OrazioPirataDelloSpazio (Lorenzo) wrote: > Mauro Carvalho Chehab ha scritto: >> Receiving sat signals without dishes? From some trials we had on a telco >> I used to work, You would need to use a network of low-orbit satellites, >> carefully choosing the better frequencies and it will provide you >> low bandwidth. > I also believed this, but their use geostationary orbit [1] and > terrestrial devices handly and without dishes [2] [3]. > I belive they should rely on some very robust modulation e channel > coding, but unfortunately I didn't find any specification. >From what I remember from the tests, the worse problem were related to the transmission. If you're just receiving data, it is possible to receive without a dish, depending on the transmission frequency and modulation schema. It works better with some spread spectrum modulation, since you'll have some gain due to frequency diversity. You may also use a dual antenna to gain a few more dB's. However, if you need to transmit data to the satellite (to have something close to Internet via Amateur Radio), I doubt you'll be able to do it without a highly directional antenna. > > Lorenzo > > > [1]http://en.wikipedia.org/wiki/XM_Satellite_Radio > [2]http://shop.xmradio.com/xm/ctl10600/cp49770/si4025808/cl1/xmp3_portable_radio_with_home_kit > [3]http://shop.xmradio.com/xm/ctl10600/cp56879/si4343009/cl1/xm_direct_2 > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
