1. Digital Radio Microphone in Japan
SOURCE:
ARIB
TITLE:
Digital Radio Microphones in Japan
AGENDA ITEM:
GRSC-5 5.6
CONTACT:
[gsc12_grsc5_15]
Digital Radio Microphone in Japan
Studies for use in the 800 MHz band
in Japan
Shouhei Taniguchi (ARIB)

2. Background □ Application: broadcast and non-broadcast.
SOURCE:
ARIB
TITLE:
Digital Radio Microphones in Japan
AGENDA ITEM:
GRSC-5 5.6
CONTACT:
[Digital Radio Microphone in Japan]
Background
□ Application: broadcast and non-broadcast.
□ Popularization: the amount units are currently over the 2.4 million units as general and various purpose and tends growth in Japan.
□ Operational problem: the interference between the each operation and a lack of channel at urban crowded area has been more serious recently, the analogue, however, had no way to solve these problems.
□ Latency Problem: The transparent codec that has less than 10ms latency and 1/5 compression has been successfully developed and its ability has been confirmed at official examination.
□ Transmission Reliability: To achieve the acceptable transmission error caused by fading used to be hard in high frequency transmission over 1GHz, or the propagation of wide band width over 500kHz, but the reliability of transmission in 800MHz has been confirmed at the official examination.
□ Functional requirements: the secured transmission at concert and conference, and remote and automatic operation by duplex communication.
□ Japanese Standardization: The digital radio law and the standard for general purpose will be comprised based on this results in Japan.

3. Digital Specification in Japan: The basics
SOURCE:
ARIB
TITLE:
Digital Radio Microphones in Japan
AGENDA ITEM:
GRSC-5 5.6
CONTACT:
[Digital Radio Microphone in Japan]
Digital Specification in Japan: The basics
□ Applications: general purpose for broadcast, concerts, conventions,
and various events at public halls, hotels, universities,
school, shopping malls, department stores, etc.
□ Frequency: MHz – MHz
□ Antenna Power: Less than 10mW
□ Modulation: QPSK, FSK, ASK, QAM ( without carrier modulation)
□ Transmission data speed: 128ksps
□ Audio performance: Dynamic Range more than 96dB,
Frequency up to 15kHz
□ Latency: Less than 10msec

4. RF Characteristics of the prototype
SOURCE:
ARIB
TITLE:
Digital Radio Microphones in Japan
AGENDA ITEM:
GRSC-5 5.6
CONTACT:
[Digital Radio Microphone in Japan]
RF Characteristics of the prototype
Dynamic 65dB
F.S.L
100m
10m 1m

5. Channel could be allocated with equal spacing
SOURCE:
ARIB
TITLE:
Digital Radio Microphones in Japan
AGENDA ITEM:
GRSC-5 5.6
CONTACT:
[Digital Radio Microphone in Japan]
Maximum number of channels for simultaneous operation
Analogue
6 channels
/4 MHz
Channel allocation have to be considered 3rd-order distortion at receiver
Digital
10 channels
/4 MHz
Channel could be allocated with equal spacing

6. Minimum distance between service areas to avoid interference
SOURCE:
ARIB
TITLE:
Digital Radio Microphones in Japan
AGENDA ITEM:
GRSC-5 5.6
CONTACT:
[Digital Radio Microphone in Japan]
Minimum distance between service areas to avoid interference
Definition of service area and interfered area
Service area: Whole operable area around a receiving antenna. (Radius is 60 m)
Interfered area: Area where operation of two radio microphones at the same frequency is impossible.
Assumed attenuation by obstacles is 15dB（Area where D/U for a radio microphone at the circumference cannot be
satisfied.
Comparison of no interfered area between Analogue vs. Digital
Analogue
Digital
Required D/U ratio: 40dB
Required D/U ratio: 20 dB
Interference-free distance: 30m
Interfered area
Radius: 90m
Interfered area
Radius: 240m 干渉
エリア
Interference-free distance: 180m 干渉
エリア ：
Service area
Radius: 60m
サービスエリア
Service area
Radius: 60m
Radio barrier
Attenuation: 15dB
Radio barrier
Attenuation: 15dB
Minimum distance: 180m
Minimum distance: 30m
Comparison of interference-free distance between digital and analogue systems: 1/6 (30m/180m)

7. Capable number of interference-free areas
SOURCE:
ARIB
TITLE:
Digital Radio Microphones in Japan
AGENDA ITEM:
GRSC-5 5.6
CONTACT:
[Digital Radio Microphone in Japan]
Capable number of interference-free areas
Analogue
Digital
Minimum distance 180 m
Minimum distance 30 m
Required D/U ratio: 40 dB
Required D/U ratio: 20 dB
300 m
150 m
Number of interference-free areas: 7
Number of interference-free areas: 19
Possible number of interference-free areas in digital: 2.7 times (19/7)

8. Capable number of interference-free areas at Interleave allocation
SOURCE:
ARIB
TITLE:
Digital Radio Microphones in Japan
AGENDA ITEM:
GRSC-5 5.6
CONTACT:
[Digital Radio Microphone in Japan]
Capable number of interference-free areas at Interleave allocation
Definition of service area and interfered area
Analogue
Digital
Coverage
　Radius: 60m
Minimum distance 180 m
Minimum distance 30 m
Interleave allocation: No
Interleave Allocation: Yes
150m
300m
Received Antenna
Not permitted area to use at 250kHz frequency interleave allocation
Radius: 6m
Service Area under basic channel
allocation
Increased Service Area under
basic channel allocation in Digital
Service Area under 250kHz
frequency interleave allocation
Number of interference-free areas: 7
Number of interference-free areas: 31
Possible number of interference-free areas in digital: 4.4 times (31/7)

9. SNR is improved more than 20 dB
SOURCE:
ARIB
TITLE:
Digital Radio Microphones in Japan
AGENDA ITEM:
GRSC-5 5.6
CONTACT:
[Digital Radio Microphone in Japan]
Audio Quality 1: SNR
Audio 1kHz sign wave input
Analogue
Digital
SNR is improved more than 20 dB

10. To achieve the transparent quality for audio at Codec Delay :
SOURCE:
ARIB
TITLE:
Digital Radio Microphones in Japan
AGENDA ITEM:
GRSC-5 5.6
CONTACT:
[Digital Radio Microphone in Japan]
Audio Quality 2: transparent codec
examination based on ITU-R BS1116-1
95% Confidence Interval
◆Mean Value
Result as the transparent quality
To achieve the transparent quality for audio at Codec Delay :
3.7083ms and 192kbps

11. To achieve the transparent quality for human voice at Codec Delay :
SOURCE:
ARIB
TITLE:
Digital Radio Microphones in Japan
AGENDA ITEM:
GRSC-5 5.6
CONTACT:
[Digital Radio Microphone in Japan]
Audio Quality 3: transparent codec
examination based on ITU-R BS1116-1
95% Confidence Interval
◆Mean Value
Result as the transparent quality
To achieve the transparent quality for human voice at Codec Delay :
5.5625ms and 128kbps

12. The Conclusion of Digital Advantages
SOURCE:
ARIB
TITLE:
Digital Radio Microphones in Japan
AGENDA ITEM:
GRSC-5 5.6
CONTACT:
[Digital Radio Microphone in Japan]
The Conclusion of Digital Advantages
□ Maximum number of simultaneous operable channel:
10 channels (vs. analogue: 6 channels )
□ Minimum distance to avoid interference:
30m (vs. analogue: 180m )
□ Capable number of interference-free areas :
19 ( vs. Analogue: 7 )
□ Capable number of interference-free areas considering the placement by frequency interleave :
( vs. Analogue: No )
□ Secured communication :
Yes ( vs. Analogue: No )
□ Remote operation and the other transmitted information:
Possible ( vs. Analogue: Impossible )