while (notConnected) {

    if (gsmAccess.begin(PINNUMBER) == GSM_READY) {

      notConnected = false;

    } else {

      Serial.println("Not connected");

      delay(1000);

    }

  }

  // get modem parameters

  // IMEI, modem unique identifier

  Serial.print("Modem IMEI: ");

  IMEI = modemTest.getIMEI();

  IMEI.replace("\n", "");

  if (IMEI != NULL) {

    Serial.println(IMEI);

  }
}

void loop() {

  // scan for existing networks, displays a list of networks

  Serial.println("Scanning available networks. May take some seconds.");

  Serial.println(scannerNetworks.readNetworks());

  // currently connected carrier

  Serial.print("Current carrier: ");

  Serial.println(scannerNetworks.getCurrentCarrier());

  // returns strength and ber

  // signal strength in 0-31 scale. 31 means power > 51dBm

  // BER is the Bit Error Rate. 0-7 scale. 99=not detectable

  Serial.print("Signal Strength: ");

  Serial.print(scannerNetworks.getSignalStrength());

  Serial.println(" [0-31]");

}

Table of Contents

GSM Scan Networks

Hardware Required

Circuit

Code

See Also: