Using other than a wired connection to transfer signals or power. Includes optical and (ultra)sound, but most often refers to RF (radio-frequent). Distances can be as low as centimeters (e.g. RFID), there's no upper limit.

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-4
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0answers
24 views

Best wireless mesh technology with great indoor range for sensors project? [on hold]

I'm working on a project that will have many different sensors in complex of few building, I would like to cover whole place with sensors. Idea is to document it and give out our solution in fully ...
-2
votes
0answers
39 views

DIY wireless image or video transfer [on hold]

I would like to start a DIY project for wirelessly transmitting a image or video to my raspberry pi. To start with i would like to take image using cheap camera module with I2C or some other interface ...
0
votes
1answer
36 views

Radio direction finding - dependence on source signal type

I want to make a robot that can track the direction of the transmitter that is controlling it, for example to aim a camera at the transmitter. The robot vehicle will be controlled by a 2.4ghz ...
1
vote
0answers
63 views

Wireless Mesh Sensor network comparisons [closed]

From your past experiences (don't need a whitepaper): Could you guys compare Zigbee, Z-Wave and 6LowPan? Please also include information about compatibility with regular internet protocols. I think ...
0
votes
2answers
105 views

Long range Arduino communication

The project must be able to detect the amount of water in tanks and transmit the information to a farm house it must be wireless and unfortunately there is no cell phone reception in the places that ...
23
votes
5answers
4k views

Why 2.4 GHz Band?

Bluetooth, WiFi, Zigbee, Remote Controls, Alarms, Cordless Phones etc.. Why all of these protocols, devices, etc. use 2.4 GHz band instead of 3.14 GHz. What is so special about it?
1
vote
0answers
74 views

Insufficient Power when using one power source vs two [duplicate]

So I've been working on a wireless remote relay switch using several components and have struck a break wall. The issue I'm having is that the D0 siginal output triggers the relay but only at short ...
0
votes
1answer
35 views

Distance confusion about Shuncom SZ05-ADV ZigBee module

I ordered this module looking at the datasheet that it has a range of 2000m LOS distance. But now when I test it, I can receive signal from a maximum of 50m distance! It sends 2.4GHz signals. As far I ...
0
votes
0answers
24 views

What wireless sensor network should I choose which can be customized with respect to hardware?

I am looking for a WSN OS which can accommodate approx 100 sensor nodes. I had looked at various available WSN OS like TinyOS (source code is available at GitHub) and Contiki and others but they all ...
6
votes
6answers
235 views
+200

Measuring direction of object (or angle of signal origin)

I am interested in somehow tracking the "compass" direction of a moving object from a reference-station -- in other words, something similar to submarine sonar systems (although I'm unsure how those ...
0
votes
3answers
59 views

Synchronized pulse generation from wirelessly connected boards

I want two or more boards (less than 10m range) to generate a LED blink at same time, within 1 ms difference, using wireless communication. First, due to power consumption, I am thinking to use ...
1
vote
4answers
54 views

GPS Antenna Selector: How to electronically select one antenna from multiple available antennas?

I want to connect multiple GPS antennas to a single GPS module and select one of them based on some logic. Basically, I want the module to receive signals from only the selected antenna. Is there an ...
0
votes
1answer
114 views

SC2272-M4 Behaviour when using relay SRD-05VDC-SL-C 5V DC

I'm currently encountering a problem when using a relay switch with a 5v receiver. When using the same receiver with a row of LEDS it works flawlessly. I've noticed that the relay keeps making the ...
0
votes
1answer
22 views

Could transmit/receive turnaround be improved by having a heterodyne receiver switchable between high-side and low-side injection

In some of the small radios I've worked with such as the Nordic Semiconductor 24LE line, there is a significant (100us+) delay between transmitting data and being able to receive a response. By my ...
0
votes
1answer
69 views

Why RTS/CTS do not solve completely the hidden terminal problem and exposed terminal problem?

I was doing some reading online and textbooks about the RTS/CTS protocol for wireless transmission. Although, the textbook that I read said that the hidden terminal (and exposed terminal) is solved by ...
2
votes
3answers
38 views

What is Doppler Spread

What is the plain English explanation of the Doppler Spread? Looking at different sources I come across complicated definitions which I struggle to understand. Example for such one: Doppler ...
0
votes
0answers
11 views

How do Coherence Time and Coherence Bandwidth influence the decision on the diversity scheme?

I came across a statement in a lecture slide which states: Coherence Bandwidth and Coherence Time govern our decisions about the diversity scheme that we would choose The lecture is in the field ...
1
vote
1answer
58 views

Controlling various Arduinos with Android

I have an upcoming project which requires me to use about 8 different Arduinos, probably more. They all perform a light show which turns off and on various LEDs at different timings to simulate a ...
1
vote
1answer
79 views

Antenna Diversity: two Yagi antennas to the Rx and Rx/Tx u.fl-male points on the wifi-NIC?

I looked at the BCM4312 file - available as as doc or a pdf - and it says: BCM4312 has 2 radio chains, one is a dedicated Rx chain, the other is shared by TX and > RX chain using an RF switch ...
0
votes
1answer
37 views

Remote Wireless 4CH Switch On/Off - Data PIN Network Cable

Planning Stage I'm in the planning stages of making a wireless on/off switch that will basically cut off pin 6 on a network cable. I know little about electronics and I've attempted to learn as much ...
0
votes
0answers
56 views

Why is it that using RTS/CTS in 802.11 improves its throughput?

There is a famous paper which has shown that using the RTS/CTS scheme for medium access improves the throughput of a 802.11 system compared to a classical medium access scheme. The paper: ...
2
votes
2answers
54 views

What makes DSSS a more robust transmission technique compared to FHSS?

In many textbooks it is stated that DSSS is more robust than FHSS. Especially in terms of interference and delay spread? What is the exact reason. Lets say we multiply a given bit 1 with a larger bit ...
0
votes
3answers
120 views

Is it possible to measure the distance of a WiFi access point from the receiver?

I have signal strength in dBm and frequency in MHz is is possible to find the distance?? Any idea about how to do it?
0
votes
1answer
59 views

Plain English explanation of the Space-time Code Block by Alamouti

I checked about the Space-time code block online, but all of the explanations are either short or too simple, or too mathematical and complex Could anyone here provide an explanation of what ...
1
vote
1answer
71 views

How to transmit CAN signals wirelessly without line of sight (LOS)

I have a scenario where I have an OBD-II interface transmitting data via CAN across six wires to a display. I will have power on either side of the wires, but I cannot assume that the wires will have ...
0
votes
2answers
41 views

How are the Intersymbol Interference and Symbol Time (duration) related to each other?

In a lecture slide I noticed that OFDM(Orthogonal frequency-division multiplexing) mitigates the problem of Intersymbol Intereference over wireless systems because the symbol time is increased, in ...
2
votes
1answer
35 views

Upload XBee firmware without a PC and XCTU

So, as the title suggests, I would like to know if there is a way of uploading a firmware to a XBee module, throug the serial without a PC. What I mean is, I have a microcontroller, I would have the ...
1
vote
3answers
47 views

Using Bluetooth 4.0/LE verses RF

I am asking this question in hopes to get a solid answer from anyone who has direct experience dealing with the most recent RF as well as Bluetooth 4.0/LE developments. What I am essentially trying ...
0
votes
2answers
35 views

the response of wireless channel to an input

I am reading the wireless of David Tse. In the 2nd chapter of this book there is a discussion about the response of the channel due to an input. It has said that since the channel is linear its output ...
2
votes
2answers
61 views

What phenomena does “Coherence Bandwidth”?

Could anyone please provide a simple explanation of what Coherence Bandwidth means, and how is that related to Delay Spread. I read some articles but they don't help me to form the relation between ...
1
vote
2answers
84 views

Explain Rayleigh Fading in plain English

For a couple of days I am trying to understand the Rayleigh Fading model, but I am failing to. I look at various articles and tutorials online, everything goes fine up to a points, but then a lot of ...
1
vote
2answers
79 views

Why one transistor switches on first than other

In the circuit diagram given below we have two transistors. And in the article it is given that one transistor will turn on first. Why this transistor turns on first
1
vote
1answer
91 views

Could anyone explain the two-ray ground-reflection model in plain English

I am studying about wireless communications and I need to understand the two-ray ground-reflection model for one of my assignments. However, I fail to understand it. Could anyone provide a ...
0
votes
1answer
99 views

Protecting a wireless router from voltage fluctuation

Background: I have a wireless router ASUS DSL_N12U. Input voltage and current is 12V , 1.5A respectively. I also have an Inverter (works on three modes: Solar, Battery, Mains) at my home. Problem: ...
0
votes
1answer
56 views

Coordinator + Repeater Xbee + End device configuration

I am trying to work on a Xbee based solution for transferring data from with in a specified area.I am using Xbee865LP for the same project. Now what i want to implement is Make one device act as ...
0
votes
2answers
85 views

Why is IR Transceiver transmitting/receiving rubbish?

I am trying to interface two microcontrollers wirelessly using IR transceivers. The microcontroller I'm using is ATMega164PA running on a 3.3V supply at 8MHz and the transceiver is TFDU4101-TR3. I am ...
2
votes
1answer
55 views

Wireless telecom system (cellular with Erlang and spectral efficiency)

We have a spectrum of 20MHz that we will use on a wireless cellular system, which requires 50kHz per channel. The system is using cluster size K = 4 and the radius of every cell is R = 1 km. a) ...
2
votes
3answers
96 views

Wireless EEG electrode design

Currently, all 'wireless' EEG systems acquire signals from electrodes which are wired to an amplifier, a filter, a digitizer and then finally a wireless module. I want to design a system that's ...
1
vote
1answer
80 views

How to make a simple Video Switch?

I thought making this would be simple, but I've found it a lot harder than I anticipated! What I mean is that I have one screen/monitor, and two video players (all video is through RGB component, RCA ...
2
votes
1answer
75 views

Why does frequency splitting happen when two resonant circuits are magnetically coupled in wireless power transfer?

When two circuits are tuned to a self resonant frequency and are then magnetically coupled, the resonance happens at multiple frequencies if they are near. How and why does this happen?
1
vote
1answer
131 views

What is the 'best' way of communicating with small microcontrollers/devices?

var best = "simple & cheap"; I have a server in my apartment that I have an XBEE hooked up to. I use it to communicate with another XBEE plugged into an Arduino. I am trying to hook up many ...
0
votes
5answers
158 views

Best choice for low-power, short-range wireless communication

I'm working on a project which relies on wireless communication, and I'm looking for the best alternative. These are the design requirements: Is easy to interface with Arduino Works over a small ...
0
votes
2answers
51 views

How does Signal-Noise-Ratio related to receiver power

If I have the instaneous Signal-Noise-Ratio (of the receiver), but no other information, and I am interested in the instaneous \$\mathbf{Power_{received}}\$, is there any relationship between these ...
0
votes
2answers
53 views

QAM's performace and SN

1) QAM's signal formula is $$s(t) = I(t)sin(2\pi f t) + Q(t)cos(2\pi f t)$$ The I axis and Q axis are orthogonal to each other, but its angle is 45 degrees, or 30 degrees. At how many degrees does ...
2
votes
1answer
79 views

What kind of solar panel is required to keep a mobile alive forever?

I want to build a webcam from an old mobile and I want it to be solar powered. The phone use a 3.7V lithium-ion battery of 1500mAh capacity. The phone last 24h hours on one charge. So if I'm right, ...
0
votes
2answers
81 views

Could some one explain me technically as to why the bandwidth is severly limited in underwater channel for communications?

I understand that, due to the harsh characteristics of the underwater channel, the effective bandwidth for communication underwater (using acoustics) is severely limited. But i would like to know the ...
1
vote
1answer
117 views

How to calculate the shannons channel capacity and the bandwidth, for a desired BER and EbNo value?

I understand that, for BFSK modulation scheme, to achieve BER of \$10^{-5}\$, the required Eb/No is 12 dB, and this is theoretical value of the required Eb/No predicted from the graph below: ...
2
votes
0answers
30 views

How to implement selective automatic repeat request (ARQ) frame retransmission concept in simulink after detecting frame errors using CRC-4?

I have modelled an acoustic modem in simulink, i have used the CRC-4 (STD-ITU) scheme to protect the data for transmission, On the receiver end, the CRC decoder detects the errors in the received ...
0
votes
1answer
105 views

Build simple wireless door (open/close) sensor with Arduino or Attiny84/87

I have a spare Arduino uno, a few Attiny84 and a few Attiny87. In my Raspberry PI I have installed a RFM12Pi and have a spare RFM12b to use with Arduino. Last piece I have in the drawer is a sonic ...
4
votes
5answers
290 views

Object detection using sensors and then reporting the location

I am trying to prototype a sensor + location reporting chip that will do the following: Sense if a object is present over the top of it (a vehicle to be specific) Reporting the location of the chip ...