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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1answer
13 views

How Channelization code is shared in HSDPA?

I am on my way to understand the HSDPA/HSUPA technologies. I have just started and came upon the topic of channelization code. I learned how these codes are generated - Hadamard code technique - and ...
-1
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0answers
38 views

How to understand chirp

A chirped gaussian pulse can be written as but how is the chirp generated? And how to understand the parameter chirp C as it propagates through an optical fiber?
0
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0answers
11 views

HDB3 encoder/decoder IC [closed]

Does anyone know of HDB3 encoder/decoder IC's, possibly with on-chip clock recovery? CD22103, HDB3 transcoder, is obsolete. MV1442 seems to be hard to find. Thanks!
-3
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1answer
34 views
-1
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2answers
56 views

Which of the following is most limiting factor for data transmission rate? [closed]

Which of the following is most limiting factor for data transmission rate? Attenuation distortion Phase delay Signal distortion Bandwidth I think its phase delay, but I am not sure. Can someone ...
0
votes
1answer
49 views

Estimate the bandwidth required to transmit 1Mbits/s of data using a modulation scheme which comprises 32 different frequencies and 2 amplitude levels

Estimate the bandwidth required to transmit 1Mbits/s of data using a modulation scheme which comprises 32 different frequencies and 2 amplitude levels Yes, this is a homework question that ive been ...
0
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2answers
42 views

PIC24f Get Clock Signal for external Device?

I have an external memory device with pin configuration: Data Input Data Output Connection System CLock DC 24V Ground Here is the link I need to design a code to communicate with this device. I ...
0
votes
1answer
47 views

Logic Level Shifter

I am trying to connect two devices on a PCB. One operates with 3.3V digital high and the other works with 5V digital high. I actually grouped the input and output pins (There is no bidirectional ...
-1
votes
0answers
43 views

Capacitor used between DGND Vs CGND

In my project I was using Digital GND and Chassis GND. For Both GND connected with 1ME and 100pF ceramic capacitor in parallel. Due to PCB space constraints planning to use ceramic capacitor with ...
3
votes
5answers
502 views

Transmission of a digital signal over a medium

A digital signal is said to have a infinite bandwidth. If a transmission medium cannot have infinite bandwidth then how can a digital signal be transmitted over such mediums? Please correct me if I ...
1
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1answer
37 views

what is the function of pre-emphasizer and dee-emphasizer in Stereophonic FM Receiver?

what is the purpose of theses two block ? I know that pre-emphasizer will boost the high frequencies before transmission and dee-emphasizer will reducing them by a corresponding amount in the ...
0
votes
3answers
61 views

How to reduce rise/fall time while amplifying square pulses with op amp?

I'm trying to amplify a low signal with square pulses at 20 mV using op amps. According to simulation, rise and fall time of pulses increase too much after amplification, approximately 60 us. The ...
1
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0answers
71 views

How to amplify a signal containing square pulses at milivolts to a couple volts

I was on it for a time. I'm planning to generate a signal containing square pulses from a smart phone's audio output. As I can get any shape of audio signal from smartphone's audio output, I want to ...
1
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2answers
78 views

555 as a Digital Coupler

I want to read MIDI data with an arduino (specifically an ATtiny85) for use in a synthesizer. The only method I'm aware of involves using an optocoupler such as the 6N138 found on this Instructable. ...
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0answers
20 views

duobinary coding : how to find if there an Error in a given sequence?

why we can't have even number of zero between opposite polarity ? is the same things applies for even number of ones between opposite polarity
1
vote
1answer
35 views

FSK combined with either ASK or PSK?

Why is it that we are able to combine Amplitude and Phase modulation (Resulting in QAM) but are not able to do so with frequency? Why not combine all three degrees of freedom (Amplitude, Frequency, ...
0
votes
3answers
77 views

Transmit an internet connection over wireless

My target is to transmit an internet connection (8 Mbit/s) over long range wireless RF (7.7 km) with LOS (Line Of Sight). I live in a country where there is no rules for RF transmission, so i can use ...
3
votes
1answer
69 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
59 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
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0answers
12 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
52 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
46 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
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0answers
81 views

Porting Costas Loop from Matlab to FPGA

I have designed a Costas Loop for carrier synchronization in MATLAB, here is my code: ...
0
votes
1answer
55 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
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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
77 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
51 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 ...
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0answers
48 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 ...
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votes
3answers
62 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
80 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
72 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
385 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
187 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
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0answers
24 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
59 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
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0answers
85 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
38 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
58 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
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0answers
35 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
95 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
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0answers
66 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
78 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
463 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
92 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
681 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
107 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
131 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
64 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 ...