There are several miniPCI
based radios that require half or quarter width channels on some
channels.
That *require* this?
For example, the Ubiquiti XR7 requires quarter width channels on two of
its
four available channels.
Regulatory wise? What's the restriction based on?
The XR9 requires half width channels on two if its
four available channels.
Same here, what's the restriction based on?
On 900 and the 4.9 Ghz public safety bands, the half or quarter channels are
required if you want to:
(a) Support multiple non-overlapping links within the legally allocated
bandwidth. For example, within 900 Mhz there is only 25 Mhz total available,
and only two 20-mhz channels defined (which, of course, overlap) so really
you've only got one. With 5 Mhz channels, you can operate legally near the
edge of the band without interfering with other 900 Mhz links, or
transmitting outside of the FCC allocated band.
(b) Operate legally and efficiently in the 4.9 Ghz public-safety band. The
upper and lower three channels defined by the FCC are 5Mhz and 10Mhz. 20 Mhz
operation there would violate the allocated band edges.
(b) Be compatible with other company's products that use these channels,
e.g. Proxim, Cisco, Ubiquiti, etc.
On 2.4 and 5.8 half and quarter aren't a legal requirement, but they
certainly are necessary for efficient operation!
Tom S.
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