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
Doc ID 023517 Rev 1
1/13
www.st.com
Contents
AN4148
Contents
1
2
3
An overview of ARIB STD-T93 regulation . . . . . . . . . . . . . . . . . . . . . . . . 3
Application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Transmitter parameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.1
Permissible values for spurious emission intensity . . . . . . . . . . . . . . . . . . 8
4
Receiver parameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.1
Conducted spurious component at receiver . . . . . . . . . . . . . . . . . . . . . . . 10
5
6
Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2/13
Doc ID 023517 Rev 1
AN4148
An overview of ARIB STD-T93 regulation
1
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 out-
of-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.
Doc ID 023517 Rev 1
3/13
An overview of ARIB STD-T93 regulation
AN4148
Table 1.
value of the permissible value of the unwanted emission intensity
Maximum permissible value of the unwanted
emission intensity
[nW] e.i.r.p.
[dBm] e.i.r.p.
- 36
- 30
100 kHz
1 MHz
Reference bandwidth
Frequency band [GHz]
Below 1
Above 1
250
1000
Table 2.
value of the conducted spurious component at receiver
Maximum permissible value of the unwanted
emission intensity
[nW] EIRP
[dBm] EIRP
-54
-54
100 kHz
1 MHz
Reference bandwidth
Frequency band [GHz]
Below 1
Above 1
4
4
4/13
Doc ID 023517 Rev 1
AN4148
Application circuit
2
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
Doc ID 023517 Rev 1
5/13
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
