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Re: FMCW radar question...



Willam,
I would guess that either your FM modulation is too narrow or your receiver
has a narrow pass band. You will always see changes in output at the
detector from the phase interference and doppler from moving targets. A
stationery target is related to the frequency shift related to the roung
trip time mixing with the frequency a the time of arival of the return
signal. 12.4 microseconds per natutical mile was the round trip time used to
calibrate ships radars. You need a triangular waveform to modulate the
oscillator. As a NM is 6000 feet, 60 feet would give you a time of .124
microseconds. If your carrier (output of the Gunn Diode changed 100 KHz per
microsecond, you should have a frequency of 12.4 KHz for a target at 60
feet.

Hope this helps,
Art KC6UQH
----- Original Message -----
From: William Leijenaar <pe1rah@yahoo.com>
To: <amsat-bb@amsat.org>
Sent: Friday, April 22, 2005 6:44 AM
Subject: [amsat-bb] FMCW radar question...


> Hi AMSATs,
>
> Are there any hams that have (design) experience with
> FMCW radar systems ???
>
> I am doing some experiments with a self made system to
> get it working as a distance meter.I have a modulated
> 10GHz signal as source (I see it on Spec.Analyser),
> but the only thing it detects is movement but not
> distance of a none moving object.
>
> It seems that physics is not working right here,
> I am out of options, and looking for sugestions...
>
> It seems a none amsat topic, but for a future moon
> landing mission this radar might be helpfull ;o)
>
> 73
> William
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