These three modes offer a strategy that is similar to the 2K, 4K, and 8K modes of DVB‑T/H. In ISDB‑T, these system modes provide different carrier spacing between OFDM carrier frequencies. The modes indicate bandwidth, carrier interval, and number of carriers in the OFDM symbols, as shown in Table: ISDB‑T Modes and Parameters.
ISDB‑T Modes and Parameters
Transmission Parameter
Mode 1
Mode 2
Mode 3
Bandwidth
5.575 MHz
5.573 MHz
5.572 MHz
Carrier Interval
3.968 kHz
1.984 kHz
0.992 kHz
Number of Carriers
1405
2809
5617
The mode number and the fraction of the Effective Symbol (Data) that is used for a Guard Interval are both chosen by pressing the Mode, GI submenu key in the Meas Setup (2/2) menu (refer to Figure: FFT Start and Guard Interval). The Select Mode, GI list box contains the available choices. For example, selecting 3, 1/4 means that Mode 3 will be used and that the Guard Interval will be one‑fourth the size of the effective symbol.
Guard Intervals
The mode number and the fraction of the Effective Symbol (Data) that is used for a Guard Interval are both chosen by pressing the Mode, GI submenu key in the Measurement Setup menu. The Select Mode, GI list box (refer to Figure: Select Mode, GI List Box) contains the available choices.
Select Mode, GI List Box
FFT Start
Figure: FFT Start and Guard Interval illustrates a Guard Interval that is one‑fourth of the effective symbol. Note that it could also be one‑eighth, or one‑sixteenth of the length of the Effective Symbol. For additional information, refer to Section FFT Start.
