Disklavier

--- In disklavier@yahoogroups.com, James Fry <groups@j...> wrote:
> This sounds really cool - does it use some form of digital signing
on each 
> message, or strong encryption on the data stream to prevent this?

It's not encryption - it's a simpler scheme.

The radio module used by MIDIjet Pro uses a "direct sequence spread
spectrum" radio interface.  DSSS generates and transmits a redundant
bit pattern for each bit to be transmitted.  So, in addition to
separating units by frequency (the 31 channels), the units are
separated by code (they can use different sets of redundant bit
patterns - sometimes called chipping codes).  

Each radio module has a unique ID.  As a part of the manufacturing
process, the receiver and transmitter are "bound" together, such that
the transmitter learns the receiver's ID.  Based on this ID, the units
coordinate with each other and pick a common chipping code.

Hence, if I go to your concert, and I have my own MIDIjet Pro
transmitter, I can't send out data to your receiver even if I'm on the
same radio channel.  My transmitter has been bound to a different
receiver, uses a different chipping code, and your receiver will not
play back the data.

Regards,
Richard Audette
Classic Organ Works
http://www.organworks.com/midijet/
905-475-1275