Hello Matt,

Looked at your project -- very interesting and novel. My basic advice is to
get the Pic to do more of the work for you, both on the outgoing and
incoming signals. A lot of your incoming circuitry can be reduced with
algorithms in the microcontroller.

FYI, we did a commercial sonar project years ago with a PIC 16C57 (no
interrupts) that resolved to .6 inches over greater than the range you
mention. Basically you just have to sample the incoming waveform more
frequently. Are you using the Murata, Polaroid or other transducers?

Tom

> I'm hoping to use it as a sensor on a roving robot.  I
> concentrated on resolution- so I can resolve things to from
> about 6 inches
> to about 4 feet (until I get a 16C711) which will double the
> range to a
> whopping 6 feet.  My resolution within that range is about 2 inches.
>
> My azimith resolution is poor, due to the transducers that
> I'm using,  I've
> found much more focused transducers, but they are much larger
> and far more
> expensive.  I fully realize that size and gain are coupled,
> but I'm hoping
> I can figure out a way to increase gain (and correspondingly
> the resolution)
> without resorting to a far more expensive transducer.  A couple of the
> ideas I have been toying with are parabolic reflectors and
> phased arrays of
> transducers (actually just multiple transducers placed the
> proper number of
> wavelengths apart, driven in paralell).
>
> So, please take a look, and let me know what you think.
>