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 ...
- 7,145
6
votes
How are three satellites sufficient to find a unique point in GPS? What happens in case of an overlap?
You can't ignore the difference between 2D and 3D in this situation. To a first approximation, all GPS satellites are located on the surface of a sphere. There is no way that any three points on a ...
- 6,984
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 ...
- 7,145
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
How can I find the emission power of a WiFi mobile phone antenna?
Typically, the max is 100mW (20dBm). You can refer to an example wifi chip datasheet (This one is used in many mobile phones with Snapdragon processor) -
https://developer.qualcomm.com/download/sd410/...
3
votes
Accepted
Wireless communication modules transmitting through body
The reason you can't find many modules around 100 MHz is that it's not an open frequency and you generally need a permit to transmit at those frequencies.
Another reason is that you will face some ...
- 331
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 ...
- 11.5k
3
votes
How can I find the emission power of a WiFi mobile phone antenna?
There is a list of some widely used devices and their transmit power (and many other properties) in an easily digestible table: https://clients.mikealbano.com/
The most smartphones seem to be just ...
- 131
3
votes
How are three satellites sufficient to find a unique point in GPS? What happens in case of an overlap?
how are three satellites sufficient to find a unique point in gps?
They are not. It takes four satellites minimum.
GPS needs to solve for the point in four dimensions, X, Y, Z and time. Four ...
- 11.5k
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
Accepted
Why GPS receivers are more sensitive than GSM or WiFi receivers?
There are a few factors at play.
Firstly as Olin indicated the signal bandwidth and data rates are different.
It is a fundamental rule of information theory that the maximum amount of data you can ...
- 766
2
votes
Most practical way to wirelessly transmit a single bit of information?
To be totally honest there is really only one technology you should be looking for.
Infrared, all you need is a light transistor and a infrared led, thats it. Cheap as hell, well known, and robust ...
- 3,684
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.
- 6,182
2
votes
Accepted
Can wider range (i.e. 600-700 MHz) antenna replace lower range (650-700 MHz) antenna?
The operational frequency operational range of the proposed antenna is within the frequency range of the old antenna. It should not be an issue from frequency standpoint. If the gains are similar ...
- 7,145
2
votes
Bandwidth vs Capacity
Your understanding is correct. Here is an alternate definition from Wikipedia - Bandwidth
Bandwidth is the difference between the upper and lower frequencies in a continuous band of frequencies. ...
- 7,145
2
votes
Why do we always use 3.8 x 10^(-3) value as Forward Error Correction (FEC) threshold?
I found this.
Which states:
For example, for 7% overhead HD-FEC with a NCG
of 9.19 dB at a corrected BER of 10−15, the pre-FEC BER should be lower than $3.8 × 10^{−3}$ [4],
which is regarded as ‘...
- 5,629
1
vote
Do they sell some sort of non-"consumery" GPS trackers?
The issue is not GPS. The issue at hand is how to get the device to communicate with YOU. What that generally means is connection to either cell networks and all the costs that entails, or a private ...
- 7,148
1
vote
Was our wireless home telephone in the 1990s encrypted or completely insecure? And how did it work so far from home?
1 & 3: I imagine it had some sort of short-wave radio capability, much like a walkie talkie. This would communicate to your "base" and transmit the rest of the call over the phone line for non-...
- 2,357
1
vote
Small wireless proximity device to alert me when my cat gets into my WiFi range
If your objective is only to determine device in range, and you've located a suitable wireless camera to meet your size requirements, such a device could be used without privacy concerns if you ...
- 7,307
1
vote
How can a Wi-Fi access point be visible from one device but not from another?
Based on the post here are few things to look for and some publicly available open source tools.
First you might want to check the operating frequency, 2.4 GHz, 5GHz or both.
When you are setting ...
- 7,145
1
vote
Accepted
Most practical way to wirelessly transmit a single bit of information?
Few of the technologies that fit well are Bluetooth Low Energy and Thread. Both of them operate in the 2.4 GHZ ISM band. Also you might want take a look at Zigbee. These all offer basic level of ...
- 7,145
1
vote
Accepted
Why does India have more than 1 MCC (Mobile Country Code)?
The Mobile Network Code (MNC) is either a two digit ("European" standard) or three digit ("North American" standard) identifier, with in the Mobile Country Code (MCC).
According to https://en....
- 12.6k
1
vote
How to decode radio thermometer / hygrometer bytes to floats?
This is not a full answer but I can't comment yet due to too less reputation, sorry.
I+J seems to have a strong correlation with the temperature. I did a scatter plot of I+J vs. Temp and I can see at ...
- 163
1
vote
Accepted
What criteria to focus on when selecting a BLE module?
Looking at if the device supports BLE 4.0, 4.1, 4.2 or 5.0 is a good start. Not all BLE modules are 5.0 capable. What type is distance range might be a parameter to consider some BLE module have line ...
- 7,145
1
vote
dB/s/Hz in spectrum efficiency
As with any physical equation, the units of a constant, in this case "spectrum efficiency," are chosen so that the final result is in the units desired. So, if you're going for an answer in dB, then ...
- 4,259
1
vote
Making my microcontroller transmit audio to any bluetooth headphones/speakers
There are Bluetooth adapters available which will hook into audio system via 3mm jack or optical jack and broadcast the music to your headset.
However if you want to receive the music into your phone,...
- 22.8k
1
vote
Accepted
Can you detect the operation of a wireless radio (or other wavelength) receiver?
many radio receivers contain a circuit called an IF oscillator. the output of this oscillator is added to the radio frequency signal that the radio is receiving to downconvert the incoming high ...
- 15.3k
1
vote
How can I make a GPS traceable microchip?
I second Pisda's point, but lets get hypothetical here:
RFID and related chip technology already uses a chip that is powered by the radio signal send to it. So in 'theory' you could use that to ...
- 11
1
vote
Accepted
Why don't cellphones use unidirectional antennas?
This is called beamforming, which exists in the 802.11 wireless standard.
Matthew S. Gast, 802.11ac: A Survival Guide, glossary:
Beamforming
A method of using precise phase shifts on an antenna array ...
- 387
Only top scored, non community-wiki answers of a minimum length are eligible