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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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Real World Range of C-Band (3.7Ghz) versus EBS/BRS (2.5Ghz) mid-band 5G

I am aware that with all things being equal, lower frequencies propagate better. Thus, T-Mobile’s 2.5Ghz spectrum should have better range than AT&T’s and Verizon’s 3.7Ghz spectrum. T-Mobile ...
Jeremy Lund's user avatar
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Setting MQTT subscriber sleep intervals via periodic broadcasting

I have a system that consists of several field units which periodically (every 10 minutes) wake up and publish data to a MQTT topic. I am hosting the MQTT broker myself on a Linux server. I would like ...
Microcontroller Enjoyer's user avatar
7 votes
1 answer
504 views

5G and Radar Altimeter Interference - Am I Taking Crazy Pills?

I can't understand where the math supports the concept of 5G frequencies interfering with aircraft altimeters. Can anyone point out the holes in my logic or educate me? Knowns: Aircraft altimeter ...
1337_Pawn's user avatar
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Is it POSSIBLE for a wireless device to use the cellular frequencies without approval from the FCC

My question is purely hypothetical and does NOT apply to any real life scenarios. Is it possible for a wireless device to use the cellular quad band successfully without FCC approval or knowledge.
David J's user avatar
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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 ...
EarthLord's user avatar
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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? ...
Iresh Dissanayaka's user avatar
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0 answers
68 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 ...
Gary's user avatar
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2 votes
1 answer
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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 ...
Trevin Corkery's user avatar
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81 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 ...
James M. Lay's user avatar
0 votes
1 answer
433 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 ...
user37872's user avatar
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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 ...
Aditya Saini's user avatar
2 votes
2 answers
591 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 ...
Todd Messenger's user avatar
2 votes
1 answer
837 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 ...
Prashanth Kumar G N's user avatar
3 votes
2 answers
991 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 ...
foo's user avatar
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1 vote
2 answers
179 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 ...
user16307's user avatar
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1 vote
2 answers
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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. ...
user2676271's user avatar
0 votes
2 answers
377 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 ...
Dzmitry Sankouski's user avatar
0 votes
2 answers
46 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 ...
Eric's user avatar
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2 votes
1 answer
707 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 ...
Ben N.'s user avatar
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2 answers
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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 ...
bob bob's user avatar
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1 vote
1 answer
234 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 ...
DurandA's user avatar
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0 votes
1 answer
133 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 ...
Kinka-Byo's user avatar
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0 votes
2 answers
50 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 ...
hawk's user avatar
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1 answer
63 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 ...
sadhna's user avatar
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1 vote
2 answers
378 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 ...
sadhna's user avatar
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3 votes
0 answers
81 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 ...
Ace's user avatar
  • 143
1 vote
2 answers
69 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 ...
andrey's user avatar
  • 504
0 votes
2 answers
70 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 ...
Maryam Magdy's user avatar
0 votes
2 answers
83 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, ...
Maryam Magdy's user avatar
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0 answers
68 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 ...
Joren Vaes's user avatar
  • 12.6k
2 votes
1 answer
1k 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 ...
wanderer's user avatar
  • 155
-1 votes
3 answers
281 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: ...
ObsessionWithElectricity's user avatar
0 votes
1 answer
40 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 ...
Ethan Anderson's user avatar
-2 votes
1 answer
292 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 ...
user3862410's user avatar
3 votes
2 answers
722 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 ...
abhiarora's user avatar
  • 962
5 votes
1 answer
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 "...
skot9000's user avatar
  • 113
1 vote
1 answer
366 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? ...
SJa's user avatar
  • 125
0 votes
1 answer
3k views

SIM900A no carrier issue

I'm using a SIM900A mini v3.8.2 GSM/GPRS board to make a phone call on certain conditions. I have connected the module through a CH340 USB to TTL converter to a PC (Windows 10) for testing. All ...
Tehseen's user avatar
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0 votes
0 answers
27 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 ...
Teodorism's user avatar
  • 123
0 votes
2 answers
216 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 ...
macdonaldtomw's user avatar
0 votes
2 answers
446 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 ...
skot9000's user avatar
  • 113
0 votes
2 answers
78 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 ...
user541686's user avatar
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5 votes
1 answer
528 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 ...
arduinofanboy's user avatar
1 vote
0 answers
198 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 ...
Michael Santiago's user avatar
13 votes
6 answers
4k 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 ...
macdonaldtomw's user avatar