>The Spectra
would be around $20k with external antennas. A licensed product is going to be
at least that, and probably $5k more.
Sit
back and actually think for a second about this comparison, and you'll realize
that a similarly performing "unlicensed" solution will cost
MUCH MORE (and be much riskier) relative to the licensed
solution
The
main difference is that the spectra requires 30 Mhz of ABSOLUTELY CLEAN SPECTRUM
in both the vertical and horizontal polarities (150 Mb "Air Rate" transmits on
V-pol & 150 Mb "Air Rate" transmits on H-pol -- cut off 1 polarity, you
halve throughput)
In
addition, the Rx sensitivity of the Spectra at the 300 Mb data rate (256 QAM) is
-59 dB with an output power of +18 (so you'll need HUGE dishes to guarantee the
link budget)
So,
lets do a "theoretical" path calc / comparison (15 miles)
11 Ghz
Licensed Link (100 Mb Full Duplex)
Rx
Sensitivity: -76 dBm
Tx
Power: +21 dBm
4'
Dish: +39 dBi
Expected RSSI: -42.9 (>30 dB of fade margin = ROCK SOLID LINK
=)
5 GHz
Spectra
Rx
Sensitivity: -59 dB
Tx
Power: +18
6'
Dish: +34 dBi
Expected RSSI: -49.4 (~10 dB of fade margin w/ 2' more of each
dish)
Then
there's all sort of "real-world" performance issues that occur with higher-order
modulation schemes and license-exempt operation
-Charles
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