# Questions tagged [dsp-puzzle]

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### DSP Puzzle: What network will create this waveform?

What network consisting of two unit sample delays, three multipliers (with constant gain coefficients), and three adders can we create to convert a square wave into the waveform as shown below: The ...
• 48.9k
151 views

### Adding Independent Noise

Signal processing often involves managing and optimizing Signal to Noise Ratio (SNR). To achieve this, one may need to work with noise budgets and ensure that any additional additive noise sources are ...
• 48.9k
277 views

### What is the frequency response of a filter with impulse response $h(t)=\frac{\cos(\omega_0t)}{\pi t}$?

Most of us have come across the impulse response of an ideal (continuous-time, unity gain) low pass filter with cut-off frequency $\omega_0$: $$h_{LP}(t)=\frac{\sin(\omega_0t)}{\pi t}\tag{1}$$ The ...
• 89k
152 views

### Subtract Lowpass from Wire to Get Allpass

One technique to make a high pass filter is to subtract a lowpass filter from a wire (meaning subtract the output of the filter from the input as I have demonstrated in this post). What lowpass can ...
• 48.9k
68 views

### Effect of Passband Slope on a BPSK Constellation

What is the effect of a passband slope on a BPSK constellation? (This is a companion question to the related "DSP Puzzle" for QPSK) Specifically given a linear slope (in magnitude, not dB), ...
• 48.9k
274 views

### Effect of Passband Slope on QPSK Constellation

What is the effect of a passband slope on a QPSK (or any QAM) constellation? Specifically given a linear slope (in magnitude, not dB), and no phase distortion (linear phase or even zero-phase) how ...
• 48.9k
411 views

### Questions about the sampling frequency mapping relation to 2π

Continued from the previous two questions Q3: When $f_o$ isn't a multiple of $F_s$ , can $F_s$ still map to $2\pi$？ Answer: $F_s$ always map to $2\pi$ under digital (normalized) frequency domain. Q4:...
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199 views

### How and why does sample frequency Fs be mapped to 2π?

Q1: Can anyone give a further explanation on this sentence? Each time $f_o$ is a multiple of $F_s$, the argument of the exponential is a multiple of $2\pi$ Q2: - must $f_o$ be a multiple of $F_s$?
• 19
188 views

### How to demodulate DominoEx-like signal with liquid dsp?

I found a proprietary protocol that is used on ham radio bands. The author have published details,claiming that it's a version of DominoEX with slightly different baud rate and FEC. I want to try to ...
199 views

### Algorithm to Count Zeros Outside Unit Circle for FIR Filter

As detailed in this post Can I set a constraint on the first tap of an FIR filter such that its inverse is stable? I show how Cauchy's Argument Principle can be used to easily confirm if an FIR filter ...
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1 vote
350 views

### Modelling zero padded OFDM as circular convolution between channel and FFT frame

This is meant to be a puzzle so please preface your answer with spoiler notation by typing the following two characters first ">!"  An often mentioned negative side of the zero padded OFDM is that it ...
• 2,602
649 views

### 2nd Order Type 2 PLL for Tracking Frequency Error

This is a "DSP Puzzle", Please preface your answer with spoiler notation by typing the following two characters first ">!" as the intention is for readers to think through what the solution might be ...
• 48.9k
1 vote
457 views

### Z-Transform and DFT

I have $$H(z) = \frac{\left[b_0 + b_1 \cdot z^{-1}\right]}{\left[1 + a_1z^{-1} + a_2 \cdot z^{-2}\right]}$$. Why is it that I can calculate the spectrum between $0$ and $0.5 \cdot f_s$ by calculating ...
1 vote
130 views

### Amplitude modulation in pure sine wave [duplicate]

I am generating sine wave in MATLAB with following code ...
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3k views

### What do the filter coefficients in digital filter represent?

Could you help me? How can I understand the function of the filter coefficients practically? In the simple case, it is the impulse response of the LTI system. but how do they work?
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1k views

### Where is the flaw in this derivation of the DTFT of the unit step sequence $u[n]$?

This question is related to this other question of mine where I ask for derivations of the discrete-time Fourier transform (DTFT) of the unit step sequence $u[n]$. During my search for derivations I ...
• 89k
736 views

### Simplest All Digital GMSK Modulator

How to simply implement an all digital GMSK modulator with no multipliers? The implementation approach should be applicable to GMSK modulation with $BT=0.5$ or less (where intentional ISI is ...
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2k views

### More Simultaneous Dynamic Range with Fixed Point or Floating Point?

What data path would have more simultaneous dynamic range: 32 bit fixed-point or 32 bit floating-point? Why? To clarify "simultaneous dynamic range": This is the ability to discern strong ...
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4k views

### Nyquist's Stability Criterion and Cauchy's Argument Principle

Background: Nyquist's Stability Criterion for linear-time-invariant systems makes use of Cauchy's argument principle to determine if any zeros in the characteristic equation are in the right-half ...
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434 views

### Convert a Park McClellan FIR Solution to Achieve Stop-band Roll-off

Often it is more desirable to have a roll-off versus frequency of the rejection in the stopband; for example resampling filters where all the alias image locations fold into the first Nyquist Zone. ...
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