jsmar

I don't know anything about FLO TV, but I do know that the ATSC M/H standard contains support for energy efficiency. Basically, a M/H device will be able to turn the receiver on and off between M/H groups, only receiving the groups that it cares about. It will be able to do this because of the following two features of the standard:

1) The ATSC M/H standard contains signaling information so that the receiver can know at what time the next group that it is interested in will be sent. Each frame contains signaling information for the current frame in the first two subframes and then for the last three subframes it switches to "signaling in advance" that the receiver can use to determine when the next group will be transmitted.

2) In order to be able to turn off the receiver and turn it on again the receiver has to be able to reaquire the signal very quickly. The ATSC M/H standard has 6 training sequences that are sent within the data that help to enable that. I've been reading the low level parts of the standard in detail, and it is amazing how much trouble they had to go through to get these sequences, which span many packets, through unmolested to the final transmission stage. Every time I find something that I wonder "why did they do that" I later realize it is because of the training sequences. It's all about the training sequences at the low level .