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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 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. ...
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116 views

Mcu keeps reseting because of noise

I have a circuit in which there is a mcu lpc1768 and a gsm module sim800l. For power I use DC/DC converter and made a 4.2v using lm2576 for sim800l. Used that voltage, I made a 3.3v using ams1117 and ...
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43 views

SIM800C-DS power supply schematic

I have drawn a circuit diagram of a power supply for a SIM800C-DS IC from the datasheet but is it right or wrong? I am confused as it's my first time. I also want to know where to connect the ...
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76 views

Can I use the same antenna for GSM and RF433 MHz?

I've already designed a PCB with GSM/GPRS chip and also with RF 433MHz receiver only (without transmitter). I would like to know if I can use the same antenna for both GSM/GPRS module and RF 433MHz ...
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1answer
22 views

Telit cellular module pins connection

I have the UE910 cellular module from Telit. I have manufactured a PCB containing the module but it's not working (power is reaching it but serial program not communicating with the tx and rx pins). I ...
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1answer
24 views

SIM800: AT-command to get connected sender ids

I want to roughly estimate where my Arduino currently is. For this, I want to fetch the identification numbers of the stations it is currently connected to, so I can put them into an API which then ...
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30 views

How to post file to HTTP server with SIM7600I

I have tried AT commands provided by SIMCOM, but the module is not responding. AT+HTTPPOSTFILE,AT+HTTPREADFILE commands are giving error even for execution command....
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25 views

SIM800L Disconnecting Issue

I'm doing a project using SIM800L ebay module.I can send & receive SMS & calls. The problem is, on workbench its working, but in actual site environment when the GSM signal is low & it ...
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1answer
68 views

GSM Modem Transmission Issue

I'm having a problem getting this GSM modem to work with an FPGA (Spartan 3). I've already implemented UART transmission on the FPGA side,the MAX232 to convert TTL->RS232, and 3.3V->5V logic level ...
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1answer
108 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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114 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
38 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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1answer
41 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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1answer
80 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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75 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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105 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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53 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
134 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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1answer
123 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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1answer
87 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
175 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
67 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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616 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
54 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
425 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
119 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
488 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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1answer
48 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
65 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
100 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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834 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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1answer
246 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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1answer
52 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
163 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
117 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
401 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
1k 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
162 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
59 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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1answer
163 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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0answers
580 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
369 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
525 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
490 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
167 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
456 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
858 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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1answer
86 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
385 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 ...