AN4117
Application note
Using the SPIRIT1 transceiver under EN 300 220 at 434 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 in both 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 433.050 to 434.790 MHz band. There are no specific
requirements in this band, no specific use and no channel spacing are defined. Devices
supporting audio and video applications use a digital modulation method with a maximum
bandwidth of 300 kHz. Devices supporting digital voice have a maximum bandwidth not
exceeding 25 kHz. The maximum allowed output power is +10 dBm (10 mW).
For details of the regulatory limits in the 433.050 - 434.790 MHz SRD frequency bands,
please refer to the ETSI EN 300 220-1 v2.3.1 [2] and ERC recommendation 70-03 [3].
These can be downloaded from www.etsi.org and www.ero.dk respectively.
October 2012
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www.st.com
Contents
AN4117
Contents
1
Application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2
Transmitter parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3
2.1
Adjacent channel power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2
Modulation bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.3
Unwanted emissions in the spurious domain . . . . . . . . . . . . . . . . . . . . . . 12
Receiver parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.1
Receiver sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2
Blocking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.3
Receiver spurious radiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4
Measurement equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5
Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
6
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2/22
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AN4117
List of figures
List of figures
Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure 8.
Figure 9.
Figure 10.
Figure 11.
Figure 12.
Figure 13.
Figure 14.
Figure 15.
Figure 16.
Figure 17.
Figure 18.
Figure 19.
Figure 20.
Figure 21.
SPIRIT1 application daughterboard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
SPIRIT1 application daughterboard plugged into the motherboard . . . . . . . . . . . . . . . . . . . 5
Daughterboard schematic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Adjacent power measurement, 12.5 kHz narrowband channel spacing, 1.2 Kbps data rate,
1 kHz frequency deviation, 2-FSK modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Adjacent power measurement, 12.5 kHz narrowband channel spacing, 2.4 Kbps data rate,
2.4 kHz frequency deviation, GFSK (BT=0.5) modulation . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Adjacent power measurement, 25 kHz narrowband channel spacing, 4.8 Kbps data rate,
2.4 kHz frequency deviation, GFSK (BT=0.5) modulation . . . . . . . . . . . . . . . . . . . . . . . . . . 9
ETSI spectral mask measurement limits and sub-band edges. . . . . . . . . . . . . . . . . . . . . . 10
Spectral mask measurement, 12.5 kHz narrowband channel spacing,1.2 Kbps data rate,
1 kHz frequency deviation, 2-FSK modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Spectral mask measurement, 12.5 kHz narrowband channel spacing, 2.4 Kbps data rate,
2.4 kHz frequency deviation, GFSK (BT=0.5) modulation . . . . . . . . . . . . . . . . . . . . . . . . . 11
Spectral mask measurement, 25 kHz narrowband channel spacing, 4.8 Kbps data rate,
2.4 kHz frequency deviation, GFSK (BT=0.5) modulation . . . . . . . . . . . . . . . . . . . . . . . . . 11
Spectral mask measurement, 100 kHz channel spacing, 38.4 Kbps data rate, 20 kHz
frequency deviation, GFSK (BT=1) modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Spectral mask measurement, 500 kHz channel spacing, 250 Kbps data rate, 127 kHz
frequency deviation, GFSK (BT=1) modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Unwanted emission in the spurious domain mask below 1 GHz . . . . . . . . . . . . . . . . . . . . 13
Unwanted emission in the spurious domain mask above 1 GHz . . . . . . . . . . . . . . . . . . . . 13
Sensitivity vs. data rate with 1% BER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
RX blocking vs. CW interferer offset with 1% BER, 12.5 kHz channel . . . . . . . . . . . . . . . . 16
RX blocking vs. CW interferer offset with 1% BER, 25 kHz channel . . . . . . . . . . . . . . . . . 16
RX blocking vs. CW interferer offset with 1% BER, 100 kHz channel . . . . . . . . . . . . . . . . 17
RX blocking vs. CW interferer offset with 1% BER, 500 kHz channel . . . . . . . . . . . . . . . . 17
RX spurious radiation below 1 GHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
RX spurious radiation above 1 GHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
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Application circuit
1
AN4117
Application circuit
Figure 1 shows an image of the SPIRIT1 application daughterboard. The application is
made up of two boards: a daughterboard and a motherboard. The daughterboard includes
the SPIRIT1 with the circuits necessary for its functioning. For correct functionality, the
daughterboard must be plugged into a motherboard (see Figure 2) by two header 5x2
connectors (J6 and J7).
The motherboard is provided with an STM32L152VBT6 micro to correctly program the
transceiver. The micro is programmed with a firmware developed for the SPIRIT1
application. A graphical user interface (GUI) has been developed to correctly program the
SPIRIT1.
The daughterboard is provided with a 52 MHz XTAL to provide the correct oscillator to the
SPIRIT1.
The SPIRIT1 has an internal SMPS that drastically reduces power consumption, making it
the best in class for applications on this bandwidth. The SMPS is fed from the battery (1.8 V
to 3.6 V) and provides a programmable voltage (1.4 V typ.) to the device. An SMA connector
is present to connect the board at the antenna or at the instrumentation to verify the correct
functionality and the ETSI standard request.
A few passive parts (inductors and capacitors) are used as matching/filtering for the power
amplifier (PA) and a balun network for the receiver.
To reduce application costs, the SPIRIT1 is designed to work without an external antenna
switch. This daughterboard is designed to show the SPIRIT1 functions in this condition. An
application with an antenna switch can certainly be realized but is not described in this
document.
Figure 1.
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SPIRIT1 application daughterboard
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AN4117
Application circuit
Figure 2.
SPIRIT1 application daughterboard plugged into the motherboard
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6/22
7
Application circuit
AN4117
Daughterboard schematic
!-V
AN4117
2
Transmitter parameters
Transmitter parameters
All the measurements here reported are performed with the following parameters: Tc = 25
°C, Vdd = 3.0 V, f = 434.030 MHz. They are also measured with the reference design
reported in EN 300 220 v1 [2] Annex A.1.
The modulation bandwidth, adjacent channel power, and unwanted emissions in the
spurious domain measurements are here reported. The measurements are realized
according to EN 300 220 v1 [2] sections 7.6, 7.7 and 7.8.
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 which conforms to the
requirements given in EN 300 220-1 v2.3.1 (2010-02) [2] Annex C.
In this application note, ACP measured with 12.5 kHz and 25 kHz channel spacing are
investigated. For these measurements the integrated bandwidths of the adjacent channel
are 8.5 kHz and 16 kHz respectively. The ETSI limit for the ACP is 10 µW (-20 dBm) for 12.5
kHz channelization and 200 nW (-37 dBm) for 25 kHz channelization.
Figure 4 and 5 illustrate the measured ACP at the 434.3 MHz center frequency with 12.5
kHz channelization, Figure 6 illustrates the measured ACP with 25 kHz channelization. The
data rate for the modulated signal in Figure 4 is set to 1.2 Kbps, the frequency deviation is
set to 1 kHz, and the modulation is set to 2-FSK. The data rate for the modulated signal in
Figure 5 is set to 2.4 Kbps, the frequency deviation is set to 2.4 kHz, and the modulation is
set to Gaussian FSK (GFSK) with BT = 0.5. The data rate for the modulated signal in
Figure 6 is set to 4.8 Kbps, the frequency deviation is set to 2.4 kHz, and the modulation is
set to Gaussian FSK (GFSK) with BT = 0.5.
The output power integrated around the carrier is 12 dBm in the bandwidth and with average
detection. With this power the ACP is -38 dBm in the first two cases and -43 dBm in the third
case. The SPIRIT1 is fully compliant with the ETSI transmitter adjacent channel power
requirements with margin.
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Transmitter parameters
Figure 4.
AN4117
Adjacent power measurement, 12.5 kHz narrowband channel spacing,
1.2 Kbps data rate, 1 kHz frequency deviation, 2-FSK modulation
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Figure 5.
!-V
Adjacent power measurement, 12.5 kHz narrowband channel spacing,
2.4 Kbps data rate, 2.4 kHz frequency deviation, GFSK (BT=0.5)
modulation
ϭϬ
Ϭ
WсͲϯϴĚŵ
ϴ͘ϱŬ,nj
ϴ͘ϱŬ,nj
ͲϭϬ
KƵƉƵƚƉŽǁĞƌĚŵ
ͲϮϬ
ͲϯϬ
ͲϰϬ
ͲϱϬ
ͲϲϬ
ͲϳϬ
ͲϴϬ
ϴ͘ϱŬ,nj
ͲϵϬ
ϰ͘ϯϯϵϳнϬϴ
ϰ͘ϯϯϵϵ нϬϴ
ϰ͘ϯϰϬϭ нϬϴ
ϰ͘ϯϰϬϯ нϬϴ
&ƌĞƋƵĞŶĐLJ,nj
8/22
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ϰ͘ϯϰϬϱ нϬϴ
ϰ͘ϯϰϬϳ нϬϴ
!-V
AN4117
Transmitter parameters
Figure 6.
Adjacent power measurement, 25 kHz narrowband channel spacing,
4.8 Kbps data rate, 2.4 kHz frequency deviation, GFSK (BT=0.5)
modulation
ϭϬ
Ϭ
WсͲϰϯĚŵ
ͲϭϬ
ϭϲŬ,nj
ϭϲŬ,nj
KƵƉƵƚƉŽǁĞƌĚŵ
ͲϮϬ
ͲϯϬ
ͲϰϬ
ͲϱϬ
ͲϲϬ
ͲϳϬ
ͲϴϬ
ϭϲŬ,nj
ͲϵϬ
ϰ͘ϯϯϵϳнϬϴ
ϰ͘ϯϯϵϵ нϬϴ
ϰ͘ϯϰϬϭ нϬϴ
ϰ͘ϯϰϬϯ нϬϴ
&ƌĞƋƵĞŶĐLJ,nj
2.2
ϰ͘ϯϰϬϱ нϬϴ
ϰ͘ϯϰϬϳ нϬϴ
!-V
Modulation bandwidth
The range of the modulation bandwidth includes all associated side-bands above the
appropriate emissions level and the frequency error or drift under extreme test conditions.
The frequency drift in extreme test conditions primarily depends on the crystal quality, which
is not included in this report.
Figure 7 illustrates the ETSI spectral mask with which the radio must comply at the subband edges. Basically, there are only two limit thresholds; what changes is the bandwidth of
integration at the different offset regions.
The same spectral masks are reported in Figure 8, 9, 10, 11 and 12. In Figure 8 the data
rate is set to 1.2 Kbps, the frequency deviation is set to 1 kHz and the modulation is set to 2FSK (GFSK). In Figure 9 the data rate is set to 2.4 Kbps, the frequency deviation is set to
2.4 kHz and the modulation is set to Gaussian FSK (GFSK) with a BT = 0.5. In Figure 10 the
data rate is set to 4.8 Kbps, the frequency deviation is set to 2.4 kHz and the modulation is
set to Gaussian FSK (GFSK) with a BT = 0.5. In Figure 11 the data rate is set to 38.4 Kbps,
the frequency deviation is set to 20 kHz and the modulation is set to Gaussian FSK (GFSK)
with a BT = 1. In Figure 12 the data rate is set to 250 Kbps, the frequency deviation is set to
127 kHz and the modulation is set to Gaussian FSK (GFSK) with a BT = 1. The applied
output power is set to 11 dBm.
With these parameters, the spectral masks of SPIRIT1 comply with ETSI [2] subclause 7.7.
Doc ID 023222 Rev 1
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Transmitter parameters
Figure 7.
AN4117
ETSI spectral mask measurement limits and sub-band edges
D"MK(Z
D"MK(Z
D"MK(Z
D"MK(Z
FC
Note:
FE
F EK(Z
F EK(Z
F E-(Z
!-V
fc is the emission center frequency.
fe is the sub-band edge frequency.
Only the upper half of the emission is shown. The lower half is a mirror image.
Figure 8.
Spectral mask measurement, 12.5 kHz narrowband channel spacing,
1.2 Kbps data rate, 1 kHz frequency deviation, 2-FSK modulation
ϮϬ
ϭϬ
Ϭ
Ͳ ϯϬĚŵ
ͲϭϬ
KƵƉƵƚƉŽǁĞƌĚŵ
ͲϮϬ
ͲϯϬ
Ͳ ϯϲĚŵ
Ͳ ϯϲĚŵ
ͲϰϬ
ͲϱϬ
ͲϲϬ
ͲϳϬ
ͲϴϬ
ͲϵϬ
ϰ͘ϯϮϱϯнϬϴ
ϰ͘ϯϯϬ ϯнϬϴ
ϰ͘ϯϯϱϯнϬϴ
ϰ͘ϯϰϬϯнϬϴ
ϰ͘ϯϰϱϯнϬϴ
ϰ͘ϯϱϬϯ нϬϴ
ϰ͘ϯϱϱϯнϬϴ
&ƌĞƋƵĞŶĐLJ,nj
!-V
10/22
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AN4117
Transmitter parameters
Figure 9.
Spectral mask measurement, 12.5 kHz narrowband channel spacing,
2.4 Kbps data rate, 2.4 kHz frequency deviation, GFSK (BT=0.5)
modulation
ϮϬ
ϭϬ
Ϭ
Ͳ ϯϬĚŵ
ͲϭϬ
KƵƉƵƚƉŽǁĞƌĚŵ
ͲϮϬ
ͲϯϬ
Ͳ ϯϲĚŵ
Ͳ ϯϲĚŵ
ͲϰϬ
ͲϱϬ
ͲϲϬ
ͲϳϬ
ͲϴϬ
ͲϵϬ
ϰ͘ϯϮϱϯнϬϴ
ϰ͘ϯϯϬ ϯнϬϴ
ϰ͘ϯϯϱϯнϬϴ
ϰ͘ϯϰϬϯнϬϴ
ϰ͘ϯϰϱϯнϬϴ
ϰ͘ϯϱϬϯ нϬϴ
ϰ͘ϯϱϱϯнϬϴ
&ƌĞƋƵĞŶĐLJ,nj
!-V
Figure 10. Spectral mask measurement, 25 kHz narrowband channel spacing,
4.8 Kbps data rate, 2.4 kHz frequency deviation, GFSK (BT=0.5)
modulation
ϮϬ
ϭϬ
Ϭ
Ͳ ϯϬĚŵ
ͲϭϬ
KƵƉƵƚƉŽǁĞƌĚŵ
ͲϮϬ
ͲϯϬ
Ͳ ϯϲĚŵ
Ͳ ϯϲĚŵ
ͲϰϬ
ͲϱϬ
ͲϲϬ
ͲϳϬ
ͲϴϬ
ͲϵϬ
ϰ͘ϯϮϱϯнϬϴ
ϰ͘ϯϯϬ ϯнϬϴ
ϰ͘ϯϯϱϯнϬϴ
ϰ͘ϯϰϬϯнϬϴ
ϰ͘ϯϰϱϯнϬϴ
ϰ͘ϯϱϬϯ нϬϴ
ϰ͘ϯϱϱϯнϬϴ
&ƌĞƋƵĞŶĐLJ,nj
!-V
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Transmitter parameters
AN4117
Figure 11. Spectral mask measurement, 100 kHz channel spacing, 38.4 Kbps data
rate, 20 kHz frequency deviation, GFSK (BT=1) modulation
ϭϬ
Ϭ
Ͳ ϯϬĚŵ
ͲϭϬ
KƵƉƵƚƉŽǁĞƌĚŵ
ͲϮϬ
ͲϯϬ
Ͳ ϯϲĚŵ
Ͳ ϯϲĚŵ
ͲϰϬ
ͲϱϬ
ͲϲϬ
ͲϳϬ
ͲϴϬ
ͲϵϬ
ϰ͘ϯϮϱϯнϬϴ
ϰ͘ϯϯϬ ϯнϬϴ
ϰ͘ϯϯϱϯнϬϴ
ϰ͘ϯϰϬϯнϬϴ
ϰ͘ϯϰϱϯнϬϴ
ϰ͘ϯϱϬϯ нϬϴ
ϰ͘ϯϱϱϯнϬϴ
&ƌĞƋƵĞŶĐLJ,nj
!-V
Figure 12. Spectral mask measurement, 500 kHz channel spacing, 250 Kbps data
rate, 127 kHz frequency deviation, GFSK (BT=1) modulation
ϭϬ
Ϭ
Ͳ ϯϬĚŵ
ͲϭϬ
KƵƉƵƚƉŽǁĞƌĚŵ
ͲϮϬ
ͲϯϬ
Ͳ ϯϲĚŵ
Ͳ ϯϲĚŵ
ͲϰϬ
ͲϱϬ
ͲϲϬ
ͲϳϬ
ͲϴϬ
ͲϵϬ
ϰ͘ϯϭϱϯнϬϴ
ϰ͘ϯϮϬϯ нϬϴ
ϰ͘ϯϮϱ ϯнϬϴ
ϰ͘ϯϯϬϯнϬϴ
ϰ͘ϯϯϱϯнϬϴ
ϰ͘ϯϰϬϯнϬϴ
ϰ͘ϯϰϱϯнϬϴ
ϰ͘ϯϱϬϯнϬϴ
ϰ͘ϯϱϱϯ нϬϴ
&ƌĞƋƵĞŶĐLJ,nj
2.3
ϰ͘ϯϲϬ ϯнϬϴ
!-V
Unwanted emissions in the spurious domain
Spurious emissions are unwanted emissions in the spurious domain at frequencies other
than those of the wanted carrier frequency and its side-bands associated with normal test
modulation.
A spectrum analyzer is used as external receiver. The measurement is performed setting
the SPIRIT1 with modulation and checking unwanted spurious emissions up to 4 GHz, as
described in ETSI [2] subclause 7.8.
12/22
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AN4117
Transmitter parameters
The measurement is split into two figures: in Figure 13 the unwanted spurious emission for
a frequency below 1 GHz is shown. The measurement is performed setting the instrument in
max. hold with a resolution bandwidth of 100 kHz, as requested in ETSI [2]. In Figure 14 the
unwanted spurious emission for frequencies from 1 GHz to 4 GHz is shown. The
measurement is performed setting the instrument in max. hold with a resolution bandwidth
of 1 MHz, as requested in ETSI [2]. In the two images the mask request from ETSI is also
reported.
The unwanted emissions in the spurious domain of SPIRIT1 comply with ETSI [2] subclause
7.8.
Figure 13. Unwanted emission in the spurious domain mask below 1 GHz
ϮϬ
^Ɖŝƌŝƚ
ϭϬ
d^/ŵĂƐŬ
Ϭ
KƵƚƉƵƚƉŽǁĞƌĚŵ
ͲϭϬ
ͲϮϬ
ͲϯϬ
ͲϰϬ
ͲϱϬ
ͲϲϬ
ͲϳϬ
ͲϴϬ
ϭ͘ϬϬнϬϳ
ϭ͘ϭϬнϬϴ
Ϯ͘ϭϬнϬϴ
ϯ͘ϭϬнϬϴ
ϰ͘ϭϬнϬϴ
ϱ͘ϭϬнϬϴ
ϲ͘ϭϬнϬϴ
ϳ͘ϭϬнϬϴ
ϴ͘ϭϬнϬϴ
ϵ͘ϭϬнϬϴ
&ƌĞƋƵĞŶĐLJ,nj
!-V
Figure 14. Unwanted emission in the spurious domain mask above 1 GHz
ͲϮϬ
^Ɖŝƌŝƚ
d^/ŵĂƐŬ
ͲϮϱ
KƵƚƉƵƚƉŽǁĞƌĚŵ
ͲϯϬ
Ͳϯϱ
ͲϰϬ
Ͳϰϱ
ͲϱϬ
Ͳϱϱ
ͲϲϬ
ϭ͘ϬϬнϬϵ
ϭ͘ϱϬнϬϵ
Ϯ͘ϬϬнϬϵ
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Receiver parameters
3
AN4117
Receiver parameters
All the measurements here reported are performed with the following parameters: Tc = 25
°C, Vdd = 3.0 V, f = 434.300 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, the
blocking, and the receiver spurious radiation. The adjacent channel selectivity is referred to
receiver category 1, 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 a BER of 1% is obtained.
To reduce the power consumption, an internal SMPS is integrated into the SPIRIT1.
Figure 15 demonstrates the ETSI 1% BER sensitivity limit (red line) and the SPIRIT1
sensitivity for different data rates with SMPS. This application note outlines the expected
performance when using the SPIRIT1 under EN 300 220-1 (v2.3.1, 2012-02) [2] at 434.3
MHz, without defining the maximum channel spacing. To show the real performance of the
SPIRIT1 transceiver, different channel spacings are shown. The test conditions are:
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●
2-FSK modulation, 1.2 kHz data rate, 1 kHz frequency deviation, 12.5 kHz channel
spacing
●
GFSK modulation with BT = 0.5, 2.4 kHz data rate, 2.4 kHz frequency deviation,
12.5 kHz channel spacing
●
GFSK modulation with BT = 0.5, 4.8 kHz data rate, 2.4 kHz frequency deviation,
25 kHz channel spacing
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Receiver parameters
●
GFSK modulation with BT = 1, 38.4 kHz data rate, 20 kHz frequency deviation,
100 kHz channel spacing
●
GFSK modulation with BT = 1, 250 kHz data rate, 127 kHz frequency deviation,
500 kHz channel spacing.
The SPIRIT1 is fully compliant with the ETSI category 2 receiver sensitivity requirements
with large margin.
Figure 15. Sensitivity vs. data rate with 1% BER
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3.2
Blocking
Blocking is a measurement of the capability of the receiver to receive a wanted modulated
signal without exceeding a given degradation due to the presence of an unwanted input
signal at any frequency other than those of the spurious responses or the adjacent channels
or bands.
All the blocking results are measured by positioning the input power 3 dB above the
measured sensitivity limit reported in the previous section with a primary signal source
generator. A second generator with an unmodulated signal is used as the interferer and
combined with the primary signal using a power combiner. The second interferer generator
is placed at the desired frequency offset and the power is increased until the BER
degradation of 1% is obtained.
ETSI specifies the blocking limits in absolute values at two points: ±2 and ±10 MHz. The
limit for the category 2 receiver at ±2 MHz is ≥ 35 dB - 10log(BWkHz/16 kHz), at ±10 MHz it
is ≥ 60 dB - 10log(BWkHz/16 kHz). Figure 16 to Figure 19 show the blocking curves with,
respectively, 12.5 kHz, 25 kHz, 100 kHz, and 500 kHz channel bandwidth.
The SPIRIT1 is fully compliant with the ETSI category 2 receiver blocking requirements with
large margin.
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Receiver parameters
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Figure 16. RX blocking vs. CW interferer offset with 1% BER, 12.5 kHz channel
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Figure 17. RX blocking vs. CW interferer offset with 1% BER, 25 kHz channel
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Receiver parameters
Figure 18. RX blocking vs. CW interferer offset with 1% BER, 100 kHz channel
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Figure 19. RX blocking vs. CW interferer offset with 1% BER, 500 kHz channel
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Receiver spurious radiation
Spurious radiations from the receiver are components at any frequency, radiated by the
equipment.
A spectrum analyzer is used as the external receiver. The measurement is performed
setting the SPIRIT1 with modulation and checking receiver spurious emissions up to 4 GHz
as described in ETSI [2] subclause 8.6.
The measurement is split into two figures: in Figure 20 the spurious radiation for frequency
below 1 GHz is shown. The measurement is performed setting the instrument in max. hold
with a resolution bandwidth of 100 kHz, as requested in ETSI [2]. In Figure 21 the spurious
radiation for frequencies from 1 GHz to 4 GHz is shown. The measurement is performed
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Receiver parameters
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setting the instrument in max. hold with a resolution bandwidth of 1 MHz, as requested in
ETSI [2]. In the two images the mask request from the ETSI is also reported.
The receiver spurious radiation of SPIRIT1 complies with ETSI [2] subclause 8.6.
Figure 20. RX spurious radiation below 1 GHz
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Figure 21. RX spurious radiation above 1 GHz
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4
Measurement equipment
Measurement equipment
The following equipment was used for the measurements.
Table 1.
Measurement equipment
Measurement
Instrument type
Instrument model
RX
Signal generator
Agilent ESG E4438C
TX
Signal analyzer
R&S FSIQ7
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Reference
5
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AN4117
Reference
1.
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)”.
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6
Revision history
Revision history
Table 2.
Document revision history
Date
Revision
01-Oct-2012
1
Changes
Initial release.
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AN4117
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