# Tag Info

Accepted

### Interpretation of Clarke's Doppler power spectral density

A simple, "non-technical" way of thinking of it is the fact that the Doppler frequency is proportional to $\cos\theta$. The amplitudes of cosine, however, are not uniformly distributed, but are ...
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### Radar signal processing flow chart

Part of your misunderstanding comes from the fact that there are many ways in which the radar signal processing chain is implemented. Depending on the type of radar, targets of interest, hardware, etc....
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### Interpretation of Clarke's Doppler power spectral density

In addition to Carlos answer, I want to correct your general understanding: What I understand of Doppler spread is that the relative motion between Transmitter (TX) and Receiver (RX) change the ...
• 6,218
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### How to remove the modulation before doing frequency offset estimation?

For lower-cardinality PSKs like the QPSK, the "classical" way is to take the signal to the $M$th power, $M$ being the number of constellation points. From the shape of an $M$-PSK modulation, ...
• 31.1k
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### In case of using a Doppler radar, do we have to use IQ demodulation to find the direction of a target?

Radar designer here: It sounds like youâ€™re talking about pulse-Doppler (PD) radar systems. For PD radars, the process is essentially as you described: Generate a waveform (typically at IF) and then ...
• 863
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### Use of complex numbers to calculate Doppler effect?

Bottom Line First What you suggest will only work if your signal is at baseband and not at a carrier, which is usually the best way to do any simulation work regardless. If your signal is not at ...
• 51.9k
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### Matched filter loss due to frequency offset

Short answer; I'll try to come back and improve this later. Recall that a matched filter is equivalent to a sliding correlator. At each time instant, the sliding correlator multiplies the last $T$ (...
• 24.6k
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### Doppler shift in satellite communication systems

I would recommend playing around with one of the predict libraries e.g. https://github.com/nsat/pypredict You can go find a TLE of a satellite you're interested in from a public database, and enter ...
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### Doppler Map for a beginner pulsed radar

When correlating the signals using xcor(code below) the output signal is greater then the Matrix column size. What portion of that information is needed? This is because the default parameters of <...
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### How to interpret an Ambiguity function

The ambiguity function is used in radar systems to get the distance and the relative speed of a moving object with respect to the transmitter. Is called ambiguity because it also tells about the ...

### Pulse Doppler Radar: how to filter its Range-Doppler matrix?

Two suggestions that may independently, or combined, help to solve your problem. Consider using a different window/weighting function for your FFT processing. There are window functions with low ...
• 1,175
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### Does Radio Communication Have to Account for the Doppler Effect?

Does radio communication have to account for the doppler effect? Yes. Would be pretty terrible if that wasn't the case: RADAR wouldn't work! Do moving objects such as planes and rockets have to ...
• 31.1k

### range-doppler map to range-velocity map conversion

First some background. In radar the relationship between range rate, $v$ and Doppler frequency offset, $\Delta f$ is given by: $$v = -\frac{c}{2} \frac{\Delta f}{f_c}$$ where $c$ is the speed of light ...
• 1,175
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• 51.9k
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### MTI RADAR, DSP algorithm question

The second way is how it is done. In the fast-time (or range-bin dimension) you are right to perform the matched filter. However, Doppler information is gathered from sampling pulse-to-pulse. The MTI ...
• 2,546

### Fast/Slow Fading: How are doppler shift and coherence time related?

Here's an intuitive explanation. Imagine a communication system (wireless) in a static environment (maybe picture the inside of a closed warehouse). There will be an amount of fading, but it is static:...
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### Doppler shift in signals

It is well-known that Doppler effect shifts the received frequencies compared with the emitting frequencies. On the other hand, the time period of the sound signal is often ignored. Say a sound source ...
• 3,248
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### range-doppler map to range-velocity map conversion

In a range-Doppler map (RDM), you actually have two sample rates that define the two dimensions of the matrix: Fast-time dimension. This is usually established by the ADC to sample the pulse return. ...
• 2,546
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### unambiguous velocity $V_\max$ in radar doppler processing

Both are actually correct, but it depends on what Doppler $f_D$ frequencies we want to observe. If we only want to observe positive Doppler frequencies, that is, targets with closing (approaching) ...
• 2,546
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### doppler tolerant phase coded waveforms

You should really read this paper, Phase Coded Waveforms for Radar, on doppler tolerance and phase coded waveforms. I'll summarize section 5 on doppler intolerance for phase coded waveforms. PC ...
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