ISDB-Tmm (Terrestrial Mobile Multi-media) is an extension of the former ISDB-T standard and now is adopted for the nationwide mobile multimedia broadcasting in Japan. It is scheduled to use 207.5 MHz ~ 222 MHz frequency band.
There are a flexible number of segments in ISDB-Tmm signals, from 13 to 33 segments; then the bandwidth can vary approximately from 6 MHz to 14.5 MHz. ISDB-Tmm also offers the flexibility of combining the segments into two different super segment types as below.
Type A Super segment: 13 segments OFDM frame compliant with ARIB STD B31. A type A super segment can have up to 3 layers.
Type B Super segment: OFDM frame consisted of less or equal 14 conjugated single segments compliant with ARIB STD B29. The segments in type B super segment can have different configurations.
Click the link of each parameter below for details.
Double-click or use the drop-down menu to control the operating state of the carrier.
The format of the carrier.
Range: -50.0 to 50.0 MHz
Set the frequency offset for the carrier relative to the signal generator’s frequency setting. The valid range will be different for every format due to the different over-sampling ratios.
Range: 0 to 359 degrees
Set the initial phase of the carrier.
Range: -50 to 0 dB
Set the carrier’s power relative to the signal generator’s amplitude setting.
Range: 0 to 128
Default: 0
Set the window length of OFDM symbol.
Range: 2 to 5000
Default: 2
Set the number of frames for the ISDB-Tmm waveform.
Choice: Mode 1 | Mode 2 | Mode3
Default: Mode 3
Double-click or use the drop-down menu to select the Mode.
Three system modes represent three different spacings between OFDM carrier frequencies offered by the standard, catering for the different requirements of the distance between SFN stations and the robustness to Doppler shift during mobile-reception.
As shown in the following table, the available spacing between OFDM carrier frequencies are approximately 4 kHz, 2 kHz, and 1kHz in mode 1, mode 2, and mode 3.
|
Transmission parameter |
Mode 1 |
Mode 2 |
Mode 3 |
|---|---|---|---|
|
Carrier interval |
3.968 kHz |
1.984 kHz |
0.992 kHz |
|
Carrier modulation |
QPSK, 16QAM, 64QAM, DQPSK |
||
|
Effective symbol length (Tu) |
252 μs |
504 μs |
1.008 ms |
|
Guard-interval length (Tg) |
1/4, 1/8, 1/16, 1/32 of effective symbol length |
||
|
No. of symbol per frame (OFDM symbol) |
204 |
||
|
Inner code |
Convolutional coding (1/2, 2/3, 3/4, 5/6, 7/8) |
||
|
Outer code |
RS (204, 188) |
||
Choice: 1/4 | 1/8 | 1/16 | 1/32
Default: 1/4
Double-click or use the drop-down menu to select the Guard Interval.
The purpose of the guard interval is to introduce immunity to propagation delays, echoes and reflections, to which digital data is normally very sensitive.
Default: OFF
To enable static multi-path channel, click
on the right side of the cell, and 
Multi-path
Channel configuration window will pop up.
