AN4387 Application note Using the BlueNRG transceiver under ETSI EN 300 328 in 2400 – 2483.5 MHz band By Ugo Raia Introduction BlueNRG is a very low power Bluetooth low energy (BLE) single mode network processor, compliant with Bluetooth specifications core 4.0. The BlueNRG can act as master and slave. Bluetooth low energy technology operates in the same spectrum range (2400 - 2483.5 MHz, ISM band) as classical Bluetooth technology, but uses a different set of channels. Instead of Bluetooth technology's 79 channels of 1 MHz band, the low energy technology has 40 channels (37 data channels + 3 advertising channels) of 2 MHz band. Within the channel, data is transmitted using GFSK (Gaussian Frequency Shift Modulation). The bit rate is 1 Mbit/s, and the maximum transmit power is 10 mW (10 dBm). Further details are given in volume 6 part A of the Bluetooth Core Specification V4.0. This application note outlines the expected performance when using the BlueNRG under ETSI EN 300 328 in the 2400 to 2483.5 MHz band. For details on the regulatory limits in 2400 - 2483.5 MHz frequency band, please, refer to ETSI EN 300 328 V1.8.1 (2012-06). These can be downloaded from www.etsi.org. November 2013 DocID025465 Rev 1 1/22 www.st.com Contents AN4387 Contents 1 An overview of ETSI regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Technical requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 Application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4 Transmitter parameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 5 4.1 RF output power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4.2 Power spectral density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4.3 Occupied channel bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4.4 Transmitter unwanted emissions in out-of-band domain . . . . . . . . . . . . . 12 4.5 Transmitted unwanted emissions in spurious domain . . . . . . . . . . . . . . . 15 Receiver parameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 5.1 Receiver spurious emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 6 Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 7 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 2/22 DocID025465 Rev 1 AN4387 1 An overview of ETSI regulations An overview of ETSI regulations The use of radio equipment in most European countries is regulated through the R&TTE directive. The European Telecommunications Standard Institute (ETSI) is a standardization body that issues the standards for testing and type approval of transmitters and receivers. EN 300 328 covers the 2.4 GHz band and specifies in detail the requirements and test methods to be used for license-free operated radio equipment under class 3a, equipment using wideband modulation techniques (DSSS or FHSS). The standard defines two categories of equipment based on modulation type: Frequency Hopping Spread Spectrum (FHSS) Other types of wide band modulation (e.g. DSSS, OFDM, etc.) It also covers both adaptive and non-adaptive equipment. Adaptive equipment uses an automatic mechanism which allows the equipment to adapt automatically to its environment by identifying frequencies that are being used by other equipment. ETSI classifies Bluetooth LE as adaptive equipment using DSSS modulation. DocID025465 Rev 1 3/22 22 Technical requirements 2 AN4387 Technical requirements RF output power The RF output power is defined as the mean equivalent isotropic radiated power (e.i.r.p.) of the equipment during a transmission burst. The max allowed limit is -10 dBW (20 dBm, 100 mW). Power spectral density It is the mean equivalent isotropically radiated power spectral density during a transmission burst. Its value is limited to 10 dBm per MHz. Occupied channel bandwidth It is the bandwidth that contains 99% of the power of the signal. It shall fall completely within the band 2.4 GHz to 2.4835 GHz. Transmitter unwanted emissions in the out-of-band domain They are emissions when the equipment is in transmit mode, on frequencies immediately outside the necessary bandwidth which results from the modulation process, but excluding spurious. The transmitter unwanted emissions in out-of-band domain but outside the allocated band, shall not exceed the values provided by the mask in Table 1. Table 1. Transmitter in out-of-band domain Frequency range Transmit mask level < 2396 MHz Domain Spurious 2396 to 2398 MHz - 20 dBm/MHz Out of Band 2398 to 2400 MHz - 10 dBm/MHz Out of Band 2400 to 2483.5 MHz Allocated Band 2483.5 to 2485.5 MHz -10 dBm/MHz Out of Band 2485.5 to 2487.5 MHz -20 dBm/MHz Out of Band > 2487.5 MHz Spurious Transmitter unwanted emissions in the spurious domain Transmitter unwanted emissions in spurious domain are emissions outside the allocated band and outside the out-of-band domain (as specified in previous table), when the equipment is in transmit mode. The transmitter unwanted emissions in the spurious domain shall not exceed the values given in Table 2: 4/22 DocID025465 Rev 1 AN4387 Technical requirements Table 2. Transmitter in spurious domain Frequency range Maximum power, e.r.p. ( ≤ 1 GHz) e.i.r.p. (> 1 GHz) Bandwidth 30 MHz to 47 MHz -36 dBm 100 kHz 47 MHz to 74 MHz -54 dBm 100 kHz 74 MHz to 87.5 MHz -36 dBm 100 kHz 87,5 MHz to 118 MHz -54 dBm 100 kHz 118 MHz to 174 MHz -36 dBm 100 kHz 174 MHz to 230 MHz -54 dBm 100 kHz 230 MHz to 470 MHz -36 dBm 100 kHz 470 MHz to 862 MHz -54 dBm 100 kHz 862 MHz to 1 GHz -36 dBm 100 kHz 1 GHz to 12.75 GHz -30 dBm 1 MHz Receiver spurious emissions Receiver spurious emissions are emissions at any frequency when the equipment is in receive mode. They shall not exceed the values given in Table 3: Table 3. Receiver spurious emissions Frequency range Maximum power, e.r.p. Measurement bandwidth 30 MHz to 1 GHz -57 dBm 100 kHz 1 GHz to 12.75 GHz -47 dBm 1 MHz DocID025465 Rev 1 5/22 22 Application circuit 3 AN4387 Application circuit Figure 2 shows the BlueNRG application board photo. The application is constituted from 2 boards: a daughterboard and a motherboard. The daughterboard (see Figure 1) holds the BlueNRG with the circuits necessary for its works. The Bluetooth low energy protocol stack (GAP, GATT, SM, L2CAP, LL, RF-PHY) is embedded on the device. For the correctly functionality, the daughterboard have to be plugged on a motherboard (see Figure 2) by two header 5 x 2 connectors (J6 and J7). The motherboard is provided with a STM32L152VBT6 microcontroller to correctly program the transceiver. The micro is programmed with a firmware developed for BlueNRG application. A graphical user interface (GUI) is developed to program correctly the BlueNRG. The daughterboard is provided with a 16 MHz XTAL to provide the correct oscillator to the BlueNRG. Also a low speed crystal oscillator is mounted on the board and used from BlueNRG. An internal SMPS is present on the BlueNRG to drastically reduce the power consumption. The SMPS is fed from the battery (2.0 V to 3.6 V) and provide to device a programmable voltage (1.4 V usually). A SMA connector is present to connect the board at antenna or at instrumentation to verify the correct functionality and verify the FCC standard requests. A few of passive (inductors and capacitors) are used as matching/filtering for the power amplifier (PA) and balun network for the receiver. Figure 1. BlueNRG application daughterboard $0Y 6/22 DocID025465 Rev 1 AN4387 Application circuit Figure 2. : BlueNRG application daughterboard plugged into motherboard $0Y DocID025465 Rev 1 7/22 22 C1 VDD J1 1 3 5 7 9 C3 C4 JTAG R3 R4 R5 R6 nc nc nc nc or a 0R0_0805 between 1-3 D1 1 100p_0402_COG VBAT3 JTCK J4 HEADER 5X2 HEADER 5X2 BlueNRG-N L1 TBD_0402 VBAT1 SXTAL0 SXTAL1 RF0 RF1 VBAT2 FXTAL0 FXTAL1 24 23 22 21 20 19 18 17 C8 JTMS JTDO JTDI TBD_0402_COG C9 TBD_0402_COG VBAT2 TBD_0402 TBD_0402 TBD_0402_COG 12p_0402_COG XTAL_16M C16 100n_0402_X7R FTEST VBAT1 C17 C18 1u_0402_X5R 100n_0402_X7R R7 nS Q nW Vss SOSCOUT SOSCOUT AUXADP AUXADP AUXADN AUXADN 1 3 JP1 FTEST U3 1 2 3 4 TBD_0402_COG C14 C13 VDD nS MISO J2 SMA laterale C12 12p_0402_COG C15 100k_0402 TBD_0402_COG Q2 100p_0402_COG 3V3 C10 L2 L3 C11 AUXADP AUXADN 1 3 5 7 9 CSN CLK MOSI MISO RST C7 TBD_0402_COG 9 10 11 12 13 14 15 16 J3 SPI_MOSI SPI_CLK DIO7 DIO6 VBAT3 DIO5 DIO4 JTAG_TCK 22p_0402_COG JTAG_TMS JTAG_TDO JTAG_TDI VDD1V8 SOSCOUT N.C. AUXADP AUXADN 2 4 6 8 10 Jumper2 2 4 6 8 10 U2 2 1 2 3 4 5 6 7 8 SOSCOUT 2 IRQ 1 10k_0402 C6 Q1 VBAT1 33 MISO 32 31 CSN 30 FTEST 29 28 27 NO_SMPS 26 25 RST GND MOSI CLK IRQ 1 3 5 7 9 DocID025465 Rev 1 1 nc XTAL_32k SPI_MISO SPI_CS FTEST VDD1V2 SMPSFILT2 NO_SMPS SMPSFILT1 RESETN U1 VDD R2 150n_0402_X5R C5 nS R1 VDD 3 22p_0402_COG 3V3 VDD Solder a 10u_0805 between 1-2 2 2 4 6 8 10 100n_0402_X7R 2 JTMS JTCK JTDO JTDI C2 1u_0402_X5R NO_SMPS Male Connector 2x5 Vcc nHOLD C D 8 7 6 5 C19 100n_0402_X7R CLK MOSI VDD C20 VDD VDD VBAT2 M95640 Application circuit 8/22 Figure 3. Daughterboard schematic VBAT3 C21 C22 C23 R9 100k_0402 1u_0402_X5R 100n_0402_X7R 1u_0402_X5R 100n_0402_X7R AM17653v1 AN4387 AN4387 4 Transmitter parameter Transmitter parameter All the measurement here reported are measured with the following parameters: TC = 25 °C, Vdd = 3.3 V, f = 2402 MHz (lower frequency of the useful bandwidth), unless otherwise specified. 4.1 RF output power The measurements performed at the lowest, the middle, and the highest channel show results lower than the maximum permitted output power: Table 4. RF output power Frequency (MHz) Channel Output power 2402 37 7.5 dBm 2442 18 7.5 dBm 2480 39 7.4 dBm Figure 4. RF output power Ch 37 AM17654v1 9 8 7 6 dBm 5 4 3 2 1 0 -1 2400 4.2 2400.5 2401 2401.5 2402 MHz 2402.5 2403 2403.5 2404 Power spectral density The measurement shall be performed at the lowest, the middle, and the highest channel on which the equipment can operate. The transmitter shall be connected to a spectrum analyzer with the following settings: Start Freq: 2400 MHz; Stop Freq: 2483.5 MHz; Res BW: 10 kHz; Video BW: 30 kHz Sweep Points: > 8350; Detector: RMS; Trace Mode: Max Hold; Sweep time: Auto The measures show a value in line with the limit: 10 dBm/MHz. DocID025465 Rev 1 9/22 22 Transmitter parameter AN4387 Figure 5. Power spectral density Ch 37 AM17655v1 10 0 dBm -10 -20 -30 -40 -50 -60 2401 4.3 2401.5 2402 MHz 2402.5 2403 Occupied channel bandwidth The measurement shall be performed at the lowest and the highest frequency within the stated frequency range. The spectrum analyzer must be set with: Center Freq: The center freq of the channel under test; Res BW: ~1% of the span without going below 1%; Video BW: 3 × RBW; Freq Span: 4 MHz; Detector Mode: RMS; Trace Mode: Max Hold. Find the peak value of the trace and place the analyzer marker on this peak. Use the 99 % bandwidth function of the spectrum analyzer to measure the occupied channel bandwidth of the UUT. The measures show a value equal to 1 MHz for all channels; it fall completely within the band 2.4 - 2.4835 GHz. 10/22 DocID025465 Rev 1 AN4387 Transmitter parameter Figure 6. Occupied channel bandwidth Ch 37 AM17656v1 10 0 dBm -10 -20 -30 -40 -50 2400 2400.5 2401 2401.5 2402 MHz DocID025465 Rev 1 2402.5 2403 2403.5 2404 11/22 22 Transmitter parameter 4.4 AN4387 Transmitter unwanted emissions in out-of-band domain The measurement shall be performed at the lowest and the highest channel on which the equipment can operate. The spectrum analyzer must be set with: Centre Frequency: 2484 MHz; Span: 0 Hz; Resolution BW: 1 MHz Filter mode: Channel filter; Video BW: 3 MHz; Detector Mode: RMS Trace Mode: Clear/Write; Sweep Mode: Continuous; Sweep Points: 5000 Trigger Mode: Video trigger; Sweep Time: Suitable to capture one transmission burst For the segment 2483.5 MHz to 2485.5 MHz: – Adjust the trigger level to select the transmissions with the highest power level. – Set a window (start and stop lines) to match with the start and end of the burst and in which the RMS power shall be measured using the time domain power function. – Select RMS power to be measured within the selected window and note the result which is the RMS power within this 1 MHz segment (2483.5 MHz to 2484.5 MHz). – Compare this value with the applicable limit provided by the mask. – Increase the center frequency in steps of 1 MHz and repeat this measurement for every 1 MHz segment within the range 2483.5 MHz to 2485.5 MHz. The center frequency of the last 1 MHz segment shall be set to 2485.5 MHz - 0.5 MHz (which means this may partly overlap with the previous 1 MHz segment). For the segment 2485.5 MHz to 2487.5 MHz: Change the center frequency of the analyzer to 2486 MHz and perform the measurement for the first 1 MHz segment within range 2485.5 MHz to 2487.5 MHz. Increase the center frequency in 1 MHz steps and repeat the measurements to cover this whole range. The center frequency of the last 1 MHz segment shall be set to 2487.5 MHz - 0.5 MHz. For the segment 2398 MHz to 2400 MHz: Change the center frequency of the analyzer to 2399.5 MHz and perform the measurement for the first 1 MHz segment within range 2398 MHz to 2400 MHz. Reduce the center frequency in 1 MHz steps and repeat the measurements to cover this whole range. The center frequency of the last 1 MHz segment shall be set to 2396 MHz + 0.5 MHz. For the segment 2396 MHz to 2398 MHz: Change the center frequency of the analyzer to 2397.5 MHz and perform the measurement for the first 1 MHz segment within range 2396 MHz to 2398 MHz. Reduce the center frequency in 1 MHz steps and repeat the measurements to cover this whole range. The center frequency of the last 1 MHz segment shall be set to 2396 MHz + 0.5 MHz. A prescan analysis in the range below 2.4 GHz (Figure 7) permits to search for unwanted spurious: no particular emissions were found. 12/22 DocID025465 Rev 1 AN4387 Transmitter parameter Figure 7. Prescan of emissions in the out-of-band domain below 2400 MHz AM17657v1 0 -10 -20 dBm -30 -40 -50 -60 -70 10 510 1010 1510 2010 MHz Follows the detailed analysis in all the ranges specified by the mask; the BlueNRG meets the requirement with large margin. Figure 8. Emissions in the out-of-band domain for the range 2396-2398 MHz AM17658v1 0 -5 -10 -15 dBm -20 -25 -30 -35 -40 -45 -50 2397 2397.2 2397.4 2397.6 2397.8 2398 MHz DocID025465 Rev 1 13/22 22 Transmitter parameter AN4387 Figure 9. Emissions in the out-of-band domain for the range 2398 - 2400 MHz AM17659v1 0 -5 -10 dBm -15 -20 -25 -30 -35 -40 2399 2399.2 2399.4 2399.6 2399.8 2400 MHz Figure 10. Emissions in the out-of-band domain for the range 2483.5 - 2485.5 MHz AM17660v1 0 -10 dBm -20 -30 -40 -50 -60 2483.5 2483.7 2483.9 2484.1 MHz 14/22 DocID025465 Rev 1 2484.3 2484.5 AN4387 Transmitter parameter Figure 11. Emissions in the out-of-band domain for the range 2485.5 - 2487.5 MHz AM17661v1 0 -10 dBm -20 -30 -40 -50 -60 2485.5 2485.7 2485.9 2486.1 2486.3 2486.5 MHz 4.5 Transmitted unwanted emissions in spurious domain The measurement shall be performed at the lowest and the highest channel on which the equipment can operate. To identify potential unwanted emissions the spectrum analyzer settings are: For the range 30 MHz to 1000 MHz: Resolution bandwidth: 100 kHz; Video bandwidth: 300 kHz; Detector mode: Peak Trace Mode: Max Hold; Sweep Points: 9970 For the range 1 GHz to 12.75 GHz: Resolution bandwidth: 1 MHz; Video bandwidth: 3 MHz; Detector mode: Peak Trace Mode: Max Hold; Sweep Points: 11750 Instead, to accurately measure the individual unwanted emissions: Centre Frequency: Frequency of emission identified during the prescan; Resolution Bandwidth: 100 kHz (< 1 GHz) / 1 MHz (> 1 GHz) Video Bandwidth: 300 kHz (< 1 GHz) / 3 MHz (> 1 GHz) Frequency Span: Wide enough to capture each individual emission identified during the prescan Sweep mode: Continuous Sweep time: Auto Trigger: Free run DocID025465 Rev 1 15/22 22 Transmitter parameter AN4387 Detector: RMS Trace Mode: Max Hold The BlueNRG passes the test without problems Figure 12. Transmitted emissions in the spurious domain, range 30-1000 MHz AM17662v1 -10 -20 -30 dBm -40 -50 -60 -70 -80 30 130 230 330 430 530 MHz 630 730 830 930 Figure 13. Transmitted emissions in the spurious domain, range 2.3 - 2.396 GHz AM17663v1 0 -10 -20 dBm -30 -40 -50 -60 -70 2300 2320 2340 2360 MHz 16/22 DocID025465 Rev 1 2380 AN4387 Transmitter parameter Figure 14. Transmitted emissions in spurious domain, range 2.4875 - 12.75 GHz AM17664v1 0 -10 dBm -20 -30 -40 -50 -60 2487.5 4487.5 6487.5 8487.5 10487.5 12487.5 MHz DocID025465 Rev 1 17/22 22 Receiver parameter AN4387 5 Receiver parameter 5.1 Receiver spurious emissions The measurement shall be performed at the lowest and the highest channel on which the equipment can operate. Testing shall be performed when the equipment is in a receive-only mode. The spectrum analyzer settings are equivalent to those used for the transmitted unwanted emissions in spurious domain. No particular troubles were registered for this test. Figure 15. Receiver spurious emissions, range 30 - 1000 MHz AM17665v1 -30 -40 dBm -50 -60 -70 -80 -90 -100 30 230 430 630 MHz 18/22 DocID025465 Rev 1 830 AN4387 Receiver parameter Figure 16. Receiver spurious emissions, range 1 - 12.75 GHz AM17666v1 -30 -40 -50 dBm -60 -70 -80 -90 -100 1000 3000 5000 7000 MHz DocID025465 Rev 1 9000 11000 19/22 22 Reference 6 AN4387 Reference [1] BlueNRG Datasheet [2] ETSI EN 300 328 V1.8.1 (2012-06) [3] "Bluetooth Low Energy Regulatory Aspects", from Bluetooth SIG Regulatory Committee 20/22 DocID025465 Rev 1 AN4387 7 Revision history Revision history Table 5. Document revision history Date Revision 14-Nov-2013 1 Changes Initial release. DocID025465 Rev 1 21/22 22 AN4387 Please Read Carefully: Information in this document is provided solely in connection with ST products. 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