Questions tagged [cellular]

Cellular systems are wireless communication systems. Examples are 2G systems like GSM, 3G systems like UMTS and cdma2000, and more recently, LTE and 5G.

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110 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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0answers
32 views

4G Cellular Antenna

I have a Huawei E3372H-153 USB 4G dongle. It has two external antenna ports. What I want to know is that how can I make the full use of those two antenna ports to get the best 4G reception possible? ...
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60 views

Cell tower measurment reading [duplicate]

I made some measurements near few cell towers and i have noticed that i get 2 values that is changing every few seconds. For example i get a reading of 20uW/cm2 for few seconds and after that the ...
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74 views

Time scale comparison between fast-fading and path-loss in wireless communications channels

As I know, when receiving mobile users move, the fast-fading channels between transmitter and receivers may vary very quickly as wavelengths change, e.g., every 2.5 ms. On the other hand, when we ...
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1answer
298 views

SIM7600A gives an error when executing commands, but works after executing it again

I am currently using a WaveShare cellular modem hat for my Raspberry Pi. The module has an onboard SIM7600A. I've been reading the documentation and although all the commands work as they are ...
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79 views

Help identifying mysterious communications tower

There's a tower near my house that I thought was a cell tower, but I noticed it's not registered on the FCC map. Can anyone help me ID what type of tower this might be? I was thinking it was a ...
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1answer
109 views

Getting 4G/LTE signal through sheet metal - opening/aperture size needed?

We have a storage area, that is surrounded by corrugated sheet metal. (Appears to be galvanised steel, and probably 2-3mm thick). Inside the sheet metal, we have a LTE/4G router, on the Telstra ...
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1answer
368 views

What is the difference between capacity and throughput in context of wireless/cellular communication?

From what I understand: Throughput tells you how much data was actually transferred from a source at any given time Bandwidth tells you how much data could theoretically be transferred from a source ...
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2answers
252 views

Why do baseband processors remain on, and communicating with the tower, when the phone is shut down?

I've believed this since 1994 - that if you really want to turn off a cell phone, you need to take the battery out. But why? What is a good technical reason to keep spending battery charge and ...
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1answer
445 views

Cellular module(4G/3G/GSM) interface to host processor or microcontroller through UART how the data rate is achieved?

The majority of cellular modules are interfaced to host microcontrollers or microprocessors using UART interface or some times USB interface (where internally it's UART). But the data rate of UART is ...
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2answers
211 views

What are the units used in Shannon formula calculation?

I'm a CompSci student with absolutely no background in wireless communication who recently needs to do something with the Shannon formula: $$ R = W log_2\bigg(1+\frac{P_t H^2}{N_0 W}\bigg) $$ I need ...
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2answers
121 views

Why is FM modulation not used in modern cellular communication?

Both bluetooth and celular links use GHz level carrier waves. Yet the modulation techniques are very different. I know why FM is more resilient to noise comparing to AM. But why is FM preferred for ...
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1answer
82 views

Does using an antenna extension cable violate FCC cert?

I have a question about FCC part 15 certs. Using the Particle Cellular B series SoM, they have a "Grant of equipment authorization" to use the module as an end device. Link to the module docs below. ...
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2answers
43 views

Can I use outdoor directional antenna for cellular network indoors

There are some pretty cellular Yagi-Uda antennas in the market, but absolute majority of it is outdoor type. Given I have directional antenna with higher gain than omnidirectional antenna X, and I ...
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2answers
38 views

Where do we use arithmetic multipliers in 5G technology?

I have recently learned about arithmetic multiplication and the various types of multipliers used in digital circuit design. Now, having an interest in cellular technology, I am curious about the ...
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1answer
204 views

Accidentally connected a GPS antenna to a cellular connector and a cellular antenna to a GPS port. What can go wrong? [closed]

I have two ultra small/sub-miniature coaxial connectors on my circuit board - one for a cellular (4G) antenna and one for a GPS antenna. I accidentally connected the cellular antenna to the GPS ...
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2answers
75 views

IoT Certification Legality

I am developing an IoT product for a company. The product runs off of two alkaline batteries at a max of 3.2V. It is fully enclosed in a solid plastic case, with small panel openings for a switch and ...
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1answer
130 views

Is NB-IoT roaming possible?

I found a comment on a blog post stating that NB-IoT doesn't support roaming: nbiot do not support roaming (you must have sim from the operator that have the infrastructure). nbiot also lacks support ...
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1answer
69 views

Shannon - Hartley Theorem

Let's consider the Shannon - Hartley formula for the channel capacity \$C\$: $$C = B \log_2 (1 + S/N)$$ I have two doubts about it: 1) is it correct for TDMA, FDMA, or CDMA? And why? 2) Can a ...
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2answers
45 views

Echo in voice to the caller while receiver with headphone hving wire replace [closed]

Hi I just replaced the old wire in my headphone with new one.But while using headphone the caller hears the voices with his own echo but while me having headphone on has no issue of echo can speaks ...
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1answer
43 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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2answers
193 views

coplanar waveguide vs microstrip for gnss and cellular?

coplanar waveguide vs microstrip for gnss and cellular? I read on internet microstrip is better for signals <30Ghz but some gps manufacturer (Delorme) said that coplanar is most efficient so it's ...
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0answers
66 views

Intel Compute Stick & USB 4G Device

Id like to create a powerful IoT Edge device that has cellular capability (Wifi is undesirable). Right now the intel compute stick/neural stick almost fits the bill except that it does not have 4G ...
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2answers
62 views

Testing the RF properties of an enclosure

I need to measure RF (cellular) blocking properties of an enclosure. Is there an off-the-shelf set of tools for doing this? I'm assuming a MHz signal generator and an oscilloscope with an antenna ...
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2answers
63 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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2answers
68 views

Can I use MCU's internal oscillator when communicating with GPS and cellular modules?

Can I use MCU's internal oscillator when communicating with GPS and cellular modules? I want to avoid connecting external crystals for the MCU since they generate noise, extra components, extra costs, ...
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59 views

Cellular towers in rectangular grid

Not that far from where I live there are 6 towers that appear to be for cellular purposes in a perfect grid. You can see them in the picture I took from google maps. In the center of the road are ...
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1answer
833 views

Transmitter and Receiver antennas in mobile phones

I understand that in old cellular systems where FDD were employed, we used to have same antenna at the mobile phone (User equipment) for transmission and reception.Moreover, a duplexer was used to ...
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3answers
251 views

Does the phone transmit waves? [closed]

In a cellular connection, How much is power density (in W/m2 or mW/cm2) of the RF energy from the phone to the tower? If not possible in above units then can I know in dbm ? My phone has: Head SAR: ...
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1answer
33 views

Bridging 3G/LTE from cellphone to IOT device

I have an IOT device that needs to function as an access point, even without close by wifi signals, and then publish a wifi network. I know that I can achieve this with a 3G/LTE/GSM module but given ...
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1answer
234 views

How does cellphone idle time work?

Imagine a basic cell phone which operates in only 2G network and able to provide voice call & SMS service. Does this cell phone transmit any data to BTS in idle time (that is when the cell phone ...
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2answers
576 views

Top Ground Copper pour in PCB having three RF Sections

I am designing my second RF board (First one had BLE). This board has LoRa Components (SX1257 and SX1301), GPS (MAX-6) and 4G LTE Module (SIM7600). All the components are on top layer (red layer). My ...
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1answer
2k 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
126 views

What is the "minimum" transmit power for uplink cellular transmission

Can anyone help me in finding a good reference for minimum transmits power for uplink cellular transmission? is 0 dBm a good enough power for very low-power transmission in an indoor environment? ...
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0answers
26 views

Orientation of eNode antennas

What type of omni-directional antennas is used at an LTE base station, also known as eNode? and What is the orientation of such antennas? and how come the 3GPP path-loss model for such antennas is ...
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2answers
88 views

Force cellular modem to transmit at maximum power [duplicate]

I want to force my cellular modem to transmit at maximum power so that I can see if that is the cause of microSD card crashes that I have been experiencing in an embedded application. My modem is a ...
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2answers
372 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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2answers
70 views

Is this warning about wireless modules interfering with aircraft systems true?

I see the following warning for Sierra wireless (cellular) modems: Do not operate the Sierra Wireless modem in any aircraft, whether the aircraft is on the ground or in flight. In aircraft, the ...
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1answer
420 views

Arduino Cellular Shield EMC Testing for FCC

I have designed an Arduino shield that uses an FCC pre-certified and PTCRB cellular module and I'm wondering about EMC testing and FCC compliance. However, the main concern here is that I am using a ...
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0answers
186 views

PCB vs SMD antenna for 2G cellular IoT device

I am designing an IoT module to read water sensors in an Agricultural field, then send the data through cellular to the cloud. My design uses the SIM800H, a quad band cellular modem, to send and ...
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1answer
59 views

Can a 3G usb modem be used as a mini Cellphone Tower [closed]

I am curious to know whether small USB 3G modems could be used as cellular towers, and if you would need special firmware to do it or if it is not possible at all. They can communicate with the tower, ...
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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 ...