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Experiments to characterize the constant-rate gas depleted production behavior in core samples were performed to study the areal gas flowing mechanism of a high-pressure low-permeability heterogeneous gas reservoir, including a newly designed long-core experiment on areal heterogeneity constant-rate gas depleted production considering fracturing. In the experiments, the fluid pressure increased up to 45 MPa, and the cores of the near-wellbore high permeability area before and after fracturing and the cores of the low permeability non fractured area were connected in series to simulate the gas flowing process of the dual-area composite gas reservoir. When the irreducible water saturation is considered, the gas permeability in a high permeability area cater fracturing increased threefold. Experimental results indicated that the pressure difference in the near-wellbore high permeability area decreased rapidly after fracturing and increased in the low permeability area. The recovery:factor of each area increased titter fracturing. Fracturing could have a significant effect on increasing the recovery factor when the average permeability is relatively low. The greater the gas rate, the higher is the built-up pressure alter shut-in. Fracturing in the near-wellbore area may cause a significant decrease in the shut-in built-up pressure value.

As the most popularly utilized broadcasting network, digital terrestrial television broadcasting (DTTB) can provide multimedia information coverage for the broad audience in a very efficient way because of its characteristic of wide-range coverage and mobile reception ability. After promulgating the first generation DTTB standard, digital terrestrial/television multimedia broadcasting (DTMB), in 2006, China began to research and develop the next generation DTTB standard, namely DTMB-advanced (DTMB-A), aiming to support higher spectrum efficiency and further improve transmission reliability. In 2019, DTMB-A was accepted by ITU as the second generation international DTTB standard (as System C). Similar to DTMB, time-domain synchronous - orthogonal frequency division multiplexing (TDS-OFDM) based multi-carrier modulation scheme is adopted by DTMB-A. Thanks to the more flexible frame structure, advanced error correction coding and improved constellation mapping, DTMB-A offers 30% higher transmission capacity than DTMB under the same transmission conditions. Thus, DTMB-A can support both fixed and mobile reception more efficiently, and provide users with higher quality services such as ultra-high definition television (UHDTV). This paper first gives details of key technologies at the transmitter of DTMB/DTMB-A and introduce core algorithms at the receiver. Both laboratory test and field trial results will then be provided and analyzed, especially for the application of 4K UHDTV and single frequency network (SFN).