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I have seen a lot of companies offering a satellite phone service. But I have not seen anyway to broadcast my own signal from space.

What technology (that I can google) do they use to send their signal (on the L and Ku band)?

Martin Schröder
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Iogann Valdt
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    You can name the company, that won't be a problem. As it is, the question is a bit vague. What kind of signal do you want to transmit? TV, radio? Something else? – Hobbes Jun 11 '18 at 19:10
  • I doubt satellite phone companies would broadcast your own signal for you from space. If they would do, it would be very expensive. Transmitter power, bandwidth and time slots must be payed. – Uwe Jun 11 '18 at 19:39
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    The technology for broadcasting information is called electromagnetic radiation. For a more specific answer, you'll need to provide a more specific question. (I can't quite tell what you mean.) – jpaugh Jun 11 '18 at 20:59

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You don't broadcast a signal from space unless you're in space. So unless you get your transmitter on a satellite you are not going to "broadcast your own signal from space."

If you are using a satellite phone you transmit/broadcast to the satellite and the satellite then transmits to a ground based receiver which then connects into the terrestrial network.

Different vendors use different modulation schemes, media access, etc.

Iridium uses Differentially Encoded QPSK (DEQPSK) with an occupied bandwidth of 31.5 kHz. Each channel is spaced 41.667 kHz from each other as this is the minimum bandwidth needed for receivers to properly receive Iridium signals. Iridium uses both TDMA and FDMA in its transmissions. Source

There are other satellite communications platforms, two major ones are Globalstar and Inmarsat.

This paper provides a very good description and block diagrams of Globalstar's approach. (There's too much good stuff to quote or display.)

Globalstar uses a Direct Sequence Spread Spectrum (DSSS) waveform with BPSK modulation and CDMA for channel access. Source

Inmarsat Aero in this article is the Forward TDM link from ground station to plane. The links use OBPSK or OQPSK modulated with 600, 1200, and 10500 bps signals. The 600 and 1200 bps links are part of Inmarsat's Classic Aero service which is due to be discontinued in 2018. the 10500 bps link is part of Inmarsat's Aero H and H+ services which are capable of transmitting both data (10.5 kbps) and digital voice (9.6 kbps). Source

There are also many other satellite transmission types but mostly for data instead of phone. For example, DVB-S was primarily used for television broadcasting.

The various vendors use L, S, Ka, and other bands to transmit their signals.

Tracy Cramer
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  • It's not really any different in concept between a phone call and a satellite TV program. Either way, the majority of signals broadcast (or transmitted more narrowly) to earth from space are merely retransmissions of signals uplinked from the ground. So to get your signal broadcast from space, you uplink from the ground it in a way that will cause either a satellite to transmit it right back down, or a digital satellite to repeat the packets or store and forward the message back down. Or you first use a terrestrial link to send the content to the service provider and they uplink it... – Chris Stratton Jun 12 '18 at 05:55
  • @ChrisStratton: There are differences, a phone needs to support both transmission from and to the user. TV transmission uses only one direction and the data rate is much higher than for the phone call. – Uwe Jun 12 '18 at 07:19
  • @Uwe those differences do not apply to the question asked. The point is that contrary to your mistaken comment on the question itself, companies transmit custom signals from space for their customers all the time; it's what they do. And those signals are just a retransmission of those uplinked from the ground by or on behalf of the customer who wants it transmitted from space. – Chris Stratton Jun 12 '18 at 15:11
  • @ChrisStratton, Iridium for example uses a narrowband channel in the L band for handset comms but K band for ground station up and downlink and inter-satellite comms. It also 'routes' data so the "signal" would have to be completely demodulated to raw data and then the data re-modulated to be sent out. That means the "signals" are not retransmitted - the data is, but not the "signals". Some vendors do actually employ a 'bent-pipe' where the signal is taken down to baseband and then mixed back up to RF. So, in a sense it's the same signal but not really. There ARE times when words matter. – Tracy Cramer Jun 12 '18 at 20:33
  • @TracyCramer - if you would read more carefully you would see that variations such a packet level repeating and store-and-forward were already mentioned. It remains fundamentally true in the vast majority of cases that the origin of the information is on earth. – Chris Stratton Jun 12 '18 at 20:37
  • @ChrisStratton, I stand by my comment that the same "signals" are not simply retransmitted. One doesn't simply take RF and change it from 1.65GHz to 1.67GHz. It must be mixed down to baseband (or IF if you prefer), which destroys the original 'signal', and then back up to RF. If you can show me evidence to the contrary in satellite communications I will stand corrected. – Tracy Cramer Jun 12 '18 at 20:41
  • @TracyCramer - actually you can build a transponder by going directly from one frequency to another. Mixing down to baseband does give some additional options for bandpass filtering, but it's not the only way. Nor would anyone in the field generally consider mixing down to baseband to "destroy the original 'signal'". But more fundamentally, it doesn't really matter if the modulation goes intact from ground to space to ground or if only the information payload does - it remains true that the way you broadcast information from space is generally to bounce the information off a satellite. – Chris Stratton Jun 12 '18 at 20:52