DCCF Conversion

The official FCC document KDB558074 "Guidance for Compliance Measurements on Digital Transmission System, Frequency Hopping Spread Spectrum System, and Hybrid System Devices Operating under Section 15.247 of the FCC Rules" clearly states that DTS device can use DCCF conversion to obtain RSE results.

In November 2019, Telecommunication Certification Body (TCB) Council held a workshop where it further explained the DCCF applicability among DTS devices. It is an update to Q#3 in KDB558074.

For DCCF calculation formula, refer to Section 7.5 of ANSI C63.10-2020 American National Standard of Procedures for Compliance Testing of Unlicensed Wireless Devices or the calculation instructions in test report sample from "Certification Notes".

For duty cycle (△) description and instrument settings, please refer to Section 11.6 of ANSI C63.10-2020 American National Standard of Procedures for Compliance Testing of Unlicensed Wireless Devices, as shown in the figure below.

Suppose that in a certain FCC certification test, Ton = 144.23 μs = 0.144 ms, Tp = 1.26 ms, then Duty Cycle Value = 11.43% is calculated according to the formula: Duty Cycle Value = Ton/Tp. The test diagram for transmitted duty cycle value is shown below.

Then the FCC RSE average value is computed as follows.

1. Measure the RSE MaxPeak values directly.

   Table 1 Peak value reference

   Frequency (MHz)	MaxPeak (dBµV/m)	Limit (dBµV/m)	Margin (dB)	Height (cm)	Pol	Azimuth (deg)	Corr. (dB)
   1440.300000	42.18	74.00	31.82	200.0	H	265.0	1.2
   4802.900000	49.67	74.00	24.33	200.0	H	151.0	11.8
   7206.700000	60.08	74.00	13.92	150.0	H	44.0	15.3
   12010.900000	67.71	74.00	6.29	150.0	H	36.0	21.1
   16813.400000	59.62	74.00	14.38	150.0	H	226.0	24.5
   17646.400000	56.79	74.00	17.21	150.0	H	113.0	29.2

2. Calculate DCCF: DCCF =20 * log(Ton/Tp) = 20 * log (0.144/1.26) = -18.84 dB
3. Calculate average value: Average value = Peak value + DCCF
4. The average values obtained through conversion are shown below, obtained by subtracting 18.84 dB from the MaxPeak values presented in the table above.

   Table 2 Average value reference

   Frequency (MHz)	Average (dBµV/m)	Limit (dBµV/m)	Margin (dB)	Height (cm)	Pol	Azimuth (deg)	Corr. (dB)
   1440.300000	23.34	54.00	30.66	200.0	H	265.0	1.2
   4802.900000	30.83	54.00	23.17	200.0	H	151.0	11.8
   7206.700000	41.24	54.00	12.76	150.0	H	44.0	15.3
   12010.900000	48.87	54.00	5.13	150.0	H	36.0	21.1
   16813.400000	40.78	54.00	13.22	150.0	H	226.0	24.5
   17646.400000	37.95	54.00	16.05	150.0	H	113.0	29.2