FCC 15.249 要测试Duty Cycle吗？

2021-8-30 14:24| 发布者: 曾工| 查看: 9430| 评论: 5|原作者: 曾工|来自: 电磁兼容网

摘要: 47 CFR § 15.249 - Operation within the bands 902-928 MHz, 2400-2483.5 MHz, 5725-5875 MHZ, and 24.0-24.25 GHz. 15.249我们测试的时候不考虑duty cycle 占空比这个修正系数，按15.231的话，考虑这个duty cy ...

47 CFR § 15.249 - Operation within the bands 902-928 MHz, 2400-2483.5 MHz, 5725-5875 MHZ, and 24.0-24.25 GHz.

15.249我们测试的时候不考虑duty cycle 占空比这个修正系数，按15.231的话，考虑这个duty cycle的修正系数来算AV平均值的。

FCC 15.249 - CFR-2009-Title47 标准下载

CFR-2009-title47-vol1-sec15-249.pdf

FCC PART 15.249 TEST REPORT

FCC PART 15.249 TEST REPORT.pdf

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引用曾工 2021-8-30 14:29

47 CFR § 15.249 - Operation within the bands 902-928 MHz, 2400-2483.5 MHz, 5725-5875 MHZ, and 24.0-24.25 GHz.

(a) Except as provided in paragraph (b) of this section, the field strength of emissions from intentional radiators operated within these frequency bands shall comply with the following:

Fundamental frequency	Field strength of fundamental (millivolts/meter)	Field strength of harmonics (microvolts/meter)
902-928 MHz	50	500
2400-2483.5 MHz	50	500
5725-5875 MHz	50	500
24.0-24.25 GHz	250	2500

(b) Fixed, point-to-point operation as referred to in this paragraph shall be limited to systems employing a fixed transmitter transmitting to a fixed remote location. Point-to-multipoint systems, omnidirectional applications, and multiple co-located intentional radiators transmitting the same information are not allowed. Fixed, point-to-point operation is permitted in the 24.05-24.25 GHz band subject to the following conditions:

(1) The field strength of emissions in this band shall not exceed 2500 millivolts/meter.

(2) The frequency tolerance of the carrier signal shall be maintained within ±0.001% of the operating frequency over a temperature variation of −20 degrees to +50 degrees C at normal supply voltage, and for a variation in the primary supply voltage from 85% to 115% of the rated supply voltage at a temperature of 20 degrees C. For battery operated equipment, the equipment tests shall be performed using a new battery.

(3) Antenna gain must be at least 33 dBi. Alternatively, the main lobe beamwidth must not exceed 3.5 degrees. The beamwidth limit shall apply to both the azimuth and elevation planes. At antenna gains over 33 dBi or beamwidths narrower than 3.5 degrees, power must be reduced to ensure that the field strength does not exceed 2500 millivolts/meter.

(d) Emissions radiated outside of the specified frequency bands, except for harmonics, shall be attenuated by at least 50 dB below the level of the fundamental or to the general radiated emission limits in § 15.209, whichever is the lesser attenuation.

(e) As shown in § 15.35(b), for frequencies above 1000 MHz, the field strength limits in paragraphs (a) and (b) of this section are based on average limits. However, the peak field strength of any emission shall not exceed the maximum permitted average limits specified above by more than 20 dB under any condition of modulation. For point-to-point operation under paragraph (b) of this section, the peak field strength shall not exceed 2500 millivolts/meter at 3 meters along the antenna azimuth.

[54 FR 17714, Apr. 25, 1989, as amended at 55 FR 25095, June 20, 1990; 67 FR 1625, Jan. 14, 2002; 77 FR 4914, Feb. 1, 2012]

引用李亭亭 2021-8-30 21:41: 1,我司目前產品;主頻為923MHz/每次發射時間為8m/100m Sec 測試所引用之法規;

923MHz TX

限制於QP limit <= 94dBuV

2,因我司新客戶未來新產品有TX功率提高要求請貴司評估參考附件資料;是否有其他法規條文,能滿足下列條件

923MHz TX

PK limit <= 114 dBuV & AV limit <= 94 dBuV

引用曾工 2021-8-30 21:45: TX PK limit & AV limit与TX功率提高没有绝对的对应关系，不是说当Tx功率增大的时候，这个谐波杂散就一定会变高，只是说有这个谐波增大的可能。

谐波杂散的高低与工程师的设计以及RF filter的使用有很大关系，理论上我们的产品设计都是要主频也就是你说的Tx增大，而这个杂散理论上设计完美的话，是不存在的。所以，还是不要纠结这个功率增大会影响杂散的这个问题。

引用 xdouliu 2021-9-10 16:53: 曾工: TX PK limit & AV limit与TX功率提高没有绝对的对应关系，不是说当Tx功率增大的时候，这个谐波杂散就一定会变高，只是说有这个谐波增大的可能。谐波杂散的高低与 ...

15.249 测试的不仅仅是谐波杂散，更多的是对主频的限制。往往15.249测试主频容易fail.

引用曾工 2021-9-10 17:12: xdouliu 发表于 2021-9-10 16:53
15.249 测试的不仅仅是谐波杂散，更多的是对主频的限制。往往15.249测试主频容易fail.
...

是的，主频功率，频率偏移、边带，这些应该供应商的软件应该比较好处理。往往杂散难搞

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FCC 15.249 要测试Duty Cycle吗？

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