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Difference between pi/4 QPSK and pi/4 DQPSK
Hi all, continuing on the difference previously stated, I just have a quick Q about the demodulation side of the the DQPSK, at the encoder im using the mapping: delta_phi(i) = phi(i) - phi(i-1) with QPSK mapping: B1 B2 phi 0 0 0 0 1 pi/2 1 1 pi 1 0 3*pi/2 and then i transmit only delta_phi across ... 27 May 2010 07:03
Soft decision decoding of Repetition code
Hi, I am trying to design a receiver structure for system with a channel code (Convolutional code/block code) followed by a repetition code at the transmitter side. I understand MAP/ML decoder for the combined code is optimal in terms reducing the Bit error rate of the system. I would like to use two optim... 27 May 2010 01:40
Direct form II transposed filter implementation
Hi, I am trying to implement the filter function in Matlab and it is described as "The filter function is implemented as a direct form II transposed structure: y(n) = b(1)*x(n) + b(2)*x(n-1) + ... + b(nb+1)*x(n-nb) - a(2)*y(n-1) - ... - a(na+1)*y(n-na) where n-1 is the filter order, which h... 25 May 2010 13:30
Correlation error derivation?
Say I'm correlating a known signal against a received signal, obviously there's going to be some error in my peak location due to noise. I know you can formulate the error as a function of bandwidth, correlation time and SNR, but I've never seen it derived. Does anyone know of a good resource that derives this varian... 25 May 2010 13:30
kalman filter to improve the gps data received from an iPhone
Hi, I am currently working on an navigation application for an iPhone device. The GPS data that I receive is not very accurate and I want to use a kalman filter. The problem is that I don't really know how to build the kalman equations for x and y coordinates. What kind of model should I use? ... 11 Jun 2010 01:37
not possible to receive data through DMA (McBSP)
Dear all i am trying to implement a McBSP transfer through DMA . i can transmit data through MCBsp using DMA but couldn't receive . i checked by polling the RXRD bit, data is coming , but when i changed it to DMA it is not working . hope experts in this group can help me in this case Thanks in advance for your... 27 May 2010 00:36
Gaussian assumption and Calculating the loglikelihood ratio
Hi All On AWGN channel (y=x+n), the LLR, L_y, corresponding to the channel output can be written as L=2/sigma^2*y, where x is BPSK modulated symbols. However, when the channel is frequency selective, and at the receiver end, a filter based equalizer (LE or DFE) is used to mitigate the ISI, do we still calcul... 10 Jun 2010 12:14
Interfacing 3adau1701 with 1 eeprom in i2c
hi all.. In my project(a 6 Channel audio device) i'm using three ADAU1701. In preliminary session of project i used separate eeprom for each ADAU. Since each ADAU carry less algorithm i thought to use single eeprom for 3 ADAU and to connect three using i2c mode. I used sigma studio s/w for coding. But here exis... 25 May 2010 06:55
Voice Quality Assessment in VoIP networks
There are two main methods to assess voice quality subjective and objective. Subjective method involves human listeners to evaluate voice quality thus being able to discover all relevant sides of voice quality. ITU has developed a set of recommendations for subjective testing including P.800 that defines an importa... 25 May 2010 04:47
Non-intrusive voice quality testing software for single-ended speech quality assessment
Modern standard methods for evaluating quality of transmitted speech Voice quality is one of the main characteristics of speech transmission systems. When analyzing voice quality one must not only consider audio signal degradation caused by transmission over telecom channels, but also specifics of speaker's voice... 25 May 2010 04:47
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