DIY Satellite Web Radio

DIY Satellite Web Radio

[OrazioPirataDelloSpazio (Lorenzo)]

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Hi all,
I'm not a DVB expert but I'm wondering if this idea is feasible:
For an "amateur" web radio, for what I know, it is really hard to
being listened in cars, like people do with commercial satellite radio
[1] . Basically this is unaffortable for private user and this is
probably the most relevant factor that penalize web radios againt
terrestrial one.

My question is: is there any way to use the current, cheap, satellite
internet connections to stream some data above all the coverage of a geo
satellite? and make the receiver handy (so without any dishes) ?

Probably by introducing some _very_ redundant code inside the stream
that we upload through the modem and that the satellite will stream from
the sky, we can get some S/N db. The patch to do at the receiver is just
software or maybe hardware?




Lorenzo


[1] http://www.xmradio.com/



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Re: DIY Satellite Web Radio

[Mauro Carvalho Chehab]

Em 30-11-2009 17:13, OrazioPirataDelloSpazio (Lorenzo) escreveu:
> Hi all,
> I'm not a DVB expert but I'm wondering if this idea is feasible:
> For an "amateur" web radio, for what I know, it is really hard to
> being listened in cars, like people do with commercial satellite radio
> [1] . Basically this is unaffortable for private user and this is
> probably the most relevant factor that penalize web radios againt
> terrestrial one.
> 
> My question is: is there any way to use the current, cheap, satellite
> internet connections to stream some data above all the coverage of a geo
> satellite? and make the receiver handy (so without any dishes) ?

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.

This will likely cost a lot of money, if you find someone providing a
service like that. One trial for such network were the Iridum
project. AFAIK, the original company bankrupted due to the very high costs of
launching and managing about a hundred satellite network.

I'm not tracking such things nowadays, but I won't doubt that you would
find someone providing this kind of services. I think the telephones that
are onboard of some flight companies use a satellite service like that.

> Probably by introducing some _very_ redundant code inside the stream
> that we upload through the modem and that the satellite will stream from
> the sky, we can get some S/N db. The patch to do at the receiver is just
> software or maybe hardware?

You'll likely need to design an special hardware for such usage.

Cheers,
Mauro.

Re: DIY Satellite Web Radio

[OrazioPirataDelloSpazio (Lorenzo)]

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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.

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


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Re: DIY Satellite Web Radio

[Mauro Carvalho Chehab]

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
> 

Re: DIY Satellite Web Radio

[Manu Abraham]

On Mon, Nov 30, 2009 at 11:13 PM, OrazioPirataDelloSpazio (Lorenzo)
<ziducaixao@autistici.org> wrote:
> Hi all,
> I'm not a DVB expert but I'm wondering if this idea is feasible:
> For an "amateur" web radio, for what I know, it is really hard to
> being listened in cars, like people do with commercial satellite radio
> [1] . Basically this is unaffortable for private user and this is
> probably the most relevant factor that penalize web radios againt
> terrestrial one.
>
> My question is: is there any way to use the current, cheap, satellite
> internet connections to stream some data above all the coverage of a geo
> satellite? and make the receiver handy (so without any dishes) ?

FWIW, you wont need a satellite dish (some of them operate in the L
Band), unless you are very much out of the footprint, with a weak
signal. Nevertheless, a parabolic reflector will give you a higher
gain, but again that's not the choice for a receiving aerial in a
moving vehicle. Such use cases use in some cases a flat panel antenna
or an antenna array.

DVB-RCS wouldn't work as it needs to be really pointed to the
satellite, nor any Ku or C band transponders. The lower you are in the
spectrum, the more likely to have a better reception with a lower gain
reflector.


http://en.wikipedia.org/wiki/1worldspace
http://www.worldspace.com/howitworks/receivers/AGFwssr.html
http://www.worldspace.com/coveragemaps/antennaguide.html
http://www.satdirectory.com/--worldspace.html

Regards,
Manu

Re: DIY Satellite Web Radio

[Manu Abraham]

On Tue, Dec 1, 2009 at 12:42 AM, Mauro Carvalho Chehab
<mchehab@redhat.com> wrote:
> Em 30-11-2009 17:13, OrazioPirataDelloSpazio (Lorenzo) escreveu:
>> Hi all,
>> I'm not a DVB expert but I'm wondering if this idea is feasible:
>> For an "amateur" web radio, for what I know, it is really hard to
>> being listened in cars, like people do with commercial satellite radio
>> [1] . Basically this is unaffortable for private user and this is
>> probably the most relevant factor that penalize web radios againt
>> terrestrial one.
>>
>> My question is: is there any way to use the current, cheap, satellite
>> internet connections to stream some data above all the coverage of a geo
>> satellite? and make the receiver handy (so without any dishes) ?
>
> 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.
>
> This will likely cost a lot of money, if you find someone providing a
> service like that. One trial for such network were the Iridum
> project. AFAIK, the original company bankrupted due to the very high costs of
> launching and managing about a hundred satellite network.

Low orbital satellites aren't geo-stationary. Technically speaking, a
broadcaster would use only geo-stationary satellites for broadcast
services. The basic reason: A broadcaster simply would have rented out
a transponder on an existing satellite from a satellite operator, or
still: if the broadcaster is a major player, they would have a few
satellites of their own to provide coverage over multiple regions, but
still: they are indeed geo-stationary satellites (you will need a very
large number of satellites to provide services in a low orbital
position, similar to the Iridium network, which is not practically
feasible for a broadcaster. Even the Iridium network had a hard time
taking off!)

Regards,
Manu