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Questions tagged [channel]

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36 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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0answers
42 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
40 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
37 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
91 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
177 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
144 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
89 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
178 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
46 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
203 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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81 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
46 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
29 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
342 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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2answers
92 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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0answers
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
147 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
34 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
344 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
1k 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
203 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
218 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
67 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
84 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
108 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
398 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/...
3
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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
488 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 ...
2
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1answer
221 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
892 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, ...
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1answer
694 views

What does “capacity achieving code” mean?

I am an electrical engineer passed several courses in information theory and coding theory, however as I think now, I see that I have not understand the basic ideas in these concepts till now. We ...
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1answer
186 views

Does the Free Space Path Loss model apply to all types of electromagnetic waves, including light?

The free-space path loss model describes the attenuation of the electromagnetic (EM) signal as a function of the distance between Tx and ...
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1answer
780 views

How does modulation technique affect channel capacity?

Shannon's channel capacity formula does not consider modulation techniques. How then does LTE achieve high data rate using advanced modulation techniques? P.S: I am novice in RF and signal processing....
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1answer
129 views

Clarification on region of operation in MOSFETs

So this is going to be a series of questions: Enhancement MOSFETs: N-Channel: So applying positive voltage and up to the gate, relative to source, lets more and more current through until it ...
2
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1answer
3k views

Avr multiple ADC and PWM channels

I've been trying to make a program that would continuously read analog values from 3 different pins and then make a PWM signal corresponding to each of those 3 pins. So basically, 3 output PWM ...
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2answers
825 views

Why are there more than one programming channels on PIC32?

Previously, I was working with PIC16 and PIC18 series, and none of them provided multiple channels for programming. Now, I am designing my first PIC32 circuit, and I'm very confused with these ...