QPE6105A
FCC Certification Guide
– Bluetooth™ Low Energy Mode
Subject to change without notice | All rights reserved. © 2022-2023 Qorvo, Inc.
GP335_UM_20021 Version 1.00
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3.3
Bluetooth Low Energy Duty Cycle Correction Factor
3.3.1 Application limited
The maximum BLE TX duty cycle is application dependent. The maximum duty cycle is measured over a
100 ms observation interval.
If the application limits the duty cycle in a 100 ms interval to e.g., 10%, the correction factor for the average
spurious emission field strength becomes:
Correction factor is
20 * LOG (0.10) =
-20 dB
.
3.3.2 TX Frequency Domain Duty Cycle / Spreading
According to the Bluetooth Core specification, the minimum number of RF channels to maintain a BLE
connection is
2
. Consequently, if the connection interval is ≤ 50 ms, the RF energy in a 100 ms observation
period will be spread over at least 2 physical RF channels. The channel separation is N * 2 MHz (N = 1, 2,
3…) which is larger than the 1 MHz RBW filter that should be used according to the FCC.
Correction factor is
20 * LOG (0.5) =
-6 dB.
3.3.3 Summary FCC Duty Cycle Correction
IF connection int
erval is ≤ 50 ms the
frequency spreading
provides -
6 dB
duty cycle correction.
The maximum duty cycle in Application Mode, combined with the frequency domain spreading, results in a
total correction factor, in this example:
Total correction factor is
-
20 dB + -6 dB =
-26 dB.
FCC rules limits the correction factor to
-20 dB.
3.4
Measurement of Radiated Emissions at the Band Edge
To measure the band edge spurious emissions, please refer to the guidelines in FCC Publication 558074
[12].
NOTE
: according to Bluetooth Core Specification, 2 Mbit/s is not used on the advertisement channels. This
implies that the data rate on 2402 MHz, 2426 MHz and 2480 MHz is
1 Mbit/s
.
3.5
Bluetooth Low Energy Frequency Range
The BLE PHY supports 40 channels, these channels follow the BLE standard channel numbering.
These RF channels have center
frequencies 2402 + k * 2 MHz
, where k = 0 … 39.
“k” is the channel number.
The lowest RF frequency with k= 0 is 2402 MHz, the highest RF frequency with k= 39 is 2480 MHz.
3.6
Frequency Generation Scheme
3.6.1 TX mode
The local oscillator operates on 2 times the TX frequency. The local oscillator is directly modulated.
3.6.2 RX mode
The local oscillator operates on
(Fo + 2) * 2
, where Fo is the frequency of the RF channel [MHz].