dm00061752

AN4148
Application note
Using the SPIRIT1 transceiver under ARIB STD-T93 in the
315 MHz band
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 license-free ISM and SRD frequency
bands at 169, 315, 433, 868, 915 and 920 MHz.
The ARIB (Japanese association of radio industries and businesses) was established in
response to several trends such as the growing internationalization of telecommunications,
the convergence of telecommunications and broadcasting, and the need for promotion of
radio related industries. The scope of the ARIB organization is to define the basic technical
requirements for standard specifications of radio equipment.
This application note outlines the expected performance when using the SPIRIT1 under
ARIB STD-T93 [2] in the 315 MHz band. For details on the regulatory limits in the 315 MHz
frequency band, please refer to the ARIB STD-T93 regulations [2].
These can be downloaded from www.arib.or.jp/english/index.html
August 2012
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www.st.com
Contents
AN4148
Contents
1
An overview of ARIB STD-T93 regulation . . . . . . . . . . . . . . . . . . . . . . . . 3
2
Application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3
Transmitter parameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.1
4
Permissible values for spurious emission intensity . . . . . . . . . . . . . . . . . . 8
Receiver parameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.1
Conducted spurious component at receiver . . . . . . . . . . . . . . . . . . . . . . . 10
5
Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
6
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2/13
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AN4148
1
An overview of ARIB STD-T93 regulation
An overview of ARIB STD-T93 regulation
The ARIB STD-T93 standard provides for telemetry radio equipment designed to
automatically indicate and/or record the results obtained by measuring instruments located
remotely; telecontrol radio equipment for transmission of signals to activate, change or
deactivate the functions of devices located remotely by means of radio waves; data
transmission radio equipment intended for the transmission of information to be processed
primarily by machines, or of previously processed information that uses the frequency of
315 MHz. Expected application is air pressure monitoring equipment for tire and keyless
entry systems for automotive. Audio and sound data is eliminated from this regulation.
The operating frequency band is defined as above 312 MHz to below 315.25 MHz. The
antenna power for frequencies above 312 MHz and below 315.25 MHz must be below 25
µW (- 16 dBm) EIRP (equivalent isotropically radiated power). Also, antenna power (EIRP)
shall be below 205 uW (- 6.9 dBm) when the center of the frequency band added deviation
of frequency to occupied frequency band is between 312 MHz and 315.05 MHz.
There are no specific requirements for the modulation method, modulation rate, frequency
deviation, coding type, and adjacent channel leakage power.
The permissible value for an occupied bandwidth (the bandwidth such that the mean power
radiated below its lower frequency limit and above its upper frequency limit are each equal
to 0.5% of the total mean power radiated by a given emission) shall be 1 MHz.
“Spurious emission” refers to the emission on a frequency or frequencies which are outside
the permitted bandwidth and the level of which may be reduced without affecting the
corresponding transmission of information, including a high harmonic emission, a low
harmonic emission, a parasitic emission and an intermodulation product, but excluding an
out-of-band emission.
“Out-of-band emission” refers to the emission which results from the modulation process on
a frequency or frequencies outside the permitted bandwidth.
“Unwanted emission” refers to the emission consisting of the spurious emission and the outof-band emission.
“Permissible value of the unwanted emission intensity” refers to the permissible value
defined according to the mean power of unwanted emissions of each modulated frequency
supplied to the feeder. Permissible value of the unwanted emission intensity is shown in
Table 1.
For the receiver part, a conducted spurious component is defined. Permissible value of the
receiver conducting spurious components is defined in Table 2.
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An overview of ARIB STD-T93 regulation
Table 1.
value of the permissible value of the unwanted emission intensity
Frequency band [GHz]
Maximum permissible value of the unwanted
emission intensity
Reference bandwidth
[nW] e.i.r.p.
[dBm] e.i.r.p.
Below 1
250
- 36
100 kHz
Above 1
1000
- 30
1 MHz
Table 2.
value of the conducted spurious component at receiver
Frequency band [GHz]
4/13
AN4148
Maximum permissible value of the unwanted
emission intensity
Reference bandwidth
[nW] EIRP
[dBm] EIRP
Below 1
4
-54
100 kHz
Above 1
4
-54
1 MHz
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AN4148
2
Application circuit
Application circuit
Figure 1 shows an image of the SPIRIT1 application board. The application is made up of 2
boards: a daughterboard and a motherboard. The daughterboard contains the SPIRIT1 with
the circuits necessary for it to work. For correctly functionality, the daughterboard must be
plugged into the motherboard (see Figure 2) by two header 5x2 connectors (J6 and J7).
The motherboard is provided with an STM32L152VBT6 microcontroller to correctly program
the transceiver. The microcontroller is programmed with firmware developed for the SPIRIT1
application. A graphical user interface (GUI) is 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 application on this bandwidth. The SMPS is fed from the battery (1.8 V
to 3.6 V) and provides the device with a programmable voltage (1.4 V typical). An SMA
connector is present to connect the board to an antenna or to instrumentation to verify the
correct functionality and verify the ETSI standard request.
A few of passive devices (inductors and capacitors) are used for matching/filtering in the
power amplifier (PA) and balun network for the receiver.
To reduce application costs, the SPIRIT1 is designed to work without an external antenna
switch. The daughterboard is designed to show the SPIRIT1 functionality in this condition.
Clearly, an application with antenna switch can be realized, but this is not described in this
document.
Figure 1.
SPIRIT1 application daughterboard
AM13146v1
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Application circuit
Figure 2.
AN4148
SPIRIT1 application daughterboard plugged into the motherboard
AM13147v1
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3V3
10
8
6
4
2
9
7
5
3
1
10
8
6
4
2
9
7
5
3
1
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R_0R0_0402
B2=433MHz
6
R8
XOUT
B3=868MHz
B3=915MHz
B3=920MHz
R_0R0_0402
R11
R_0R0_0402
R10
R_0R0_0402
R9
8
R_0R0_0402
GPIO_1
7
B1=315MHz
XIN
R7
GPIO_2
9
Mount
resistor
relative to
used band
C_12P_0402_C0G_J_50
RXP
B0=169MHz
VBAT2
11
12
13
14
15
C_TBD_0402_C0G
C19
L7
L_10U_0805
C_10P_0402_C0G_J_50
C10
REXT
TX
SMPS2
21
R_0R0_0402
GPIO_3
10
C9
RXN
XTAL
SDn
SMPS1
GND
NX3225GA-xxMHz (XTAL) Y1
VREG
SPIRIT1_2
4 SCLK
5
CSn
VBAT1
R6
SDO
SDI
SCLK
CSn
20
3 SDI
19
J7
HEADER 5X2
C21
C_100p_0402_C0G
C_100n_0402_X7R
C0
17
2 SDO
18
1 GPIO_0
U1
C_330p_0402_C0G
C22
SDn
C20
C_1U_0603_X7R_K_6V3
16
GPIO0
GPIO3
GPIO2
GPIO1
SPIRIT_DUMMY1
VCC_RF
L8
C4
C1
L_TBD_0402
L2
C_TBD_0402_C0G
L_TBD_0402
L4
C_TBD_0402_C0G
C5
C_TBD_0402_C0G
C_TBD_0402_C0G
C8
C13
C_TBD_0402_X7R
C_TBD_0402_C0G C_TBD_0402_C0G
C2
C3
C_TBD_0402_C0G
L3 L_TBD_0402
C_TBD_0402_C0G
C7
C_TBD_0402_C0G
L_TBD_0402
L_TBD_0402
L6
C6
L5
C_TBD_0402_C0G
C15
L1
C14
C12
C_100n_0402_X7R
L_TBD_0402
L9
C11
C_1U_0603_X7R_K_6V3
R13
R_TBD_0402
R12
R_TBD_0402
L0
L_TBD_0402_50M
L_TBD_0402
L_TBD_0402
DUMMY3
3V3
J1
RF_IN/OUT
Figure 3.
DUMMY3
J6
HEADER 5X2
SPIRIT_DUMMY2
AN4148
Application circuit
Daughterboard schematic
AM13166v1
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Transmitter parameter
3
AN4148
Transmitter parameter
All of the measurements reported here are measured using the following parameters:
Tc = 25 ° C, Vdd = 3.0 V, f = 313.5 MHz (middle frequency of the useful bandwidth), unless
otherwise specified.
The maximum output power of the SPIRIT1 in this band is 10 dBm, so all the measurements
are performed at the levels required by the standard, that is - 16 dBm.
The permissible value for an occupied bandwidth defined in the standard is 1 MHz. The
occupied bandwidth from the SPIRIT1 when the maximum permitted data rate and deviation
are used is lower than 1 MHz, so no measurements are performed to verify this parameter.
There are no specific requirements in the standard about setting of detector or video
bandwidth (VBW) of the spectrum analyzer used for the measurement. The detector will be
set to peak, the video bandwidth will be set equal to the resolution bandwidth, and the
display will be set to peak hold.
3.1
Permissible values for spurious emission intensity
“Spurious emission” refers to the emission on a frequency or frequencies which are outside
the permitted bandwidth and the level of which may be reduced without affecting the
corresponding transmission of information, including a high harmonic emission, a low
harmonic emission, a parasitic emission and an intermodulation product, but excluding an
out-of-band emission.
“Out-of-band emission” refers to the emission which results from the modulation process on
a frequency or frequencies outside the permitted bandwidth.
“Unwanted emission” refers to the emission consisting of the spurious emissions and the
out-of-band emissions.
“Permissible value of the unwanted emission intensity” refers to the permissible value
defined according to the mean power of unwanted emissions of each modulated frequency
supplied to the feeder. Permissible values of the unwanted emission intensity are shown in
Table 1. The measurements performed are printed in Figure 4 and 5. From these images it
is possible to see that all of the requirements are met.
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AN4148
Transmitter parameter
Figure 4.
TX spurious emission below 1 GHz
0
Output power
ARIB mask
-10
Output power [dBm]
-20
-30
-40
-50
-60
-70
0.0E+00
1.0E+08
2.0E+08
3.0E+08
4.0E+08
5.0E+08
6.0E+08
7.0E+08
8.0E+08
9.0E+08
1.0E+09
Frequency [Hz]
AM13276v1
TX spurious emission above 1 GHz
0
Output power
ARIB mask
-10
-20
Output power [dBm]
Figure 5.
-30
-40
-50
-60
-70
1.0E+09
1.5E+09
2.0E+09
2.5E+09
3.0E+09
3.5E+09
4.0E+09
4.5E+09
5.0E+09
Frequency [Hz]
AM13277v1
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Receiver parameter
4
AN4148
Receiver parameter
ARIB compliance in ARIB STD-T93 [2] in the 312 to 315.25 MHz band only pertains to
emissions and harmonics. There are no receiver sensitivity, selectivity or blocking
measurements to comply with ARIB STD-T93 standard [2].
4.1
Conducted spurious component at receiver
Spurious radiation from the receiver are components at any frequency, radiated by the
equipment. The spurious emission strength at the antenna input must be less than the
values in Table 2.
The measurement results are shown in Figure 6 and 7. All standard requirements are met
from the SPIRIT1 in receiver mode.
Figure 6.
TX spurious emission below 1 GHz
-40
Output power
ARIB mask
-45
Output power [dBm]
-50
-55
-60
-65
-70
0.0E+00
1.0E+08
2.0E+08
3.0E+08
4.0E+08
5.0E+08
6.0E+08
7.0E+08
8.0E+08
9.0E+08
1.0E+09
Frequency [Hz]
Figure 7.
AM13278v1
TX spurious emission above 1 GHz
-40
Output power
ARIB mask
-45
Output power [dBm]
-50
-55
-60
-65
-70
1.0E+09
1.5E+09
2.0E+09
2.5E+09
3.0E+09
3.5E+09
Frequency [Hz]
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Doc ID 023517 Rev 1
4.0E+09
4.5E+09
5.0E+09
AM13279v1
AN4148
5
Reference
Reference
1.
SPIRIT1 datasheet
2.
ARIB STD-T93: “315 MHz band telemeter, telecontrol and data transmission radio
equipment for specified low-power radio station”
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Revision history
6
AN4148
Revision history
Table 3.
12/13
Document revision history
Date
Revision
06-Aug-2012
1
Changes
Initial release.
Doc ID 023517 Rev 1
AN4148
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