The XC900M acts as a Ubiquiti XR9 (and I _think_ SR9) by default;
it uses the same 900MHz<->2.4GHz downconverter mapping.
However it has an alternative frequency mapping which squeezes in a couple
more half/quarter rate channels. Since the default HAL doesn't support
fractional tuning (sub-1MHz) in 2.4GHz mode on the AR5413/AR5414, they
implement it using a jumper.
Datasheet: http://www.xagyl.com/download/XC900M_Datasheet.pdf
Thankyou to Xagyl Communications for the XC900M NICs and Edgar Martinez
for organising the donation.
Tested:
* XC900M <-> XC900M
* Ubiquiti XR9 <-> XC900M
TODO:
* Test against SR9 and GZ901 if possible (the IEEE channel<->frequency
mapping may not match up, thanks to the slightly different channels
involved)
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