HopeRF feedback

Werner Almesberger werner at openmoko.org
Tue Jun 22 19:58:08 EDT 2010

Wolfgang Spraul wrote:
> How about 433 MHz? Is that a band that can be certified globally?

The 433 MHz band seems to be available everywhere. Unfortunately,
it's very narrow, with a width of only 1.74 MHz. The 915 MHz band
is a comfortable 26 MHz wide. [1]

868 MHz is also narrow (2 MHz) and seems to have a bunch of
additional frequency use restrictions, see [2].

It also seems to be easier to find alternative chips for the 915
MHz band than for 433 MHz. Not sure about 868 MHz. The Microchip
MRF49XA would be somewhat similar, although without the Gaussian
filter and all the packet handling the EZRadioPRO chips have.
According to [3], it's also based on the original EZRadio design
from Integration Associates.

Interesting detail: Microchip specify the same (very simple)
matching circuit for the 868 MHz and the 915 MHz band. [4]

[1] http://en.wikipedia.org/wiki/ISM_band
[2] http://iaf-bs.de/projects/ism-433-868.en.html
[3] http://www.microchip.com/forums/tm.aspx?high=&m=434798&mpage=1#434798
[4] http://ww1.microchip.com/downloads/en/DeviceDoc/70590b.pdf

- Werner

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