System Technical Description Exhibit 2

0178-EX-CM-2018 Text Documents

General Motors Research Corporation

2018-08-23ELS_214709

Exhibit #2 GPS Re-Radiation System Technical Description GM proposes to install the five (5) fixed GPS re-radiation GLI-Metro-G repeaters which will be located indoors in the test crash hall, which is a facility/building located at the General Motors Milford Proving Grounds in Milford, Michigan. The building in question is used exclusively for GM operations to conduct vehicle crash testing and telematics system testing under a variety of constraints and scenarios. A total of two rooftop active antennas (one existing, one new) will be used and locations are as follows: No. Rooftop Antenna Latitude Longitude Location (receives GPS signal from satellites) 1. Active Antenna FCC license acquired already 2. Active Antenna 42°33'52.76"N 83°40'42.19"W Outdoor/Rooftop The locations of the GPS Repeaters (with their attached passive transmitting antennas) for which GMRC seeks approval are given in the following table. Repeater A is existing and an FCC license has already been acquired for it; only a change in power level is being proposed. GMRC proposes to add Repeaters B, C, D, E, and F to the license. Repeater Transmitting Equipment Latitude Longitude Location A GLI-Metro-G Repeater 42°33'56.60"N 83°40'42.70"W Indoor B GLI-Metro-G Repeater 42°33'55.53"N 83°40'42.70"W Indoor C GLI-Metro-G Repeater 42°33'54.10"N 83°40'42.70"W Indoor D GLI-Metro-G Repeater 42°33'54.10"N 83°40'42.41"W Indoor E GLI-Metro-G Repeater 42°33'52.54"N 83°40'42.41"W Indoor F GLI-Metro-G Repeater 42°33'52.54"N 83°40'42.48"W Indoor 1

Below is the system diagram of the crash test facility, showing the GPS repeater locations. Below is the aerial view of the crash test facility with the GPS repeater locations (A is existing, B, C, D, E, and F are proposed). 2

Emission Calculations Emission calculation per antenna/GPS repeater1 are explained below, and compliance with Redbook section 8.3.27 is demonstrated. For simplicity the calculations are performed as if the antenna were omnidirectional, i.e. the figure for forward gain (gain in the main lobe) is used in all directions. This simplification is acceptable because it never falsely indicates compliance with Redbook section 8.3.27; the simplification never results in understatement of the power (and in some cases results in overstatement of the power). Repeater A re-radiates both L1 and L2, while Repeaters B, C, D, E, and F re-radiate L1 but not L2. Power Settings The GPS repeater offers an output power setting, which is a whole number from -85 to -65 inclusive. It specifies the output power of the repeater, which is then supplied to the passive transmitting antenna that is attached to the repeater. The proposed output power settings in order to receive good coverage in the crash test facility are as below: Repeater Transmit ERP L1 Transmit ERP L2 Units A -65 -65 dBm B -70 NA dBm C -70 NA dBm D -70 NA dBm E -70 NA dBm F -65 NA dBm Assessment against 8.3.27 section “e” Section 8.3.27 of the NTIA “Manual of Regulations and Procedures for Federal Radio Frequency Management (Redbook)”, Sept 2017 Revision of the Sept 2015 edition, states the following in section “e”: “The area of potential interference to GPS reception (e.g., military or contractor facility) has to be under the control of the user.” In this request for license modification GMRC considers the “area of potential interference to GPS reception” to be the area in which the received power (as EIRP) is greater than -140 dBm. The crash test facility (the building shown earlier) is located inside the GM Milford Proving Grounds, which is a large private access controlled campus surrounded by a fence. Thus this campus is clearly under the control of the user. For each repeater, the area in which the received power is greater than -140 dBm EIRP falls completely within this campus, and thus the area of potential interference to GPS reception is under the control of the user. Therefore the proposed solution is in compliance with 8.3.27 section “e”. The calculations that support this claim are provided below. First we define the area of potential interference for each repeater by calculating the distance of the -140 dBm threshold from that repeater. 1 Each GPS re-radiator consists of a repeater with an attached passive transmitting antenna. 3

After that we show that all of these areas of potential interference are within the GM Milford Proving Grounds and thus are “under the control of the user”. Calculate areas of potential interference Antenna A - L1 Calculation Label Parameter Value Units Notes / Formula A Transmit ERP 316 pW Output power of repeater B Frequency 1575.42 MHz L1 center frequency C Distance 505 feet Distance at which received power falls below -140 dBm EIRP = D * 3.2808 feet/meter D Distance 154 meters Distance at which received power falls below -140 dBm EIRP E Free Space Path Loss 80.1 dB = 20 * log(B) + 20 * log(D) - 27.55 F Transmit ERP -65.0 dBm Output power of repeater = 10 * log(A / 1,000,000,000) G Transmit EIRP -62.85 dBm Output power of repeater = F + 2.15 H Antenna Gain 3 dBi I Received Power -140.0 dBm =G–E+H Threshold of Interest 4

Antenna A - L2 Calculation Label Parameter Value Units Notes / Formula A Transmit ERP 316 pW Output power of repeater B Frequency 1227.60 MHz L2 center frequency C Distance 459 feet Distance at which received power falls below -140 dBm EIRP = D * 3.2808 feet/meter D Distance 140 meters Distance at which received power falls below -140 dBm EIRP E Free Space Path Loss 77.2 dB = 20 * log(B) + 20 * log(D) - 27.55 F Transmit ERP -65.0 dBm Output power of repeater = 10 * log(A / 1,000,000,000) G Transmit EIRP -62.85 dBm Output power of repeater = F + 2.15 H Antenna Gain 0 dBi I Received Power -140.0 dBm =G–E+H Threshold of Interest Antenna B - L1 Calculation Label Parameter Value Units Notes / Formula A Transmit ERP 100 pW Output power of repeater B Frequency 1575.42 MHz L1 center frequency C Distance 284 feet Distance at which received power falls below -140 dBm EIRP = D * 3.2808 feet/meter D Distance 86.7 meters Distance at which received power falls below -140 dBm EIRP E Free Space Path Loss 75.2 dB = 20 * log(B) + 20 * log(D) - 27.55 F Transmit ERP -70.0 dBm Output power of repeater = 10 * log(A / 1,000,000,000) G Transmit EIRP -67.85 dBm Output power of repeater = F + 2.15 H Antenna Gain 3 dBi I Received Power -140.0 dBm =G–E+H Threshold of Interest 5

Antenna C - L1 Calculation Label Parameter Value Units Notes / Formula A Transmit ERP 100 pW Output power of repeater B Frequency 1575.42 MHz L1 center frequency C Distance 284 feet Distance at which received power falls below -140 dBm EIRP = D * 3.2808 feet/meter D Distance 86.7 meters Distance at which received power falls below -140 dBm EIRP E Free Space Path Loss 75.2 dB = 20 * log(B) + 20 * log(D) - 27.55 F Transmit ERP -70.0 dBm Output power of repeater = 10 * log(A / 1,000,000,000) G Transmit EIRP -67.85 dBm Output power of repeater = F + 2.15 H Antenna Gain 3 dBi I Received Power -140.0 dBm =G–E+H Threshold of Interest Antenna D - L1 Calculation Label Parameter Value Units Notes / Formula A Transmit ERP 100 pW Output power of repeater B Frequency 1575.42 MHz L1 center frequency C Distance 284 feet Distance at which received power falls below -140 dBm EIRP = D * 3.2808 feet/meter D Distance 86.7 meters Distance at which received power falls below -140 dBm EIRP E Free Space Path Loss 75.2 dB = 20 * log(B) + 20 * log(D) - 27.55 F Transmit ERP -70.0 dBm Output power of repeater = 10 * log(A / 1,000,000,000) G Transmit EIRP -67.85 dBm Output power of repeater = F + 2.15 H Antenna Gain 3 dBi I Received Power -140.0 dBm =G–E+H Threshold of Interest 6

Antenna E - L1 Calculation Label Parameter Value Units Notes / Formula A Transmit ERP 100 pW Output power of repeater B Frequency 1575.42 MHz L1 center frequency C Distance 284 feet Distance at which received power falls below -140 dBm EIRP = D * 3.2808 feet/meter D Distance 86.7 meters Distance at which received power falls below -140 dBm EIRP E Free Space Path Loss 75.2 dB = 20 * log(B) + 20 * log(D) - 27.55 F Transmit ERP -70.0 dBm Output power of repeater = 10 * log(A / 1,000,000,000) G Transmit EIRP -67.85 dBm Output power of repeater = F + 2.15 H Antenna Gain 3 dBi I Received Power -140.0 dBm =G–E+H Threshold of Interest Antenna F - L1 Calculation Label Parameter Value Units Notes / Formula A Transmit ERP 316 pW Output power of repeater B Frequency 1575.42 MHz L1 center frequency C Distance 505 feet Distance at which received power falls below -140 dBm EIRP = D * 3.2808 feet/meter D Distance 154 meters Distance at which received power falls below -140 dBm EIRP E Free Space Path Loss 80.1 dB = 20 * log(B) + 20 * log(D) - 27.55 F Transmit ERP -65.0 dBm Output power of repeater = 10 * log(A / 1,000,000,000) G Transmit EIRP -62.85 dBm Output power of repeater = F + 2.15 H Antenna Gain 3 dBi I Received Power -140.0 dBm =G–E+H Threshold of Interest 7

Distances from repeaters to edge of area under the control of the user The crash test facility building is located inside the GM Milford Proving Grounds. This private access controlled campus is surrounded by a fence which constitutes the edge of the area under the user’s control. The closest fence to the building is the fence that lies to the south of the building and runs east-to-west. In the below figure, this fence is the red line near the bottom. Orange brackets/text in the figure show the approximate distances between the various repeaters and the southern fence. As shown in the above figure: • The distance from Repeater A to the fence is 381 meters. • The distance from Repeater B to the fence is 348 meters. • The distance from Repeaters C and D to the fence is 304 meters. • The distance from Repeaters E and F to the fence is 256 meters. 8

Summary and Conclusion The following table summarizes the above results: Area of Potential Interference vs. User Control Repeater Band Distance at which Distance from Area of potential received power falls repeater to edge interference is under below -140 dBm EIRP of campus control of user? (meters) (meters) A L1 154 381 YES A L2 140 381 YES B L1 86.7 348 YES C L1 86.7 304 YES D L1 86.7 304 YES E L1 86.7 256 YES F L1 154 256 YES For each repeater the area of potential interference is under the control of the user, and therefore the proposal is compliant with Redbook section 8.3.27 section “e”. Assessment against 8.3.27 section “f” As stated above the proposed solution is in compliance with 8.3.27 section “e”. Therefore the requirements of section “f” are not applicable. However for completeness we assess each repeater against the requirement in section “f” below. Section “f” imposes a maximum permissible EIRP in dBm called “𝑃𝑇𝑚𝑎𝑥”, which is calculated according to the following formula: 𝑃𝑇𝑚𝑎𝑥 = 𝑃𝑅 + 20 log10 𝑓 + 20 log10(30 + 𝑑) − 27.55 Where: 𝑃𝑇𝑚𝑎𝑥 is the maximum permissible EIRP in dBm 𝑃𝑅 is the power received at 30 meters from the building (i.e. -140 dBm/24 MHz) 𝑓 is frequency in MHz (i.e. 1575.42 for L1, 1227.60 for L2, 1176.45 for L5) 𝑑 is the distance between the radiator and the closest exterior wall of the building in meters. The following calculations determine 𝑃𝑇𝑚𝑎𝑥 for each repeater. 9

Antenna A - L1 Calculation Label Parameter Value Units Notes / Formula A 𝑃𝑅 -140 dBm Power received at 30 meters from the building B 𝑓 1575.42 MHz L1 center frequency C 𝑑 7.24 meters Distance between the radiator and the closest exterior wall of the building D 𝑃𝑇𝑚𝑎𝑥 -72.2 dBm Maximum permissible EIRP = A + 20 * log(B) + 20 * log(30 + C) − 27.55 E 𝑃𝑇𝑚𝑎𝑥 60.3 pW Maximum permissible EIRP = 10(D/10)+9 Antenna A – L2 Calculation Label Parameter Value Units Notes / Formula A 𝑃𝑅 -140 dBm Power received at 30 meters from the building B 𝑓 1227.60 MHz L2 center frequency C 𝑑 7.24 meters Distance between the radiator and the closest exterior wall of the building D 𝑃𝑇𝑚𝑎𝑥 -74.3 dBm Maximum permissible EIRP = A + 20 * log(B) + 20 * log(30 + C) − 27.55 E 𝑃𝑇𝑚𝑎𝑥 37.2 pW Maximum permissible EIRP = 10(D/10)+9 Antenna B - L1 Calculation Label Parameter Value Units Notes / Formula A 𝑃𝑅 -140 dBm Power received at 30 meters from the building B 𝑓 1575.42 MHz L1 center frequency C 𝑑 9.22 meters Distance between the radiator and the closest exterior wall of the building D 𝑃𝑇𝑚𝑎𝑥 -71.7 dBm Maximum permissible EIRP = A + 20 * log(B) + 20 * log(30 + C) − 27.55 E 𝑃𝑇𝑚𝑎𝑥 67.6 pW Maximum permissible EIRP = 10(D/10)+9 10

Antenna C - L1 Calculation Label Parameter Value Units Notes / Formula A 𝑃𝑅 -140 dBm Power received at 30 meters from the building B 𝑓 1575.42 MHz L1 center frequency C 𝑑 5.93 meters Distance between the radiator and the closest exterior wall of the building D 𝑃𝑇𝑚𝑎𝑥 -72.5 dBm Maximum permissible EIRP = A + 20 * log(B) + 20 * log(30 + C) − 27.55 E 𝑃𝑇𝑚𝑎𝑥 56.2 pW Maximum permissible EIRP = 10(D/10)+9 Antenna D - L1 Calculation Label Parameter Value Units Notes / Formula A 𝑃𝑅 -140 dBm Power received at 30 meters from the building B 𝑓 1575.42 MHz L1 center frequency C 𝑑 4.61 meters Distance between the radiator and the closest exterior wall of the building D 𝑃𝑇𝑚𝑎𝑥 -72.8 dBm Maximum permissible EIRP = A + 20 * log(B) + 20 * log(30 + C) − 27.55 E 𝑃𝑇𝑚𝑎𝑥 52.5 pW Maximum permissible EIRP = 10(D/10)+9 Antenna E - L1 Calculation Label Parameter Value Units Notes / Formula A 𝑃𝑅 -140 dBm Power received at 30 meters from the building B 𝑓 1575.42 MHz L1 center frequency C 𝑑 4.61 meters Distance between the radiator and the closest exterior wall of the building D 𝑃𝑇𝑚𝑎𝑥 -72.8 dBm Maximum permissible EIRP = A + 20 * log(B) + 20 * log(30 + C) − 27.55 E 𝑃𝑇𝑚𝑎𝑥 52.5 pW Maximum permissible EIRP = 10(D/10)+9 11

Antenna F - L1 Calculation Label Parameter Value Units Notes / Formula A 𝑃𝑅 -140 dBm Power received at 30 meters from the building B 𝑓 1575.42 MHz L1 center frequency C 𝑑 7.90 meters Distance between the radiator and the closest exterior wall of the building D 𝑃𝑇𝑚𝑎𝑥 -72.0 dBm Maximum permissible EIRP = A + 20 * log(B) + 20 * log(30 + C) − 27.55 E 𝑃𝑇𝑚𝑎𝑥 63.1 pW Maximum permissible EIRP = 10(D/10)+9 The following table summarizes the above calculations. Repeater Band Output Gain of Output ERP Output Maximum ERP of Antenna of Antenna EIRP of Permissible Repeater (dBi) (dBm)2 Antenna EIRP (dBm) (dBm) (dBm)3 A L1 -65 3 -62 -59.85 -72.2 A L2 -65 0 -65 -62.85 -74.3 B L1 -70 3 -67 -64.85 -71.7 C L1 -70 3 -67 -64.85 -72.5 D L1 -70 3 -67 -64.85 -72.8 E L1 -70 3 -67 -64.85 -72.8 F L1 -65 3 -62 -59.85 -72.0 Conclusions As noted earlier, the proposal is compliant with section “e” of Redbook section 8.3.27, and thus section “f” is not applicable. Section “f” calculations are given here only for information. One should also bear in mind that while the antenna is directional, the calculations treat the antenna as omnidirectional; more specifically the main lobe gain of the antenna is used in all directions, resulting in overstatement of the power in the side lobes and back lobe. Thus the proposal is closer to meeting the “-140 dBm at 30 meters from the building” threshold than the above calculations indicate. Also it should be remembered that the repeaters will be located in a metal building with few windows, resulting in greater signal attenuation – and thus lower power outside the building – than the above calculations indicate. 2 Output ERP of Antenna = Output ERP of Repeater + Gain of Antenna 3 EIRP (dBm) = ERP (dBm) + 2.15 12

The following two pages discuss the GLI-Metro-G specifications for transmission of GPS and GLONASS 13

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Document Created: 2018-08-23 12:06:50
Document Modified: 2018-08-23 12:06:50
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