[Hackrf-dev] LF-HF front end for hams.

[Michael Ossmann]

On Fri, Jun 06, 2014 at 11:36:16AM -0400, Ariel M Gil wrote:
>
> Is anyone currently working on a front end to use hackrf as a
> practical HF transceiver for hams?

I have something in the works that might do the job, but I'm not sure if
it would meet your requirements exactly.

I am working on an "oscilloscope" front-end expansion board that plugs
into the baseband header.  It will have two BNC connectors with input
circuits compatible with common oscilloscope probes, and then there is a
bunch of adjustable gain between the inputs and the baseband header
(which directly connects to the dual ADCs).

Most of the design process is selecting amplifier ICs to provide gain
and single-ended to differential conversion.  My favorite part so far is
ADRF6516.  I particularly like the adustable filtering it provides.  The
only thing I don't like about it is that it has only one gain
configuration for both channels.  It would be nice to have some separate
gain control for each channel, so I am thinking about putting an
additional dual gain stage in front of the ADRF6516.  The best part for
the job may be AD8332.  Although it is expensive, it would give me quite
a bit of per-channel gain control and also does single-ended to
differential conversion which I need.

The board would be useful as a USB oscilloscope and data logger for
signals between 0 and 10 MHz (with a practical limit more likely around
8 or 9 MHz).  It would also be useful as a generic baseband receiver
that can plug into an external RF front-end either on a single input (10
MHz max bandwidth) or quadrature (20 MHz max bandwidth).

I would also like to add a transmit section to do basically the same
thing in the reverse direction, serving as an arbitrary waveform
generator or RF baseband transmitter, but I haven't started designing
that section yet.

Do you think this would meet your needs?

Mike