Test Report

Applicant Information

Applicant: SHENZHEN LOFREE CULTURE CO., LTD.

Product: Fresnel Dual Mode Mechanical Keyboard

Model(s): OE907

FCC ID: 2AC59-OE907

Testing Laboratory

Laboratory: Shenzhen Microtest Co., Ltd. [Microtest Detection]

Website: http://www.mtitest.com

Address: 101, No. 7, Zone 2, Xinxing Industrial Park, Fuhai Avenue, Xinhe Community, Fuhai Street, Bao'an District, Shenzhen, Guangdong, China

Tel: (86-755)88850135 Fax: (86-755) 88850136 E-mail: mti@51mti.com

Instructions

1. This test report shall not be partially reproduced without the written consent of the laboratory.
2. The test results in this test report are only responsible for the samples submitted.
3. This test report is invalid without the seal and signature of the laboratory.
4. This test report is invalid if transferred, altered, or tampered with in any form without authorization.
5. Any objection to this test report shall be submitted to the laboratory within 15 days from the date of receipt of the report.

Test Result Certification

Test Engineer: David Lee

Reviewed By: Leon Chen

Approved By: Tom Xue

1 General Description

1.1 Description of the EUT

RF Specification

1.2 Description of test modes

1.2.1 Operation channel list

1.2.2 Test channels

Note: The test software has been used to control EUT for working in engineering mode, that enables selectable channel, and capable of continuous transmitting mode.

1.2.3 Description of support units

1.3 Measurement uncertainty

This uncertainty represents an expanded uncertainty expressed at approximately the 95% confidence level using a coverage factor of k=2.

2 Summary of Test Result

Note: N/A means not applicable.

3 Test Facilities and Accreditations

3.1 Test laboratory

4 Equipment List

5 Test Result

5.1 Antenna requirement

15.203 requirement

An intentional radiator shall be designed to ensure that no antenna other than that furnished by the responsible party shall be used with the device. The use of a permanently attached antenna or of an antenna that uses a unique coupling to the intentional radiator shall be considered sufficient to comply with the provisions of this section. The manufacturer may design the unit so that a broken antenna can be replaced by the user, but the use of a standard antenna jack or electrical connector is prohibited. This requirement does not apply to carrier current devices or to devices operated under the provisions of 15.211, 15.213, 15.217, 15.219, 15.221, or 15.236. Further, this requirement does not apply to intentional radiators that must be professionally installed, such as perimeter protection systems and some field disturbance sensors, or to other intentional radiators which, in accordance with 15.31(d), must be measured at the installation site. However, the installer shall be responsible for ensuring that the proper antenna is employed so that the limits in this part are not exceeded.

Description of the antenna of EUT

The antenna of EUT is PCB antenna (Antenna Gain: 1.87 dBi). which is no consideration of replacement.

5.2 AC power line conducted emissions

5.2.1 Limits

Note 1: the limit decreases with the logarithm of the frequency in the range of 0.15 MHz to 0.5 MHz.

5.2.2 Test Procedures

1. The test setup is refer to the standard ANSI C63.10-2013.
2. The EUT is connected to the main power through a line impedance stabilization network (LISN). All support equipment is powered from additional LISN(s).
3. Emissions were measured on each current carrying line of the EUT using an EMI test receiver connected to the LISN powering the EUT.
4. The test receiver scanned from 150 kHz to 30 MHz for emissions in each of the test modes described in Item 1.2.
5. The test data of the worst-case condition(s) was recorded.

5.2.3 Test setup

Diagram Description: A test setup diagram shows the EUT & Support Units connected to a LISN. A Test Receiver is connected to the LISN. The setup includes a Vertical Ground Reference Plane and a Horizontal Ground Reference Plane. The EUT is placed 80cm above the ground plane, and the LISN is 40cm away from the EUT. The Test Receiver is positioned at a distance.

5.2.4 Test Result

Notes: All modes of operation of the EUT were investigated, and only the worst-case results are reported.

Calculation formula:
Measurement (dBμV) = Reading Level (dBμV) + Correct Factor (dB)
Over (dB) = Measurement (dBμV) – Limit (dBμV)

Phase L Results:

Phase N Results:

5.3 20dB occupied bandwidth

5.3.1 Limits

None, for reporting purposes only.

5.3.2 Test setup

Diagram Description: A test setup diagram shows the EUT connected to a Spectrum Analyzer.

5.3.3 Test procedures

1. Test method: ANSI C63.10-2013 Section 6.9.2.
2. The transmitter output of EUT is connected to the spectrum analyzer.
3. Spectrum analyzer setting: RBW=30 kHz, VBW=100 kHz, detector= Peak.

5.3.4 Test results

Graphical Results Summary: The graphs show the 20dB occupied bandwidth for GFSK mode at channels CH0, CH39, and CH78. The measured bandwidths correspond to the values in the table above.

5.4 Conducted peak output power

5.4.1 Limits

For frequency hopping systems operating in the 2400-2483.5 MHz band employing at least 75 non-overlapping hopping channels, and all frequency hopping systems in the 5725-5850 MHz band: 1 watt. For all other frequency hopping systems in the 2400-2483.5 MHz band: 0.125 watts.

5.4.2 Test setup

Diagram Description: A test setup diagram shows the EUT connected to a Spectrum Analyzer.

5.4.3 Test procedure

1. Test method: ANSI C63.10-2013 Section 7.8.5.
2. The EUT was set to continuously transmitting in the max power during the test.
3. The transmitter output of EUT is connected to the spectrum analyzer.
4. Spectrum analyzer setting: RBW > 20dB occupied bandwidth, VBW ≥ RBW, detector= Peak.

5.4.4 Test results

Graphical Results Summary: The graphs display the peak conducted output power for GFSK mode at channels CH0, CH39, and CH78, confirming the measured values against the limit.

5.5 Carrier frequency separation

5.5.1 Limits

Frequency hopping systems shall have hopping channel carrier frequencies separated by a minimum of 25 kHz or the 20 dB bandwidth of the hopping channel, whichever is greater. Alternatively, frequency hopping systems operating in the 2400-2483.5 MHz band may have hopping channel carrier frequencies that are separated by 25 kHz or two-thirds of the 20 dB bandwidth of the hopping channel, whichever is greater.

5.5.2 Test setup

Diagram Description: A test setup diagram shows the EUT connected to a Spectrum Analyzer.

5.5.3 Test procedure

1. Test method: ANSI C63.10-2013 Section 7.8.2.
2. The EUT was set to hopping mode during the test.
3. The transmitter output of EUT is connected to the spectrum analyzer.
4. Spectrum Setting: RBW = 30 kHz, VBW = 100 kHz, detector= Peak.

5.5.4 Test results

Graphical Results Summary: The graph illustrates the carrier frequency separation for GFSK mode, showing a separation greater than the limit.

5.6 Average time of occupancy

5.6.1 Limits

The average time of occupancy on any channel shall not be greater than 0.4 seconds within a period of 0.4 seconds multiplied by the number of hopping channels employed.

5.6.2 Test setup

Diagram Description: A test setup diagram shows the EUT connected to a Spectrum Analyzer.

5.6.3 Test procedure

1. Test method: ANSI C63.10-2013 Section 7.8.4
2. The EUT was set to hopping mode during the test.
3. The tranistter output of EUT is connneted to the specturm analyzer.
4. Spectrum analyzer setting: RBW = 1MHz, VBW = 3MHz, Span = 0Hz, Detector = Peak, weep time: As necessary to capture the entire dwell time per hopping channel.
5. Repeat the measurement using a longer sweep time to determine the number of hops over the period specified in the requirements. The sweep time shall be equal to, or less than, the period specified in the requirements. Determine the number of hops over the sweep time and calculate the total number of hops in the period specified in the requirements, using the following equation:
6. The average time of occupancy is calculated from the transmit time per hop multiplied by the number of hops in the period specified in the requirements.

5.6.4 Test results

Notes:
1. Period time = 0.4 (s) * 79 = 31.6(s)
2. Average time of occupancy = Pulse width * Number of pulses in 3.16s * 10

Graphical Results Summary: The graphs illustrate pulse width and number of pulses for DH1, DH3, and DH5 packets, supporting the calculated average time of occupancy.

5.7 Number of hopping channels

5.7.1 Limit

Frequency hopping systems in the 2400-2483.5MHz band shall use at least 15 channels.

5.7.2 Test setup

Diagram Description: A test setup diagram shows the EUT connected to a Spectrum Analyzer.

5.7.3 Test procedure

1. Test method: ANSI C63.10-2013 Section 7.8.3
2. The EUT was set to hopping mode during the test.
3. The tranistter output of EUT is connneted to the specturm analyzer.
4. Spectrum analyzer setting: RBW = 100 kHz, VBW = 300 klHz, Detector = Peak.

5.7.4 Test results

Graphical Results Summary: The graph displays the spectrum across the operating band, showing multiple hopping channels utilized by the GFSK mode.

5.8 Conducted emissions at the band edge

5.8.1 Limits

In any 100 kHz bandwidth outside the frequency band in which the spread spectrum or digitally modulated intentional radiator is operating, the radio frequency power that is produced by the intentional radiator shall be at least 20 dB below that in the 100 kHz bandwidth within the band that contains the highest level of the desired power, based on either an RF conducted or a radiated measurement, provided the transmitter demonstrates compliance with the peak conducted power limits. If the transmitter complies with the conducted power limits based on the use of RMS averaging over a time interval, as permitted under paragraph (b)(3) of this section, the attenuation required under this paragraph shall be 30 dB instead of 20 dB. Attenuation below the general limits specified in §15.209(a) is not required. In addition, radiated emissions which fall in the restricted bands, as defined in §15.205(a), must also comply with the radiated emission limits specified in §15.209(a) (see §15.205(c)).

5.8.2 Test setup

Diagram Description: A test setup diagram shows the EUT connected to a Spectrum Analyzer.

5.8.3 Test procedure

1. Test method: ANSI C63.10-2013 Section 6.10.4
2. The EUT was set to non-hopping mode & hopping mode during the test.
3. The transmitter output of EUT is connected to the spectrum analyzer.
4. Spectrum analyzer setting: RBW = 100 kHz, VBW = 300 kHz, Detector = Peak.

5.8.4 Test results

Graphical Results Summary: The graphs show conducted emissions at the low and high band edges for both non-hopping and hopping modes. The emissions outside the band are significantly below the 20 dB limit relative to the in-band power.

5.9 Conducted spurious emissions

5.9.1 Limits

In any 100 kHz bandwidth outside the frequency band in which the spread spectrum or digitally modulated intentional radiator is operating, the radio frequency power that is produced by the intentional radiator shall be at least 20 dB below that in the 100 kHz bandwidth within the band that contains the highest level of the desired power, based on either an RF conducted or a radiated measurement, provided the transmitter demonstrates compliance with the peak conducted power limits. If the transmitter complies with the conducted power limits based on the use of RMS averaging over a time interval, as permitted under paragraph (b)(3) of this section, the attenuation required under this paragraph shall be 30 dB instead of 20 dB. Attenuation below the general limits specified in §15.209(a) is not required. In addition, radiated emissions which fall in the restricted bands, as defined in §15.205(a), must also comply with the radiated emission limits specified in §15.209(a) (see §15.205(c)).

5.9.2 Test setup

Diagram Description: A test setup diagram shows the EUT connected to a Spectrum Analyzer.

5.9.3 Test procedure

1. Test method: ANSI C63.10-2013 Section 6.10.4
2. The EUT was set to non-hopping mode & hopping mode during the test.
3. The transmitter output of EUT is connected to the spectrum analyzer.
4. Spectrum analyzer setting: RBW = 100 kHz, VBW = 300 kHz, Detector = Peak.

5.9.4 Test results

Notes: All modes of operation of the EUT were investigated, and only the worst-case results are reported. The worst-case mode: TX mode (GFSK).

Graphical Results Summary: The graphs show conducted spurious emissions for GFSK mode across various frequency ranges. All measured spurious emissions are significantly below the applicable limits.

5.10 Radiated spurious emission

5.10.1 Limits

§ 15.247 (d) In any 100 kHz bandwidth outside the frequency band in which the spread spectrum or digitally modulated intentional radiator is operating, the radio frequency power that is produced by the intentional radiator shall be at least 20 dB below that in the 100 kHz bandwidth within the band that contains the highest level of the desired power, based on either an RF conducted or a radiated measurement, provided the transmitter demonstrates compliance with the peak conducted power limits. If the transmitter complies with the conducted power limits based on the use of RMS averaging over a time interval, as permitted under paragraph (b)(3) of this section, the attenuation required under this paragraph shall be 30 dB instead of 20 dB. Attenuation below the general limits specified in § 15.209(a) is not required. In addition, radiated emissions which fall in the restricted bands, as defined in § 15.205(a), must also comply with the radiated emission limits specified in § 15.209(a) (see § 15.205(c)).

§ 15.209 Radiated emission limits; general requirements.

Note 1: the tighter limit applies at the band edges.

Note 2: the emission limits shown in the above table are based on measurements employing a CISPR quasi-peak detector except for the frequency bands 9-90 kHz, 110-490 kHz and above 1000 MHz. Radiated emission limits in these three bands are based on measurements employing an average detector.

§ 15.35 (b) requirements: When average radiated emission measurements are specified in this part, including average emission measurements below 1000 MHz, there also is a limit on the peak level of the radio frequency emissions. Unless otherwise specified, e.g., see §§ 15.250, 15.252, 15.253(d), 15.255, 15.256, and 15.509 through 15.519, the limit on peak radio frequency emissions is 20 dB above the maximum permitted average emission limit applicable to the equipment under test.

5.10.2 Test setup

Diagram Description:

Below 30MHz: The setup includes EUT & Support Units on a Turn Table (80cm height) above a Ground Plane. A Test Receiver is used. The distance is indicated as 3m.

30MHz~1GHz: The setup includes EUT & Support Units on a Turn Table (80cm height) above a Ground Plane. An Ant. Tower with a variable height (1-4m) is used, and a Test Receiver is connected. The distance is indicated as 3m.

Above 1GHz: The setup includes EUT & Support Units on a Turn Table (150cm height) above a Ground Plane. An Ant. Tower with a variable height (1-4m) is used, and a Spectrum analyzer with a Pre-amplifier is connected. The distance is indicated as 3m. Absorber material is shown.

5.10.3 Test procedure

1. Test method: ANSI C63.10-2013 Section 6.3, 6.4, 6.5, 6.6, 6.10.
2. The EUT is placed on an on-conducting table 0.8 meters above the ground plane for measurement below 1GHz, 1.5 meters above the ground plane for measurement above 1GHz.
3. Emission blew 18 GHz were measured at a 3 meters test distance, above 18 GHz were measured at 1.5-meter test distance with the application of a distance correction factor.
4. The frequency range of interest is monitored at a fixed antenna height and EUT azimuth. The EUT is rotated through 360 degrees to maximize emissions received. The antenna is scanned from 1 to 4 meters above the ground plane to further maximize the emission. Measurements are made with the antenna polarized in both the vertical and the horizontal positions.

KDB 558074 D01 15.247 Meas Guidance v05r02: The use of a duty cycle correction factor (DCCF) is permitted for calculating average radiated field strength emission levels for an FHSS device in 15.247. This DCCF can be applied when the unwanted emission limit is subject to an average field strength limit (e.g., within a Government Restricted band) and the conditions specified in Section 15.35(c) can be satisfied. The average radiated field strength is calculated by subtracting the DCCF from the maximum radiated field strength level as determined through measurement. The maximum radiated field strength level represents the worst-case (maximum amplitude) RMS measurement of the emission(s) during continuous transmission (i.e., not including any time intervals during which the transmitter is off or is transmitting at a reduced power level). It is also acceptable to apply the DCCF to a measurement performed with a peak detector instead of the specified RMS power averaging detector. Note that Section 15.35(c) specifies that the DCCF shall represent the worst-case (greatest duty cycle) over any 100 msec transmission period.

Test instrument setup

5.10.4 Test results

Notes:

The amplitude of spurious emissions which are attenuated more than 20 dB below the limits are not reported.

All modes of operation of the EUT were investigated, and only the worst-case results are reported.

There were no emissions found below 30MHz within 20dB of the limit.

Calculation formula:
Measurement (dBμV/m) = Reading Level (dBμV) + Correct Factor (dB/m)
Over (dB) = Measurement (dBμV/m) – Limit (dBuV/m)

Radiated emissions between 30MHz – 1GHz (Horizontal Polarization):

Radiated emissions between 30MHz – 1GHz (Vertical Polarization):

Radiated emissions 1 GHz ~ 25 GHz

GFSK - 2402 MHz TX mode

GFSK - 2441 MHz TX mode

GFSK - 2480 MHz TX mode

Radiated emissions at band edge

GFSK - Low band-edge

GFSK - High band-edge

Photographs of the Test Setup

See the appendix – Test Setup Photos.

Photographs of the EUT

See the appendix - EUT Photos.

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