Active RADAR minimum pulse

Hello to all,

I am working on what approximates an active RADAR for the interrogation
of a temperature sensitive microwave resonator. For this project, I
will be using GNU Radio libraries and a USRP 1 device. In my research,
I have discovered some issues that might pertain to this project in
attempt to use the USRP in a RADAR application. Among these seem to be
the lack of synchronization between transmit and receive, issues related
to coherence with all but the BasicRX and BasicTX daughterboards (and
for these two boards, coherence depends on front-end provided by the
user), and a high minimum pulse width due to interpolation of the output

With regards to the issue of synchronization, I believe that for my
application I should be able to work around this problem as I do not
require precise time measurement. I do, however, need to be able to
ensure a particular response can be tracked with the excitation
waveform. This seems likely to be simple to implement. I do not
require phase coherence for my application, so this is not an issue

What I do need however, is to generate relatively short RF pulses. For
my application, a pulse time between 10 - 50 ns should be sufficient.
It seems to me that there is no way to bypass the interpolation that
occurs during digital up-conversion and thus the only way to operate the
DACs at there maximum rate is to interpolate. Can anyone confirm this?

What I am wondering is, could there be some way to create a buffered
output that can be used to generate a highspeed waveform that is not
interpolated or upconverted. For obvious reasons this waveform would
have to be periodic, but for my application and others like it, I don’t
see the issue here. Has this been done already? Any thoughts on how to
implement it?

~Jeffrey L., K1VZX

~Jeffrey L., K1VZX