CAPSat EMC Analysis

0343-EX-CN-2018 Text Documents

University of Illinois at Urbana-Champaign

2018-11-09ELS_219577

EMC Analysis Out of Band EMC Analysis Out of Band, CAPSat Introduction and Summary of Results Radio operating licenses have been requested from the FCC as follows: Lower frequency Center frequency Upper frequency Bandwidth [MHz] [MHz] [MHz] [kHz] Uplink 402.65 402.675 402.70 50 Downlink 401.15 401.175 401.20 50 This report provides a domestic and international electromagnetic compatibility study with existing users, as required by the FCC. The FCC OET and FCC International Bureau databases were searched, as were the ITU SNS and MIFR databases. From these queries, it was determined that coordination efforts are required with NOAA, GHGSat, and JC2Sat. Additionally, a radio station in Monterey Mexico was identified to be registered in the ITU MIFR database operating at a center frequency of 402.95 MHz. This station will hereafter be referred to as “the Monterey station”. It should be noted that a search of public records available online from the Instituto Federal de Telecomunicaciones (IFT), the official telecommunications regulatory agency of Mexico, yielded no licenses issued at the frequency 402.95 MHz in the state of Nuevo León where the Monterrey station is located. Though it is possible that records of past licenses may be incomplete, as the IFT only recently replaced its predecessor in 2013, the lack of any active licenses on file (as well as the 26-year time gap since the station was registered in the MIFR) suggests the possibility that the Monterrey station may no longer be in operation. All coordination efforts have been approved, and the ground station operations for CAPSat are not expected to interfere with the Monterrey station. Table 1 summarizes the identified relevant operators with whom coordination actions were taken, and the outcome of the coordination effort. Details for each effort are included in the appendix. Table 1: Summary of Coordination Efforts Operator Action Outcome Artifact NOAA Requested Coordination Approved Appendix Figure #1 Coordination GHGSat Requested Coordination Approved Appendix Figure #2 Coordination JC2SAT Requested Mission Cancelled Appendix Figure #3 Coordination Page 1

EMC Analysis Out of Band Power Flux Density at Earth Surface, Out of Band, Monterey Station The FCC requested an analysis for potential interference of the uplink (Ground station to CubeSat) Earth surface operations. This section analyzes the potential for interference with operation of the radio station in Monterey, Mexico. See Appendix Figure 4 for more information. Monterey Station Parameters Center Frequency: 402.95 MHz Bandwidth: 16.0 kHz EIRP: 17.8 dBW Radius of Operation: 25km Power Spectral Density at Maximum Radius of Operation: The Laboratory for Advanced Space Systems at Illinois (LASSI) operates a ground station located in Urbana, IL, at the Electrical and Computer Engineering building at the University of Illinois. The ground station uses an Ettus Research N210 software defined radio, operating at 50W output power, with an M2 401CP14 antenna having max gain of 11.5dBIc, cable loss of 7.4 dB, which will provide an estimated transmit power of 128.82W EIRP. According to preliminary tests conducted on the radio by students at the University of Illinois, the roll off of the transmitting spectrum at 50W power output will yield operational maximum power settings as follows: • -3 dB at 10 kHz; • -20 dB at 25 kHz; • -40 dB at 50 kHz; • -60 dB at 140 kHz, • -80 dB at 240 kHz, which just reaches the lower limit of Monterey Station Bandwidth In the uplink (ground station to CubeSat), an Ettus Research N210 SDR will be used with directional antennas and power amplifiers to deliver a transmit power of 21.1 dBW (128.82W). This analysis assumes the receiver in Mexico is in the middle of the beam at the highest gain point, even though the elevation of the antenna is always 10 degrees or above. Page 2

EMC Analysis Out of Band Power Spectral Density Analysis Uplink: Considering that the in-band power of the transmitting signal is approximately uniformly distributed over the operating bandwidth of 50 kHz, this results in a power spectral density of 128.82W / 50 kHz = 2.58W/Hz or 4.12 dBW/Hz. The out-of-band power of the transmitting signal is radiated through a 401CP14 11.5 dBi Yagi ground station antenna mostly in the adjacent 25 kHz bandwidth to the left and to the right of the operating band. The out-of-band PSD at 240 kHz away from the carrier frequency is attenuated by –80dB relative to the in-band frequencies, resulting in an out-of-band PSD of 11.5dBIc – 4.12 dBW/Hz – (80dB) = -72.62 dBW/Hz for these frequencies. The out-of-band frequencies of the transmitted signal will be further attenuated by propagation pathloss from the CAPSat ground station to Monterey station by a distance of 1,959km, which for the 401 MHz band (0.748 m wavelength) is equal to 150.3 dB. Pathloss Calculation: Thus, the out-of-band PSD at a potential satellite receiver operating in a bandwidth that is 240 kHz away from the operating bandwidth of the CubeSat radio, is -72.62 - 150.3 dB = -222.92 dBW/Hz. The interference analysis calculations are summarized in the following table: Table 2: Summary of Interference Analysis at Monterey Station Uplink Ground station: Monterrey Mexico Peak transmit power [dBW] 17.8 dBW In-band radiated PSD [dBW/Hz] 4.12 dBW/Hz Transmitting spectrum roll off at 240 kHz –80dB away from CAPSAT bands [dB] Transmit antenna gain [dBi] 11.5 dBi Path loss to DCS receiver [dB] 150.3 dB Out-of-band PSD at Monterey receiver -222.92 dBW/Hz [dBW/Hz] Page 3

EMC Analysis Out of Band Appendix Figure 1: NOAA Coordination Approval Page 4

EMC Analysis Out of Band Figure 2: GHGSat Coordination Approval Page 5

EMC Analysis Out of Band Figure 3: JC2Sat Mission Cancellation Page 6

EMC Analysis Out of Band Figure 4: ITU MIFR Database Results - Monterey Station Page 7

EMC Analysis Out of Band Page 8

EMC Analysis Out of Band Page 9


Document Created: 2018-11-09 09:49:10
Document Modified: 2018-11-09 09:49:10
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