Sharan Basappa (@Sharan123)

VLSI Manager. DSP is my area of interest apart from VLSI

Re: channel coding and puncturing

Reply posted 3 years ago (11/24/2019)
Ok. So, the receiver needs to be informed about the channel encoding configuration/control?

channel coding and puncturing

New thread started 3 years ago
with respect to puncturing associated with channel coding, I have a question.So, when a code word is punctured at the transmitted how does the receiver know the...

Re: Error correcting codes

Reply posted 3 years ago (11/18/2019)
Thanks.On memory less coding method:if a coding method does not involve delays of some sort. It means that output is a function of current inputs and not previous...

Error correcting codes

New thread started 3 years ago
Hi All,I would like to know if my understand as given below is correct,Error correcting codes can be classified into1) Block codesBlock codes are memory less2) convolution...

phase change

New thread started 3 years ago
Hi,Can anyone explain how to change the phase of a signal.For example, if I have a sine signal, how can I modify its phase?

5G NR, Numerology and bandwidth part

New thread started 3 years ago
I have a question related to 5G NR numerology and bandwidth part.I would like to refer to the following article as a reference.http://www.techplayon.com/5g-nr-bandwidth-part-bwp/Please...

Re: concept of bandwidth

Reply posted 3 years ago (10/26/2019)
Hello Rick, I think I am focusing with the term and hence the actual issue is not being discussed. I am copying part of your response below so that we can discuss...

Re: concept of bandwidth

Reply posted 3 years ago (10/25/2019)
Hello Rick,In digital domain, where data to be transmitted is available then I have to readout or sample the data before doing final RF processing to transmit. Probably,...

Re: concept of bandwidth

Reply posted 3 years ago (10/23/2019)
Hi Rick,I would like to reverse the process and ask my follow-up questions ...Assume, you have sampled an analog signal to produce time domain sequence x(n). Now...

Re: concept of bandwidth

Reply posted 3 years ago (10/22/2019)
Hello dgshaw,Regarding point 1 above.let me take an example so that I am not confused again.Let us take an array of data = [1,2,3,4,5,4,3,2,1,-1,-2,-3,-4,-5,-4,-3,-2,-1...

Re: concept of bandwidth

Reply posted 3 years ago (10/22/2019)
Hello Rick,I often get confused with the concept of bandwidth of a signal.Further, I also get confused when it comes to data transmission as the data exists as digital...

Re: concept of bandwidth

Reply posted 3 years ago (10/22/2019)
Hi Greg,Is it because you eventually transmit 8 bits in the former case vs 16 bits in the latter. The latter has 8 additional 0s even though both of them are equal...

Re: concept of bandwidth

Reply posted 3 years ago (10/21/2019)
Thanks, Greg.so, instead of having 1,2,3,4 if I have 2,4,6,8 numbers, you mean to say the bandwidth occupied by such a signal will change. I thought, only the power...

concept of bandwidth

New thread started 3 years ago
I am trying to understand the concept of bandwidth from a point of view of bandwidth occupied by a signal.Let me take an example to state my question.Let us assume...

FFT of a sine wave signal

New thread started 3 years ago
I am computing FFT of a sine wave signal. Since this is a signal with a single frequency, I was expecting FFT to give one spike indicating the presence of a single...

Re: OFDM questions

Reply posted 3 years ago (10/18/2019)
Thanks a lot. A few follow-up questions ...On question 1, so the LTE standard defines exactly which sub-carriers to be used then?On the NB-IoT, in case of a 2048...

OFDM questions

New thread started 3 years ago
I have a few general questions pertaining to OFDM ...Let us assume an 1048 point IFFT and number of number of sub-carriers as 600.1)  in this case, does it matter...

Re: channel capacity and data rate

Reply posted 3 years ago (10/13/2019)
Hello Mike,So, irrespective of what method I use to do source encoding or modulation method, the above equation stands?Also, a follow-up question.Since SNR is related...

channel capacity and data rate

New thread started 3 years ago
The max data rate for a given channel and SNR is given as,rate = available BW * log2(1+SNR)In the above equation, in using th term log2(1+SNR), is there a fundamental...

Octave code

New thread started 3 years ago
Hi All,Are there example octave code that shows different modulation schemes including quadrature modulation?Thanks,

Re: Few questions on wireless and LTE

Reply posted 3 years ago (09/29/2019)
thanks a lot

Re: Few questions on wireless and LTE

Reply posted 3 years ago (09/29/2019)
20MHz bandwidth means the signal occupies 20MHz of bandwidthHow can I ensure that the signal occupies 20 MHz bandwidth.I am sure it does not happen automatically. Is...

Re: Few questions on wireless and LTE

Reply posted 3 years ago (09/28/2019)
2) The modulation type is Orthogonal Frequency Division Multiplexing (OFDM), and the mixing you are describing sounds like "direct conversion"As I understand, first...

Few questions on wireless and LTE

New thread started 3 years ago
Hello,I have a few questions related to wireless and I will use LTE standard to put these questions.1) if we look at the sub-carriers frequency plot, we see sub-carriers...

Re: picture inter and intra prediction

Reply posted 4 years ago (05/06/2019)
jbrower,Thanks. I have seen multiple references. They explain pretty well how Intra and Inter prediction work in case of H.264 and H.265. However, I don't find description...

Re: inverse quantization

Reply posted 4 years ago (04/29/2019)
Sorry. I am not referring to IQ in the context of ADC/DAC. Sorry for the confusion.

Re: inverse quantization

Reply posted 4 years ago (04/29/2019)
Artmez,Yes, I am referring to IQ in the context of DCT and image processing.

inverse quantization

New thread started 4 years ago
I understand the process of quantization but I am unable to understand inverse quantization process.Can someone please provide some background into this?Thanks,

Re: half and quarter sample meaning

Reply posted 4 years ago (04/28/2019)
Thanks. Do you know why half pel or quarter pels are needed?Eventually, display is always in terms of pixels.

Re: half and quarter sample meaning

Reply posted 4 years ago (04/24/2019)
Hello all,Thanks for the replies. The snippet is from an HEVC tutorial.Anyway, I do understand what interpolation is in image processing context.But what I am not...

half and quarter sample meaning

New thread started 4 years ago
Hi everyone, I am new to the world of image and video processing and have been going through some documents to understand some basics. At multiple places, I see...

PHY, L1, Baseband

New thread started 4 years ago
I am often confused between PHY, L1 and Baseband processing.Are they same? if not, can anyone help with some explanation please.Thanks,

Re: Energy and power

Reply posted 5 years ago (07/28/2017)
Thanks a lot.

Energy and power

New thread started 5 years ago
I am trying to understand Energy and Power concepts as applied to discrete electrical signals.Is the concept of power needed because periodic signals will have infinite...

Re: complex exponential - what Am I missing?

Reply posted 5 years ago (06/15/2017)
Cedron,Thanks. I will take a look.

Re: complex exponential - what Am I missing?

Reply posted 5 years ago (06/14/2017)
Apologies. That was really stupid of me

complex exponential - what Am I missing?

New thread started 5 years ago
The following is from Wikipedia - https://en.wikipedia.org/wiki/Euler%27s_formulabelow is what I get when I try for 0 and 30 deg>> sqrt(cos(0)+sin(0))ans = ...

Re: DFT

Reply posted 6 years ago (05/20/2017)
Thanks to everyone for helping me on this topic.I have refined my earlier Matlab to include 3 different examples, as follows:1) example 1 - signal is a single tone;...

Re: DFT

Reply posted 6 years ago (05/16/2017)
I've never heard the term "observation window" applied to the frequency domain.  It may be correct in some philosophical way, but it'll confuse people.I think my...

Re: DFT

Reply posted 6 years ago (05/16/2017)
sure. Thanks a lot

Re: DFT

Reply posted 6 years ago (05/16/2017)
You should be careful about what you mean by "fully described".  Mathematically that may be fine.  You state fs=4*f0.  And, 4 samples only covers a time span...

Re: DFT

Reply posted 6 years ago (05/15/2017)
Thanks a lot. Some follow-up questions below.I did not understand what you mean by "I can compute DFT of 4 points and my N points in frequency domain cannot go...

Re: DFT

Reply posted 6 years ago (05/15/2017)
Thanks, Dgshaw6.1) You are correct.  If you have 4 time domain points, then you will have 4 frequency domain points. The frequency domain points will be complex...

DFT

New thread started 6 years ago
I would like to get some concepts cleared on DFT. I will use a single tone signal (say of frequency f0) in time domain to explain my questions.DFT equation for reference...

Re: DTFT of a signal

Reply posted 6 years ago (05/13/2017)
Kaz,This is DFT computation. I am not able to understand where the term (exp(-j*2*pi*k*n/N)) is computed in the DFT expression is computed. Obviously, something...

Re: DTFT of a signal

Reply posted 6 years ago (05/13/2017)
Dear Rick,You are right about computing DTFT at 401 discrete points.The idea is to evaluate X(e^j*omega) and examine its periodicity. That's the reason why it is...

DTFT of a signal

New thread started 6 years ago
I have re-created a Matlab code to compute DTFT of a signal. The example is from a text book.The following is the code:n = 1:10;x = (0.9*exp(j*pi/3)).^n;k = -200:200;w...

Re: Magnitude/phase vs real/imaginary

Reply posted 6 years ago (05/11/2017)
ok. Thanks. One follow-up question. Why is that we don't usually see plots of complex value directly. For example, if the following is the complex array:3+2j, 2+3j,...

Re: Magnitude/phase vs real/imaginary

Reply posted 6 years ago (05/10/2017)
I agree but my question is, what inference I can draw by looking at a re/im plot? I have looked at a few plots and I cant make much sense out of it. Magnitude/Phase...

Magnitude/phase vs real/imaginary

New thread started 6 years ago
In DFT plots, multiple plots are shown. One if magnitude/phase and second one being, real/imaginary.One can look at magnitude part of the plot and get an idea about...

Re: DFT of a signal and system

Reply posted 6 years ago (05/07/2017)
ok. thanks

Re: DFT of a signal and system

Reply posted 6 years ago (05/07/2017)
ok. thanks

Re: DFT of a signal and system

Reply posted 6 years ago (05/05/2017)
Ok. So, typically windowing is applied to incoming samples before they are passed to filer? Though in practical designs, I have not seen anyone implementing window...

Re: DFT of a signal and system

Reply posted 6 years ago (05/05/2017)
Thanks. I did not realize this.

Re: DFT of a signal and system

Reply posted 6 years ago (05/05/2017)
thanks

DFT of a signal and system

New thread started 6 years ago
I would like to know if there is any difference between the two purely from a DFT computation:a) DFT of a signalb) DFT of an impulse response of a LTI systemI assume...

Re: sum of sinusoids

Reply posted 6 years ago (04/28/2017)
This is how the plot looks like:

Re: sum of sinusoids

Reply posted 6 years ago (04/28/2017)
Hello Rick,Actually, I have taken screenshot for the plots. So, some portion of my windows background is appearing. I will update the code for modified L value...

Re: sum of sinusoids

Reply posted 6 years ago (04/27/2017)
This the code listing with updated frequencies:Fs = 100;            % Sampling frequencyT = 1/Fs;           % Sampling periodL1 = 100;            ...

sum of sinusoids

New thread started 6 years ago
I would like to know the consequence of adding 2 sinusoids of different frequencies. I assume that the result is not a pure sinusoid. I have tried a octave example...

Re: LTE Uplink transmit

Reply posted 6 years ago (04/15/2017)
thank you very much

Re: PAPR (peak to average power ratio)

Reply posted 6 years ago (04/15/2017)
everyone, thanks a lot for your responses

Re: LTE Uplink transmit

Reply posted 6 years ago (04/14/2017)
high PAPR results in higher power consumption. Is this the only issue? I have read that high PAPR will also result in sub-carrier interference. Is this correct?

PAPR (peak to average power ratio)

New thread started 6 years ago
I would like to know the relevance of peak to average power ratio and what is the ideal (or preferred) value? #OFDM

LTE Uplink transmit

New thread started 6 years ago
We know that in #LTE downlink transmit uses #OFDM but in case of uplink transmit, OFDM scheme is not used. Can someone explain the reason behind this?

Re: Hermitian matrix

Reply posted 6 years ago (03/28/2017)
thanks. Can you throw some light on the application of Hermitian matrix. I have seen this in the context of receive diversity in a wireless system where multiple...

Re: Hermitian matrix

Reply posted 6 years ago (03/28/2017)
thanks. Can anyone please let me know an application of Hermitian matrix?

Re: Hermitian matrix

Reply posted 6 years ago (03/27/2017)
thanks. I surely misunderstood matrix conjugate when element has only real form - a or a + 0*i

Hermitian matrix

New thread started 6 years ago
I would like to clarify about Hermitian matrix. I am referring to the following URL to understand this:http://mathworld.wolfram.com/HermitianMatrix.htmlIt is defined...

Re: code rate vs rate matching in FEC/Channel coding

Reply posted 6 years ago (03/26/2017)
fzzy,I assume that code rate is a simple function that can be part of any FEC block (Turbo, LDPC) and just needs FEC to select subset of FEC encoded bits. Probably,...

Re: code rate vs rate matching in FEC/Channel coding

Reply posted 6 years ago (03/26/2017)
slartibartfast,I am trying to understand the concept better. So, useing any standard (e.g. LTE) is fine. Is puncturing a part of rate matching scheme? I assume decisions...
I am getting a little confused between rate matching vs code rate as applied at FEC/Channel coding.How and when what code rate and rate matching is applied?Are these...

Re: Signal power at the receiver

Reply posted 6 years ago (03/10/2017)
Dear Fred,Thanks a lot. My follow up question is above, if you could kindly answer ...

Re: Signal power at the receiver

Reply posted 6 years ago (03/10/2017)
Dear dgshaw6,The waveforms shown are the RF or antenna input. You have assumed that these signals are what they look like when baseband data is transformed into...

Re: Signal power at the receiver

Reply posted 6 years ago (03/09/2017)
to explain my question further, please refer to the figure below. Both the signals are same except for the amplitude/power at the receiver. In this case, what difference...

Re: Signal power at the receiver

Reply posted 6 years ago (03/09/2017)
Q: Does the power at the receiver matter at the RF or the baseband stage?A: The receiver adds noise to the receive signal - so more signal power means more signal-to-noise-ratio...

Signal power at the receiver

New thread started 6 years ago
In the context of wireless communication, I would like to know the relevance of power at the receiver side. In literature it is mentioned that received power should...

Re: Sampling frequency in Baseband

Reply posted 6 years ago (03/08/2017)
Thanks, Oliviert. I think it is clear now.Occupied BW = 15000*1200Total BW = 15000*2048Sample rate = 1//total BW

Re: Sampling frequency in Baseband

Reply posted 6 years ago (03/07/2017)
oliviert,sorry, I am opening an old topic. referring to the equation: 30.72*1200/2048 = 18Though the value is 18 MHz, I am still not sure what the N point FFT has...

Re: measure signal power

Reply posted 6 years ago (03/07/2017)
thanks

Re: measure signal power

Reply posted 6 years ago (03/07/2017)
Kaz,in reality, such signals would cancel each other anyway even before they appear at the filter input. If I just compute power of 2 sine waves individually then...

Re: measure signal power

Reply posted 6 years ago (03/07/2017)
Kaz, Rick,I have used the approach given by Fernandoorg to measure power of various signals and it looks as below:1 power of input signal 1.994952 power of output...

Re: measure signal power

Reply posted 6 years ago (03/04/2017)
I hope I have done it correctly. The following is how the plots look like:

Re: measure signal power

Reply posted 6 years ago (03/04/2017)
Kaz,Thanks. I could do that but what can I expect assuming the filter is a low pass filter?

Re: measure signal power

Reply posted 6 years ago (03/03/2017)
All,Thanks a lot for your inputs.Dear Rick,Thanks. Probably, this is what I am looking for.I would like to come back to my main intention of computing the power.Input...

measure signal power

New thread started 6 years ago
I have implemented a filter and passing composite signal with multiple frequencies.I would like to measure the power of signal before and after filtering. This is...

Re: Cyclic prefix concept in LTE

Reply posted 6 years ago (03/01/2017)
Multipath propagation on primitive level makes two things: previous symbol can step on current one; current symbol can step on the next oneTo clarify, with multipath...

Re: Cyclic prefix concept in LTE

Reply posted 6 years ago (03/01/2017)
thanks, gmsk1. So, cyclic prefix itself does not eliminate interference effects but helps the receiver in equalization ...

Re: Cyclic prefix concept in LTE

Reply posted 6 years ago (03/01/2017)
rrlagic,thanks. Could you indicate how adding cyclic prefix reduces ISI?

Cyclic prefix concept in LTE

New thread started 6 years ago
I am trying to understand cyclic prefix concept that is used in LTE. Referring to the figure above, there are 3 copies of the symbol received by the receiver. So,...

Re: Filter design

Reply posted 6 years ago (02/27/2017)
Sigh! Why I did not think about this earlier. Yes, I was referring to sampling an analog signal when I referred to Fs.

Re: Filter design

Reply posted 6 years ago (02/27/2017)
Dear Rick,Sorry about that. To summarize, keeping f1 and f2 constant, we are varying Fs and deriving value of N for 2 cases of Fs. Is this correct understanding?If...

Re: Filter design

Reply posted 6 years ago (02/27/2017)
Dear Rick,Thanks. I want to clarify on your explanation.So, in the above example, f1 and f2 remain same.Fs is either Fs = 19200 or 384000 KHz.N is either 115 or...

Re: Filter design

Reply posted 6 years ago (02/27/2017)
Hi Kaz,I don't understand what you mean by f1 and f2 change with Fs. Typically, these are independent parameters I start with irrespective of Fs. Can you please...

Re: Filter design

Reply posted 6 years ago (02/25/2017)
Dear Rick,I am still trying to wrap my head around the equation and what you mention about the transition bandwidth being ratio of (f2-f1)/FsN = dB*Fs/(22*delta_f);So,...

Re: Filter design

Reply posted 6 years ago (02/24/2017)
Dear Rick,Case 1: f1 = 10000; f2 = 15000; Fs = 192000Case 2: f1 = 10000; f2 = 15000; Fs = 384000My design parameter remain the same in case 1 and case 2. In case...

Re: Filter design

Reply posted 6 years ago (02/23/2017)
Dear Rick,Keep design parameters same in the above equation, can I not Fs independently? This is the case I was referring to when I said increasing Fs

Re: Filter design

Reply posted 6 years ago (02/23/2017)
Dear Rick, Michael, Fred, Kaz,Thanks. I really appreciate your inputs. I think I am clear on the original question. At least, I have lot of input for consumption.One...

Filter design

New thread started 6 years ago
Pardon me if my question is very basic.I would like to know why in the design of an Filter in Matlab, one has to specify sampling frequency.It looks like the cut-off...

Re: MIMO naming convention

Reply posted 6 years ago (02/16/2017)
Thanks a lot ... this really helps

MIMO naming convention

New thread started 6 years ago
The MIMO naming convention seems confusing to me.SISO – Single Input Single Output system – 1 1 Tx antenna , 1 1   Rx antennaSIMO – Single Input Multiple...

Re: Source coding in WiFi or LTE

Reply posted 6 years ago (01/16/2017)
Thanks, fpgaplayer ...

LTE concept of TTI

New thread started 6 years ago
Hello All,The concept of TTI in #LTE has always confused me. I am giving a brief understanding from a base station perspective.So, assuming BW is fixed (e.g. 20...

Re: LTE power allocation

Reply posted 6 years ago (01/08/2017)
Apologies. That is my mistake

LTE power allocation

New thread started 6 years ago
Hello All,In case of #LTE, it is mentioned (http://www.sharetechnote.com/html/Handbook_LTE_Dow...) that control channels are made strong wrt to other channels. This...

Re: Source coding in WiFi or LTE

Reply posted 6 years ago (12/31/2016)
Makes perfect sense. I forget that entities like Basestations are just conduits for ends users data.

Re: Source coding in WiFi or LTE

Reply posted 6 years ago (12/31/2016)
Sorry, rrlagic. I am asking about source coding and not channel coding. In digital communication, Huffman or RLC are examples of source coding ...I have been working...

Source coding in WiFi or LTE

New thread started 6 years ago
Hi,I am interested to know what source coding method is used in case of #WiFi or #LTE. I assume Turbo coding or LDPC are used for channel coding.Thanks,

Re: down conversion vs de-modulation

Reply posted 6 years ago (11/25/2016)
Thanks a lot, Tarik

Re: down conversion vs de-modulation

Reply posted 6 years ago (11/25/2016)
Thanks a lot. I think I get it now ...

Re: down conversion vs de-modulation

Reply posted 6 years ago (11/19/2016)
Dear Rick,Currently, this is more of an hands-on to get better understanding. I assume your reference to low pass filter is due to 2 frequency bands that result...

Re: down conversion vs de-modulation

Reply posted 6 years ago (11/19/2016)
Dear Tarik,Thanks a lot such detailed explanation.you can create RRC filtered waveform which represents your information in digital domain, up sample it, convert...

Re: down conversion vs de-modulation

Reply posted 6 years ago (11/19/2016)
Hello Rick,Thanks for answering. I just implemented a small Matlab code for DUC and then I got this doubt. I used a pure sine tone to do this. My next exercise would...

Re: down conversion vs de-modulation

Reply posted 6 years ago (11/19/2016)
Hi Ahmed,Thanks a lot for the detailed explanation. One more question - what is the practical application of DDC or DUC?Thanks,

down conversion vs de-modulation

New thread started 6 years ago
I am a bit confused between digital down conversion and de-modulation (or up conversion and modulation). Let us assume I receive a modulated signal where a base...
Dear Fred and others,I think my incorrect terminology might have created confusion. I am sorry about that. So, let me re-phrase my question without using fancy/formal...
I have a question regarding FFT and representing a discrete periodic signal using DTFS.From the equation of DTFS, it appears that it is same as inverse Fourier transform.DTFS...

LTI system

New thread started 6 years ago
I would like to know if there an intuitive way, without going through rigorous maths, to check if a given system is LTI system or not.I have the following examples...

Re: LTE - concept of layer mapping

Reply posted 6 years ago (10/24/2016)
THanks. Can you explain, how in case of 3x2 system, layers = 2 is arrived at?

LTE - concept of layer mapping

New thread started 6 years ago
I am interested to conceptually understand the layer mapping stage in #LTE downlink processing.While all the literature clearly describe how the layer mapping is...

Re: convolution coding for FEC

Reply posted 6 years ago (10/15/2016)
All,Thanks a lot. YOu are right. I should probably spend a little more time on this topic. I have got access to MIT lecture notes. I will have a look ...thanks...

Re: convolution coding for FEC

Reply posted 6 years ago (10/14/2016)
Dear @drmike, @motilito, @Tim Wescott,Thanks a lot for spending your valuable time and providing inputs.Few additional questions based on the inputs:If there are...

convolution coding for FEC

New thread started 6 years ago
Hello,This question is to get concepts clear than nitty-gritties.In case of convolution coding, I am confused how puncturing where bits are removed at encoder and...

Re: Sampling frequency in Baseband

Reply posted 6 years ago (10/14/2016)
Hello Kevin,True. The 30.72 MHz rate is at the baseband and data is in terms of I & Q.

Re: Sampling frequency in Baseband

Reply posted 6 years ago (10/12/2016)
Thanks, Tim and Oliviert

Re: Sampling frequency in Baseband

Reply posted 6 years ago (10/12/2016)
Hello Tim,Thanks for the response. Actually, Nyquist in the above case confuses me a lot. They say occupied bandwidth of a 20 MHz system is 18 MHz. In that case,...

Re: Sampling frequency in Baseband

Reply posted 6 years ago (10/12/2016)
Just a follow-up question: 1 Symbol of baseband data has to be transmitted in ~66 us. Irrespective of the sampling rate, 1 symbol of baseband digital data has...

Sampling frequency in Baseband

New thread started 6 years ago
I would like to know importance of sampling frequency in the baseband. I am using #LTE as an example.If we take a 20 MHz system, the sampling frequency is specified...

Re: LTE Downlink TX understanding

Reply posted 6 years ago (09/27/2016)
Hello rrlagic,(OFDM symbol period) = 1 / (subcarrier spacing * IFFT size)Thanks. OFDM symbol period is constant across system bandwidth.Did you mean, sampling time...

Re: LTE Downlink TX understanding

Reply posted 6 years ago (09/27/2016)
Hello Prashant, This zero padding is done towards both positive and negative frequency bands(424 on each positive and negative end of the 2048 point IFFT) to ensure...

Re: LTE Downlink TX understanding

Reply posted 6 years ago (09/27/2016)
Hello Napier,Thanks. So, one question. Before the OFDM stage, the inputs are first mapped onto constellation points and then I/Q data go into OFDM stage. So, when...

LTE Downlink TX understanding

New thread started 6 years ago
Hello All,I would like to get some clarification wrt to the #LTE downlink process at the Basestation side.I am using a 20 MHz system to be specific in my questions.It...

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