AN4110 STMICROELECTRONICS | Alldatasheet
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Technical content
Datasheet sections
- 1 Application circuit
- 2 Transmitter parameter
- 2.1 Adjacent channel power
- 2.2 Modulation bandwidth
- 2.3 Unwanted emissions in the spurious domain
- 3 Receiver parameters
- 3.1 Receiver sensitivity
- 3.2 Blocking
- 3.3 Receiver spurious radiation
- 4 Measurement equipment
- 5 Reference
- 6 Revision history
July 2012 Doc ID 023182 Rev 1 1/18 AN4110 Application note Using the SPIRIT1 transceiver under EN 300 220 at 868 MHz By Placido De Vita Introduction The SPIRIT1 is a very low power RF transceiver, intended for RF wireless applications in the sub-1 GHz band. It is designed to operate both in the licence-free ISM and SRD frequency bands at 169, 315, 433, 868 and 915 MHz. This application note outlines the expected performance when using the SPIRIT1 under EN 300 220-1 (v2.3.1, 2012-02) [2] in the 863 to 870 MHz band. This band is divided into sub- bands where the application, the maximum radiated power, the channel spacing and/or the mitigation requirement (duty cycle etc.) are different. The maximum allowed output power is +27 dBm (500 mW) in 869.4 to 869.65 MHz, and it is variable in the other sub-bands (see Table 5 in ETSI EN 300 220-1 v2.3.1 [2]). This application note relates to +10 dBm (10 mW) applications. For details on the regulatory limits in the 863.000 - 870.000 MHz SRD frequency bands, please refer to the ETSI EN 300 220-1 v2.3.1 [2] and ERC recommendation 70-03 [3].
1 Application circuit
transceiver. The micro is programmed with firmware developed for the SPIRIT1 application. A graphical user interface (GUI) has been developed to correctly program the SPIRIT1. applications that work in the 863.000 - 870.000 MHz bandwidth. battery (1.8 V to 3.6 V) and provides a programmable voltage (1.4 V typically) to the device. to verify the correct functionality and verify the ETSI standard request. amplifier (PA) and balun network for the receiver. Figure 1. SPIRIT1 application daughterboard
Figure 3. Daughterboard schematic
Transmitter parameter AN4110 6/18 Doc ID 023182 Rev 1
2 Transmitter parameter
All the measurements here reported are performed with the following parameters: Tc = 25 °C, Vdd = 3.0 V, f = 868.300 MHz. The modulation bandwidth and adjacent channel power measurements are here reported. The measurements are realized according to EN 300 220 v1 [2] sections 7.6 and 7.7.
2.1 Adjacent channel power
The adjacent channel power (ACP) is defined as the amount of the modulated RF signal power which falls within a given adjacent channel. This power is the sum of the mean power produced by the modulation, hum and noise of the transmitter. This measurement is applicable only to narrowband systems. This test measures the power transmitted in the adjacent channel during continuous modulation. The ACP is measured with a spectrum analyzer that conforms to the requirements given in the EN 300 220-1 v2.3.1 (2010-02) [2] annex C. In this application note the ACP measured with 25 kHz channel spacing is investigated. For this measurement the integrated bandwidth of the adjacent channel is 16 kHz and the ETSI limit for the ACP is 200 nW (-37 dBm). Figure 4 illustrates the measured ACP at the 868.3 MHz center frequency. The data rate is set to 9.6 kbps, the frequency deviation is set to 2.4 kHz, and the modulation is set to gaussian FSK (GFSK) with a BT = 1. The output power integrated around the carrier is 11 dBm in a 16 kHz bandwidth and with average detection. With this power the ACP is -39 dBm, that is 2 dB better than the ETSI limit. In Figure 4 the alternate channel power (ALT) is also reported. With this power the ALT is - 46 dBm. Regarding the ALT, no specification is defined in the ETSI standard. The SPIRIT1 is fully compliant with the ETSI transmitter adjacent channel power requirements with margin.
Figure 4. Adjacent power measurement, 25 kHz narrowband channel spacing,
2.2 Modulation bandwidth
appropriate emissions level and the frequency error or drift under extreme test conditions. is not included in this report. integration at the different offset regions. parameters, the spectral masks of the SPIRIT1 comply with ETSI [2] subclause 7.7.
Figure 7. Spectral mask measurement, 100 kHz channel spacing, 38.4 kbps data
2.3 Unwanted emissions in the spurious domain
described in the ETSI [2] subclause 7.8. ETSI [2]. In the two images the mask request from the ETSI is reported also.
AN4110 Receiver parameters Doc ID 023182 Rev 1 11/18
3 Receiver parameters
All the measurements here reported are performed with the following parameters: Tc = 25 °C, Vdd = 3.0 V, f = 868.300 MHz. The product family of short range radio devices is divided into three receiver categories, each having a set of relevant receiver requirements and minimum performance criteria. The set of receiver requirements depends on the choice of receiver category by the equipment provider. The SPIRIT1 is a transceiver that meets receiver category 2. According to EN 300 220-1 (v2.3.1, 2012-02) [2], a category 2 receiver is described as “Medium reliable SRD communication media, e.g. causing inconvenience to persons, which cannot simply be overcome by other means”. The main parameters that must be measured for category 2 devices are the sensitivity and the blocking. The adjacent channel selectivity refers to receiver category 1, and so it is not necessary for SPIRIT1 to meet this parameter.
3.1 Receiver sensitivity
The receiver sensitivity is the minimum level of the signal at the receiver input, produced by a carrier at the nominal frequency of the receiver, modulated with the normal test signal modulation, which produces the performance of a bit error rate (BER) of 10-2 without correction. Under normal test conditions, the value of the typical usable sensitivity for 25 kHz channel spacing equipment with a 16 kHz bandwidth should not exceed -107 dBm. If the RX bandwidth is not 16 kHz, the sensitivity limit is modified according to the following formula: Equation 1 The measurement is performed using an RF signal source generator centered at the same receiver frequency with the wanted modulation signal. The demodulated data and clock are taken from the SPIRIT1 receiver and sent to the same generator to perform the BER measurement. The generator signal level is reduced and then a BER of 1% is obtained. To reduce the power consumption, an internal SMPS is integrated into the SPIRIT1. Figure 10 demonstrates the ETSI 1% BER sensitivity limit (red line) and the SPIRIT1 sensitivity for different data rate with internal and external SMPS. This application note outlines the expected performance when using the SPIRIT1 under EN 300 220-1 (v2.3.1, 2012-02) [2] in the 863.000 - 870.000 MHz band, without defining the maximum channel spacing. In order to show the real performance of the SPIRIT1 transceiver, different channel spacings are shown. The test conditions are: 2-FSK modulation with 1 kHz frequency deviation and 6 kHz channel bandwidth for the 1.2 kbps data rate, 2-FSK modulation with 20 kHz frequency deviation and 100 kHz channel bandwidth for the 38.4 kbps data rate, GFSK (BT = 1) modulation with 127 kHz frequency deviation and 540 kHz channel bandwidth for the 250 kbps data rate and MSK modulation with 812 kHz channel bandwidth for the 500 kbps data rate. The SPIRIT1 is fully compliant with the ETSI category 2 receiver sensitivity requirements with large margin.
Figure 10. Sensitivity vs. data rate with 1% BER
3.2 Blocking
degradation of 1% is obtained. rate; Figure 12 shows the blocking curve with 500 kbps data rate. does not have to be under this regulation.
Figure 11. RX blocking vs. CW interferer offset with 1% BER, 1.2 kbps data rate Figure 12. RX blocking vs. CW interferer offset with 1% BER, 500 kbps data rate
3.3 Receiver spurious radiation
described in the ETSI [2] subclause 8.6.
4 Measurement equipment
The following equipment was used for the measurements. Table 1. Measurement equipment
5 Reference
- SPIRIT1 datasheet. 2. ETSI EN300 220 V2.3.1: “Electromagnetic compatibility and Radio spectrum Matters (ERM); Short Range Devices (SRD); Radio equipment to be used in the 25 MHz to 1000 MHz frequency range with power levels ranging up to 500 mW”. 3. CEPT/ERC/Recommendation 70-03: “Relating to the use of short range devices (SRD)”. 4. CEN/TC prEN 13757-4:2011.10: “Communication systems for meters and remote reading of meters - Part 4: Wireless meter readout (radio meter reading for operating in SRD bands)”.
6 Revision history
Table 2. Document revision history 11-Jul-2012 1 Initial release.