Related to all communication systems that use a given digital sequence as an interface between the source and the channel input.

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17 views

What sampling rates will give uncorrelated samples of x(t).considering the mean of the Random Variable 'x' to be zero?

What sampling rates will give uncorrelated samples of x(t) ? Considering the mean of the Random Variable 'x' to be zero. My Thinking: Since the mean of the random variable 'x'is zero,then it will ...
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1answer
38 views

How is CPM Modulation Different from PSK?

Continuous phase modulation has been described to me very similar to wikipedia's definition, which basically indicated that the CPM is different from QPSK, for example, because QPSK abruptly shifts ...
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1answer
20 views

How does SMBus receive byte command protocol know what to send?

Im programming an I2C device to act as a PMBus slave. Looking at the SMBus protocols (which PMBus is built on) the Receive Byte command has a format described as follows: ...
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1answer
27 views

parameter that limits data rate in communication

In communication, the maximum data rate that can be achieved is given by Shannon as C=B*log2(1+SNR) bits/sec. Supposing that I've a very high SNR and an infinite bandwidth, then can data be ...
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2answers
37 views

sampling rate, data rate and bandwidth

I'm new to digital communication. How are the terms data rate and sampling rate related to the term "bandwidth" . Am I missing something here?.Can someone explain me in detail? thanks in advance, ...
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1answer
28 views

Group delay when using a matched filter

Supposing I have a discrete time signal x(n). when I pass this through an FIR filter h(n), and again pass this result through h(n) again (essentially this is a second order filtering), the group delay ...
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2answers
59 views

Usage of complex filters in communication

In the last stage of a communication transmitter, at the front end a filter is used to eliminate unwanted signals from other frequencies. As far as I read in literature, are these filters "real" ...
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3answers
66 views

using C libraries inside verilog

I'm implementing a radio in Verilog. the time taken for bit reversal while computing the FFT is more. it is almost equal to a symbol time (OFDM system). Can I use a FFT library in C, which can be ...
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1answer
31 views

How do data and address strobes cause input to be latched?

Often in digital systems when multiple components communicate with each other they use strobe signals. Among these are data and address strobes. The strobe signal being asserted means that the data or ...
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2answers
81 views

Circuit to throw out 1st bit of every 17-bit sequence?

I have a system that currently uses two Maxim DS1867 digital potentiometers in a daisy-chain configuration. In a new addition to the system I would like to use a new digital potentiometer part like ...
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1answer
31 views

Prove a theorem about an upper bound for entropy of a random vector

There is a theorem that: if Z is any zero-mean, complex random vector with covariance \$E[ZZ^H]=R_z\$, then \$H(Z)\leq \log|{\pi eR_z}|\$, with equality holding if and only if Z has a circularly ...
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36 views

Form of the received signal in a MIMO communication

I am reading an article which is related to MIMO communication networks. Consider that there are \$U\$ users, each of them have \$J_{u}, u=1,...U\$, different layers. We want to calculate the received ...
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53 views

Difference between “user” and “layer”

I am new to multiple access communication theory. I read some articles on LDS, and I thought that "layers" is a term used for "users" (In another language I thought that for example when we say "we ...
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2answers
117 views

Why interfaces and buses gets faster with every version if they are physically the same?

An interface or computer expansion bus gets faster with every version eg. PCI express 1.0 is 4GB/sm, PCI express 2.0 is 8GB/s, PCI express 3.0 is 16GB/s. I understand that things like microprocessors ...
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2answers
51 views

Spreading vector

I am reading an article that is about CDMA. In that article I encountered a term "spreading vetor". I searched some books such as Proakis and Gallager to see what it means. I even surfed internet for ...
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3answers
129 views

What exactly does a 10-transistor XOR gate look like?

I need a schematic for a 10-transistor xor gate, I have searched everywhere and I see 8, 12, 6, but I can't see 10. What does it look like in a transistor like picture?
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65 views

Would my project be affected by lack of a filter?

I have chosen to do a final project, I will be transmitting bits using a wien bridge oscilator, I want a 160 MHZ sine wave and I have chosen values for it. I have chosen the AD8041 op amp because it ...
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1answer
29 views

RF Solutions ZULU module

I am trying to set up a remote battery voltage checker that will radio the voltage read from the battery to a computer. I went for the ZULU module (by mistake as I should have brought the ZULU-M ...
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0answers
78 views

Why is “throughput” called “bandwidth”?

But back in school, I had learned that the "bandwidth" of a communication channel is the frequency of the highest-frequency signal minus that of the lowest-frequency signal that it can carry. Yet in ...
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31 views

How to generate random fading variables using Nakagami-M distributions

I am trying to write my own mat-lab code to generate Nakagami random variables, As we know due to multi-path propagation we have random attenuation and delay. I have a signal coming out and I want ...
14
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2answers
149 views

HDMI and I\$^2\$C

I was having a look at the HDMI pinout and I thought: why would they use I\$^2\$C for the display-host communication? My question here is about the design metrics that lead to this choice. HDMI is a ...
2
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3answers
123 views

What happens if SINR is < 1?

What happens if the SINR of a signal is less than 1 in a (wireless) network? Is that practical at all to have a SINR < 1? Using the Shannon capacity formula, it seems that we must be able to have ...
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2answers
49 views

Is it possible to put one E0 voice signal directly into a STM1 frame

I've been going through STM1 frame structure recently. Is it possible to put a single E0(64kbps) voice channel directly into a stm1 frame or should it be put sequentially into a E1 and then to an E2 ...
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1answer
177 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 ...
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3answers
80 views

Laser emitter for serial communications?

I want to build a 2-way serial communications rig using low cost LED lasers. 9600 baud would be ok, but faster speeds would be more useful. (This is purely a hobby project. The further I can establish ...
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2answers
97 views

Fan in Fan out problem

Fan out is the maximum number of inputs that can be connected to a specific output. Why can’t we connect more number of inputs to this output?
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1answer
113 views

Signal drawing based on a constellation diagram

Constellation diagram of a communication system is given. S1(t) -> 0, S2(t) -> 1 Φ1 and Φ2 are basis functions and Tb is the bit period. How can I draw S1(t),S2(t) and decision boundaries?
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1answer
88 views

Quantization levels and SNR

Im' trying to build a big picture of telecommunication and i'm stuck in a topic, related to digital communication. But the problem is that i can't go too deep into the topic because it is imensely ...
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1answer
132 views

BFSK Modulation Output

I'm having trouble understanding outputs of a BFSK modulator. $$S_1(t) = cos(πt/T)$$ $$S_2(t) = cos(2πt/T)$$ If the input 0 or 1, how can I calculate the output? Edit: There is a formula to ...
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2answers
87 views

QAM's Demodulation

Let me confirm how the demodulation process of QAM is. $$s(t)=I(t)sin(2πft)+Q(t)cos(2πft)$$ Then we have to guess \$I(t)\$ and \$Q(t)\$ in order to know what the said bit formation of the ...
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2answers
106 views

SNR vs Signal Strength for digital throughput

I'm trying to compare two antennas, A and B for WiFi. A is showing: Signal Strength of -77dBm, but SNR of 9dB. B is showing: ...
2
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1answer
84 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) ...
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2answers
117 views

Can I use this IR Transceiver for communication and obstacle avoidance?

I am building two robots. For communication and obstacle avoidance I am using Infrared. I bought this IR transceiver TFDU4101-TR3 (http://www.farnell.com/datasheets/1675739.pdf)which I thought I could ...
3
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1answer
89 views

What does “50 ohm system” mean?

I'm looking to use the following switch to switch an SPI bus ( CLK <= 2Mhz) between two different devices. I'm reading the datasheet to see if the the frequency of the signals are going to be ok, ...
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3answers
95 views

Long distance communication

I am looking for a cheap single wired solution to transfer data of some sensors connected to a uC over a distance of 1 KM from a control room on UART. The data is of 16 bytes, no high speed ...
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1answer
64 views

Definition of link gain for an optical system

Is the link gain the gain of the whole system or just over the diode? And why does the threshold current of a diode laser have no impact on link gain whereas increases in slope efficiency have a major ...
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1answer
81 views

Designing a simple energy-efficient communication protocol?

What is the required background knowledge in order to be able to understand and work on the design of a communication protocol which has to be robust, simple and capable of coping with short contact ...
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1answer
127 views

Why are there so many signal grounds for PCI Express?

PCIe connections have one to two ground contacts per differential signal pair. Why is this the case? On the boards that I have been studying, all of these pins are tied together onto the same ground ...
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0answers
49 views

Calculating the frequency of CPM signal in System Generator

I have a circuit which has been designed by System Generator to be implemented on FPGA. The circuit's output is a CPM (Continuous Phase Modulation) signal in which it is apparent that its ...
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1answer
184 views

why when calculating rise time we use 2.2 × tau? (RC Low Pass Circuit)

I am just trying to understand why we use 2.2×Tau when calculate the rise time. I can't find a derivation anywhere, I don't understand where this 2.2 came from.
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3answers
286 views

the causes of Fading of signals

I have read about fading of signals , and I have notice that the major cause of fading is multipath , but I have ask myself , what about attenuation , noise and free space loss , all of these make the ...
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4answers
98 views

Why don't you ever see a “anything” over (cable type)?

Possibly an obvious answer, and I'm new to electronics. You can easily find converters that convert a specific type of signal to another cable to be decompressed on the other end (example, a VGA over ...
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3answers
82 views

the implementaion of communication systems [closed]

I wonder , Why when we study communications systems , we just study the theoretical part(Math) , and we never touch the electrical circuits that used to implements this systems , I have asked my DR. ...
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1answer
68 views

Why Direct Broadcast satellite is interrupted by climatic conditions?

Television signals received through direct satellite service are mostly interrupted by the climatic conditions. But other communication systems that uses satellites are not that much affected. Why is ...
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1answer
148 views

What is wrong with this SPI implementation

I designed a system with RaspberryPi and STM32F407's, communicating with each other via SPI interfaces. For the last 3 months, tests were OK but yesterday a RaspberryPi and 2 of STM32F407's SPI ...
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1answer
57 views

What is digital Termination and when is it used?

I have heard transmission line termination but today I came across this "Digital termination" but couldn't find out why is it used and what effect does it have on digital signals?
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3answers
70 views

Bandwidth and wire parameters

Does the physical features of a wire like surface area, length or specific resistance form any sort of limit to the bandwidth of signals that can be passed through that wire?
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2answers
276 views

USB to USB data transfer using microcontroller [closed]

Is that possible that we can communicate two USBs,I mean data transfer between two USB without PC ? How we can transfer data without PC between two USBs ?So please anybody can give me some idea how ...
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60 views

16 QAM input data frequency?

I am simulating 16 QAM transmiter and reciver in MATLAB , using randint() function to generate input data stream. But I dont know what is the frequency of these input bits generated by randint() ...
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194 views

I need to calculate the average power spectral density after passing packets through a butterworth filter using MATLAB

I am trying to generate 100 packets(row vectors each of size 8192) of random bits(1,-1),filter them using butterworth filter and then plot their average power spectral density. I have to do this ...