Shenzhen CTA Testing Technology Co., Ltd. FCC PART 15 SUBPART C TEST REPORT
Report Reference No.: CTA24061701501
FCC ID: 2AC59-OE921
Summary
General Remarks
Date of receipt of test sample: Jun. 15, 2024
Testing commenced on: Jun. 15, 2024
Testing concluded on: Jun. 22, 2024
Product Description
Product Description: FLOW Lite 84-Key Triple Mode Low-Profile Mechanical Keyboard
Model/Type reference: OE921
Power supply: DC 3.7V From battery and DC 5.0V From external circuit
PC information (Auxiliary test supplied by testing Lab): Model: E470C, Trade Mark: thinkpad
Hardware version: V2.0
Software version: 6BEAA702
Testing sample ID: CTA240617015-1# (Engineer sample), CTA240617015-2# (Normal sample)
Bluetooth BLE: Supported type: Bluetooth low Energy, Modulation: GFSK, Operation frequency: 2402MHz to 2480MHz, Channel number: 40, Channel separation: 2 MHz, Antenna type: PCB antenna, Antenna gain: -1.66 dBi
Equipment Under Test
Power supply system utilised:
- Power supply voltage: 230V / 50 Hz, 120V / 60Hz
- Other: DC 3.7V From battery and DC 5.0V From external circuit
Short description of the Equipment under Test (EUT)
This is a FLOW Lite 84-Key Triple Mode Low-Profile Mechanical Keyboard. For more details, refer to the user's manual of the EUT.
EUT operation mode
The Applicant provides command "*#*#3646633#*#*" access (Engineer mode) to control the EUT for staying in continuous transmitting (Duty Cycle more than 98%) and receiving mode for testing. There are 40 channels provided to the EUT and Channel 00/19/39 were selected to test.
Operation Frequency:
| Channel | Frequency (MHz) |
|---|---|
| 00 | 2402 |
| 01 | 2404 |
| 02 | 2406 |
| 19 | 2440 |
| 37 | 2476 |
| 38 | 2478 |
| 39 | 2480 |
Block Diagram of Test Setup
A block diagram illustrates the test setup, showing the EUT (module) connected to a DC 5.0V source from a PC.
Related Submittal(s) / Grant (s)
This submittal(s) (test report) is intended for filing to comply with Section 15.247 of the FCC Part 15, Subpart C Rules.
Modifications
No modifications were implemented to meet testing criteria.
Test Environment
Address of the test laboratory
Shenzhen CTA Testing Technology Co., Ltd., Room 106, Building 1, Yibaolai Industrial Park, Qiaotou Community, Fuhai Street, Bao'an District, Shenzhen, China.
Test Facility
The test facility is recognized, certified, or accredited by the following organizations: FCC-Registration No.: 517856 Designation Number: CN1318. Shenzhen CTA Testing Technology Co., Ltd. is listed on the US Federal Communications Commission list of test facilities. A2LA-Lab Cert. No.: 6534.01. Shenzhen CTA Testing Technology Co., Ltd. is listed by American Association for Laboratory Accreditation. The 3m-Semi anechoic test site fulfils CISPR 16-1-4 according to ANSI C63.10 and CISPR 16-1-4:2010.
Environmental conditions
Radiated Emission: Temperature: 23 °C, Humidity: 44 %, Atmospheric pressure: 950-1050mbar
AC Main Conducted testing: Temperature: 24 °C, Humidity: 47 %, Atmospheric pressure: 950-1050mbar
Conducted testing: Temperature: 24 °C, Humidity: 46 %, Atmospheric pressure: 950-1050mbar
Test Conditions and Results
AC Power Conducted Emission
Test Configuration: A diagram shows the test setup for AC Power Conducted Emission, including the EUT, LISN, EMI receiver, and reference ground plane.
Test Procedure: The EUT was set up on a 0.8m high table, connected via a LISN to the AC power source. Emissions were measured on each current carrying line using a spectrum analyzer/receiver. Scans were performed for Line 1 and Line 2, covering frequencies from 150 KHz to 30MHz.
AC Power Conducted Emission Limit:
| Frequency range (MHz) | Limit (dBuV) Quasi-peak | Average |
|---|---|---|
| 0.15-0.5 | 66 to 56* | 56 to 46* |
| 0.5-5 | 56 | 46 |
| 5-30 | 60 | 50 |
* Decreases with the logarithm of the frequency.
Test Results: BLE 1Mpbs was tested at Low, Middle, and High channels. The worst result for BLE 1Mpbs High channel was reported. Both 120 VAC, 50/60 Hz and 240 VAC, 50/60 Hz power supplies were tested, with the worst result for 120 VAC, 60 Hz reported.
A graph shows the AC Power Conducted Emission levels for Line L (Horizontal polarization) and Line N (Vertical polarization) against frequency, with QP and AV limits indicated. A data table lists specific measurements for frequencies from 0.1545 MHz to 27.087 MHz, including QP/AV readings, factors, limits, and margins, all indicating 'PASS'.
Radiated Emissions and Band Edge
Test Configuration: Diagrams illustrate the test setups for frequency ranges 9 KHz - 30MHz (using a loop antenna), 30MHz – 1000MHz (using a broadband antenna), and above 1GHz-25GHz (using a horn antenna). All setups involve the EUT, turntable, ground plane, coaxial cable, and test receiver/spectrum analyzer at specified distances (0.8m or 1.5m height, 3m or 1m-4m antenna distance).
Test Procedure: The EUT was placed on a turntable at 0.8m or 1.5m height. Measurements were taken by rotating the antenna from 1m to 4m and the turntable from 0° to 360°, with polarization adjusted (horizontal/vertical). Tests covered frequencies from 9KHz to 25GHz. Specific receiver/spectrum settings (RBW, VBW, detector) were used for different frequency ranges.
Field Strength Calculation: Field strength (FS) is calculated as FS = RA + AF + CL - AG, where RA is Reading Amplitude, AF is Antenna Factor, CL is Cable Attenuation Factor, and AG is Amplifier Gain.
Radiation Limit: According to FCC §15.209(a), field strength limits are specified for various frequency bands. According to §15.247(d), emissions outside the operating band must be at least 20dB below the in-band level.
Test Results: The EUT was tested in X, Y, Z positions, with X being the worst case. BLE 1Mpbs was tested across channels. Radiated emissions from 9 KHz to the 10th harmonic were verified, with no significant emissions found above system noise floor.
Data tables and graphs present the results for Horizontal and Vertical polarizations for radiated emissions from 30MHz to 1GHz, and for frequencies above 1GHz (up to 25GHz) for specific channels (2402MHz, 2440MHz, 2480MHz), showing emission levels, limits, margins, and other measurement parameters. Band-edge measurements for conducted emissions are also presented.
Maximum Peak Output Power
Limit: The Maximum Peak Output Power Measurement is 30dBm.
Test Procedure: The EUT's antenna was removed, and a low loss RF cable connected it to a power sensor for measurement.
Test Configuration: A diagram shows the EUT connected to a Power Sensor.
Test Results: For GFSK 1Mbps, output power was measured for channels 00, 19, and 39. Values ranged from -0.45 dBm to -0.84 dBm, all within the 30.00 dBm limit, resulting in a 'PASS'.
Power Spectral Density
Limit: For digitally modulated systems, the power spectral density shall not be greater than 8 dBm in any 3 kHz band.
Test Procedure: The procedure involved setting RBW ≥ 3 kHz, VBW ≥ 3x RBW, and using a peak detector with max hold. Measurements were performed to determine the maximum power level.
Test Configuration: A diagram shows the EUT connected to a SPECTRUM ANALYZER.
Test Results: For GFSK 1Mbps, power spectral density measurements for channels 00, 19, and 39 were -15.63 dBm/3KHz, -16.92 dBm/3KHz, and -16.71 dBm/3KHz respectively, all below the 8.00 dBm/3KHz limit, resulting in a 'PASS'. Spectrum analyzer plots visually confirm these results.
6dB Bandwidth
Limit: For digital modulation systems, the minimum 6 dB bandwidth shall be at least 500 kHz.
Test Procedure: The transmitter output was connected to a spectrum analyzer with 100 KHz RBW and 300 KHz VBW. The 6dB bandwidth was defined as the total spectrum where power is higher than peak power minus 6dB.
Test Configuration: A diagram shows the EUT connected to a SPECTRUM ANALYZER.
Test Results: For GFSK 1Mbps, the 6dB bandwidths for channels 00, 19, and 39 were measured as 0.708 MHz, 0.704 MHz, and 0.684 MHz respectively, all exceeding the 500 kHz limit, resulting in a 'PASS'. Spectrum analyzer plots visually confirm these results.
Out-of-band Emissions
Limit: Radio frequency power produced by the intentional radiator outside the 100 kHz bandwidth shall be at least 20 dB below the in-band level.
Test Procedure: The transmitter output was connected to a spectrum analyzer with RBW=100 kHz, VBW= 300 kHz, peak detector, and max hold. Measurements were made of in-band reference level, bandedge, and out-of-band emissions.
Test Configuration: A diagram shows the EUT connected to a SPECTRUM ANALYZER.
Test Results: The measurement frequency range was from 30MHz to the 10th harmonic of the fundamental frequency. The lowest, middle, and highest channels were tested to verify spurious emissions and bandedge data. Spectrum analyzer plots are provided for these measurements.
Antenna Requirement
Standard Applicable: According to FCC 47 CFR Section 15.203, intentional radiators must be designed with a permanently attached antenna or a unique coupling mechanism. Standard antenna jacks or connectors are prohibited.
FCC CFR Title 47 Part 15 Subpart C Section 15.247(c) (1) (I): Details regulations for transmitting antennas with directional gain greater than 6dBi, requiring power reduction.
Antenna Connected Construction: The gain of the antenna was -1.66 dBi.
Remark: Antenna gain data is provided by the customer. Shenzhen CTA Testing Technology Co., Ltd. assumes no responsibility for the accuracy of this data.
Test Setup Photos of the EUT
Photographs illustrating the test setup for the EUT are provided, showing the equipment arrangement in the testing environment.
Photos of the EUT
Multiple photographs display the LOFREE FLOW Lite mechanical keyboard from various angles, including top, bottom, and internal views, showcasing its design and components.
