Justification of Power

1106-EX-ST-2014 Text Documents

MIT Wireless Center

2014-12-07ELS_156672

In this exhibit, we justify our power levels based on:
Our correspondence with the FCC OET (Inquiry tracking #223852)
KDB 890966
FCC Part 15.517

The device operates indoors and transmits an FMCW signal, which continuously sweeps
between 5.46 GHz and 7.25 GHz. We consulted with the FCC OET (#223852) with respect to
measuring the average and peak power associated with an FMCW signal for our application,
and they referred us to KDB 890966. Hence, in what follows, we justify the device’s emissions
in accordance with KDB 890966.

Peak Power:
The device transmits a 0.12mW signal narrowband signal (1KHz bandwidth).
This is lower than the peak power requirement of 0dBm (1mW) of 15.517.

Average Power:
To calculate the average power, we follow the instructions for KDB 890966, which states that
the average factor is computed as follows:
Average factor = (sweep freq. time/sweep span in MHz)/cycle time
Given that the device continuously sweeps from 5.46GHz to 7.25GHz, and repeats every
2.5ms, the average factor is:
Average factor = (2.5e3/1790)/2.5e3 = 1/1790
Hence, the average power is: 0.12mW/1200 = 67.04uW. This corresponds to a power of
41.7dBm, which is lower than the 41.3dBm average power threshold according to 15.517

Document Created: 2018-12-07 23:50:07
Document Modified: 2018-12-07 23:50:07

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