Questions tagged [bpsk]

BPSK, a mechanism of modulation is expanded Binary Phase Shift Keying.

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13 votes
1 answer
11k views

How to perform carrier phase recovery in software?

What are the options for recovering the phase of a BPSK signal in software? The only resources I can find online contain circuit diagrams – there seems to be no one willing to explain this to people ...
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13 votes
1 answer
1k views

What are the various definitions for $\rm SNR$, and their associated methods for measuring it?

The definition of $\rm SNR$ seems to be somewhat of a tower of babel in industry. What definitions of $\rm SNR$ are there (feel free to site application), and how exactly can it be measured for that ...
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9 votes
2 answers
5k views

How to soft decode DQPSK?

I'm successfully soft-decoding D-BPSK by taking the dot-product of the constellation-position of the symbol and of the previous symbol. If the result is >= 1, then the symbol phase hasn't changed and ...
8 votes
1 answer
5k views

How to determine where to sample for demodulation of BPSK signals?

I have a simple BPSK demodulator. Very simply, the signal comes in and is split into two branches, one for I and one for Q. The I branch is mixed with a sin wave of the carrier, and the Q branch ...
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8 votes
1 answer
265 views

How to send / receive a short impulse in an extremely noisy signal with high timing accuracy?

I am pretty new to DSP. I need a computer to transmit data to a receiver through audio signals in a loud outdoor environment. (I am writing the software for both sender and receiver so I can design ...
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6 votes
1 answer
8k views

Simulating BPSK Costas Loop in Matlab

I am trying to implement BPSK demodulator in FPGA. First, I am modeling the system in MATLAB. Now, I am trying to design Costas Loop for carrier synchronization. This is the block diagram I'm trying ...
5 votes
1 answer
6k views

Phase synchronization in BPSK

In BPSK for demodulation at the receiver end we do phase recovery between received wave and carrier wave. We can find the phase difference between the carrier and received waves using : PLL And ...
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4 votes
4 answers
6k views

Why does OFDM use cyclic-prefix while QPSK uses root-raised cosine filters?

My understanding is that BPSK/QPSK/... are often implemented with root-raised cosine (RRC) filters to reduce ISI and bandwidth. OFDM can be understood to be BPSK/QPSK/... implemented on multiple ...
4 votes
2 answers
2k views

Why does FEC seem to make BER worse at low Eb/N0?

I've been plotting BER curves and am wondering why FEC seems to make a BER curve worse at low Eb/N0 than the un-coded theoretical BER curve? My example plot below is for Differential BPSK using a ...
4 votes
2 answers
329 views

Shannon capacity limit & FEC comparisons

In this figure from Fundamentals of Digital Communications by Madhow , pp 328 there is a comparison of a rate 1/3 turbo code with the shannon limit for rate 1/3 BPSK: Trying to understand the limit ...
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4 votes
1 answer
2k views

Energy per bit ($E_b$) in BPSK with non-unity channel gain

I would like to know what is exact and correct definition of $E_b$ (energy per bit) in digital communication. Consider I have a model such as r=a*x+n where <...
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4 votes
1 answer
858 views

Matlab: What should be the BER performance for BPSK using Constant Modulus Algorithm equalizer

I need help in plotting the Bit error curve or the symbol error curve for BPSK modulation scheme for varying Signal to Noise ratios or Eb/N0. The plot should show the simulated versus the theoretical ...
4 votes
3 answers
577 views

Do BPSK vs QPSK have the same performance?

I'm trying to re-learn digital communication theory again and am creating a bit error probability simulation for various modulations. So far I've added BPSK, QPSK, and 8PSK and below is a plot that ...
3 votes
2 answers
3k views

High modulation index PSK - carrier recovery

How to recover the carrier of a PSK signal that has high modulation index (eg. 750 symbols per second at carrier frequency 1500 Hz)? I guess that a PLL will not be able to lock onto it with such ...
3 votes
2 answers
665 views

Intersymbol Interference -- Root raised cosine filter redundant if doing impulse response equalization?

I'm implementing DBPSK (differential binary phase-shift keying) over audio (44.1kHz sample-rate) using software. Eventually I'll use multiple audio frequencies at once, so I'm using FFTs and inverse ...
3 votes
1 answer
2k views

Adding AWGN noise with a correct noise power to the signal

I would like to add AWGN noise to my BPSK and QPSK signal. So assume the BPSK signal is x1 and QPSK signal is x2. The ...
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3 votes
1 answer
4k views

Rectangular 8 QAM bit error rate calculation

I am simulating an 8-QAM communication system over an AWGN channel for various signal to noise ratios, in order to plot the average bit error. However I have not been able to derive an equation for ...
3 votes
1 answer
453 views

Designing a PI filter for a Costas Loop

I am currently trying to implement a Costas Loop in order to demodulate a BPSK signal. Here is the reference block diagram I have been using to design the loop:Costas Loop Block Diagram I originally ...
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3 votes
1 answer
2k views

QPSK Data Rate vs Bandwidth at Passband: Why can it only transmit 1 bit per Hz and not 2 bits per Hz?

1) This is a follow up question to the most up-voted answer to this question. 2) The accepted answer is that "QPSK transmits 1 bit per Hz at passband". 3) The theory found in books seems to agree ...
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3 votes
1 answer
397 views

Applying Viterbi algorithm to compensate for ISI in PSK31

I am implementing a receiver for the amateur radio mode PSK31. It is effectively a BPSK modulation with a pulse shape of a raised cosine twice the width of one symbol. Here are four consecutive pulses,...
3 votes
0 answers
195 views

Synchronization of BPSK with variable-length symbols (ISO 14443)

Does anyone have an idea how one would perform BPSK symbol synchronization if symbol length is allowed to vary? As dumb as that sounds, this is not a theretical question.The "Proximity" Type B NFC ...
2 votes
2 answers
1k views

Bandpass filter BPSK

I have a question concerning BPSK and the bandpass filter that seems to be sometimes placed before the receiver circuit (the receiver is a mixer and lowpass filter). Basically, from what I've noticed,...
2 votes
2 answers
15k views

Relation between Bandwidth and Baud-Rate for 8-PSK

I have a query on relationship between Baud Rate and Bandwidth for 8-PSK. In 8-PSK as 3 bits together form a symbol, so Bandwidth = 2R/3 , R is Bit Rate As bit ...
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2 votes
1 answer
2k views

Beginner BPSK demodulation question

I'm writing a simple application in Python that sends and receives data over binary PSK using audio signal. I used cos() for 0 and -cos for 1. On the receiver side I figured I can demodulate by ...
2 votes
2 answers
559 views

Prevent negative image with BPSK modulation in a complex signal

In a baseband complex signal, I need to generate a BSPK modulated signal at a given frequency. If I generate a CW at this frequency, all is good. However, when I then BPSK modulate the CW, I get a ...
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2 votes
1 answer
792 views

Block diagram of M-PSK modulation and demodulation

I have come across this quadrature modulator block diagram in many books and websites: I've read that the quadrature modulator allows to realize many different digital modulations, including ...
2 votes
1 answer
83 views

BPSK consecutive same symbols

I have a question regarding BPSK. If we want to modulate the bit stream $[0, 0]$ with $T_\text{ bit}=0.25 \text{ sec}$ and the carrier frequency of the cosine that carries the BPSK signal is $2\ \rm ...
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2 votes
3 answers
2k views

Real-time BPSK demodulation

I am currently studying BPSK demodulation. Most probably my question very basic but i am having difficulties to understand the case of real-time bpsk demodulation. Basically, all the examples (matlab,...
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2 votes
1 answer
2k views

Find beginning of signal for BPSK Demodulation

I want to store a small amount of data in a sound file recorded by a microphone but I know nearly nothing about signal processing. I managed to demodulate my data encoded using binary phase shift ...
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2 votes
1 answer
4k views

What is the meaning of BPSK(n)

I am doing some research into GNSS (Global Navigation Satellite Systems) and have come across various signals listed as having the in-phase or quadrature channels modulated with BPSK(2) or BPSK(10), ...
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2 votes
1 answer
2k views

DPSK vs PSK Error Probability

BACKGROUND The bit error probability for BPSK under AWGN is easily derived from tail probabilities of Gaussian distributions and results in $$P_e = Q\biggr(\sqrt{\frac{2E_b}{N_o}}\biggl)$$ The ...
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2 votes
1 answer
803 views

Non-coherent receiver for DBPSK: Implementation details

I am implementing a non-coherent receiver for DBPSK. I have a computer science background with little knowledge of DSP so my questions here may seem obvious. The design of the receiver I am trying to ...
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2 votes
1 answer
89 views

Averaging of a phase flipping signal

Suppose I want to average a signal $s(t)$ which consists of several spectral components without any DC offset. I sample $M$ points in the time domain. I am interested in the power spectrum which I get ...
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2 votes
1 answer
355 views

Meaning of AWGN complex and real noise under BPSK Decision Scheme

I'm currently studying error correcting codes and decided to replicate some common Bit Error Rate curves under BPSK modulation. I initially had trouble to convert SNR to a Gaussian $\sigma$ because I ...
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2 votes
1 answer
152 views

Root raised cosine parameter

I try to create matched filter for receive BPSK signal. Sampling rate of the signal is 228000 Hz, data rate 1187.5 symbols/sec, signal was shaped using root raised cosine filter with rolloff factor = ...
2 votes
0 answers
101 views

How to find the noise power in my simulation

I am currently working a tricky communication chain that I want to simulate into Matlab. The chain is like a classic BPSK modulator/demodulator chain, but where the BPSK modulated signal has been ...
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2 votes
0 answers
109 views

GPS CDMA signal acquisition (BPSK modulation)

Sorry, this may be a rookie question: I have a CDMA gps communication in BPSK. Codes have a duration equal to $1\ \text{ms}$ and their length is 1023. At the carrier frequency ($f_c = 1.57524\ \text{...
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2 votes
1 answer
416 views

How to demodulation BPSK in real case(through a channel)?

I am configuring a channel sounding system. Using PRBS to correlate for time delay. Some details as follow. Generate PRBS. Using BPSK to modulate PRBS and Tx transmit. Rx receive signal and ...
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2 votes
0 answers
178 views

Having trouble transmitting/receiving a BPSK signal using two USRPs

I am relatively new to working with SDRs and GNURadio and I am attempting to generate a BPSK signal and transmit it through one USRP and receive and demodulate it on another USRP. I am using GNURadio ...
2 votes
0 answers
246 views

How does a Costas Loop lock to one of multiple BPSK signals

I've been looking into how GPS receivers work in terms of signal processing. When a GPS receiver tracks the received signal, it often uses a Costas loop to synchronize the carrier. How that works ...
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1 vote
1 answer
2k views

MATLAB: Adding Noise with Regard to Signal to Noise Ratio (SNR) or EbNo?

A signal x takes values from an alphabet set. My objective is to estimate the channel parameters hest using adaptive methods and ...
1 vote
1 answer
2k views

GPS Coarse Acquisition PRN Codes

Are the actual 1023 bit sequences for each of the 32 GPS satellites available to consumers? I found the IS GPS 200 but it doesn't list the entire sequences. Are verified sequences available for ...
1 vote
3 answers
409 views

Bpsk demodulator implementation

For a project I'm trying to implement a BPSK demodulator on some random wave files, I'm getting a few difficulties: How do I know my bit rate, i.e. how many bits each 'real data bit' I'm having. How ...
1 vote
1 answer
497 views

why does the decision boundary change in BPSK? is it true?

I am working on modulation and demodulation of BPSK using python. i made a code for modulation and demodulation,while demodulate i tried to compare my actual data bit stream with demodulated bit ...
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1 vote
2 answers
128 views

BPSK based audio digital communication system

As part of my diploma thesis I'm implementing digital communication system based on audio transmission in free space (STMF401RE + analog microphone). I'm using BPSK modulation and I've implemented ...
1 vote
1 answer
159 views

Phase correction algorithm: minimisation phase error

Thank you for your participation in my discussion in advance. I am working on the implementation of a phase correction. Currently, I have finished the algorithm. I think it is a standard algorithm ...
1 vote
1 answer
388 views

Detect low power DSSS-BPSK signal

I have heard that it is possible to detect a low power (ie not visible on a spectrum analyzer) DSSS-BPSK (direct sequence spread spectrum) signal even when you don't know the spreading code by ...
1 vote
1 answer
552 views

Is Phase Locked Loop is essential for BPSK signal reception?

I'm noob in DSP studying BPSK communication between speaker and microphone using acoustic signal. I read article of this BPSK communication which says it needs Phase Locked Loop(PLL) sequence to match ...
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1 vote
1 answer
2k views

Spectral Effeciency of BPSK

The null-to-null bandwidth of the main lobe of a BPSK signal is twice the symbol rate. BPSK transmits one bit per symbol, so the signal bandwidth is twice the bit rate. That has been shown on a few ...
1 vote
1 answer
642 views

Finding $E_b/N_0$ when coding rate is $R_c$

I would like to calculate $E_b/N_0$ when the code rate is $R_c$ for BPSK signal. What I got this $$ E_b/N_0= \frac{1}{2R_mR_c \sigma^2} $$ and that is the case also according to this page. $R_m=1$ ...
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