Chirp or Pure Tone?
Chirp or Pure Tone?
(OP)
Hello, I was wondering whether to use a linear chirp or a single frequency in measuring the doppler shift. We are using a monostatic setup and are emitting a frequency of 21k. Standard radar practices say to use a linear chirp instead of a pure tone. Why is that?
Thanks
Thanks





RE: Chirp or Pure Tone?
TTFN
I can do absolutely anything. I'm an expert!
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers
RE: Chirp or Pure Tone?
"21k" = 21 kHz? Audio? Is this a school project?
RE: Chirp or Pure Tone?
Thanks for the website IRstuff. However, I don't believe that range nor resolution is an issue in the setup I have.
RE: Chirp or Pure Tone?
TTFN
I can do absolutely anything. I'm an expert!
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers
RE: Chirp or Pure Tone?
The other case, where the object is moving (let's say towards you), will look like a horizontal line followed by a time delay (this time delay will be different in duration, shorter in fact, then the previous case) and then another horizontal line (higher then the first due to the doppler effect). Given the time delay and the speed of sound, is it possible to find the distance to the person?
The person / object is moving; so the object moving towards you will have a speed v1 and the speed of sound will be c. The time it takes to receive the signal is t. So the equation to find the distance from the source (which emits the pure tone) to the object would have to involve calculus because the distance is constantly changing. Correct?
Edit: Calculus is not involved. I just though about it and the only thing that matters is the distance and instant the sound wave and the moving object collide. This can be treated like the first case, at that instant, the object is stationary and the sound wave reflects off. The only thing to account for then is the velocity of the object after the sound wave hits it.
RE: Chirp or Pure Tone?
RE: Chirp or Pure Tone?
TTFN
I can do absolutely anything. I'm an expert!
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers
RE: Chirp or Pure Tone?
If one was really ambitious, one might use two waveform concepts at the same time (within a pulse). Either at two adjacent frequencies, or perhaps even (conceptually) stacked hierarchically.
RE: Chirp or Pure Tone?
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?