HopeRF feedback

Werner Almesberger werner at openmoko.org
Fri Jun 25 19:41:28 EDT 2010


JDH services wrote:
> isn't the hard part of gmsk the demodulation?

I don't know enough about signal processing to tell with certainty,
but I would think so, too. Of course, if Silab's examples set up
the transmitter such that it generates a signal with all the
properties of MSK we could find, and Silab's examples aren't just
a hoax, then they must also have solved the demodulation.

This leaves the possibility that there are more properties we
haven't thought of yet. I guess the folks at qi-hw could just ask
HopeRF whether this is really MSK/GMSK or just something that
happens to look incredibly similar.

Whether the chips can do MSK or not can be relevant, because MSK
is closely related to OQPSK [1], which is used at quite a few
places (although most of them, e.g., ZigBee, are at 2.4 GHz.) So a
chip that is able to modulate/demodulate OQPSK would be more useful
than one that isn't.

[1] A "hands on" description of the difference can be found here:
    http://www.dsprelated.com/showmessage/62707/1.php

- Werner




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