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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2
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1answer
40 views

Multiple SPI Busses in Ribbon Cable

I have a multiple SPI busses running through a ribbon cable which is 15cm long. What is the best CS, SCK, MOSI, MISO orientation to avoid the cross talk between each wire and is it enough to use ...
1
vote
1answer
47 views

How do you design a circuit to implement the Bipolar Line coding Technique?

Bipolar NRZ http://www.tutorialspoint.com/data_communication_computer_network/images/bipolar.jpg In this technique alternate 1's will have alternate polarities and 0's will be zero itself.
0
votes
0answers
9 views

MU-LAW COMPANDER for a 10-bit Quantzer … ? how many level will be needed to represent the lowest 30% of the signal for U=0 and U=10

for a 10-bit Quantzer how many level will be needed to represent the lowest 30% of the signal for U=0 and U=10 ? I know it it is u=0(simply no compression) so # of level = 0.3(2^10) which is = 307.2 ...
0
votes
3answers
50 views

Spreading of a pulse in time domain

I have a small doubt. Suppose I transmit just 2 square pulse with frequency of 100 MHz over a wireless channel, will it spread in the time domain when received by a wireless receiver. In other words, ...
0
votes
1answer
36 views

Weak pull down for SPI

I am using Arduino(does not matter) and 8 x 12 bit-ADCs to read some values. I created a prototype which consists of a Shift Register(SR) and all outputs of SR are connected to individual ADC's ...
1
vote
0answers
47 views

Porting Costas Loop from Matlab to FPGA

I have designed a Costas Loop for carrier synchronization in MATLAB, here is my code: ...
1
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0answers
60 views

Basic “filtering” in digital communications [migrated]

I am completely stuck on solving some problems for my digital communications class. Junior level undergrad class, so fairly basic. I have been searching around all day for related articles etc but ...
0
votes
1answer
47 views

Is it safer to use multiple RS-485 point to point connections compared to a daisy chain?

When wiring multiple RS485 slaves to a master equipped with a RS232/RS422/RS485 interface*: is it safer to wire multiple point to point connections from the hub with their own termination resistor, ...
12
votes
4answers
2k views

Why AT command set?

Frankly, Why do all communication ICs(or at least many of them or most famous or popular) such as Bluetooth or WIFI or GSM or etc support AT command set? why don't they have a simple pin for D/C(Data ...
0
votes
0answers
50 views

Best way to send a simple digital signal wirelessly (close-range)?

I have a small device which powers two vibrating motors. I would like the vibrating motors to be wireless (ie, not actually connected to the device). Here's some more info: Here's the vibrating ...
0
votes
1answer
37 views

what is the digital communication format that the bluetooth module communicates with

I am using ATtiny2313 microcontroller along with a bluetooth module(HC-05) to communicate with my laptop. Heres my doubt, How does the bluetooth module communicate with the laptop. i.e. what is the ...
0
votes
0answers
41 views

Transmitting data over Long range ,using a Low Power Circuit

I Have Been Designing a BOT That Would Travel Along the Pipeline And Detect Leakage Using Ultrasound Efficiently,And Locate The Position of Leakage Using A GPS MODULE using the Arduino,I have make it ...
0
votes
2answers
40 views

Sampling Rate Passband Signal

What is the maximum/minimum possible sampling rate for the signal to be full recovered for a passband signal?
2
votes
1answer
75 views

Is it true to add 22 Ohm resistor to help in impedance macthing?

I read somewhere (sorry can't find the source) that adding 22 Ohms resistor on digital line helps in matching impedance. Is it true? Is this a common value? Where should this be added? Near node A or ...
0
votes
1answer
62 views

Digital signal over AM radio [closed]

I am trying to send a digital signal over radio and I am having trouble modulating the input to the radio circuit. I am a complete beginner so I am doing this only as a learning exercise. I have the ...
1
vote
0answers
147 views

How to calculate the SQNR of the PCM system in dB?

Assume that the input signal S(t) is sinusoidal with amplitude A and quantized to R number of binary bits, how can I calculate the SQNR of the PCM system in dB? I know that the output ...
1
vote
2answers
86 views

What is The Difference Between PAM And ASK

In Digital Communication can We use PAM in place of ASK The Diagram is Given as The Book Later Talks about Symbols. I Don't Understand, in PAM we don't have specific signal as input like in ASK ...
0
votes
0answers
23 views

How to measure the QoS of an anlog wireless link

I am working with FSK transmitter and modulator on the 433 MHz band, I am wondering how can I measure the QoS of the resultant link given that The receiver reports the received analog data only with ...
3
votes
1answer
56 views

Storage lifetime considerations for electronics

I am working on a single board computer that I am aiming to last for up to 30 years. It will be based on this design, with a lm7805 voltage regulator circuit and address + data line LEDs. I am ...
0
votes
0answers
52 views

Mueller Muller CDR

For a clock data recovery in a reciever a phase detector is used. In my case I want to understand how the Mueller Muller CDR works. And also what its advantages and disadvantages are. The ...
0
votes
1answer
33 views

Probability of receiving a fixed bit sequence in a binary symmetric channel

What is the probability of receiving 1111 irrespective of what was transmitted? \$0.1^4 + 0.9^4 = 0.6562 \$ I am not sure about my answer because I think in my ...
1
vote
2answers
49 views

Outputting raw bitstream via USB

I am extremely new to this and I'm learning by building stuff myself so please let me know if this is too vague and I'll elaborate if I can. I'm sure this is something very simple, but can't figure ...
14
votes
3answers
3k views

How can over 24 GHz communication be possible?

I read the article Google wants the US' wireless spectrum for balloon-based Internet. It says to use over 24 GHz frequency spectrum for communication. Is it ever possible to generate that high ...
0
votes
0answers
31 views

Implement Automatic Gain control for 16 QAM

How can I implement an automatic gain control for 16 QAM modulation in Matlab preferably without channel estimation (trial and error may be).
1
vote
1answer
81 views

Digital I/O pins connections between IC

I want to ask how is right to connect enable in ICs and digital communication between ICs. Take for example this: want to ask about this 3 examples: Should I use a resistor and how I choose it ...
1
vote
0answers
57 views

How do I draw M-PAM curves of Channel Capacity Vs SNR?

I've seen the following figure in several different articles: (this one was taken from here) I understand that channel capacity of the Gaussian signal is ...
1
vote
2answers
77 views

Monitoring serial communications between two PCBs?

Someone was asking me if it would be possible to monitor the serial communication between two PCBs and output something that is readable. The PCBs are part of an automatic door system - I'm not sure ...
3
votes
6answers
419 views

Implementation and usage of gray code?

Generally and briefly, are there any direct application of gray code in electronics? If so, what are they?
1
vote
2answers
86 views

Is it allowed to stop and restore I2C transmission?

Is it allowed to stop and restore I2C transmission? I would like to stop it in different periods of transmission and then after for example 500ms restore it to the state when it was stopped. I'm ...
2
votes
3answers
458 views

How to read a push-pull output

I recently came across a sensor that had a "push-pull" output. I can't find anywhere how to read such an output: Is it some particular kind of analog output? I would want to read it with the ...
0
votes
0answers
67 views

SIM900 GSM module power LED on but can't get signal

When I connect my module to power the power LED stays on but I can't get signal LED blinking. I am connecting it to my PC via serial port and using Putty software. I am using a SIM900 Flyscale module. ...
1
vote
1answer
91 views

A circuit to prevent parasitic powering of FT232RL by MCU, will it work?

In a previous question I asked how to prevent the MCU TX pin (3.3V when idle) from powering an FT232RL Usb to Serial chip via the TX line: Preventing parasitic powering of FT232RL by ATMega328P I ...
18
votes
10answers
4k views

Is there any way to use half-bits?

As most people here know, by using 4 bits, we are able to count from 0 to 15 (0123456789ABCDEF in hexadecimal). But if we were to only count up to 9, we would still be using 4 bits, and the digits ...
2
votes
1answer
57 views

choice of parity bits for linear block codes

We know that in linear block codes the codeword for a given a message is generated by multiplying the message with the generator matrix G . The generator matrix consists of a sub-matrix which is the ...
0
votes
0answers
21 views

A closed form for calculating shaping gain

As we know, in a communication system, we can divide the overall gain into coding gain and shaping gain, but I have not seen any closed form formula for calculating shaping gain, but the definition ...
0
votes
0answers
225 views

Transferring data from FPGA to PC (new to FPGAs)

FPGA beginner here. I have a Basys2 FPGA board(i code in verilog) and i wish to make it communicate with my PC. Currently it receives data from a slave device and stores it in an 64 bit register. ...
0
votes
0answers
21 views

Error Correcting Codes - Communications

I'm doing a research on the the physical effect of unbalancing the fraction of 1's and 0's in digital communications. Can anyone quote a specific FEC code that adds for example up to 20% overhead to ...
3
votes
2answers
156 views

TTL Long Distance Transmission Alternatives

I am working on a system that gets data from a sensor via a TTL connection. Currently, the data that is gathered from the sensor is sent to another part of the system via a set of modems. The ...
0
votes
0answers
28 views

Variance of background thermal noise wireless communications?

I am new to this forum and hope I can get some help. I have been reading a paper on wireless communications, in this paper a base station with power P=25 is serving a certain user. The user is ...
0
votes
3answers
218 views

How to increase range of zigbee?

I have a Zigbee Pro with Arduino whose range is 2 miles as per specifications. But practically its maximum range is only 200 meters. I am using XCTU software. Is there any setting/configuration in ...
-1
votes
1answer
814 views

Noise level, SNR and BER relationship in BPSK modulation

I would like to know what is the relationship between SNR, noise level and BER in BPSK modulation scheme? Can you please tell me the formula?
0
votes
1answer
348 views

What is the difference between 1-bit SDIO vs SPI?

What exactly is the between 1-bit SDIO vs SPI? Does one have advantages/disadvantages over the other?
0
votes
2answers
385 views

What is the minimum bandwidth required for a digital communication system using 32-QAM modulation?

If the bit rate of the digital communication system is 'R' Kbps & the modulation used is 32-QAM, what is the minimum bandwidth required for ISI free transmission? My understanding & analysis ...
0
votes
0answers
51 views

what is superposition coding?

In the context of multiple access techniques, there is a coding scheme called "Superposition Coding" or particularly "Superposition Coding with Successive Decoding(SCSD)". I surfed the internet, and ...
1
vote
1answer
122 views

Difference between spectral efficiency and bit rate

I am reading articles about error correcting codes, facing to a term "spectral efficiency". Due to the context, I guessed that it means "bit rate", but I wonder are these two terms equivalent or not? ...
2
votes
1answer
184 views

Why it has used BPSK modulation after OFDM?

I am quite new to OFDM modulation. I am reading this from a tutorial. In one of its parts, for showing amplitude variation of the OFDM signals, there is a graph that has used 8 sub-carriers and BPSK ...
0
votes
0answers
48 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 ...
2
votes
1answer
66 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 ...
0
votes
1answer
54 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: ...
1
vote
2answers
47 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 ...