In general, a TS obtained by receiving and demodulating a broadcast wave does not include hierarchical information or IIP, and therefore cannot be used directly as a “broadcast TS” input to a modulator.

For this reason, some demodulators that support broadcast TS output adopt a method of regenerating broadcast TS by internally remultiplexing (REMUX) the demodulated TS.

However, when such internally remultiplexing demodulators are used for TTL retransmission, there is an inherent risk.
The TS transmitted via broadcast waves is carefully multiplexed within the broadcast station’s MUX equipment, with precise control over packet intervals and audio/video timing. In demodulators that perform internal REMUX, this TS is recombined inside the device, which may not preserve the original high-quality TS generated at the broadcast station.

Features of DMB-2-ISDBT (Maintaining Original Quality)

Using a proprietary method, the DMB-2-ISDBT directly adds TMCC to the received TS, enabling it to reproduce the original broadcast TS almost exactly as it was.

Compared to conventional REMUX-type demodulators, this allows retransmission while maintaining the original quality.

Furthermore, at the retransmission site, modulation output is synchronized to a highly accurate reference clock obtained from GPS or similar sources. Therefore, the broadcast TS input to the modulator must also be synchronized to this reference clock.

The broadcast TS output by the DMB-2-ISDBT maintains the data rate of the input broadcast TS. Since the broadcast TS data rate is synchronized to the reference clock within the broadcasting station, the output TS of the DMB-2-ISDBT can be regarded as indirectly synchronized to the broadcaster’s reference clock.

As a result, the modulation clock at the retransmission point and the data rate of the DMB-2-ISDBT output TS become pseudo-synchronized, enabling stable retransmission over long periods.