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Someone should do a DMB piece to be inclued here.
Capacity
editGiven that the L-band (1452-1492 MHz) only has 23 channels (channel 1 being a center frequency of 1452.816, proceeding at 1.744 MHz intervals to 1491.184 MHz for channel 23), and each channel can carry only 5 CD-quality "programs", what sort of capacity is there on each channel for additional "programs" of non-CD quality? For example, if each channel carried five music radio stations, how many "talk" stations could a channel carry with, say, the usual FM fidelity?
Furthermore, how can DAB be compared to cellular telephony? Will a DAB receiver lock onto the strongest signal source, and therefore how close together can two transmitters be and use the same channel? I know that the US isn't adopting Eureka 147, but if it did (and the entire 1452-1492 band was cleared for the use), would there be enough capacity for it to accommodate all existing AM and FM stations in the United States? I think of cities like Los Angeles, where there might be too many stations to possibly accommodate them all without enlarging the band or adding additional bands other than 1452-1492. What other standardized bands exist and if so, what are the frequency specifications and channel numbers (as I identified in the first paragraph)? GBC 19:22, 15 October 2006 (UTC)
Oh, yes, I see on the main DAB article that there is also a "Band III", in the upper VHF band from 174 to 240 MHz, which overlaps on our VHF TV channels 7 to 13 (174-216). Would it be technically possible to "slot in" DAB transmitters on frequencies in that band that would not interfere with digital TV signals in the same 6 MHz range? That would certainly provide more channel options for a Eureka deployment in North America. It seems to me that all DAB systems should employ a "standards signal", say at 223 MHz VHF and 1451.95 MHz UHF; a receiver would check those two frequencies, and find there a standard format signal that tells the receiver which channel configuration is being used and what the frequencies are, so that units could be used anywhere in the world and lock into the national configuration, even if there are small offsets of frequencies or variations in channel width and signal rate. GBC 22:02, 15 October 2006 (UTC)