Frequency Stability Measurements

FCC ID: OIIDTSA1900-2

Test Report

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FCCID_37322

Omnipoint Technologies, Inc. Exhibit 15 FCC ID: OIIDTSA1900-2 Page 1 of 5 EXHIBIT 15 FREQUENCY STABILITY MEASUREMENTS Measurements of DTSA frequency stability were performed in accordance with the requirements of §§ 24.235 and 2.1055; procedures and results are described in this exhibit. Requirements In general, as required by § 24.235, the frequency stability of broadband PCS equipment “shall be sufficient to ensure that the fundamental emissions stays within the authorized frequency block.” However, as a GSM-compliant terminal, the stability of the DTSA carrier frequency is accurate to within 0.1 ppm of the received frequency from the base station (J-STD007, Air Interface: Volume 1, Section 7.4.1; and GSM 05.10, "Digital cellular telecommunications system (Phase 2); Radio subsystem synchronization"). Measurements of transmitter frequency stability are described in § 2.1055 and are necessary to obtain a Certification grant of equipment authorization. As required by § 2.1055, these measurements are to be made as follows: 1. Over variations of ambient temperature from -30° to +50° centigrade at intervals of 10° centigrade. 2. Over variations of primary supply voltage from 85 to 115 percent of the nominal line voltage of 120 VAC (variations from 102 VAC to 138 VAC). In addition, because the DTSA operates from a DC input voltage over a specified +7 to +32 VDC range, measurements of transmitter frequency stability were also made as follows (as requested by Greg Czumak of the FCC OET): 3. Over variations of DC input voltage from 5.9 VDC to 37.0 VDC (approximately +/- 15% beyond the specified DC input voltage range of +7 to +32 VDC). Measurement Procedure Measurements of DTSA frequency stability were performed using the Rhode & Schwarz CMD 55 Digital Radio Communications Tester. Variation in ambient temperature were accomplished using a Hanse HALT/HASS environmental test chamber; variations in AC and DC input voltages made use of an AC variac powering an Artesyn AC/DC supply (co-located with the DTSA in the Hanse chamber) and a DC power supply, respectively. Specific procedures for both methods of powering the unit were as follows: This document contains PROPRIETARY and CONFIDENTIAL information of Omnipoint Technologies, Inc.

Omnipoint Technologies, Inc. Exhibit 15 FCC ID: OIIDTSA1900-2 Page 2 of 5 DTSA Powered by Artesyn NFN40-7612 AC/DC Power Supply (12 VDC Output) 1. Configure the DTSA: • Location Hanse environmental test chamber (unit and supply) • Input voltage AC input to Artesyn supply powering unit varied during test (Artesyn output = 12.0 VDC) • Mode Transmit, random data pattern selected using PC controller • RF Output Power Maximum level (step 0, 30 dBm nominal) selected using the PC controller • Frequency Channel 661 (1880.0 MHz) selected using the PC controller 2. Set the Hanse Environmental Chamber to -30° C. Soak the DTSA and Artesyn AC/DC supply for ten minutes (powered off) to allow unit to reach a steady state temperature (as measured on the DTSA PCB itself). 3. Set AC line voltage to 102 VAC (85% of nominal 120 VAC line voltage); DC input to unit = 12.0 VDC (nominal). 4. Measure and record carrier frequency ten times in succession using the R&S CMD 55. 5. Set AC line voltage to 138 VAC (115% of nominal 120 VAC line voltage); DC input to unit = 12.0 VDC (nominal). 6. Measure and record carrier frequency ten times in succession using the R&S CMD 55. 7. Increase chamber temperature by 10° C. Soak unit for ten minutes to allow unit to reach steady state at new temperature. 8. Repeat steps 3 through 7 until final measurements made at +50 ° C. This document contains PROPRIETARY and CONFIDENTIAL information of Omnipoint Technologies, Inc.

Omnipoint Technologies, Inc. Exhibit 15 FCC ID: OIIDTSA1900-2 Page 3 of 5 DTSA Powered by Variable Output DC Supply 1. Configure the DTSA: • Location Hanse environmental test chamber (unit only) • Input voltage DC input to unit varied during test (5.9 to 37 VDC) • Mode Transmit, random data pattern selected using PC controller • RF Output Power Maximum level (step 0, 30 dBm nominal) selected using the PC controller • Frequency Channel 661 (1880.0 MHz) selected using the PC controller 2. Set the Hanse Environmental Chamber to -30° C. Soak the DTSA for ten minutes (powered off) to allow unit to reach a steady state temperature (as measured on the DTSA PCB itself). 3. Set DC input to unit to 5.9 VDC. 4. Measure and record carrier frequency ten times in succession using the R&S CMD 55. 5. Set DC input to unit to 37.0 VDC. 6 Measure and record carrier frequency ten times in succession using the R&S CMD 55. 7. Increase chamber temperature by 10° C. Soak unit for ten minutes to allow unit to reach steady state at new temperature. 8. Repeat steps 3 through 7 until final measurements made at +50 ° C. Measurement Results Table E15.1 summarizes the DTSA frequency stability measurements taken in accordance with the preceding procedures. The Maximum Frequency Deviation columns (in Hertz and ppm) show the largest frequency deviations from the desired carrier frequency over the ten measurements made at each combination of temperature, line and DC input voltage. Plots of these results (maximum deviation from desired carrier in Hertz) are presented in Figure E15.1. In all cases, the frequency stability of the DTSA over variations in ambient temperature, and AC (to DC supply) and DC input voltages are sufficient to ensure that the fundamental emission will stay within its authorized frequency block. No data is provided for the -30° C temperature because the DTSA will not operate at this temperature. On-board temperature sensing circuitry detects when the ambient temperature falls below -20° C and shuts the unit off. Operation is thus only possible at ambient temperatures of -20° C and higher; measurements were attempted at -30° C to ensure that the unit did indeed shut down as designed. This document contains PROPRIETARY and CONFIDENTIAL information of Omnipoint Technologies, Inc.

Omnipoint Technologies, Inc. Exhibit 15 FCC ID: OIIDTSA1900-2 Page 4 of 5 Table E15.1. Frequency stability measurement results. Ambient Line (AC) or DC Maximum Frequency Maximum Frequency Temperature input Voltage Deviation (Hz) Deviation (ppm) (degrees C) 50° 102 VAC -2186 -1.16 138 VAC -2175 -1.16 5.9 VDC -1674 -0.89 37 VDC -1768 -0.94 40° 102 VAC -1349 -0.72 138 VAC -1331 -0.71 5.9 VDC -931 -0.50 37 VDC -857 -0.46 30° 102 VAC -429 -0.23 138 VAC -433 -0.23 5.9 VDC 60 0.03 37 VDC 40 0.02 20° 102 VAC 518 0.28 138 VAC 521 0.28 5.9 VDC 14 0.01 37 VDC -106 -0.06 10° 102 VAC 1346 0.72 138 VAC 1332 0.71 5.9 VDC 1817 0.97 37 VDC 1821 0.97 0° 102 VAC 2145 1.14 138 VAC 2127 1.13 5.9 VDC 2554 1.36 37 VDC 2593 1.38 -10° 102 VAC 3624 1.93 138 VAC 3556 1.89 5.9 VDC 4480 2.38 37 VDC 4557 2.42 -20° 102 VAC 4853 2.58 138 VAC 4832 2.57 5.9 VDC 4584 2.44 37 VDC 4819 2.56 -30° 102 VAC EUT SHUT-DOWN N/A 138 VAC EUT SHUT-DOWN N/A 5.9 VDC EUT SHUT-DOWN N/A 37 VDC EUT SHUT-DOWN N/A This document contains PROPRIETARY and CONFIDENTIAL information of Omnipoint Technologies, Inc.

Omnipoint Technologies, Inc. Exhibit 15 FCC ID: OIIDTSA1900-2 Page 5 of 5 Maximum Frequency Deviation (Varying DC Voltage Across Temp) Tem perature(ºC) -30ºC -20ºC -10ºC 0ºC 10ºC 20ºC 30ºC 40ºC 50ºC 5500 5000 4500 4000 3500 Frequency Variation(Hz) 3000 5.9VDC 2500 2000 37VDC 1500 1000 500 0 -500 -1000 -1500 -2000 -2500 Maximum Frequency Deviation (Varying AC Supply Across Temp) Temperature(ºC) -30ºC -20ºC -10ºC 0ºC 10ºC 20ºC 30ºC 40ºC 50ºC 5500 5000 4500 4000 3500 Frequency Variation(Hz) 3000 2500 102 VAC 2000 1500 138 VAC 1000 500 0 -500 -1000 -1500 -2000 -2500 -3000 Figure E15.1. Graphical representation of Frequency Stability Results. This document contains PROPRIETARY and CONFIDENTIAL information of Omnipoint Technologies, Inc.

Omnipoint Technologies, Inc. Exhibit 15 FCC ID: OIIDTSA1900-2 Page 6 of 5 During normal operation, the GSM (PCS1900) network and terminal (mobile) work in conjunction to ensure an overall (long-term) frequency stability of 0.1 ppm. The base station measures the receive frequency from each terminal and, once every ten TDMA frames, commands the terminal to adjust its RF carrier frequency as required to maintain the required stability. The measurements of frequency stability described in this Exhibit were performed with this closed-loop frequency adjustment disabled, to ensure that the frequency stability of the DTSA, by itself, is sufficient to keep the RF carrier within the authorized frequency block. As the measurement results indicate, this is indeed the case. Furthermore, during normal operation the frequency stability of the DTSA complies with the 0.1 ppm requirement specified in the GSM standards previously referenced. This document contains PROPRIETARY and CONFIDENTIAL information of Omnipoint Technologies, Inc.


Document Created: 2001-06-25 16:41:52
Document Modified: 2001-06-25 16:41:52
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