Questions tagged [linear-chirp]

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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-\...
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2answers
32 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 ...
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0answers
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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:
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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 ...
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2answers
211 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 ...
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1answer
69 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\...
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1answer
54 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),...
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1answer
290 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 ...
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0answers
139 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 ...
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1answer
3k 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 ...
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1answer
399 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 ...
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3answers
810 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 ...
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2answers
168 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 ...
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3answers
3k 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 ...
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1answer
193 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 ...
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2answers
894 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 ...
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2answers
929 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 ...
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1answer
639 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 ...
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1answer
2k views

Basic question about chirp signal

Suppose I generate chirp signal with the following python code: ...
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2answers
930 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. ...
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3answers
7k 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?(...
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1answer
316 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 ...
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2answers
812 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 ...
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2answers
792 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?