Re: Amplitude response of a Biquad Filter

Started by rkthebad in comp.dsp15 years ago 45 replies

Hello, I have implemented a 5-band equalizer in fixed point using the formulae provided in the Cookbook. I get the desired output when I...

Hello, I have implemented a 5-band equalizer in fixed point using the formulae provided in the Cookbook. I get the desired output when I intend to boost/cut the higher 4 bands. But, when I am trying to boost the first band, the output becomes distorted. I noticed that a cut on the first band works perfectly fine. Assumption : Wrong implementation of filter coefficients???? Well, ...


GSM Co-channel Interference Reduction

Started by hardheart in comp.dsp11 years ago 5 replies

Dear All, I am doing a project of GSM baseband signal processing and now facing the problem of how to reduce the cochannel and adjacent channel...

Dear All, I am doing a project of GSM baseband signal processing and now facing the problem of how to reduce the cochannel and adjacent channel interference. The main modules I have implemented are channel estimation and MLSE equalizer, but I find the MLSE performance in terms of Bit Error Rate is not good enough when interference exits. I have three questions here. 1, some internet artic...


some qustions about equalizers, timing and carrier recovery

Started by Pavel Schukin in comp.dsp14 years ago 1 reply

Hello, everybody! My questions are short: 1)Can i apply equalizer before timing reovery? Or I should get timing previously? 2) Are there...

Hello, everybody! My questions are short: 1)Can i apply equalizer before timing reovery? Or I should get timing previously? 2) Are there equalizers which adjust timing? 3) I have signal with dramatic ISI. Can I apply timing recovery if the eye opening is small? 4)Are there algorithms which get timing sinchronization of baseband GMSK signal having just I and Q components? 5)Are there algorit...


OFDM burst Size!!

Started by santosh nath in comp.dsp18 years ago 6 replies

Hi all, As we know the burst size is defined in GSM/EDGE mobile system as 156.25 symbols which takes 577 micro secs. This helps us to update...

Hi all, As we know the burst size is defined in GSM/EDGE mobile system as 156.25 symbols which takes 577 micro secs. This helps us to update our "Equalizer" burst by burst. The symbol synchronization is done per burst basis-meaning we calculate the time of arrival of a burst correlating known training sequence with received samples.After calculating the actual time offset we adjust start ...


Timing Recovery for Blind Demodulation

Started by McNab in comp.dsp15 years ago 7 replies

Hi! I'm working on a simulation of blind QAM demodulation in Matlab. So far i have implemented AGC, Carrier Phase tracking loop and a CMA...

Hi! I'm working on a simulation of blind QAM demodulation in Matlab. So far i have implemented AGC, Carrier Phase tracking loop and a CMA equalizer - but i have not yet implemented symbol timing recovery. I have seen numerous references to Band-Edge Timiing Recovery (BETR), wich seem to do the trick quite well. I just can't seem to find a lot of information on how it works! I have read "Pass...


Single carrier FDE

Started by Richard_K in comp.dsp13 years ago 1 reply

Hi, I wrote a MATLAB program for single carrier cyclic prefix (SC-CP) frequency domain equalizer (FDE)that is adapted by LMS algorithm. Based...

Hi, I wrote a MATLAB program for single carrier cyclic prefix (SC-CP) frequency domain equalizer (FDE)that is adapted by LMS algorithm. Based on the simulation results, it converges well. However, when the LMS algorithm is modified to NLMS algorithm, it couldn't converge. If given that x[n] is the column input vector to the FDE for the kth block, how should I normalize the step size? Is th...


Help with Orfanidis filters

Started by davidross in comp.dsp15 years ago 9 replies

Dear List, I am currently working my way through the following Orfanidis Paper - High-Order Digital Parametric Equalizer Design. It is...

Dear List, I am currently working my way through the following Orfanidis Paper - High-Order Digital Parametric Equalizer Design. It is available for download here - http://www.ece.rutgers.edu/~orfanidi/ece521/hpeq.pdf It describes how higher order parametric equalizers can be designed through first designing analog low shelf filters and then convert these to equivalent low shelf di...


Gaussian curve, logarithmic width

Started by Rock Lobster in comp.dsp14 years ago 4 replies

Hello, at the moment, I'm trying to implement a parametric equalizer using a gaussian curve. It actually works fine so far, but one thing...

Hello, at the moment, I'm trying to implement a parametric equalizer using a gaussian curve. It actually works fine so far, but one thing isn't really perfect: The width of the curve should grow by increasing frequency, which it doesn't at the moment. I'm programming with Java and my formula looks like this: y = Math.pow(Math.E, -q * Math.pow(frq, 2)) * gain * (1 / 2 * PI) for maybe b...


Linkwitz-Riley bandpass filter design

Started by carleeto in comp.dsp13 years ago 14 replies

Hi Everyone, I have read a lot about the good phase response of the Linkwitz-Riley filter and would like to design a 3 band equalizer using it....

Hi Everyone, I have read a lot about the good phase response of the Linkwitz-Riley filter and would like to design a 3 band equalizer using it. I will primarily be coding in C++. Most of the Linkwitz-Riley design guides that I have found online help one to design for analog circuitry. Could anyone could point me towards material that would help me to translate my 3 band eq from cut-off freq...


LTE OFDM timing synchronization

Started by gobruins in comp.dsp11 years ago 4 replies

we are working on the OFDM synchronization for 3GPP LTE, So far we have implemented the timing and fractional frequency synchronization using...

we are working on the OFDM synchronization for 3GPP LTE, So far we have implemented the timing and fractional frequency synchronization using the Maximum Likelihood method proposed in 'On Synchronization in OFDM Systems Using the Cyclic Pre?x'. The ML estimates of timing and frequency offset are then processed by the loop filter. It works pretty well. After the equalizer clearly I can tell


Efficient implementation of fractionally spaced equalizer

Started by S Singh in comp.dsp18 years ago 3 replies

I am trying to understand the efficient implementation of FSE, briefly described in...

I am trying to understand the efficient implementation of FSE, briefly described in http://spsc.inw.tugraz.at/courses/asp/ws01/schwingshackl.pdf (Fig 4) As an example of T/2 FSE, what I understand is that it separates out even and odd sample streams and apply the Tapped Delay Line (TDL) adaptive filters separately. the output of both filters are added. My question is how it is an efficient i...


Channel Equalization

Started by rider in comp.dsp17 years ago 3 replies

Hi! I want to add a channel equalizer into my my BPSK receiver. I have a confusion where to place this module. Either in pass-band or...

Hi! I want to add a channel equalizer into my my BPSK receiver. I have a confusion where to place this module. Either in pass-band or in base-band? Currently my receiver performs following sequence of events: 1) The received pass-band signal r(t) is sampled at Fs (8 times the symbol/bit rate fb) and demodulated using a Costas Loop carrier recovery and LPF. This LPF filter gives a base-b...


Sophisticated dynamic filter

Started by sdsp in comp.dsp16 years ago 4 replies

Hi I need to create a software dynamic digital filter running in windows XP with those characteristics: When the input level goes over the...

Hi I need to create a software dynamic digital filter running in windows XP with those characteristics: When the input level goes over the threshold, after a delay, the filter become active. When the input level returns under the threshold, the filtering in disabled after an other delay. The best situation would be to have a graphic equalizer filter, but a filter boosting highest frequen...


adaptive precoding and pre-equalization

Started by mobi in comp.dsp14 years ago 1 reply

I was trying to search through literature in order to find advantages and disadvantages of adaptive pre-coding and pre-equalization...

I was trying to search through literature in order to find advantages and disadvantages of adaptive pre-coding and pre-equalization over adaptive post-equalization. I failed. Can anyone point to a good reference. 2ndly on adaptive pre-equalization there are only three papers when we search ieeexplore. I was thinking of using indirect learning architechture as a pre-equalizer mentioned in D....


GMSK/MSK constellation derotation and Channel impulse response estimation

Started by ane in comp.dsp13 years ago 4 replies

I am trying to implement a GMSK receiver I have a block diagram of the receiver which is like this Received IQ Samples - > constellation...

I am trying to implement a GMSK receiver I have a block diagram of the receiver which is like this Received IQ Samples - > constellation derotation -> CIR estimation from training sequence -> MLSE (viterbi) equalizer The constellation derotation is supposed to collapse the four end points of GMSK constellations (+1, +j,-1,-j) to a two point (+1,-1) constellation. My question is how


Unbiased Correlation Estimate

Started by porterboy in comp.dsp17 years ago 3 replies

The Matlab function xcorr has an 'unbiased' option whereby the estimated correlation values are scaled by a value relative to their lag. How...

The Matlab function xcorr has an 'unbiased' option whereby the estimated correlation values are scaled by a value relative to their lag. How does this give an unbiased estimate? Any good references? A further question: I'm using xcorr to generate the correlation values in the Weiner-Hopf equations for an FIR equalizer. Should I use the 'unbiased' option? Cheers my Dears


ADDS-21161N-EZLITE SISD GraphicEQ Demo on VDSP++3.5

Started by in comp.dsp16 years ago 1 reply

Hello guys, I want to know if any of you has been able to run the SISD Graphic EQ demo which is included with VisualDSP++ 3.5 (and former...

Hello guys, I want to know if any of you has been able to run the SISD Graphic EQ demo which is included with VisualDSP++ 3.5 (and former versions of the tools). This is a nice demo, which runs a 10 band Graphoic Equalizer on the ADDS-21161N-EZLITE, with a nice interface on which the user, from within an EzKit session controls the sliders of the EQ. I remember I could run it on Visu...


Crossover networks. Can someone recall the name?

Started by Jerry Avins in comp.dsp16 years ago 72 replies

Vladimir Vassilevsky wrote: > > > Jerry Avins wrote: > > > > A linear-phase phono equalizer completely louses up the transient >...

Vladimir Vassilevsky wrote: > > > Jerry Avins wrote: > > > > A linear-phase phono equalizer completely louses up the transient > > response. A "perfect" linear-phase speaker crossover often sounds much > > worse that the minimum-phase analog approximation that it replaced. > > > > Don't look at the transient response and linear phase will sound just as > good as the minimal pha


reduction of noises using FRM technique

Started by enricophpdsp in comp.dsp11 years ago 1 reply

hello, I read the IEEE paper published by Yong Lian and Jiang Hong Yo ,2004 on the topic THE REDUCTION OF NOISES IN ECG SIGNAL USING FREQUENCY...

hello, I read the IEEE paper published by Yong Lian and Jiang Hong Yo ,2004 on the topic THE REDUCTION OF NOISES IN ECG SIGNAL USING FREQUENCY RESPONSE MASKING BASED FIR FILTER. In this paper the author has proposed a modified FRM technique in which he is using prefilter-equalizer filter. I want to ask that why this modified technique has been used instead of the conventional method ? ...


Fair comparison between time domain equalizer and OFDM

Started by cpshah99 in comp.dsp11 years ago 10 replies

Hi All So far I have worked on time domain equalizers such as LE and DFE. Recently I have started to work on OFDM systems. And I am trying to...

Hi All So far I have worked on time domain equalizers such as LE and DFE. Recently I have started to work on OFDM systems. And I am trying to compare the performance for Proakis channel B which is three tap channel. First system: map the info bits to BPSK, pass the symbols through channel, add noise. The channel output I write it as y=conv(h,x)+noise, where h=[0.407 0.815 0.407] and x= +/-...