e.g., SDTV could be delivered using a more robust setting than the corresponding HDTV service. Adaptive coding and modulation (ACM) to allow flexibly adapting transmission parameters to the reception conditions of terminals, e.g., switching to a lower code rate during fading. Four modulation modes: QPSK and 8PSK are proposed for broadcast applications, and can be used in non-linear transponders driven near to saturation. 16APSK and 32APSK are used mainly for professional, semi-linear applications, but can also be used for broadcasting though they require a higher level of available C/N and an adoption of advanced pre-distortion methods in the uplink station in order to minimize the effect of transponder nonlinearity. Improved rolloff: α = 0.20 and α = 0.25 in addition to the roll-off of DVB-S α = 0.35. Improved coding: a modern large LDPC code is concatenated with an outer BCH code to achieve quasi-error-free (QEF) reception conditions on an AWGN channel. The outer code is introduced to avoid error floors at low bit-error rates. A single forward error correction or FEC frame may have either 64,800 bits (normal) or 16,200 bits (short). If VCM or ACM is used, the broadcast can be a combination of normal and short frames. Several code rates for flexible configuration of transmission parameters: 1/4, 1/3, 2/5, 1/2, 3/5, 2/3, 3/4, 4/5, 5/6, 6/7, 8/9, and 9/10. Code rates 1/4, 1/3, and 2/5 have been introduced for exceptionally poor reception conditions in combination with QPSK modulation. Encoding values 8/9 and 9/10 behave poorly under marginal link conditions (where the signal level is below the noise level). However, with targeted spot Ku or Ka band downlinks these code rates may be recommended to prevent out-of-region viewing for copyright or cultural reasons. Optional input stream synchronization to provide a constant end-to-end delay. Depending on code rate and modulation, the system can operate at a C/N between −2.4 dB (QPSK, 1/4) and 16 dB (32APSK, 9/10) with a quasi-error free goal of a 10−7 TS packet error rate. Distance to the Shannon limit ranges from 0.7 dB to 1.2 dB. Modes and features of DVB-S2 in comparison to DVB-S: Use cases Envisaged scenarios for DVB-S2 by the standard document are: Broadcasting television services in SDTV or HDTV. Optionally, this transmission may be backwards compatible with DVB-S, but does not benefit from the 30% extra bandwidth. Interactive services including Internet access. Data generated by the user may be sent