Questions tagged [linear-chirp]

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Bandwidth for a binary chirp spread spectrum system

Let's say data rate requirement for some application is 36Kbps. For a binary Chirp spread spectrum system, SF=6 is taken so that M=64. Time * bandwidth = 64. If binary 1 is represented as Upchirp and ...
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Object Detection using audible sonar

I am currently working on a project of identifying the position and angle of the objects in an environment using sonar (audible) about 1 to 2 m away from a desktop speaker within an angular sector of ...
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Relation between bandwidth and amplitude of auto correlation of chirp signal

I am trying to understand the properties of chirp signals and their characteristics. I plotted the autocorrelation of a chirp signal in MATLAB. How can I compute the relation between the amplitude of ...
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Frequency response of chirp signal changes when extracting burst from repeating chirp waveform

I hope i can make myself clear enough, even though i might not be familiar with the right terms. Using GNU Radio, i created a chirp signal with a sawtooth signal source into a frequency mod block, as ...
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guidance for designing a pilot signal

Introduction I wish to design a pilot signal which will be used to estimate the channel, and will be sent prior to data, on a wireless acoustic link (underwater acoustic communication). I've been ...
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question with chirped signal

I have some difficulty understanding the following question. I have written a code to plot continuous and discrete version of the chirped signal. ...
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Designing a Chirp in the Frequency Domain

I am trying to create a chirp signal in the frequency domain, by simply setting the magnitudes of each frequency bin to one, and then setting the phase delay function such that the resulting time ...
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4 votes
1 answer
286 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 ...
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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 ...
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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?
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643 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 ...
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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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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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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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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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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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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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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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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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1 vote
1 answer
7k 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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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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3 answers
1k 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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2 answers
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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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5 votes
4 answers
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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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2 answers
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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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3 votes
2 answers
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 ...
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4 votes
2 answers
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, but I can't figure out, without a good example, why would this result in spectral zooming? (or develop some time intuition like viewing it as ...
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1 answer
721 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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2 votes
1 answer
3k views

Basic question about chirp signal

Suppose I generate chirp signal with the following python code: ...
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2 answers
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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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3 answers
10k 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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4 votes
1 answer
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"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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4 votes
2 answers
901 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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2 votes
2 answers
956 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?
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