I would maintain that this particular application is a gizmo
- of interest to an informed and well-resourced aficionado.
Without an effective external aerial, which would rather
defeat the ideal of portability of a smartphone, it is unlikely
to be impressive on MF. With a short wire antenna, it
might well perform on HF and above. It will certainly be
interesting to read empirical reports from users already
owning a high-end smartphone.

For MF applications, a uldx rx with DSP would be
preferable, especially when budget is an issue.

SDR radio implementations with more appropriate
hardware are indisputably now well established
and proven. Unfortunately, my resources do not
allow me to participate, although I would be interested
in a diy application with free software that would work
on an ancient system :-)

Michael UK
ex 9Q5TS