Shahram Shafie is a visionary RF/mmW/Microwave Architecture and System Engineer with a career spanning in both the academia and the industry. Currently, Shahram is providing 5G and IoT technologies consultation for transmitter and receiver chains in addition to market trends.

Re: Frequency planning in RF sampling ADCs

Reply posted 9 months ago (10/17/2020)
In general, ADC sampling rate is function of signal of interest BW.  The larger signal BW, the higher ADC sampling rate, Nyquist rate.
In my view if the impairment is AWGN both in RF or BB domain, the expected value for BER at given Eb/N0 or SNR should be the same. The fact that there is delta...
Sara,Based on Mike and Rick feedback, we can think of Imaginary numbers enable us/electrical engineers to keep track of "negative frequencies" or "Spectrum".Complex...
Hello Sara,Hope all is well.My view is that all numbers are a language to count something and keep track of "goods".Greek and Roman mathematicians believed in positive...

Re: ICI avoidance in OFDM

Reply posted 2 years ago (07/02/2019)
It sounds like you are assuming every single carrier in the OFDM signal is shifted by fixed amount and that is known to the receiver.  Is that correct understanding...

Re: inverse quantization

Reply posted 2 years ago (04/29/2019)
Sounds like you may be referring to "reconstruction" of signal after it is being "quantized". If that is the question, then you would need to learn about sampling...

Re: half and quarter sample meaning

Reply posted 2 years ago (04/23/2019)
Sounds like interpolating.  What is the context?
Hello naumankalia,The digitizer probably consists of ADC and DSP, according to your algorithm for noise calculation.Regarding ADC, the quantization noise within...
Hello Pramod,dB computations or calculations are in addition or subtraction.In fact, that is one of the two reasons going to logarithm in first place.The equation...

Re: Digital Modulator Artefacts

Reply posted 2 years ago (03/22/2019)
David,Would you share the datasheet?Best regards,Shahram Shafiehttps://ortenga.com/

Re: Digital Modulator Artefacts

Reply posted 2 years ago (03/21/2019)
Hello David,The span is 10GHz with 8.25GHz center frequency, therefore each horizontal division is about 825MHz. The unwanted lobes are roughly +/- ~200MHz around...

Re: Slow fading channel & SNR

Reply posted 2 years ago (03/13/2019)
"Slow fading" refers to comparison with respect to Symbol Rate, SR.There are Large and Small Scale Fading, see "Fading Manifestations and Mitigation Techniques"https://ortenga.com/blog/#FadingSmall...
Hello Sudarshan, I agree with Rick regarding more clarifications of the problem statement. In spite of that, let me makes some assumptions based on what may be...

Re: PSD estimation when I have oversampled data

Reply posted 3 years ago (01/18/2019)
Hello,There are at least 2 questions you posed.  In order to address them, it requires to clarify what you meant by "noise" in the "siganl(s) + noise process"?Noise...

Re: FMCW MIMO radar RX post processing pipe.

Reply posted 3 years ago (01/12/2019)
Hello,It appears that you have already answered the question, there will be some trade off.Perhaps, you can quantify the trade off DOA resolution angle vs. computation...

Re: Not understanding digital signal processing

Reply posted 3 years ago (01/06/2019)
If your question is regarding the following equationx(n) = sin(2pi * f * nt) = sin(2pi * f * nt + 2pi * m) = sin(2pi(f + m/nt)nt)Then, sinusoidal is periodic function,...

Re: Modulator output power level

Reply posted 3 years ago (12/05/2018)
...

Re: Modulator output power level

Reply posted 3 years ago (12/04/2018)
Here is the list of constraints that you need to find out, in order to design and budget analog vs. digital dynamic range. Maximum RF output power, FCC for North...

Re: Modulator output power level

Reply posted 3 years ago (12/04/2018)
Even for Radio or TV broadcasting stations where the transmitter output a fixed RF power, there is a need for dynamic range to account for part to part and temperature...

Re: choose the antialiasing filter

Reply posted 3 years ago (11/19/2018)
Although the datasheet does not refer directly to settling time, there are other parameters which are function of it. ADC has high input impedance, say 1KOhms,...

Re: Starting point for non-gaussian estimation

Reply posted 3 years ago (09/28/2018)
What would be the use case of "Non Gaussian" noise?That probably answer part of your question.Would the use cases include using Rayleigh or Rician distribution? Best...

Re: OFDM Constellation.

Reply posted 3 years ago (09/25/2018)
Any carrier could cause the smearing of the I/Q constellations.Can you remove them?

Re: OFDM Constellation.

Reply posted 3 years ago (09/25/2018)
The circle is in "const3.jpg" file, which is smearing all symbols.If the demodulator works with training symbols, then the recorded signal may have the impairment.  You...

Re: OFDM Constellation.

Reply posted 3 years ago (09/25/2018)
OK, the circle on the I/Q constellation represents CW/carrier (i.e. a sinusoidal). That is impairment that could be part of the recorded signal or generated by...

Re: OFDM Constellation.

Reply posted 3 years ago (09/25/2018)
Sounds like you are feeding the recorded data to your data analysis tool, such as matlab to demodulate the recorded signal, correct?What does "each Square" represent?I...

Re: OFDM Constellation.

Reply posted 3 years ago (09/25/2018)
...

Re: GFSK parameters

Reply posted 4 years ago (05/21/2017)
Hello dgshaw6,The frequency deviation is error in center frequency, and function of HW implementation, wouldn't be related to BT, 3dB BW.BT is related to 3dB BW...

Re: Bit width in a digital delta sigma

Reply posted 4 years ago (03/11/2017)
Hello Deba, In any data converter, i.e. ADC or DAC, the number of bits, ENOB, or dynamic range would be a function of required SNR, sampling frequency, adjacent...
Hello Nelson,Your questions are very interesting.My background is with Electromagnetic Waves, aka EM, however feel that some of wave attribute may apply to Sound...
Lucky_12,Distorted signal means, you cannot recover the original signal or information.Non-linearity causes distortion.  Here is a webinar on Non-linearity and...

Re: Why do we want an amplifier to be linear?

Reply posted 4 years ago (01/31/2017)
Hello Lucky_12,Adding to some of the answers regarding to your questions.Linearity of any device, including amplifier, is relative parameter.  In other words, any...

Re: TWTAs as compared to SSPAs

Reply posted 4 years ago (01/29/2017)
Hello Lucky_12,Sounds like everyone else has already answered your questions.Just wanted to add that by BW, that means the amplifier (or any other device) meets...
Case 1: you have a closed form equation, calculate the power at maximum and 1/2 power on each side of the beam in the plane you are interested, compute the half...

Re: Linear array Directivity Index

Reply posted 5 years ago (08/29/2016)
You can look up equation 3.92 in Antenna Theory and Design by Warren Stutzman and Gary Thiele for directivity of linear array, equally spaced elements.Keep in mind...

Re: Linear array Directivity Index

Reply posted 5 years ago (08/28/2016)
Why would you want array spacing greater than half wavelength?It would create Grating Lobe, Unwanted Lobe in undesired direction.That is why all literature keep...

Re: ADPLL vs Linear PLL

Reply posted 5 years ago (08/03/2016)
Hello Chess,This online webinar will be helpful to you.PLLhttps://ortenga.com/ortenga800/Best regards,Shahram

Re: Application of computer with invertible arithmetic?

Reply posted 5 years ago (07/25/2016)
Application Specific Integrated Circuits, ASIC, can be designed if the algorithm is robust and efficient.  Nowadays ASIC consists of billions of gates with GHz...

Re: Application of computer with invertible arithmetic?

Reply posted 5 years ago (07/25/2016)
5G technology will require more efficient yet robust data handling.  The 5G technology is in process of standarization, and if this new algorithm is any more efficient/implementable than...

Re: Application of computer with invertible arithmetic?

Reply posted 5 years ago (07/24/2016)
There are applications in Wireless Communications.Please let me know via email, if you would like to follow up with a video call forum to explore more.My consulting...

Re: "System Identification" Ideas

Reply posted 5 years ago (07/24/2016)
Hello Fred,Do you know all inputs and corresponding/desired outputs?If so, how many are there inputs vs. outputs?It should be manageable in coming up with an algorithm.Best...

Re: Application of computer with invertible arithmetic?

Reply posted 5 years ago (07/24/2016)
Hello Bob,What do you mean when you say "special forward linear transform algorithms without the need to specify any inverse algorithm"?Does that imply knowing FFT,...

Re: Phase locked Loop Bandwidth for second order system

Reply posted 5 years ago (07/20/2016)
You are welcome, Chess.If you want to learn more about PLL, look up the following webinar link;https://ortenga.com/ortenga800/Best regards,Shahram

Re: Phase locked Loop Bandwidth for second order system

Reply posted 5 years ago (07/16/2016)
Hello Chess,Here is a link to a paper with derivations in terms of PLL parameters;http://users.ece.gatech.edu/pallen/Academic/ECE_64...Keep in mind, these type of...

Re: Phase locked Loop Bandwidth for second order system

Reply posted 5 years ago (07/12/2016)
Hello Chess,There are number of ways to determine the loop bandwidth of PLL, it depends whether you are specifying PLL requirements based on application, having...

Re: Adding 45 degrees phase shift to a FIR bandpass

Reply posted 5 years ago (07/12/2016)
Hello Wolf,To my understanding, as an RF engineer, digital filter is weighting the magnitude of time signal.  On the other hand, a phase shifter is basically a...

Re: Zero IF vs Low IF receivers

Reply posted 5 years ago (07/11/2016)
Hello Tom,The Low IF signal is centered at 200KHz instead of ZIF that would be the difference.  If you are using I/Q processing, then the following article is the...

Re: A digital filter question

Reply posted 5 years ago (07/05/2016)
Hello Rick,Intuitively, it makes sense.  For instance, in case of LPF in the negative feedback; the low frequencies are subtracted from incoming, all frequencies,...

Re: A digital filter question

Reply posted 5 years ago (07/05/2016)
Thanks for response, Tim.Shahram

Re: A digital filter question

Reply posted 5 years ago (07/04/2016)
Thanks Rick.Happy 4thShahram

Re: A digital filter question

Reply posted 5 years ago (07/04/2016)
Hello Tim,I was wondering if you have any reference material that covers the theory behind this topic?if so, would you point me to that?Happy 4th,Shahram

Re: A digital filter question

Reply posted 5 years ago (07/04/2016)
Hello Rick,This is very interesting questions and answers.  I was wondering what you meant by "digital implementation"?Does that mean you are looking for impulse...

Re: Interleaved ADC Spurs and Levels

Reply posted 5 years ago (06/17/2016)
It is not clear the set up that you have, however if you set the signal generator to 10dBm, it does NOT mean that the ADC input is 10dBm.  There are signal generator...

Re: Starting A Sucessfull Independent Engineering Firm

Reply posted 5 years ago (06/17/2016)
You will need to: Define clearly the service or product and estimate competitive cost/price for it, competitive and differentiator analysis, i.e. business plan...

Use this form to contact shafie7

Before you can contact a member of the *Related Sites:

  • You must be logged in (register here)
  • You must confirm you email address