CWTWB1U331Automobile Security System

Exterior, Front Exterior, Back

Interior circuit, front Interior, front case Interior circuit, back Interior, rear case w/battery

CIRCUIT DESCRIPTION TRANSMITTER The hand-held RF transmitter consists of the housing, three or four control buttons, microcontroller, an UHF oscillator (Colpits configuration) and a 3 volt battery. The microcontroller uses an internal oscillator running at 4.0 MHz, and the RF oscillator uses a SAW based oscillator to resonate at 315.0 MHz. The modulation format used will be ASK, with a Rolling/Manchester code data format. Once the user presses a button power is applied to the microcontroller which turns the RF oscillator on and off at the rate of the Rolling/Manchester code data being sent. The signal is then sent to the receiver module via RF data transmission. The module will then act upon the RF data received and will perform certain functions in correspondence to which transmitter button is pressed.

ENGINEERING STATEMENT IN REGARD TO MEASUREMENTS ON Alps Electric Co., Ltd. FCC ID: CWTWB1U331 A. INTRODUCTION Hyak Laboratories Inc. has been authorized by Alps Electric Co., Ltd., to perform measurements on a transmitter to determine compliance with FCC Rules, Subpart C. The device is a low powered, battery operated transmitter designed for remote control of automobile security systems. It operates at a nominal 315 MHz frequency. The transmitter, con- structed on an etched circuit card, is powered from a 3 volt lithium battery. An integral, etched-circuit antenna is used. The device meets the provisions of Para. 15.231(a)(1) since it is a manually operated device used for alarm system control, and automatically ceases transmission within 5 seconds of push- button switch release. B. DESCRIPTION OF MEASUREMENT FACILITIES A description of the Hyak Laboratories Inc. radiation test facility is a matter of record with the FCC. The facility was accepted for radiation measurements on October 1, 1976, and is currently listed as an acceptable site. C. DESCRIPTION OF MEASUREMENT PROCEDURE: RADIATED MEASUREMENTS Measurements of transmitter radiation field strength were made using ANSI C63.4 (1992) as the test procedure. Measurements were made with 3 meter spacing between the transmitter under test and the test equipment antenna. The transmitter under test was placed on a rotatable table approximately 80 cm in height. The power supply was a fresh battery. C. DESCRIPTION OF MEASUREMENT PROCEDURE: RADIATED MEASUREMENTS (Continued) Measurement of field strength was made through use of HP 8596E and Tektronix 494P spectrum analyzers in conjunction with a HP 8447D and Avantek wide band, low noise preamplifiers; and an Advantest R3361A spectrum analyzer with quasi-peak detector. Singer DM-105A series calibrated dipoles were used as the test antennas in the 25-1000 MHz range. An EMCO 3115 calibrated horn antenna was used between 1 and 4.4 GHz. An analysis of time domain measurements (see plots in Figures 1, 2, and 3) was made to determine average field intensity of the fundamental and any harmonics outside of forbidden bands. Sample calculations are included in Figure 4. Based on time domain observations, and using the procedures of Figure 4, a correction factor for a nominal 100 mS averaging interval was computed. Data for radiated emissions in Table 1 includes this correc- tion factor. For emissions that fell in forbidden bands below 1 GHz the CISPR quasi-peak detector was used. For each spurious emission identified between 30 MHz to the tenth harmonic the test assembly was rotated for maximum pickup, the test antenna varied in elevation and the test antenna polari- zation shifted between horizontal to vertical in order to maximize observed signals. The measurement procedure included recording the worst-case field strength for receiving antenna polarization, test antenna height variation from 3 feet to 10 feet, test sample rotation, and placing the test sample on each of its major planes. The spectrum was checked from 30 MHz to the tenth harmonic. All emissions not reported were more than 20 dB below the permit- ted level or below FCC limits but in the ambient/system noise floor. Tabulation of the measurements are shown in Table 1. Specific forbidden band scans were made per Paragraph 15.205 and 15.209. D. REPORT OF RADIATED MEASUREMENTS Table 1 lists the frequency and amplitude of all signals observed from 30 MHz to the tenth harmonic that were within 20 dB of the limits of FCC Rules. The averaging factor is included as noted. 2 FIGURE 1 COMPLETE WORD TRANSMISSION Horizontal: 10 milliseconds/Div Vertical: 10 dB/Div. Resolution: 10 kHz (Time domain) PULSE CHARACTERISTICS FCC ID: CWTWB1U331 FIGURE 1 3 FIGURE 2 WORD DETAIL Horizontal: 5 milliseconds/Div Vertical: 10 dB/Div. Resolution: 1 MHz (Time domain) PULSE CHARACTERISTICS FCC ID: CWTWB1U331 FIGURE 2 4 FIGURE 3 BIT DETAIL Horizontal: 2 milliseconds/Div Vertical: 10 dB/Div. Resolution: 1 MHz (Time domain) PULSE CHARACTERISTICS FCC ID: CWTWB1U331 FIGURE 3 5 SAMPLE COMPUTATIONS Using the time domain plots of Figures 1 through 3, maximum "on" time over any 100 mS interval is: Pulses: “Long” 0.6mSx25 = 15 “Short” 0.2mSx40 = 8 23 Duty Cycle: 23/100 = 0.23 20 Log 0.23 = -12 dB SAMPLE COMPUTATIONS FCC ID: CWTWB1U331 FIGURE 4 6 TABLE 1 RADIATED FIELD INTENSITY Measured at 3 meters 15.231(b) Meter 1 Antenna Field 2 Calc. Field 3 Frequency Reading Factor Intensity Intensity FCC Limit dB to (MHz) (dBm) (dB) uV/m @ 3m uV/m @ 3m uV/m @ 3m Limit 314.900 -44.0 21.8 17378.0 4365.2 6035.5 - 2.8 629.800 -76.4 28.5 901.6 226.5 603.5 - 8.5 944.680 -97.6 32.6 125.9 31.6 603.5 -25.6 1259.580 -88.0 25.1 160.3 40.3 603.5 -23.5 1574.460 -96.8 26.1 65.3 16.4 500.0* -29.7 1889.360 -100.0 27.7 54.3 13.6 603.5 -32.9 2204.300 -89.6 28.8 204.2 51.3 500.0* -19.8 2519.200 -103.2 29.6 46.8 11.8 603.5 -34.2 2834.100 -92.0 30.4 186.2 46.8 500.0* -20.6 3149.000 -96.4 31.2 123.0 30.9 603.5 -25.8 Note 1: Peak detector reading without averaging. Note 2: uV/m = Log - 1dBu/m 20 dBu = dBm + antenna factor + 107 Note 3: Field Intensity calculated from peak value and -12 dB peak/average factor. *Forbidden Band All other emissions to the tenth harmonic were below FCC limits. (Unit was measured on 3 major planes) RBW: 100 kHz to 1 GHz; 1 MHz if > 1GHz (Measured at 1 m extrapo- lated to 3 m). No video filtering. Peak responding, rms calibrated detector. RADIATED FIELD INTENSITY FCC ID: CWTWB1U331 TABLE 1 7 D. FORBIDDEN BAND MEASUREMENTS Any spurious signals from the transmitter that fell in a forbidden band are identified in Table 1. All forbidden bands, per Paragraph 15.205, from 73 MHz to 4.4 GHz were searched and any applicable emissions above noise or interference levels are shown in Table 1. E. OCCUPIED BANDWIDTH A plot of occupied bandwidth is shown in Figure 5. The device meets bandwidth restriction of Paragraph 15.231(c); 26 dB points are less than 50 kHz with worst-case modulation. (Limit is …

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Test Set-Up