10 votes
Accepted

Protecting device from microwaves in microwave oven.. but allowing Bluetooth?

Your best option for wireless communication in this situation is some kind of optical link. Consumer microwaves typically operate at a frequency of 2.45 GHz and Bluetooth operates from 2.4 GHz to 2....
10 votes
Accepted

Is interference between aircraft an issue for fly-by-wireless technology?

Cross-interference between aircraft is a high unlikely event because all commercial aircraft designs have to pass DO-160 environmental testing requirements. Among the DO-160 testing specification is ...
9 votes

Is interference between aircraft an issue for fly-by-wireless technology?

To add to what Russell said, it would take a very stupidly designed protocol to allow the comands from one aircraft to control the other, even assuming that cross-reception is good. As a everyday ...
  • 11.3k
8 votes

Is interference between aircraft an issue for fly-by-wireless technology?

Modern communications systems are able to achieve essentially any desired data rate and degree of message integrity in any well-enough-defined environment. It's "just a matter" of the degree of effort,...
7 votes

Protecting device from microwaves in microwave oven.. but allowing Bluetooth?

With regard to protecting active electronics inside the oven, you have the choice of either absorbing the microwaves (e.g., water jacket) or reflecting the microwaves (any high-conductivity metal). ...
  • 6,759
7 votes
Accepted

What are the pros and cons of between Zigbee and Z-Wave communication protocols used in IoT device space?

I will leave the main part of the previous answer below, as it contains more information about the differences between several radio protocols. As for the differences between Zigbee 3.0 and Z-Wave, ...
  • 631
7 votes
Accepted

How were the tones for DTMF chosen?

From: Engineers Garage Dual Tone Multi-Frequency: $f_1$ = 697Hz, 770Hz, 852Hz, 941Hz. $f_2$ = 1209Hz, 1336Hz, 1477Hz, 1633Hz. A key press on a DTMF keypad means a combination of $f_1$ and $f_2$ (...
6 votes
Accepted

Why do bluetooth headsets get interference (choppy sound quality) outdoors?

As you might have already realized there is a good reason that some of Bluetooth headset are inexpensive. Poor design. High quality, well designed Bluetooth headset tend to be expensive. Also not all ...
6 votes

Would not a telephone call (from the late 1950s) auto-disconnect if one of the parties "closes the handle"?

If you could truly indefinitely keep a line open for anyone who calls you, by simply not hanging up on your end, the potential for abuse is endless. That's the way the POTS (plain old telephone ...
  • 8,823
5 votes

Is interference between aircraft an issue for fly-by-wireless technology?

No, crossed communications would be a total non-issue. Think of it like a home wireless network. All your devices at home can talk to each other on your WiFi network, and the same is true for your ...
  • 5,960
4 votes
Accepted

Will the water in a gold fish bowl signficantly abosorb Bluetooth or WiFi if transciever is at bottom of bowl?

There is information out there, but probably the best way to find out is to actually try it. Grab a small Bluetooth or Wifi device and seal it in a waterproof enclosure or bag, and submerge it to the ...
4 votes

What is the difference between Bluetooth Low Energy and Bluetooth BR/EDR in Park mode?

There are many factors that make BLE low power, and I have attempted to address as many of them as possible. In order to better understand the power consumption differences between Bluetooth classic ...
4 votes
Accepted

How can I make a GPS traceable microchip?

Firstly you seem to be under the common misunderstanding that the GPS satellites somehow calculate where a GPS receiver is. They don't. The satellites are transmit only systems (ignoring the command ...
  • 766
4 votes

Why is WiFi increasing frequency?

why not scrap all the obsolete bands and reassign the 1 GHz - 6 GHz range to WiFi? First of all, these bands are not obsolete, there are many uses that might seem outdated, but won't go away easily. ...
  • 141
4 votes

Why radio communication was limited to military use and did not become popular with general public like cell phones have become today?

The radio spectrum is limited. There are is only a finite range of frequencies over which we can transmit so you if have two people communicate by directly transmitting to each other over two ...
  • 3,520
4 votes
Accepted

Does anybody know what this symbol is?

This symbol means that the contact number you have called was connected via Voice over WiFi (VoWiFi) technology instead of VoLTE. Your service automatically shifts to VoWiFi whenever there is a WiFi ...
4 votes

What are the differences between a standing wave ratio meter and a frequency counter?

The frequency of an electromagnetic wave (or any other wave form) is the number of times that the wave reaches the maximum over a specific period of time. This is common when referring to radio ...
  • 6,427
3 votes
Accepted

Why only the spectrum range of radio waves can be reflected from atmospheric layers while higher ranges (Infrared-Visible Light-Ultraviolet) can't?

Different materials reflect, absorb, and scatter different wavelengths of light. The ionized layer at the edge of earth's atmosphere happens to reflect a certain range of wavelength while ...
  • 11.3k
3 votes

signal-to-interference-plus-noise ratio (SINR) and others calculation

First, you should link in a reference to the Hata and Ericsson models. I haven't heard of them, and a quick search on Google didn't give anything. Path loss and received signal strength are typically ...
3 votes
Accepted

Why does the LTE Specification define SC-FDMA as the modulation scheme for the reverse link?

SC-FDMA is encoded and transmitted from the handset where there are power tradeoffs. This encoding is better than OFDMA for the handset for the following related reasons: Reduces peak to average ...
  • 1,106
3 votes

How is it possible that an *undertaker* invented the automatic telephone exchange? And as early as in 1888?

You may be misunderstanding what "undertakers" actually did in this time period. Even in the 1950s in the UK when I was growing up, in rural areas the local undertaker not only did the carpentry and ...
  • 12.5k
3 votes

With the "plain old telephone system", would two neighbors be able to call each other privately?

Joe and Sue's calls would go to their exchange where the lines were terminated on an automatic exchange. There is (generally) no electronics between their wall socket and the exchange circuits so ...
  • 8,823
3 votes

Rotary Phones vs Pushbutton -- why did we ever have rotary?

The reason is simple - the timing in the evaluation of technology. The required technology to make touchtone signal possible, Dual-tone multi-frequency signaling (DTMF), wasn't developed/introduced by ...
  • 7,696
2 votes

Protecting device from microwaves in microwave oven.. but allowing Bluetooth?

Is there a way to have this device communicate with another device outside of the microwave oven without the microwaves interfering with it? Not with most local wireless communication protocols ...
2 votes
Accepted

Why is Li-Fi faster than regular wifi?

The wave propagation speed is only relevant when you start approaching the theoretical limit of that type of wave's ability to transmit information. For an analogy, consider people having a ...
  • 3,211
2 votes

What is the thinnest possible depth of any given material required to display an image?

Let's assume that you are using OLEDs (organic light emitting diodes) which can emit a photon when charged with an electron. You could build a single molecule pixel (just nip down to the corner store ...
  • 206
2 votes
Accepted

What kind of signal is the signum function? A power signal or an energy signal?

First point is that signum is not continuous with the jump at $t=0$. Second because of the absolute value in the integral it has the same $E$ and $P$ as a constant signal $1$. This means that $E_{...
2 votes

A 40MHz oscillator in usb wifi adapter

Generally when you need to scale up a clock you use a PLL (Phase lock loop). A very crude explanation is that you have a voltage controlled oscillator at roughly the required frequency. You divide ...
  • 766
2 votes

Tethered Balloons vs Towers for Wireless Communication

They would be a great hazard to air traffic; The umbilical would be essentially invisible to passing aircraft. In spite of regulations not to fly here or there.
  • 5,952

Only top scored, non community-wiki answers of a minimum length are eligible