| reply to Ad astra
Re: Observations said by Ad astra:
For the 3.5 Mhz wide employed channel used by Amperion in this test, there are a total of two slots below 30 MHz where that channel may be placed that would avoid overlapping amateur allocations and zero places that simultaneously avoid the amateur and broadcast allocations.
There's one additional slot in the 30-50 MHz region in which Ameprion's hardware can operate that wouldn't overlap police/fire/public safety allocations; provided that is the NTIA agrees it's okay for BPL to share with the DoD.
Frequency management for the BPL architecture described would seem not to be a delicate jigsaw puzzle, but rather a game of musical chairs with someone always being left out.
Also consider that they have to use different frequencies between repeater segments. Frequencies can be reused further down the line, but it's my understanding that you need to have several repeater segments before a frequency can be reused. So it's very likely you'll see that 3.5 Mhz downstream and 2.5 Mhz upstream channel hit every chunk of 2-30 Mhz somewhere in a given neighborhood.
Something I wonder about is what kind of bit density they are getting. If it's something like 2 bits per hertz, it won't take long to saturate a 3.5 Mhz channel with traffic, especially when you're carrying traffic from other segments in the neighborhood back to the feedpoint and you take into account the "overhead tax". |
