Questions tagged [linear-chirp]
The linear-chirp tag has no usage guidance.
28
questions
2
votes
1answer
53 views
Demodulating a LoRa data symbol
LoRa integrate data into symbols by selecting the starting frequency of an up chirp. The resulting up chirp traverses across BW and arrives at the same place it started. At the demodulator, this chirp ...
0
votes
1answer
52 views
Is it possible to observe more area in azimuth than physically traveled in stripmap SAR?
I have been examining stripmap SAR algorithms, mainly Range Migration Algorithm. When I check the textbook examples so far I always saw the data trajectory is larger than scene that is observed. An ...
0
votes
1answer
64 views
Range Compression
How exactly is the SAR image resolution increased by the linear frequency modulation of the transmitted signal and further by the compression of range and azimuth?
0
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2answers
102 views
Phase of the chirp signal
I'm having a tough time understanding the phase increments which are quadratic in nature in the chirp signal. When I see consecutive samples, what will I see in terms of phase and if I have to measure ...
0
votes
1answer
216 views
Equation of wave in Linear frequency modulation?
We know that we have the following equation for wave.
$$g(t)=A\cos(\omega t+\theta_0)=A\cos(2\pi ft+\theta_0)$$
The equation of frequency with respect to time will be:
$$f(t)=\frac{Bt}{\tau}+f_c-\...
0
votes
2answers
51 views
Chirp after T seconds
Suppose we have this signal from this wiki page
$a(t)=\sin(\varphi_o + f_0t + (f_1-f_0)t^2/T)$
The article tells that T is a period of chirp modulation in which frequency changes. So my question is ...
0
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0answers
44 views
Need help with detecting onset of audio in wav file
I'm new to DSP and I'm learning as I go. I have an audio file with a chirp signal(2kHz). I played and recorded this chirp signal and the recording has a lot of environmental sounds.
Here is my code:
0
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0answers
91 views
Chirp resolution as a function of bandwidth
My question concerns about the Chirp resolution during the crosscorrelation as a function of the sampling rate and available bandwidth. Suppose at a transmitter a chirp signal is transmitted (ranging ...
2
votes
2answers
417 views
Doppler Shifting A Chirp Signal
So I have a digital linear chirp signal:
$$ x[n] = \sqrt{\frac{2}{N}} \cdot \cos\Big( 2 \pi \frac{f_{0}}{f_{s}}n + \pi \frac{B}{N} n^{2}\Big) $$
Where $f_{0}$ is the initial frequency, $f_{s}$ is ...
1
vote
1answer
121 views
Carrier frequency of chirp signal
I am computing the link budget for a communication-radar (CoRadar) system. The formula for maximum distance, in communication, is:
$d_{max} = \sqrt{\frac{P_t}{\tau}\frac{G_t G_{r, comm} \lambda^2}{(4\...
0
votes
1answer
60 views
finding the audio pulse compression peak in extra-low SNR scenario?
I just want to obtain some general ideas for such a scenario: if the environmental noise is extremely strong and the audio signal at the receiver is extremely weak(for instance, low range propagation),...
0
votes
1answer
449 views
matched filter of chirp signals
In simulating linear frequency modulated (LFM) chirp signals, with the parameters:
Pulse width, bandwidth.
I find the matched filter response to be this:
In particular, there is a increase in the ...
0
votes
0answers
180 views
Spectrum of received signal from radar fm-cw
I obtained actual data from a researcher, consisting of a matrix composed of several received signals from an up-ramp fm-cw radar.
Wouldn't be reasonable to plot the spectrogram of a ramp up and ...
1
vote
1answer
4k views
What is meant by LFM (Linear Frequency Modulation) waveform?
I m a newbie in radar experiment on which currently i m working, and I m trying to understand the transmitted waveform which is LFM (Linear Frequency Modulation), but unable to interlink between the ...
0
votes
1answer
568 views
chirp signal - Frequency spectrum characteristics
I am confused with my own intuition of the frequency response of a chirp signal.
In this case, the chirp signal is a frequency modulated signal with initial frequency starting at 100 Hz and ending at ...
4
votes
3answers
989 views
Matched filter loss due to frequency offset
I'm working with a pulsed radar signal which uses linear chirp pulses. I perform pulse compression by applying a matched filter of the simulated chirp waveform and recording the location and power of ...
1
vote
2answers
182 views
Decoupling two signals where one is a delayed version of the other
I have a signal $y(t)$ that consists of the sum of two signals where one is a time delayed version of the other.
$ y(t) = x(t) + x(t-t_{d}) $
$x(t)$ is known but the time delay $t_d$ is not.
I ...
4
votes
3answers
4k views
Pulse Compression(Chirp) SNR Gain
I've created both single tone signal and a LFM chirp signal with same pulse duration and cross correlated both of them with their own(matched filter). Peak points of both results were same as expected ...
0
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2answers
296 views
how fast can you sweep sinewave
I am asking specifically about discrete sound signal, non dithered 16 bit 48000 Hz pcm/wav format.
My question is, how fast can you change sinewave frequency before it distort? Imagine a frequency ...
3
votes
2answers
1k views
The frequency response function (FRF) fails to detect the antiresonance of a system
I am trying to identify a vibrational systems by computing the frequency response function (FRF) of the system when a chirp signal is applied to its input. After comparing the FRF computed and the ...
3
votes
2answers
2k views
Can anyone explain how does CZT (Chirp Z Transform) really help in 'spectral zooming'?
I found some explanation alongwith the Matlab Code here: http://prod.sandia.gov/techlib/access-control.cgi/2005/057084.pdf
but I can't figure out, without a good example, why would this result in ...
0
votes
1answer
680 views
FMCW SAR chirp return from target modelling
I have to Model a chirp signal that was return from a Distance D from target and then multiply with the reference transmitted signal. Which will give me beat frequency signal and then fft to get the ...
1
vote
1answer
2k views
Basic question about chirp signal
Suppose I generate chirp signal with the following python code:
...
0
votes
2answers
1k views
Spectrogram of a chirp and its FFT
This question follows from an answer to this other question: Conceptual question on FFT and chirp signal
I wrote a code starting from the spectrogram to compare it with the FFT result.
...
3
votes
3answers
8k views
Conceptual question on FFT and chirp signal
If I take the FFT of a sinusoid I will get a plot whit all the energy of the signal concentrated at the sinusoid frequency. But what happens if I have a signal in which the frequency keeps changing?(...
4
votes
1answer
337 views
“chirp” with arbitrary period
Say you have a linear chirp, which is a bit like a sinusoid with a gradually increasing period, but instead of the linearly increasing period, could you pick an arbitrary value, like the red line in ...
4
votes
2answers
840 views
Finding linear chirp parameters from a low quality spectrogram, possibly with image processing techniques?
tl;dr: What is a fast way to get the equation of this line?
I have to extract the "line of best fit" from this data (shown below), and many others like it (so I need a robust method). It is a a ...
2
votes
2answers
841 views
How can the FFT be used for estimating linear chirp parameters?
Consider a linear chirp signal, i.e. $f(t) = f_0 + kt$, where $f_0$ is the starting frequency, and $k$ is the chirp rate. After applying an FFT, how would I find the starting frequency and chirp rate?
