Test Report

FCC ID: GQ428T

Test Report

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FCCID_556215

The University of Michigan Radiation Laboratory 3228 EECS Building Ann Arbor, MI 48109-2122 Tel: (734) 764-0500 Measured Radio Frequency Emissions From TRW GMT900 TPMS Transmitter Model(s): 15825475 Report No. 415031-253 June 21, 2005 Copyright © 2005 For: TRW, Inc. 24175 Research Drive Farmington Hills, MI 48335-2642 Contact: Michael Young Tel: 248-442-5316 Fax: 248-442-7241 PO: Verbal Tests supervised by: Measurements made by: Report approved by: _____________________ Valdis V. Liepa Valdis V. Liepa Research Scientist Summary Tests for compliance with FCC Regulations Part 15, Subpart C, and Industry Canada RSS-210, were performed on TRW model(s) 15825475. This device is subject to the Rules and Regulations as a Transmitter. In testing completed on June 6, 2005, the device tested in the worst case met the allowed FCC specifications for radiated emissions by 2.7 dB (see p. 6). Besides harmonics, there were no other significant spurious emissions found; emissions from digital circuitry were negligible. The conducted emission tests do not apply, since the device is powered from a 12 VDC battery.

1. Introduction TRW model(s) 15825475 was tested for compliance with FCC Regulations, Part 15, adopted under Docket 87-389, April 18, 1989, and with Industry Canada RSS-210, Issue 5, November, 2001. The tests were performed at the University of Michigan Radiation Laboratory Willow Run Test Range following the procedures described in ANSI C63.4-2003 "Methods of Measurement of Radio-Noise Emissions from Low-Voltage Electrical and Electronic Equipment in the Range of 9 kHz to 40 GHz". The Site description and attenuation characteristics of the Open Site facility are on file with FCC Laboratory, Columbia, Maryland (FCC Reg. No: 91050) and with Industry Canada, Ottawa, ON (File Ref. No: IC 2057). 2. Test Procedure and Equipment Used The pertinent test equipment commonly used in our facility for measurements is listed in Table 2.1 below. The middle column identifies the specific equipment used in these tests. Table 2.1 Test Equipment. Test Instrument Eqpt. Used Manufacturer/Model Spectrum Analyzer (0.1-1500 MHz) Hewlett-Packard, 182T/8558B Spectrum Analyzer (9kHz-22GHz) X Hewlett-Packard 8593A SN: 3107A01358 Spectrum Analyzer (9kHz-26GHz) X Hewlett-Packard 8593E, SN: 3412A01131 Spectrum Analyzer (9kHz-26GHz) Hewlett-Packard 8563E, SN: 3310A01174 Spectrum Analyzer (9kHz-40GHz) Hewlett-Packard 8564E, SN: 3745A01031 Power Meter Hewlett-Packard, 432A Power Meter Anritsu, ML4803A/MP Harmonic Mixer (26-40 GHz) Hewlett-Packard 11970A, SN: 3003A08327 Harmonic Mixer (40-60 GHz) Hewlett-Packard 11970U, SN: 2332A00500 Harmonic Mixer (75-110 GHz) Hewlett-Packard 11970W, SN: 2521A00179 Harmonic Mixer (140-220 GHz) Pacific Millimeter Prod., GMA, SN: 26 S-Band Std. Gain Horn S/A, Model SGH-2.6 C-Band Std. Gain Horn University of Michigan, NRL design XN-Band Std. Gain Horn University of Michigan, NRL design X-Band Std. Gain Horn S/A, Model 12-8.2 X-band horn (8.2- 12.4 GHz) Narda 640 X-band horn (8.2- 12.4 GHz) Scientific Atlanta , 12-8.2, SN: 730 K-band horn (18-26.5 GHz) FXR, Inc., K638KF Ka-band horn (26.5-40 GHz) FXR, Inc., U638A U-band horn (40-60 GHz) Custom Microwave, HO19 W-band horn(75-110 GHz) Custom Microwave, HO10 G-band horn (140-220 GHz) Custom Microwave, HO5R Bicone Antenna (30-250 MHz) X University of Michigan, RLBC-1 Bicone Antenna (200-1000 MHz) X University of Michigan, RLBC-2 Dipole Antenna Set (30-1000 MHz) X University of Michigan, RLDP-1,-2,-3 Dipole Antenna Set (30-1000 MHz) EMCO 2131C, SN: 992 Active Rod Antenna (30 Hz-50 MHz) EMCO 3301B, SN: 3223 Active Loop Antenna (30 Hz-50 MHz) EMCO 6502, SN:2855 Ridge-horn Antenna (300-5000 MHz) X University of Michigan Amplifier (5-1000 MHz) X Avantak, A11-1, A25-1S Amplifier (5-4500 MHz) X Avantak Amplifier (4.5-13 GHz) Avantek, AFT-12665 Amplifier (6-16 GHz) Trek Amplifier (16-26 GHz) Avantek LISN Box University of Michigan Signal Generator Hewlett-Packard 8657B 2

3. Configuration and Identification of Device Under Test The DUT is a 315 MHz Tire Pressure Monitor Sensor (TPMS) transmitter, 7 x 6 x 1.5 inches in size. When the vehicle is in motion it transmits tire pressure information to a receiver in the vehicle. It can also be activated by exposure to a 125 kHz LF signal; a procedure used in factory/set-up operations. When the vehicle is in motion the transmission consists of four quasi-Manchester encoded words repeated every 60 seconds (typically). The transmitter 315 MHz carrier is generated by a SAW stabilized oscillator. The coding is generated by a micro and is ASK encoded on the carrier. The DUT was designed and manufactured by TRW, 24175 Research Drive, Farmington Hills, MI 48335-2642. It is identified as: TRW TPMS Transmitter Model(s): 15825475 FCC ID: GQ428T IC: 1470A-9T One device (production) was provided. The two models are identical, except for the model number. For testing, the DUT was activated by LF in alert (set-up) mode. Under such., the transmission consisted of 8 word packets and lasted for 4 seconds. 3.1 Modifications Made There were no modifications made to the DUT by this laboratory. 4. Emission Limits The DUT tested falls under the category of an Intentional Radiators and the Digital Devices. For FCC, it is subject to Part 15, Subpart C, (Section 15.231), Subpart B, (Section 15.109), and Subpart A, (Section 15.33). For Industry Canada it is subject to RSS-210, (Sections 6.1 and 6.3). The applicable testing frequencies with corresponding emission limits are given in Tables 4.1 and 4.2 below. As a digital device, the DUT is considered as a Class B device. 4.1 Radiated Emission Limits Table 4.1. Radiated Emission Limits (FCC: 15.33, 15.35, 15.109; IC: RSS-210, 6.2.2(r)). (Digital Class B) Freq. (MHz) Elim (3m) µV/m Elim dB(µV/m) 30-88 100 40.0 88-216 150 43.5 216-960 200 46.0 960-2000 500 54.0 Note: Average readings apply above 1000 MHz (1 MHz BW) Quasi-Peak readings apply to 1000 MHz (120 kHz BW) 3

Table 4.2. Radiated Emission Limits (FCC: 15.231(e), IC: RSS-210; 6.1, 6.3 Table 4). (Data Transmission) Fundamental Spurious** Frequency Ave. Elim (3m) Ave. Elim (3m) (MHz) (µV/m) dB (µV/m) (µV/m) dB (µV/m) 260.0-470.0 1500-5000* 150-500 315.0 2418 67.7 241.8 47.7 322-335.4 Restricted 399.9-410 200 46.0 Bands 608-614 960-1240 1300-1427 1435-1626.5 Restricted 500 54.0 1660-1710 Bands 1718.9-1722.2 2200-2300 * Linear interpolation, formula: E = -2833.2 + 16.67*f (MHz) ** Measure up to tenth harmonic; 120 kHz RBW up to 1 GHz, 1 MHz RBW above 1 GHz 4.3 Conducted Emissions Limits The conductive emission limits and tests do not apply here, since the DUT is powered by a 12 VDC battery. 5. Radiated Emission Tests and Results 5.1 Anechoic Chamber Measurements To familiarize with the radiated emission behavior of the DUT, the DUT was first studied and measured in a shielded anechoic chamber. In the chamber there is a set-up similar to that of an outdoor 3-meter site, with a turntable, an antenna mast, and a ground plane. Instrumentation includes spectrum analyzers and other equipment as needed. In testing for radiated emissions, the transmitter was activated using the lock/unlock button with a special wooden clamp for repeated pulse emissions. It was placed on the test table flat, on its side, or on its end. In the chamber we studied and recorded all the emissions using a Bicone antenna up to 300 MHz and a ridged horn antenna above 200 MHz. The measurements made in the chamber below 1 GHz are used for pre-test evaluation only. The measurements made above 1 GHz are used in pre-test evaluation and in the final compliance assessment. We note that for the horn antenna, the antenna pattern is more directive and hence the measurement is essentially that of free space (no ground reflection). Consequently it is not essential to measure the DUT for both antenna polarizations, as long as the DUT is measured on all three of its major axis. In the chamber we also recorded the spectrum and modulation characteristics of the carrier. These data are presented in subsequent sections. We also note that in scanning from 30 MHz to 3.15 GHz using Bicone and the ridge horn antennas, there were no other significant spurious emissions observed. 4

5.2 Open Site Radiated Emission Tests After the chamber measurements, the emissions were re-measured on the outdoor 3-meter site at fundamental and harmonics up to 1 GHz using tuned dipoles and/or the high frequency Bicone. Photographs included in this filing show the DUT on the Open Area Test Site (OATS). 5.3 Computations and Results for Radiated Emissions To convert the dBm's measured on the spectrum analyzer to dB(µV/m), we use expression E3(dBµV/m) = 107 + PR+ KA – KG where PR = power recorded on spectrum analyzer, dB, measured at 3m KA = antenna factor, dB/m KG = pre-amplifier gain, including cable loss, dB When presenting the data, at each frequency the highest measured emission under all of the possible orientations is given. Computations and results are given in Table 5.1. There we see that the DUT meets the limit by 2.7 dB. 5.4 Conducted Emission Tests These tests do not apply, since the DUT is powered from a 12 VDC battery. 6. Other Measurements 6.1 Correction For Pulse Operation When the transmitter is activated (either by LF pulse or motion), it can, in the worst case, transmit 1 word consisting of 120 pulses of Manchester encoded ASK data in any 100 ms period. The Manchester encoding has a period equal to 240 µs and an on time of 122.5 µs. See Figure 6.1. Computing the worst duty factor results in KE = 120 pulses x 122.5 µs / 100 ms = 0.146 or -16.7 dB 6.2 Emission Spectrum Using the ridge-horn antenna and DUT placed in its aperture, emission spectrum was recorded and is shown in Figure 6.2. 6.3 Bandwidth of the Emission Spectrum The measured spectrum of the signal is shown in Figure 6.3. The allowed (-20 dB) bandwidth is 0.25% of MHz, or 787.25 kHz. From the plot we see that the -20 dB bandwidth is 92.5 kHz, and the center frequency is 315 MHz. 6.4 Effect of Supply Voltage Variation The DUT has been designed to be powered by 12 VDC battery. For this test, the battery was replaced by a laboratory variable power supply. Relative power radiated was measured at the fundamental as the voltage was varied from 2 to 3.5 volts. The emission variation is shown in Figure 6.4. 6.5 Input Voltage at Battery Terminals Batteries: before testing Voc = 3.0 V after testing Voc = 2.8 V Ave. current from batteries I = 8.5 mA (pulsed) 5

Table 5.1 Highest Emissions Measured Radiated Emission - RF TRW GMT900 Tx; FCC/IC Freq. Ant. Ant. Pr Det. Ka Kg E3* E3lim Pass # MHz Used Pol. dBm Used dB/m dB dBµV/m dBµV/m dB Comments 1 315.0 Dip H -25.2 Pk 18.9 19.7 64.3 67.7 3.4 flat 2 315.0 Dip V -34.4 Pk 18.9 19.7 55.1 67.7 12.6 end 3 630.0 Dip H -52.6 Pk 25.2 17.9 45.0 47.7 2.7 flat 4 630.0 Dip V -54.5 Pk 25.2 17.9 43.1 47.7 4.6 end 5 945.0 Dip H -67.9 Pk 28.9 15.7 35.6 47.7 12.1 flat 6 945.0 Dip V -72.6 Pk 28.9 15.7 30.9 47.7 16.8 end 7 1260.0 Horn H -53.4 Pk 20.6 28.0 29.5 54.0 24.5 flat 8 1575.0 Horn H -58.0 Pk 21.5 28.0 25.8 54.0 28.2 flat 9 1890.0 Horn H -48.1 Pk 22.2 28.0 36.4 54.0 17.6 flat 10 2205.0 Horn H -47.9 Pk 23.0 28.1 37.3 54.0 16.7 flat 11 2520.0 Horn H -51.9 Pk 23.9 28.3 34.0 54.0 20.0 flat 12 2835.0 Horn H -55.8 Pk 24.8 28.2 31.1 54.0 22.9 flat 13 3150.0 Horn H -58.2 Pk 25.8 27.9 30.0 54.0 24.0 flat, noise 14 15 16 17 18 * Includes 16.7 dB duty factor 19 20 21 22 Digital emissions more than 20 dB below FCC/IC Class B Limit. 23 24 25 26 27 Conducted Emissions Freq. Line Det. Vtest Vlim Pass # MHz Side Used dBµV dBµV dB Comments Not applicable Meas. 06/03/2005; U of Mich. 6

Figure 6.1. Transmissions modulation characteristics: (top) complete transmission, (center) Manchester pulse period, (bottom) Manchester pulse width. 7

Figure 6.2. Emission spectrum of the DUT (pulsed emission). The amplitudes are only indicative (not calibrated). Figure 6.3. Measured bandwidth of the DUT (pulsed emission). 8

-12.00 -13.00 Relative Amplitude (dB) -14.00 -15.00 -16.00 -17.00 -18.00 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 Relative Voltage (V) Figure 6.4. Relative emission at 315.0 MHz vs. supply voltage (pulsed emission). 9


Document Created: 2005-06-23 12:17:52
Document Modified: 2005-06-23 12:17:52
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