A frame control header (FCH) is only connected with demodulating downlink information bursts. It is not connected with uplink information bursts. The VSA utilizes data inside the frame control header to decide the Data Subcarrier Modulation Format. On the off chance that the FCH symbol is absent, the information subcarrier modulation design is automatically recognized instead. The FCH data is utilized only for the first information burst, for subsequent bursts the information subcarrier modulation format is recognized.