AN4174
Application note
Using the SPIRIT1 transceiver under the ARIB STD-T67
standard in the 426 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 Japanese association of radio industries and businesses (ARIB) was established in
response to several trends such as the growing internationalization of telecommunications,
the convergence of telecommunications and broadcasting, and the need to promote radio
related industries. The scope of the ARIB organism is defined as the basic technical
requirements for standard specifications of radio equipment.
This application note outlines the expected performance when using the SPIRIT1 under the
ARIB STD-T67 [2] standard in the 426 MHz band. For details of regulatory limits in the 426
MHz frequency band, please refer to the ARIB STD-T67 standard [2].
This can be downloaded from www.arib.or.jp/english/index.html.
October 2012
Doc ID 023728 Rev 1
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www.st.com
Contents
AN4174
Contents
1
2
3
An overview of the ARIB STD-T67 standard . . . . . . . . . . . . . . . . . . . . . . 4
Application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.1
3.2
3.3
Adjacent channel leakage power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Permissible value of the occupied bandwidth . . . . . . . . . . . . . . . . . . . . . . 13
Permissible values of spurious emission or unwanted emission . . . . . . . 13
4
Receiver parameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.1
4.2
4.3
4.4
Encoding reference sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Spurious response at effective selectivity . . . . . . . . . . . . . . . . . . . . . . . . 15
Adjacent channel selectivity at effective selectivity . . . . . . . . . . . . . . . . . 16
Limit on secondary radiated emissions . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5
6
Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
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AN4174
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.
SPIRIT1 application daughterboard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
SPIRIT1 application daughterboard plugged on the motherboard . . . . . . . . . . . . . . . . . . . . 8
Daughterboard schematic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Adjacent channel power, 2.4 Kbps data rate, 2.4 kHz frequency deviation . . . . . . . . . . . . 11
Adjacent channel power, 4.8 Kbps data rate, 2.4 kHz frequency deviation . . . . . . . . . . . . 11
Adjacent channel power, 9.6 Kbps data rate, 2.4 kHz frequency deviation . . . . . . . . . . . . 12
Adjacent channel power, 9.6 Kbps data rate, 4.8 kHz frequency deviation . . . . . . . . . . . . 12
TX spurious emission below 1 GHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
TX spurious emission above 1 GHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
RX sensitivity with 1% BER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
RX spurious emission below 1 GHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
RX spurious emission above 1 GHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
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An overview of the ARIB STD-T67 standard
AN4174
1
An overview of the ARIB STD-T67 standard
This standard provides for telemetry radio equipment designed to automatically indicate
and/or record the results obtained by measuring instruments located remotely by means of
radio waves; telecontrol radio equipment, for the transmission of signals to activate, change,
or deactivate the functions of devices located remotely by means of radio waves; and data
transmission radio equipment, intended for the transmission of information to be processed
primarily by machines, or of previously processed information.
The communication methods are those defined in
Table 1.
In the same table the operating
frequency bands, the antenna powers and the transmission time restrictions are defined.
For the transmitter, the following parameters are defined.
The antenna power (the specified or rated power that is supplied from the transmitter to the
feeder of an antenna system in normal operation and is averaged over a sufficiently long
period of time compared to the cycle of the lowest frequency) is 0.01 W (+10 dBm) or less.
However, for transmission units using a frequency between 426.025 MHz and 426.1375
MHz, the antenna power is 0.001 W (0 dBm) or less.
The frequency tolerance (the maximum allowable deviation of the center frequency of the
band occupied by emission from the allocated frequency) is ±4 x 10
-6
(± 4 ppm). This is a
very stringent requirement, a TCXO is necessary to meet the frequency tolerance
requirement.
There are no specific requirements regarding modulation method, frequency deviation and
modulation rate. In the general conditions of the ARIB STS-T67, the emission classes of the
apparatus are defined. The emission class supported by the SPIRIT1 is the F1D, which is
frequency modulation (F), one channel containing digital information, no subcarrier (1), data
transmission, telemetry or telecommand (D). The choice of the data rate and frequency
deviation is made to meet the bandwidth requirements described in
Table 1.
An adjacent channel leakage power requirement, that is the power radiated in a certain
band of the adjacent channel separated from the carrier frequency at the specified
frequency interval, is defined. The power radiated into the ± 4.25 kHz band of the frequency,
12.5 kHz in distance from the carrier frequency, is lower than the carrier power by 40 dB or
more. However, for transmitters that emit radio waves in an occupied bandwidth over 8.5
kHz and up to 16 kHz, the power radiated into the ± 8 kHz band of the frequency, 25 kHz in
distance from the carrier frequency, is lower than the carrier power by 40 dB or more.
The permissible value for an occupied bandwidth (the bandwidth in which the mean powers
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) is 8.5 kHz. However, for
transmitters emitting radio waves in an occupied bandwidth over 8.5 kHz and up to 16 kHz,
the value is 16 kHz.
Spurious emission refers to the emissions 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.
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An overview of the ARIB STD-T67 standard
Unwanted emission refers to the emissions made up of the spurious emission and the out-
of-band emission.
The 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. The permissible value of the unwanted emission intensity is 2.5 µW (-
26 dBm) or less, as measured in the average power.
For the receiver, the following parameters are defined.
The reference sensitivity (the necessary receiver input voltage in which the output bit error
rate of the device is 1 x 10-2 when the desired wave modulated is applied) is 2 µV (-101
dBm on 50 ohm) or less for receivers with channel intervals of 12.5 kHz and 25 kHz, and 2.8
µV (-98 dBm on 50
Ω)
or less for receivers with channel interval of 50 kHz.
The spurious response at effective selectivity (the ratio of the jamming wave input voltage to
the encoding reference sensitivity as the output bit error rate of the device becomes 1 x 10-
2 when an un-modulated jamming wave is applied in a state in which a desired wave input
voltage 3 dB higher than the encoding reference sensitivity is applied) is 40 dB or more.
The adjacent channel selectivity at effective selectivity (the ratio of the jamming wave input
voltage to the encoding reference sensitivity as the output bit error rate of the device
becomes 1 x 10
-2
when a jamming wave that is modulated by a signal of repetitive binary
pseudo noise with a code length of 32767 bits and is 12.5 kHz or 25 kHz in distance from
the desired wave is applied to a device with channel interval of 12.5 kHz or 25 kHz,
respectively, in a state in which the desired wave input voltage 3 dB higher than the
encoding reference sensitivity is applied) is 30 dB or more.
The frequency tolerance, as for the transmitter, is ±4 x 10
-6
(± 4 ppm). This is a very
stringent requirement, a TCXO is necessary to meet the frequency tolerance requirement.
The limit of the secondary radiated emission from the receiving equipment is, in terms of the
power of a dummy antenna circuit that has the same electrical constant as the receiving
antenna, 4 nW (-54 dBm) or lower.
Table 1.
Communication method, operating frequencies and antenna power
Operating frequency band
[MHz]
Antenna
power [W]
Transmission time restriction
TCT: 40 sec, TQT: 2 sec
(Telemetry, data transmission)
TCT: 5 sec, TQT: 2 sec
(Telecontrol, data transmission)
0.001 or less
426.0375 - 426.1125
(25 kHz interval)
TCT: 40 sec, TQT: 2 sec
(Telemetry, data transmission)
TCT: 5 sec, TQT: 2 sec
(Telecontrol, data transmission)
TCT: 40 sec, TQT: 2 sec
0.01 or less
429.2500 - 429.7375
(12.5 kHz interval)
Continuous transmission
(intermittent communication possible)
Communication method
426.0250 - 426.1375
(12.5 kHz interval)
One-way communication,
simplex operation or
broadcast communication
One-way communication,
simplex operation or
broadcast communication
429.1750 - 429.2375
(12.5 kHz interval)
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