[time-nuts] Close in phase noise of microwave VCOs
jimlux at earthlink.net
Thu Jun 18 20:42:36 UTC 2015
On 6/18/15 10:05 AM, Mark Sims wrote:
> If you want to play with a homodyne doppler radar, search Ebay for "hb100 microwave sensor". It is a cute little 10 GHz doppler module that costs around $6. It can be operated in continuous or pulsed mode. The output does require a couple of op-amps to get a TTL level output.
Those a very cool (and, by the way, easy to blow up with ESD)
The real failing of them is that they don't give you I/Q output so you
can't distinguish motion towards and away. If they had added another
mixer, life would have been really nice.
As a practical matter, if you want to fool with building your own radar
from scratch, for ranges of up to, say, 10 meters, 1 mW radiated power
and about 50dB receiver gain works pretty well. You can get your gain
either at RF (e.g. with MMIC amps) or post mixer with op amps. That
will get you an output of "tenths of a volt" (the HB100 puts out
The HB100 uses a DRO and puts out about 10-15 dBm
For more radar fun, use a VCO so you can step the frequency, and then
you can do range synthesis (FMCW radar), and if you're really ambitious,
you can build a SAR.
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