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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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how to speed up sms arduino? [on hold]

I am using sim800l to send SMS using Arduino to send an SMS it takes around 5 seconds because of the 1-second delay between AT commands. is there a way to speed up sms process ? or reduce this delay ...
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96 views

Lithium thionyl chloride for GSM application

I'm trying o use a LiSoCl2 battery in a low power GSM application. When the system is in standby only the microcontroller(MSP430) is powered(3.3v) and the GSM(5v) and sensor(5v) is turned off. The ...
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34 views

Can't type on Virtual Terminal Proteus

I've connected my SIM900a module with PC via a USB to TTL converter. I'm using Proteus Virtual Terminal for check the AT commands. The problem is I can't type anything on the Virtual Terminal. Copy ...
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2answers
32 views

Cellular chip antenna feedline width?

I have a chip cellular antenna from Pulse W3544B. In the datasheet it is said to make the transmission line 1.34 mm thick which I feel is too huge and also I wanted to make a strip line for impedance ...
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36 views

Power supply design with charging circuit

I am designing a GSM modem power supply circuit. The circuit requires a 2A power supply. The module SIM800C itself can be powered directly by Li-Ion or Li-Poly battery power. I am looking at a ...
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40 views

SIM800C returns +HTTPACTION: 1,602,0 during HTTP GET

I have several boards with SIM800C GSM module. One of them works correctly when I issue HTTP GET request (returns HTTP 200). All other boards returns HTTP 602 all the time. 602 stands for "No memory" ...
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63 views

Receiving data from SIM808

I am trying to use SIM808 module but I have no response even after sending only "AT". I am using 5V/2.5A AC/DC adapter. The board (ecb-v3.2) is rather connected well because two diodes are on all the ...
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79 views

How does GSM Module store incoming SMS in its “SM” or “ME” memory?

I am using AI Thinker A7 GSM/GPRS/GPS Module demo v7.1.(The Rx, TX, GND pins of this module are connected to tx, rx, gnd pins of the prolific Rs232-TTL converter and a virtual com port is open in ...
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43 views

GSM antenna connection from the phone does not make sense

I recently came across a phone (Samsung Galaxy Grand Prime SM-G530f) with trouble getting any network signal, I did some troubleshooting and ended up finding out that one of the pin(the GSM pin) to ...
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1answer
98 views

STM32L0/FTDI UART Transmit doesn't work

I have STM32L053 (link to overview) and I have been using STM32CubeL0 as UART examples. Also I connected FT232RL FTDI module. Everything was fine. SIM800L and FTDI modules were working fine. Next day ...
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122 views

“Leeching” clock information from cell towers

I understand that cell base stations transmit very accurate time signals among other things. Do you need a SIM card and an account to receive this information, or is it something you can "leech" with ...
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78 views

RF layout bend over Component

We lay out the RF trace for below model. GSM 900MHz RF trace maintain at 50Ω impedance. As I know, the RF trace needs to be as short as possible for better signal. Do we need to bend RF trace ...
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1answer
125 views

How can i replace a electret mic input with headphone output as input

I'm using a SIM800L GSM module for my project. In this module there is a electret mic input pin but I want to give audio to this module from headphone output from a mobile (There is no line in pin ...
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1answer
63 views

GSM Interference with Meanwell Switch mode PSU

I am having trouble with interference from a GSM modem and my switch mode PSU. I do not know much about interference and how the radiation patterns works for GSM. Below is an image of the circuit ...
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448 views

SIM800C - CME ERROR: 15 SIM wrong & CME ERROR: 10 SIM not inserted

I am making a GSM Tracker with SIM800C module. After deploying it into vehicles.. It works fine.. but after some days, it starts responding as CME ERROR: 15 SIM wrong for command AT+CPIN? & CME ...
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1answer
53 views

Adafruit 3G Module sends data but don't accept it

I'm having trouble sending commands to the GSM/GPS/3G module from Adafruit. It gives me status data at bootup without any issues (takes a few seconds). The product in use is this: https://learn....
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2answers
343 views

SIM800C GSM module works via PC but not on battery

Before giving the specifications of my project, I'd like to say that I'm a total beginner in electronics but I do have a background in IT development. I also want to apologize if this question has ...
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1answer
116 views

Why is there an inductor sort of a thing inside this antenna?

I have a 20cm antenna exactly of the same shape as shown in figure. I want to know why is there a inductor sort of a shape in its monopole? What is its purpose? Does it affects its designed frequency? ...
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1answer
375 views

SIM808 registration denied for new SIMs

I have a SIMCom SIM808 2G GSM module on a custom PCB based upon the Adafruit FONA. I got a bunch of 2G SIM cards from Aeris.net. The problem is when I first put the SIM cards in my device, I get "...
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42 views

Connecting a Lithium battery directly to the GSM module

I have a GSM module (M66 from Quectel) and a single cell Lithium battery,Based on Datasheet module operated in the 3.3 ~ 4.6 V and as I know battery deliver 3.7 ~ 4.2 V based on it's sate of charge....
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1answer
55 views

GSM antenna CPW design

I'm designing a board with a GSM modem, and the plan is to hook this up to an SMA connector and thence to an external antenna which will live outside the metal enclosure. I'm aware of the need to ...
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1answer
78 views

how to send inter-operator sms via GSM/LTE module

I am using a GSM/LTE module (EC21 Quectel) to send and recieve sms with HyperTerminal application on computer by at-commands. I can send sms to devices with the same operator (intra-operator), but ...
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679 views

IP over LwIP PPPoS with Telit GSM GL865 and STM32F7

I am using Telit GL865 GSM Modem with STM32F7 nucleo development board. I make them communicate via USART1. Firstly, I configure the modem with AT commands as below; after that, modem starts to send ...
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181 views

ESP32 GPRS Module gets into endless loop while trying to init GSM Module

I have been trying to call a init function but as result it ends in a silly endless loop. I am using ESP32DevKit and M95 GSM module on a custom circuit. The related code is shown below. ...
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46 views

Neoway M590E module error

According to neoway M590E hardware design manual, for proper operation of the sim, pins 11 & 14 (SIMIO, SIMVCC) of modem should be having high-level signals. But in my case, both pins are zero ...
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1answer
213 views

Protection against EMI

I have a complex EMI problem. There is a RPi Compute Module along with a LAN9512 and GSM modem (M66). Layout guidelines are strictly following the datasheets' recommendations, I don't think there is ...
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221 views

DIY smart phone cradle antenna

My office is located below the ground level and therefore GSM reception is not satisfying so I am using a simple 4G Antenna placed outside where the signals are strong enough. The antenna wire is on ...
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1answer
46 views

Using an RF adapter to improve LTE signal in the house

In my apartment, the GSM signal is very scarce, if not absent at all, except for a few spots, where there's a decent LTE signal and I can browse internet reliably. In order to improve the reception ...
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3answers
153 views

How do I check whether my GSM Modem works in some other country?

I am a new to choosing RF modules and I am trying to choose a module that works in Qatar. I see on FrequencyCheck, Qatar is having GSM band of 900 and 1800. So, if I choose GSM800 C, having quad ...
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1answer
106 views

AT-CIPSEND Number of Characters SIM Tech GSM modules

I am succeeding in sending an update string via a SIM800L to ThingSpeak but the channel is not updating the channel. I know the string is correct since it is provided by the site that I am posting to....
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1answer
340 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....
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1answer
964 views

SIM800L restart automatically

I know there is a similar question but it did not solve my doubts, I will be clear and concise. I recently bought the SIM800L module and then I started to try it, at the beginning it restarted itself ...
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2answers
144 views

SIM808 always returns the same temperature

I have a SIMCom SIM808 module built up on my own breakout board. Whenever I query the temperature I get back the exact same temperature, 24.11 (deg C) despite the actual temperature in the room ...
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1answer
58 views

Why GSM module connects with same apn for different operator?

I'm using SIM868 in one of the GPS tracker that is being developed. HTTP protocol is used in sending data to the server.I have tried this with SIM cards of 2 network operations,Vodafone and Airtel. <...
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2answers
1k views

Upgrading firmware of SIM800C

My SIM800C, feeded directly from a 4.0V Li-ion battery (or once, from a Delta bench PSU) through a 1500 µF capacitor, instantly turns off when it wants to join to my 2G+ European network (e.g. in <...
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154 views

External to internal antenna setup doesn't increase signal power

For a larger project where I basically want to boost phone signals indoors using an external antenna I have devised a small experiment to make sure I get the basics right before I expend a lot of ...
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543 views

Enabling SD card access on SIM808

I am currently working with SIMCom's SIM808 2G+GPS modem. In my setup, an MCU communicates with the modem over UART to save some data in the SIM808's filesystem. As the modem's built-in memory is < ...
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1answer
349 views

How can I test TCP/IP AT-Commands with server?

I'm currently using SIM868 to make a GPS tracker, I wanted to know how to test tcp/ip protocol with a server. I do not have a server but got a website and a wifi connection(DIR-600M Router) , Is ...
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1answer
463 views

What is GNSS EPO orbit prediction in SIM868?

I'm little bit confused about the purpose of GNSS EPO orbit prediction functionality in SIM868 over a hot start,cold start or warm start. I'm working on a GPS tracker project and which among the ...
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2answers
428 views

Quectel M95 Shorts Vbat pins

I have recently designed and assembled a circuit for a Quectel M95 unit to be controlled by Usart from an Atmel micro-controller. I have a problem with the power supply of the M95, I followed the ...
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1answer
159 views

Problems with RF antennas

I just created a PCBA using the module MC60 and I have some problems: I'm using a U.FL connector to connect a RF passive external antenna to the MC60, the U.FL should be on the same layer of the MC60?...
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2answers
363 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 '...
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1answer
742 views

SIMCOM vs UBLOX [closed]

I would like to know what are your thoughts on the following below. I am designing a GSM tracking device with a SIMCOM808 module and I am speaking to an antenna supplier that advises me to rather go ...
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395 views

SIM800L intermittent registration problem

I am using a SIM800L module (see below) with an ESP32 and external power supply and having trouble getting it to register on a mobile network until, that is, I touch the antenna. When the module is ...
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1answer
82 views

Can you use a amplifier and a satellite antenna to boost a GSM signal?

I have a small GSM Modem whose internal antenna sucks. I bought a small external antenna that boosted the signal a little, however I want to boost it more. Would using a typical high frequency audio ...
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1answer
328 views

Li-Po battery leaking current when connected to TP-4056 charger

I've been using a Nokia BL-5C 1020mAh, 3.7 Li-Ion battery to power up my SIM800l GSM module. Everytime I used the battery for testing out the various AT commands for maybe 30 mins or an hour, I'd ...
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421 views

SIM800l power-up problems

The datasheet of the SIM800l claims that currents can peak to around 2A during SIM registration and other network intensive activities. I tried powering up the module with the 5v output of a FTDI-USB ...
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1answer
1k views

SIM800L and PIC MCU pinout

I'm on a school project that involves, as part of it, the sending of messages to a cellphone through a SIM800L GSM module. This module will be controlled by an PIC16F648A MCU. My problem is: how to ...
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2answers
463 views

SIM7100 GSM Modem Unreliable Connection

I am trying to communicate with SIM7100 GSM modem but I could just rarely communicate with it across UART interface. I am observing the signal with an oscilloscope, I am giving 5V as High and 0V as ...
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1answer
395 views

Use a SIM card module (SIM808) with the less battery possible

I'm using a SIM808 module (on a breakout card) and I want to send only 20 bytes every 6 hours (i.e. 120 bytes per day), containing GPS position and some very short other data. So I think I'll ...