EDMI Dual Band Variant 450 Communications Hub Variant
(CS-21)
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Version / Status: 1.2
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3
Appendix - Noise
3.1
Noise Limit
Noise limits for hosts as referred to in ICHIS (Intimate Communications Hub Interface
Specification):
WAN
Permissible noise floor rise above thermal noise: ≤7 dB between 453.0 MHz and 455.0
MHz
HAN
Permissible noise floor rise above thermal noise: ≤ 3.5 dB between 2.405 GHz and
2.480 GHz
Permissible noise
floor rise above thermal noise: ≤ 7 dB between 863.25 MHz and
872.85 MHz
3.2
Noise Calculations
3.2.1
WAN
From fundamental theory, thermal noise floor in a 20 kHz bandwidth (at room temperature of 296 K)
is: -173.87 + 10*log (20 kHz) = -130.86 dBm
The required minimum carrier to noise ratio of the communication scheme and the noise figure of
the Communications Hub internal design is used to find the minimum WAN TRS.
To maintain the WAN link budget the noise contribution from the ICHIS host has been set to 7 dB
above thermal in the 20 kHz bandwidth. This equates to: -130.86 + 7 dBm = -123.86 dBm
3.2.2
HAN 2.4GHz
From fundamental theory, thermal noise floor in a 2 MHz bandwidth (at room temperature of 296 K)
is: -173.87 + 10*log (2 MHz) dBm = -110.86 dBm
Adding the required minimum carrier to noise ratio of the communication scheme and the noise
figure of the Communications Hub internal design gives a minimum TRS of -91.5 dBm (see General
Specification above).
To maintain the HAN link budget the noise contribution from the ICHIS host has been set to 3.5 dB
above thermal in the 2 MHz bandwidth. This equates to: -110.86 + 3.5 dBm = -107.36 dBm
