# Thread: Question......Re K band tuning fork

1. ## Question......Re K band tuning fork

I have a tuning fork marked 80mph X band. Does anyone know what the correct speed should be if checked aginst a K band radar gun?

2. Thanks Jim, but ok how did you calculate this? Im curious now what the calculation is.

3. 1 MPH = 1609.344 meters per hour = .44704 meters per second

wavelength = speed of light / frequency
wavelength = 299792458 meters per second / 10525000000 hertz X band
wavelength = 0.0284838439904988123515439429928741

doppler shift = 2(speed)/wavelength
doppler shift (for X-Band @ 1 MPH) = 2(.44704)/0.0284838439904988123515439429928741
doppler shift (for X-Band @ 1 MPH) = 31.3890218012088883169969539403449 Hz

So, for doppler shift for 10.525 GHz X-Band @ 80 MPH:
80 * 31.3890218012088883169969539403449 = 2511.1217440967110653597563152272 Hz

wavelength = speed of light / frequency
wavelength = 299792458 meters per second / 24150000000 hertz K-Band
wavelength = 0.0124137663768115942028985507246377

doppler shift = 2(speed)/wavelength
doppler shift (for K-Band @ 1 MPH)= 2(.44704)/0.0124137663768115942028985507246377
doppler shift (for K-Band @ 1 MPH) = 72.0232661756954539530143883776728 Hz

2511.1217440967110653597563152272 Hz (80 MPH X-Band) / 72.0232661756954539530143883776728 Hz (1 MPH K-Band) = 34.8654244306418219461697722560009 MPH

Or, 35 MPH. :wink:

That is how it is calculated. But, it is much easier to remember constants for each frequency. IACP uses:
IACP X=mph by 31.3906
IACP K=mph by 72.0301

They are a little off from mine, maybe because of the value I used for the speed of light or something...

Jim

I certainly hope that was copied out of a text file and not done out of your head just for that post....

5. :shock:

6. No, I didn't copy that from a text file.

But, I kind of know the answer to the original question just from experience:

Another simple way to do it is download my "Radar Verifier" software. It has an option to display the doppler frequency for whatever speed you type in :wink:

Jim

7. Originally Posted by amoney
ditto lol. that is alot of numbers.

8. Wow, well thanks Jim I appreciate the explination but if I knew it was that involved I would not have put you through it. I do appreciate tho.

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