Questions tagged [channel]

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Confusion about basic reference distance based path loss formula in wireless communication

In the following, I am confused about results I am getting by the reference distance based pathloss formula. My transmitter power is 1 mW (i.e. -30 dB). But the received power is much much higher than ...
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1answer
25 views

In discrete memoryless channels what is meant by output probabilities?

In my book it is mentioned that P[Y]= P(X)* P(Y/X) Where P[Y] is the output probability matrix, P(X)=input probability matrix, P(Y/X)= channel matrix. I understand the physical significance of input ...
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31 views

How to model MIMO channel matrix for numerical results

I am willing to include the channel matrix in my analytical model (which only includes pathloss and antenna gains). But from what I have seen, channel matrix can't be used to produce numerical results ...
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36 views

How to transmit a packet through WiFi interface with specific data rate?

I am doing a project called 'Device free wireless sensing through WiFi'. In the literatures, researchers using PC and WiFi routers to send and receive packet, the channel state information (CSI) can ...
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1answer
29 views

About discrete time model for wireless channel

I am trying to understand Section 2.2.3 of the book "Fundementals of wireless communication" by Tse and Viswanath. In this section the authors explain how to go from the continuous time ...
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1answer
79 views

DRAM Rank-Level Allocations

I want to do allocations on a specific DRAM rank. The smallest allocation unit in an OS such as Linux is at the page size ...
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12 views

In a communications system does the order of channels is in a cascaded channel affect the overall capacity?

I'm currently looking at capacity for cascaded channels as part of my Communications Systems module and we're looking at a question in which we have four identical channels represented by the ...
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38 views

why sometimes we need to use Broadband Transmission (Using Modulation)?

I was reading a textbook which says: Baseband transmission requires that we have a low-pass channel, a channel with a bandwidth that starts from zero. This is the case if we have a dedicated medium(...
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2answers
133 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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1answer
48 views

why a channel needs to have bandwidth requirement for digital data transmission?

I'm not from EE background and try to understand how digital is sent in a channel as a non technical audience. Let's say we use fiber optics to transmit digital data 010101...., since fiber optics ...
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35 views

Summing Audio Channels

I’m trying to sum my car stereo output. Factory output has bass on one output and mid and tweeter on another output giving me 2 channels for left and 2 channels for right. Ideally I’d like to sum ...
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1answer
83 views

Channel separation on a 3.5mm audio jack

I read an article regarding the removal of the 3.5mm audio jacks on phones. It quoted this: ...
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1answer
125 views

What is the (exact) difference between CLM and DIBL in MOSFET?

I am wrapping my head around this for a bit and I understand both effects (Channel Length Modulation, Drain Induced Barrier Lowering). While CLM is usually explained as effective decrease of the ...
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0answers
41 views

What is the “short-range outdoor model (ITU-1411) with a distance-dependent path-loss” mentioned in this paper?

I am reading the paper Graph Embedding Based Wireless Link Scheduling with Few Training Samples, and trying to reproduce some of its results. This paper aims to solve the wireless link scheduling ...
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3answers
540 views

Proper way to turn off PWM channel on STM32

I am using STM32F4 to drive a 3 phase BLDC motor and i'm using TIM1 peripheral to generate 6-step PWM(complementary pwm) but when i change the configuration and i disable 1 channel it takes some time ...
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49 views

Dual OpAmp LM358

I currently developing a sensorbox for an apartment building. Two of the sensors are MQ-2 and a MQ-7. I found a schematic which uses a LM358 dual opamp. In the datasheet it states that there are two ...
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0answers
12 views

Predict channel strength through Hidden markov model [closed]

I have to provide noise variance,channel bandwidth ,channel bandwidth’s average power received and fast fading observed as my input to hidden markov model how can this be done
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1answer
57 views

Convering bandwidth (frequency) to bit rate without knowledge of the modulation?

How would i convert a bandwidth of say 30kHz to bps if I only know the number of bits per sample (4)? (and I was using a two chanel system). I am assuming it is simply 30KHz * 2 * 4 but this may be ...
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41 views

Merging audio lines - one channel is quieter

I'm still learning digital electronics, and analogue electronics is very much a dark art for me. I have the circuit as shown below, the audio output stage for an 8-bit programmable sound generator. ...
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1answer
221 views

Derivation of the Shannon Limit

I am doing the derivation of the Shannon Limit, and I think I ran into a snag, and am in need of a bit of assistance: Background: From information theory, we know that the Shannon Limit is: $$C = W *...
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1answer
45 views

Need help with understanding the pros and cons of geometric and stochastic based channel models. Which one s preferred under which conditions?

https://www.adv-radio-sci.net/9/165/2011/ars-9-165-2011.pdf https://ieeexplore.ieee.org/document/7794648 https://pdfs.semanticscholar.org/c301/8463116117ea64f69638e15aa78fe9e84093.pdf https://www....
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1answer
43 views

What is the basic concept (philosophy) behind the modelling of Nakagami-m fading wireless channel

I understand that that NAKAGAMI-m probability density functions that describes the random behavior of signal in a wireless channel. But I am very confused about one thing, by what concept did these ...
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2answers
100 views

What is this kind of “Multiplexer” called?

First of all I am new to electronics so i might use wrong terms. What is this electronic component called or is it even a thing (Can it be bought)? I have 10 input wires/channels for example. Only ...
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0answers
309 views

STM32F407 - how do I run one motor at a time? Why do they ignore delays..?

I'm a newbie. I'm using an STM32F407 discovery board, and I want to control 6 stepper motors using PWM, especially OPM(One Pulse Mode). Till now I've made 3 stepper motors work using Timer 8 (CH1, ...
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1answer
254 views

Why does Channel Length Modulation Increase with Higher Vgs

I'm curious as to the physical reason as to why the effect of channel length modulation in an N-MOS actually increases when the Vgs voltage is increased? See the plot below: For a long channel ...
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1answer
203 views

Difference between conventional Eye-diagram voltage plot and “Eye-density” plot in ADS Keysight Simulation

I know what is eye diagram. It is the sampled voltage plot at the clock frequency (Usually) of my circuit and superimposed. If the logic 0 corresponds ...
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1answer
371 views

How do LoRa end-devices configure their upstream and downstream communication?

I'm in the process of building a LoRa end device, and am also designing protocol. I plan on using the channels specified in the AUS915 ISM Band as outlined in the LoRaWAN regional parameters (though i'...
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1answer
47 views

Decide coherent time and fade duration through empirical studies on the channel and relate them to channel modeling

I. Scenario: TX floating in the lossy heterogeneous medium with undetermined positions within a limited region; RX fixed in the air and closed to the boundary of air-lossy medium; Frequency: 500 MHz ...
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2answers
410 views

What does it mean if eye diagram voltage (0 and 1 level) goes negative?

I have created a differential channel and was testing the channel with simple testbench to check the eye diagram. Now I know the channel performance is very bad (It of several PCB transmission lines, ...
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195 views

How to setup and simulate differential TDR (Time Domain Reflectometry) in Cadence

I want to do differential TDR simulation in cadence virtuoso. I have a differential channel, made of Tlines and interconnects (passive componenets). How to setup the TDR simulation to get impedance ...
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1answer
69 views

Effect of large capacitor for differential channel in S-parameter simulation

I have created a differential channel with Transmission line and interconnects for simulation. In the real channel, there is 100nF capacitor in between 2 transmission lines. Now the problem is when I ...
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1answer
31 views

how to understand the capacity in binary symetric channel (BSC)

According to the wiki about the BSC (binary symetric channel), given the bit flip rate p, the capacity is derived as : H(p) = -p*log2(p) – (1-p)log2(1-p) C = 1 - H(p). the error probability p ...
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1answer
809 views

What is mean by channel inversion in wireless communication

Regarding the title of the question, to my understanding, Channel Inversion means that "The transmitter adapts its power to maintain constant SIR at the receiver." It is a technique used for ...
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1answer
250 views

Specification for Eye Mask Creation?

I want to create an eye mask which I can apply at the Rx eye diagram up to which I can quantify the quality of my signal at the Rx. Now my question is what are the specifications to determine eye mask ...
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45 views

Optimal Capacity of Wireless Relaying

"Optimal approach to relaying occurs when transmission is recieved simultaneously at the destination and relay." Is this still valid in the light of recent research? Are there trade-offs involved? ...
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2answers
220 views

MOSFET channel length modulation - Glossing over physics

I am having trouble understanding an aspect of the channel length modulation/pinch off of MOSFETs. My current understanding (For NMOS) is that when a positive voltage is applied to the gate, the P-...
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1answer
42 views

In a shared wireless channel, what are the factors that impact channel gain for each user?

Assume a wireless channel with bandwidth B is shared among N mobile device users. Let's say the size of data transmitted by each device is in the range [100, 1500] Kbits. How does the transmission ...
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1answer
575 views

For oscilloscope, what are the differences for Glitch Capture Channel and Sample Channel?

I'm using a Tektronix oscilloscope and I use only one channel. I export the data for that channel to a csv file and open it on my PC. I found the csv file actually contains data for two waveforms! One ...
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2answers
2k views

How is it decided what modulation is used during an 802.11 communication?

I understand, that 802.11x protocolls can use different type of modulations. BPSK, QPSK, 16-QAM, 64-QAM... I also understand that the used modulation depends on the quality of the channel, I guess on ...
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2answers
292 views

Finding the FET with lowest channel length modulation

I'm looking for the FET (JFET, MOSFET and other more advanced variants like Heterojunctions) that has the lowest channel modulation or perhaps among the lowest. Now, before anybody argues if other ...
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1answer
334 views

RFM69W Channel mechanism

I'm trying to understand how the channels for the RFM69W is created, if there is more than one. The manual specify "channelized operation", and I find channel bandwidths and that at 16 tap channel ...
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0answers
93 views

Inconsistent values read from PCA9955B error flags

The PCA9955B is a 16-channel LED driver that features programmable PWM and current and has gradation support. It also features open/short detection for all of the 16 channels, which is reported in the ...
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1answer
91 views

“Tagging” Data traveling over serial port?

If I'm reading data from multiple channels (UART) of a microprocessor, but I want it to be continuously read, I imagine the logical thing to do would be to cycle through the channels and output data, ...
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1answer
122 views

N-type channel mosfet

I try to explain how a n-channel mosfet works. But as I try to explain there is an ambiguity that I can not understand. As I read many books and searched in the internet does not say anywhere clearly ...
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1answer
627 views

Channel-Loss and Channel-Insertion-Loss

Read many time about Channel-Loss and Channel-Insertion-Loss, but confused that, is that same thing or opposite? Which has +ve or -ve values in dB? In reference to equalization of USB3.1.
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1answer
1k views

Bandwidth-Data rate relationship

From a Data Comms textbook: These are the approximate square waves (Fig 3.7a and 3.7b): This is where the effect of changes in bandwidth on data rate is determined: The problem is the explanation/...
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1answer
1k views

Why does the 802.11b DSSS signal have 22 MHz of channel width? How does the information get spread over that width? [duplicate]

This topic has got me so much confused. In terms of Wi-Fi, when we say the 802.11b has 22 MHz of Channel Bandwidth, what does it mean? When we refer to a particular Channel No. say Channel 1, it has ...
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1answer
520 views

Ideal wireless channel (coherence time/bandwidth)

Wireless channels can be characterized as either slow or fast fading based on their coherence time and signal length. Similarly, they are either flat fading or frequency selective depending on their ...
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1answer
253 views

Simulation of BPSK in fading channels

I'm trying to simulate BPSK in a channel with Rayleigh fading and AWGN, then obtain the Bit Error Probability (BEP). My program is written in C. I compared my BEP vs \$\frac{E_b}{N_0}\$ (SNR per bit) ...
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1answer
1k views

what's the purpose of multiple channels on Bluetooth Low Energy

a question I'm asking (perhaps its stupid) is that, on BLE (Bluetooth Low Energy) why do we need 40 channels?. 37 of these channels are used for connection data and the last three channels (37, ...