Questions tagged [gsm]

GSM stands for Groupe Spécial Mobile. It is a standard set developed by the European Telecommunications Standards Institute (ETSI) to describe protocols for second generation (2G) digital cellular networks used by mobile phones.

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29
votes
7answers
20k views

Why does GSM cause speakers to buzz?

Based on numerous internet resources, speaker wire acts like an antenna which picks up the transmitted signal of nearby cellphones and causes the speakers to buzz. But I'm not really buying that... A ...
6
votes
4answers
1k views

Can Cellphones be used for Ad Hoc Communication?

Can Cell Phones be (legally) used Adhoc, (ie, Point-to-Point) Communication? For example, let's say I'm in a remote area of the woods, or a valley. Can I configure cell phones to be used as true ...
13
votes
6answers
3k views

Simulate bad cell phone reception in the lab

I'm currently developing an internet of things device that utilizes a uBlox SARA-U260 gsm/3G modem. In field testing, we have had significant software/firmware issues due to poor cell phone reception ...
8
votes
2answers
2k views

Wavelengths blocked by a certain metal mesh

Introduction: I've heard about a theory, according to which you can check if there is any leakage in your microwave oven by putting your mobile phone inside and call it. However, I gave it a try and ...
7
votes
1answer
2k views

Killing GSM Buzz with Ferrite Beads

I'm trying to rid my speakers of the typical buzz from my iPhone. I get poor reception in my apartment and so it's constantly trying to find a signal, meaning I get a near-constant buzzing when the ...
1
vote
1answer
588 views

Usb 3G, 4G modems, power supply

I have read that usually a gsm module requires a power supply capable to provide up to 2A. But how can 3g modems sticks work properly when they are powered through usb port which provides only up to ...
2
votes
3answers
2k views

Is it possible to use SIM900 GPIO to control relays without using external MCU?

From the product manual / reference guide it looks like SIM900 / SIM900A is already equipped with 12 GPIOs. But could not find information on how to use these GPIOs to control relays directly, instead ...
1
vote
2answers
21k views

Connecting GSM SIM900A module with Ardunio

I have bought an SIM900A Mini V4 GSM module. Here is the module, I want to configure with arduino to send and receive SMS. Do I have to connect TXD of this module--Tx of Arduino & RXD of this ...
11
votes
10answers
52k views

What AT command should be sent to modem to get time?

I am using SIM800E. I want to know what AT command should be sent to the modem to get time? This modem has a RTC. But I need to set it automatically through cell tower. The tower can send the time to ...
3
votes
5answers
6k views

How to power a GSM Modem from a Li-Po battery?

I want to integrate an AirPrime SL6087 GSM modem into a design, this is my first try at working with a GSM module. The datasheet states that the modem draws 2A for 1mS every 4mS (max) at 3.6V, the ...
1
vote
2answers
2k views

GSM/GPRS AT command - hitting a link

I am trying to target a specific page (script) on my webserver using a GPRS modem. I can hit my domain, and get a reply back but then when I am trying to call my script it just won't let me: ...
5
votes
3answers
13k views

How to properly power sim800l module?

I have this sim800L module It has a 3.7v - 4.2v voltage requirement. So I created a simple buck regulator using MIC4576 regulator according to it's schematics and adjusted it's output to 4.2 volts. ...
3
votes
2answers
726 views

How do you independently program a GSM/GPRS IC [duplicate]

I see these GSM/GPRS modules that you can use with a microcontroller but all of them use the microcontroller to control the module using AT commands. After a bit of googling i saw this GSM/GPRS IC '...
3
votes
1answer
5k views

GSM Module gets into reboot loop

I have assembled a diy m590e gsm gprs module kit, bought from Amazon. The seller provided image is: The Schematic used to assemble the kit is: I connected it to the Laptop using a CP2102 based USB ...
2
votes
0answers
77 views

Why is GSM interference audible? [duplicate]

We have all heard the buzzing sound that your speakers makes when you use your phone near your radio or amp. My question is why does one hear this interference if GSM operates at ~800-900MHz which is ...
2
votes
4answers
14k views

how much power is radiated by cell towers?

I want to know how much power is radiated by cell towers of GSM (1.8 Ghz), 3G (2.1 Ghz), 4G (2.6 Ghz) ? I want links to references if exist.
1
vote
1answer
634 views

Relationship of antenna size to gain and directivity

This question is derived from certain answers I received for a previous question I posted. Case : Let's say I have two GSM antennas of the exact same shape, design and material. The only difference ...
1
vote
1answer
187 views

How do I correctly protect my MCU from resetting during a current surge on RF transmission?

I designed a PCB with a SIM868 module for data transmission. On the PCB, the MCU resets randomly on transmission start of the SIM module. On a breadboard setup, it worked just fine, even without caps. ...
1
vote
2answers
2k views

Circuit Design to Power the ADH8066 GSM Module

I am struggling to find the proper circuit design layout to properly power the ADH8066 GSM module and communicate with my Arduino. The ADH8066 requires a 4V power supply and can have a brief spike of ...
1
vote
1answer
314 views

Gain vs. Directivity and effect of animal body to Antennas

My design works in a foresty area inside a collar of an elephant. These areas have at least -110dBm GSM strength (accurate ref. map linked) but, usually higher as I live in a small country where GSM ...
1
vote
1answer
207 views

Error getting data from GSM SIM900

I am interfacing with GSM SIM900. I wrote a program so that I can read the SMS in SIM900. I have made a function to transmit and receive. Whenever msg comes, GSM responds with ...
1
vote
0answers
45 views

SIM800L microphone problem

I want to feed SIM800L a microphone signal. I found this page in the datasheet and it worked but I need more a sensitive microphone. I want to hear voices in room as much as possible, like a spy bug. ...
1
vote
1answer
604 views

Running GSM module from primary batteries (ER34615)

I'm designing a small telemetry system that will take measurements every few hours and send the data through 3G at the end of the day. The target battery life is 1 year. The GSM modules is an XBee 3G....
-1
votes
1answer
1k views

How to start using SIM900 mini V4.0 GSM board

I recently bought a quad-band SIM900 mini V4.0 GSM board (http://www.ebay.com/itm/SIM900-MINI-V4-0-WirelessData-Transmission-Module-with-Antenna-Cable-for-Arduino-/281493144780). My problem is quite ...