Test Report

FCC ID: MRXTG224AM02

Test Report

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FCCID_139748

The University of Michigan Radiation Laboratory 3228 EECS Building Ann Arbor, MI 48109—2122 Tel: (734) 647—1792 Measured Radio Frequency Emissions From Schrader Remote Tire Pressure Monitoring Transmitter Model: MRXTG224AM02 Report No. 415031—076 March 1, 2001 Copywrite © 2001 For: Schrader Electronics Ltd. 11 Technology Park Belfast Road Antrim N. Ireland, BT411l 1QS PO: R7459 Contact: Brendan McDonnell Tel: 011—44 2894—482078 Fax: 011—44 2894—468440 Tests supervised by:. ///’('jfl / %fi_fi/g—- Measurements made by: Report approved by Valdis V. Liepa Valdis V. Liepa CV Research Scientist Summary Tests for compliance with FCC Regulations, subject to Part 15, Subpart C, and with RSS—210 of Industry Canada were performed on Schrader Remote Tire Pressure Monitoring Transmitter. This device is subject to Rules and Regulations as a low power (data) transmitter. As a Digital Device it is exempt, but such measurements we routinely perform to assess the transmitters‘s overall emissions. The Sensor was tested " in free space", i.e., without a tire and off the rim. In testing performed between January 10 and February 18, 2001, the device tested in the worst case met the limits for radiated emissions by 5.3 dB (1735 MHz, 4th harmonic; see p. 6). Besides harmonics there were no other significant spurious emissions found. No conductive emission tests were made, since the transmitter is powered by a 3 V internal lithium battery.

1. Introduction Schrader Remote Tire Pressure Monitoring Transmitter, PN: 70503028, was tested for compliance with FCC Regulations, Part 15, adopted under Docket §$7—389, April 18, 1989, and with Industry Canada RSS—210, Issue 2, dated February 14, 1998. The tests were performed at the University of Michigan Radiation Laboratory Willow Run Test Range following the procedures described in ANSI C€63.4—1992 "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 test equipment commonly used in our facility is listed in Table 2.1 below. The second column identifies the specific equipment used in these tests. The HP 8593E spectrum analyzer is used for primary amplitude and frequency reference. Table 2.1. Test Equipment. Test Instrument Equipment Used Manufacturer/Model Cal. Date/By Spectrum Analyzer X Hewlett—Packard 8593A December 2000/UM (OkHz—22GHz) SN:; 3107A01358 Spectrum Analyzer X Hewlett—Packard 8593E December 2000/HP (IkHz—26GHz) SN:; 3107A01131 Spectrum Analyzer Hewlett—Packard 182T/8558B December 2000/UM (0.1—1500 MHz) SN: 1529A¥01114/543592 Preamplifier Watkins—Johnson December 2000/UM OMX (5—1000MHz) All —1 plus A25—18 Preamplifier Avantek Oct. 1999/ U of M Rad Lab OM (5—4000 MHz) Broadband Bicone University of Michigan June 1999/U of M Rad Lab (20—200 MHz) Broadband Bicone University of Michigan June 1999/U of M Rad Lab ooX (200—1000 MHz) Dipole Antenna Set University of Michigan June 2000/UM « (25—1000 MHz) Dipole Antenna Set EMCO 3121C June 2000/UM (30—1000 MHz) SN: 992 Active Loop Antenna EMCO 6502 December 1999/UM (0.090—30MHz) SN: 2855 Active Rod EMCO.3301B December 1999/UM (30Hz—50 MHz) SN: 3223 Ridge—horn Antenna University of Michigan March 1999/U of M Rad Lab (0.5—5 GHz) LISN Box University of Michigan Dec. 2000/U of M Rad Lab Signal Generator Hewlett—Packard 8657B January 2000/Uof M Rad Lab (0.1—2060 MHz)

3. Configuration and Identification of Device Under Test The DUT is a 3.5 x 7.0 x 1.5 cm size (including valve stem) potted tire pressure sensor/transmitter that mounts on a rim inside the tire. When the vehicle is in motion it transmits the tire pressure information to the receiver in the vehicle. The transmission consists of eight PWM words repeated typically every 30 seconds. The 434 MHz carrier is generated by a SAW stabilized oscillator. The coding is performed by an ASIC timed by a 32.768 kHz crystal oscillator. The DUT was designed and manufactured by Schrader Electronics Limited, 11 Technology Park, Belfast Road, Antrim BT41 1QS, Northern Ireland. It is identified as: Schrader Remote Tire Pressure Monitoring Transmitter Model: MRXTG224AMO02 SNs: (1) 04001266, (2) 04002244, (3) none FCC ID: MRXTG224AMO02 CANADA: Three devices were provided. These were: (1) staddard, but with access to control pads; used for CW and pulsed measurements, (2) standard for outside photographs and (3) unpotted for photographs. 3.1 EMI Relevant Modifications There were no modifications made to the DUT by this laboratory. 4. Emission Limits 4.1 Radiated Emission Limits The DUT tested falls under the category of an Intentional Radiators and the Digital Devices. For FCC it is subject to 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 a Class B device. Table 4.1 Radiated Emission Limits (FCC: 15.231(e); IC: RSS—210; 6.1, 6.3, Table 4). Data transmission. Fundamental Spurious** Frequency Ave. Ejim (3m) AVve. Eim (3m) (MHz) (uV/m) dB (uV/m) (uV/m) dB (uV/m) 260—470 1500—5000* 150—500 315 2418 67.7 241.8 47 .7 * 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

Table 4.2. Radiated Emission Limits (FCC: 15.33, 15.35, 15.109; IC: RSS—210, 6.2.2(r)). Digital (Class B). Freq. (MHz) Eiin (3m) uV/m Ejim dB(uV/m) 30—88 100 40.0 88—216 150 43.5 216—960 200 46.0 960—2000 500 54.0 Note: Quasi—Peak readings apply to 1000 MHz (120 kHz RBW) Average readings apply above 1000 MHz (1 MHz RBW) 4.2 Conductive Emission Limits The conductive emission limits and tests do not apply here, since the DUT is powered by a 3 V internal lithium 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 semi—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 the chamber we studied and recorded all the emissions using a ridged horn antenna up to 4.5 GHz. The measurements made in the chamber below 1 GHz are used for pre—test evaluation only. The measurements made above 1 GHz are also used in pre—test evaluation and in final compliance assessment. We note that for the horm antenna, the antenna pattern is more directive and hence the measurement is essentially that of free space (no ground reflection). 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 4.5 GHz, there were no other significant spurious emissions observed. 5.2 Outdoor Measurements — After the chamber measurements, the emissions were re—measured on the outdoor 3—meter site at 434 and 868 MHz using tuned dipoles and/or the high frequency bicone. Appendix shows the DUT on the open—site table. 5.3 Computations and Results . To convert the dBm measured on the spectrum analyzer to dB(uV/m), we use expression E3(dBuV/m) = 107 + Pr + Ka — Kg + 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 Kg = pulse operation correction factor, dB (see 6.1) 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 limits by 8.7 dB at fundamental and by 5.3 dB at harmonics.

6. Other Measurements and Computations 6.1 Correction For Pulse Operation The transmitter is activated by rotation of the wheel and transmits once every 33 seconds. The transmission consists of eight repeated words of (minimum) 105 ms period. In a word there are two 477.5us timing pulses and 50 Manchester format encoded data pulses 110us wide. Note, Manchester encoding uses low— high, high—low transition logic and when the highs are back—to—back, that appears as a wide pulse that actually are two pulses. See Figure 6.1. In this case, the averaging factor is Kg = (2 x 4775 + 50 x 0.110) ms / 100 ms = 0.0644or —23.8 dB (Use —20.0 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 434.0 MHz, or 1085 kHz, and from the plot we see that the —20 dB bandwidth is 53.0 kHz (actually this represents the RBW of the spectrum analyzer), and the center frequency is 433.935 MHz. 6.4 Effect of Supply Voltage Variation The DUT has been designed to be powered by a single 3 V battery. For this test, the battery was paralelled by a laboratory variable power supply and relative power radiated was measured at the fundamental as the voltage was varied from 2.75 to 3.5 volts. The emission variation is shown in Figure 6.4. 6.5 Input Voltage and Current at Battery Terminals V _= 3.0 V I = 30.0 mA (CW) The University of Michigan Radiation Laboratory 3228 EECS Building Ann Arbor, Michigan 48109—2122 (734) 647—1792

Table 5.1 Highest Emissions Measured Radiated Emission — RF Schrader/Brendan TX 434 MHz, FCC/IC Freq. Ant. Ant.| Pr Det Ka Kg E3* E3lim Pass ~ # MHz Used Pol. dBm Used dB/m dB |dBuV/m|[dBuV/m _dB Comments 1| 433.9 Dip H —23.6 Pk 21.8 21.1 64.1 72.8 8.7 |flat 2| 433.9 Dip V —25.7 Pk 21.8 21.1 62.0 72.8 10.8 |end 3| 867.8 Dip H —51.2 Pk 28.1 17.4 46.5 52.8 6.3 |flat 4| 867.8 Dip V —50.6 Pk 28.1 17.4 47.1 52.8 5.7 |end 5| 1301.7 Hom H —41l.6 Pk 21.0 28.1 38.3 54.0 15.7 |side 7| 1735.6 Hom H —32.1 Pk 21.8 28.0 48.7 54.0 5.3 |side *worst case 8| 2169.5 Hom H —44.3 Pk 22.6 27.0 38.3 54.0 15.7 |flat 9| 2603.4 Horm H —48.1 Pk 24.1 26.1 36.9 54.0 17.1 |flat 10| 3037.3 Hom H —45.7 Pk 25.5 25.0 41.8 54.0 12.2 |end 11| 3471.2 Hom H —56.7 Pk 26.8 24.6 32.5 54.0 21.5 |end 12| 3905.1 Hom H —47.9 Pk 28.2 23.5 43.8 54.0 10.2 |flat 13| 4339.0 Hom H —60.2 Pk 29.5 19.0 37.3 54.0 16.7 |side 14 15 16 17 18 *includes —20.0 dB duty factor 19 20 21 Digital Emissions Freq. Ant. Ant. Pr Det. Ka Kg E3* E3lim Pass # MHz Used Pol. dBm Used dB/m dB_ __|dBuV/m|dBuV/m _dB Comments 1 2 3 Digitzil emissi(ins are rlnore thaln 20 dB bIelow FCC| Class Bllimit 4 Conducted Emissions Freq. Line Det. Vtest Vlim Pass MHz Side |Used| dBuV |dBuV| dB Comments Not licable Meas. 01/10/01; U of Mich.

17i81142 18 FEB 2001 — MKR a 1805.00 msec REF .0 dBm AT 19 dB ~«.14 4B PEAK — — — — ~ < Las 40@ 1 ToP EJ B B nelpeey. nefecaff i eccoff en becafles bevreree D reveken es feee .k ......... dB / . : . . : N L N . "THHOAA———— 985 MHz SPAN A Hz BW 1.0 MHz vBU 300 kHz #SWP 2.090 sec 17:}35 :50 i8 FEB 2001 f * a REF .98 dBnm AT 10 PEAK — — — CENTER 489 .985 MHz SPAN A Hz #RES BW 1.0 MHz VBH 300 kHz #SWP 15.0 msec 17139109 i8 FEB 2001 a MKR a 477 .50 pseec REF .@ dBnm AT 19 dB —i7 .78 qB PEAK T ~ T T — T ~ T T .................................................................. CENTER 438.9985 MHz sPAN a Hz #RES BW 1.0 MHz VBW 300 kHz #SWHWP 1.090 msec Figure 6.1. Transmissions modulation characteristics: (top) transmission repetition, (center) transmission pulses, (bottom) pulse width. 7

18:i1159 i8 FEB 2001 REF —10.0 dBnm #at 9 ag PEAK — — — — LaGB 10 dB / VA SB SC FC CORR START & Hz STaP #RES BW 1.0 MHz VEBW 300 kHz SWHP Figure 6.2. Emission spectrum of the DUT in free space (CW emission). The amplitudes are only indicative (not calibrated). 1719126 i8 FEB 2001 zx MKR a 58 kHz REF .0 dBa AT i0 dB —~.59 dB PEAK — — — : — " — — LO 4B a : : : : 6 : : : : 0 | <—}eec cce ced ecereen Pss {ece~ fegces becveen Lecees besee dB./ — — — — . & & — — va sR — ; Een_ $C FCL.... Wikev i erreivrrrrarre lecragev ds Derrrrvere Drav eb e e se Dererrreee Dedvree e e e Derrkaa k e e Derk e es ens CORR : CENTER 4838.985 MHz SFPAN 1.000 MHz #RES BH 10 ksz VBHW 10 kHz SWP 30.0 msec Figure 6.3. Measured bandwidth of the DUT (repated pulsed emission).

—8 & §0+ C 8 $ P & 107 a C F4 —11 T T T T T T T T T 2.6 2.8 3.0 3.2 3.4 3.6 Supply Voltage, VDC Figure 6.4. Relative emission at 434 MHz vs. supply voltage. (CW emission)


Document Created: 2001-03-09 11:44:05
Document Modified: 2001-03-09 11:44:05
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