
Publication Number: 384352 
Rule Parts: 
Publication Date: 04/09/2007 
Keyword: BPL Measurement Procedure 
First Category: 
Radio Service Rules 
Second Category: 
Part 15 General 
Question: If a proposed system has a signal with a bandwidth from 4 to 22 MHz, the midband frequency of 13 MHz., corresponding to the wavelength of 23.06 meters and the wavelength for the lowest frequency is 4 MHz (wavelength of 74.95 meters), how far out should the measurements go along the line, given these potential measurement points down the line: Wavelength, midband:0, 1/4, 1/2, 3/4, 1, 1&1/2, 2 And Distance Down Power Line (m) : 0 5.765, 11.531, 17.296, 23.06, 34.592, 46.123. If the 2wavelength point for the midband frequency exceeds the halfwavelength of the lowest frequency (which would be 37.475 meters), should the 2 wavelength measurement point be included? 
Answer: Appendix C (Measurement Guidelines for Broadband Over Power Line (BPL) Devices Or Carrier Current Systems (CCS) and Certification Requirements For Access BPL Devices) of Report and Order FCC 04245 (http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC04245A1.pdf) states the requirement as follows: "Testing shall be performed at distances of 0, ¼, ½, ¾, and 1 wavelength down the line from the BPL injection point on the power line. Wavelength spacing is based on the midband frequency used by the EUT. In addition, if the midband frequency exceeds the lowest frequency injected onto the power line by more than a factor of two, testing shall be extended in steps of ½ wavelength of the midband frequency until the distance equals or exceeds ½ wavelength of the lowest frequency injected." Thus, in the example cited in the question, the measurement at 1.5 wavelengths of the midband frequency does not meet the requirement that the greatest measurement distance must equal or exceed 1/2 wavelength of the lowest frequency injected, but the measurement at 2 wavelengths of the midband frequency does meet that requirement; consequently, measurements at both the 1.5 and 2 wavelength distances are required. 
 

