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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SIMCOM 7080G Unsure about the RFGRFC INTERFACE

been reading through the SIMCOM 7080G HARDWARE manual and on 3.12 it has a RFGRFC interface circuit. what type of RF Tuner IC uses these ANT_CONTROL lines like this ? or is this just an RF switcher ...
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157 views

Impedence matching required for very short PCB trace?

I have a custom PCB using 50 ohm impedance antennas for GPS (1.575 GHz), GSM (2.4 GHz), and LoRa (868 MHz). Currently using an impedance matched board with matching track widths of 6 mil. One track ...
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67 views

Anyone having a GSM module please confirm. Is it normal to have the terminals of SIM800L EVB antenna shorted?

My SIM800L-EVB GSM module wasn't registering to network even after providing good power supplies. On troubleshooting I found that the terminals A and B, to which the antenna attaches(see img attached) ...
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72 views

180m to proper 4G reception: which approach to take to ensure good bandwidth?

I have a cabin in a remote location in Norway, and as luck has it, no cell phone reception. There is great reception up on a hill nearby. I could erect an antenna there, and the cable would be about ...
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24 views

SIM808 not supporting SSL related commands

I am using SIM808 module. It's working fine with normal MQTT over TCP. But it's not working while implementing secured MQTT. I am sending this command (AT+SSLSETROOT="C:\USER\HENRY_SSL.CRT")...
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69 views

Would it be possible to use a GSM without a SIM card?

I would like to reduce the footprint of my PCB (a simple IOT GSM impl.). Given a common GSM such as SIM800/868/900l etc. Would it be possible to completely replace the footprint of a SIM card holder (...
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43 views

Problem Understanding how to use Li-Ion battery charger IC

I want to drive a Load that consumes 2A current during data transmission for a concise amount of time, and it can tolerate a maximum of 4.4 volts (SIM800 Series GSM). It works fine with a DC adapter ...
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300 views

What does GSM 900/1800 mean?

I was looking at old Nokia 3310 phones, which have GSM 900/1800. I did some research online from a government website, along with some Google searches, to understand what GSM 900/1800 means. I got a ...
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38 views

Problem gsm with SIM868E

I am working with sim868e, I have run the serial port and I am sending and receiving commands without any problems. I am using a custom board, designed by myself. When I insert the SIM card, the ...
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38 views

Battery for GPRS module and voltage regulation

I work on a wearable GSM device powered with a LiPo battery. I want to use a switching charger with a power path. My GSM module can consume up to 2 amps during data transmission and its working ...
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112 views

Ground plane for a GSM spring antenna with 4 layer PCB

We are looking to build a 2G GSM based device with a helical spring antenna like this. The work in progress layout is as shown below: We are using a 4 layer PCB with top layer for signal, inner 1 ...
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56 views

Problem in capacitor selection

The SIM800L datasheet suggesting a low ESR capacitor for providing a 2 ampere burst current during data transmission. According to this site MLCC provides the lowest ESR at high-frequency application, ...
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How can I program my mcu stm32f103 to transmit and receive data via a server [closed]

hello I am a beginner and my final project is an alarm system, in fact I use a mcu stm32f103 and I want to transmit the data by a GSM module to a base (to access it by a mobile application) and also ...
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40 views

Are there regional constraints with the SIMCom modules? (Eg. SIM7605CE/SIM7600CE)

I recently received a SIMCom Module (Model no. SIM7605CE), shown below. The item can be (purchased online as well). The device, much like the ones used with Arduinos (like the SIM800L), is supposed ...
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48 views

SIM Card ATR Voltage Capability

I have a project where I am using an STM32 to pretend to be the SIM card of an LTE module. The actual SIM card is located elsewhere and the SMT32 acts a middle man between the LTE module and another ...
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66 views

Capacitor for reducing voltage drops

I use gsm module, which makes current bursts up to 2Amps (maybe slightly more). That causes voltage drops about 0.5V on my power supply (I use lipo battery), and than device hangs up or starts ...
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82 views

An effective way to knock down GSM on demand

I am building a test rig for a device that has a GSM module to communicate and I want to test how the FW behaves when there is a comms loss and recovery. The GSM module of the device has an antenna ...
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45 views

Arduino : send data via satellite (or other solutions) without GSM [closed]

I'm a researcher. I'm looking to build a very tiny embedded system with low power consumption. I must send data from the desert and above the ocean. To do that I think that my single option is to use ...
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105 views

Bluetooth antenna problem with SIM800C on my board

I have designed a board with a SIM800C and I have followed all details with its given datasheet. Everything is working well except the Bluetooth that gives very low antenna strength (less than 10cm.) ...
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170 views

Is GSM full-duplex?

GSM uses FDD (frequency division duplexing) and provides separate channels for uplink and downlink. I found however, in this link, that the mobile station does not receive and transmit at the same ...
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42 views

Are there any special considerations for extending a UHF-carrying coax wire in a small device?

In the process of doing a repair on a mobile phone, I've tracked down a "no service" issue to an antenna lead inside the case. Specifically, it has detached from the U.FL/MMCX (I'm not sure ...
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180 views

PCB antenna track and SMA connector controlled impedance

I designed a pcb for GSM module, using all the specifications given by the manufacturer, to have a controlled impedance. But there is a small detail that escapes me and that is not documented. When ...
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72 views

Need help with power supply circuit

i'm currently designing a device which uses GSM module. which works on 12V and if the main supply is not there, it will run on battery. right now i'm facing a problem in power supply circuit. i'm ...
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68 views

Tracking location with GSM tower triangulation

I want to track location with GSM tower triangulation. I searched and I found this API for GSM positioning. ...
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19 views

design considerations of Ethernet-spi controller

Recently I have designed board on which Ethernet and gsm module need to be placed. Already I have exported Ethernet related chip to pcb and arranged in this order s shown in below image This is how I ...
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82 views

SIM 7600ei AT command error while sending GET request

I am using the SIM7600ei module with a 4g LTE Sim. I am successfully able to get the IP address. ...
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98 views

AT commands no answers ! SIM808 and Arduino

I will try to explain my problem... I'm using a SIM808 GSM-GPS click module and a ARDUINO nano 33 IoT board, I'm sending the command "AT\r" thanks to the TX port from the ARDUINO board to ...
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69 views

Why RXD text are uncomplete in atmega328 intrupt driven USART?

I have an Atmega328p MCU which is connected to USB port by ch340 chip and I've connected it to GSM module by hardware RX/TX/GND pins. I don't send any command to USB port all commands are send by ...
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44 views

GSM Interference - SIM800L

I did a GSM based alarm system using SIM800L modules.One is transmitter & the other one is receiver.When the transmitter button pressed it will make a call to receivers number & receiver ...
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1answer
215 views

SIM800L EVB audio output on Raspberry Pi

I have a SIM800L EVB GSM module connected to a Raspberry Pi and it is working correctly. However I did not find any pins related to speaker or audio output as shown in the wiring: This is different ...
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372 views

PCB designing of GSM module

I want to design PCB of a GSM module. Inside a GSM module there is a place to put a (mobile cellular ) SIM card. And then this GSM module can send SMS text messages to different phone numbers. ...
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63 views

Send data over server from microcontroller

How large chunk data of data is send over internet using GSM module or ESP from some kind of microcontroller. As they both have a limit of data sent by TCP so how is it done and what is used to ...
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GSM vs TV broadcating

Is it true that GSM signal's field strength in the atmosphere is dependent on the current number of users whereas for TV and FM broadcating the field strength is usually constant, independent of the ...
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83 views

How to preserve signal power in a splitter?

I have a double Yagi antenna setup that I used successfully in the past, with both antenna connected directly to a 4G mobile broadband WiFi router, achieving 50-80 Mbps. The antenna have different ...
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289 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. ...
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82 views

How to put Sim808 and a microcontroller on the same PCB?

I'm families with Arduino (Nano and mini) and GSM modules and I've recently Learn about Altium Designer and I've designed (and ordered) a few simple PCBs and I've learned about Micro controller and ...
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637 views

SIM800L CREG AT command returns 0,2 when no SIM and 0,0 when SIM is inserted

I have an SIM800L module. It is connected up in the same way as this website shows,( i.e 10K resistor from Rx to Arduino data-pin and 20K resistor from Rx to ground.) Only difference is I'm using an ...
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317 views

SIM868 powers down after few seconds

I designed a circuit with SIM868 module, and i followed the recommendation from datasheet to unsure suffusion current. The main power supply is getting from VCC:12V source converted to 5V by an DC-DC ...
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279 views

How to prevent noise when connecting "speaker out" of SIM800L to audio mixer?

Aim I'm trying to build a device to be used for call center agents. They could make calls via this device, which could be connected to a PC to be able to record this conversation. Solution Build ...
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64 views

GSM DCE to TCP - mocking a GSM modem

I'm trying to interface a device (Opentherm thermostat) that actually supports to be controlled through SMS via a serial connection to a GSM modem. I'd like however to control it through TCP rather ...
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99 views

SIM800L Auto Connect..!

I want to know does the SIM800L module connect to the network automatically without any user commands? Because some modules will disconnect in low signal areas & some SIMs will be disconnected by ...
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1answer
83 views

How to wire up GSM modem (DCE) with MAX485

I am trying to figure out how to directly connect a GSM modem (say SIM800) with a MAX485. The purpose of this is to make an RS485 GSM modem. I am struggling how to wire it up, do I wire the CTS of the ...
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67 views

GSM Module + RS485 transceiver possible?

I was wondering if someone could confirm if it is feasible to interface a GSM module for example SIM900, SIM900, Quectel's M95 or Neoway's N10 , maybe if we use the RS232 interface with HW the flow ...
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117 views

How to control microphone-speaker connection between two SIM800Ls with a GPIO terminal?

There is a device consisting of two SimCom SIM800L quad-band GSM/GPRS modules and controlled by an MCU, presumably ESP8266. The idea is to let the first SIM800L call one person, the second SIM800L ...
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1k views

SIM800 doesn't give GSM location

I have problem to get exact GSM location using SIM800L. I have followed instructions in the manual. But my module just gived me latitude = 0 and longitude = 0. This is what I do with my serial ...
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48 views

Can I directly connect microphone to speaker of two SIM800Ls

There are two SimCom SIM800L quad-band GSM/GPRS modules. I would like to make some kind of call relay, such that SIM #1 accepts incoming call, then SIM #2 executes outgoing call, and once both ...
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130 views

GSM Antenna - SIM800L

I want a 90 degree rotate antenna for my SIM800L module.I couldn't find one so I hooked up a wifi antenna & it worked nicely.Does it matter for reliability? Does it match with my sim800L module? ...
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45 views

GSM SIM900 isn't communicating with the Arduino

When I connect my GSM SIM900 module to the Arduino and insert a SIM card, the Netlight and Status light blink for few seconds and then it stops. I am using 5V 1A to power the GSM and pins D7 and D8 ...
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528 views

What's this noise?

As in other years at precisely this time I'm experiencing an effect somewhat like GSM frame-rate audio breakthrough in my auditory systems - completely different frequencies but equally wideband. I've ...
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316 views

Can smaller trace width limit the current flowing through the PCB?

I am a computer science student and I am a newbie in electronics. I have designed a PCB for SIM800L, and I forgot to change the trace width of the copper rails. By default, the routing width was set ...

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