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back to article O3b's satellites on launch pad, ready to bring cats+porn to billions

This evening the first four satellites of the O3b satellite constellation are slated to launch from French Guiana, to provide connectivity to the three billion humans lacking a Google+ account. The four satellites are atop a Soyuz rocket, ready for launch at 19.53 UK time, and are headed for a Medium Earth Orbit (MEO) in order …

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Anonymous Coward

I'm curious, how are the uplinks supposed to broadcast to satellites that are always apparently moving? Or will this require some complex/potentially unreliable kit to always keep the dish pointing in the right direction.

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Silver badge

Moving antenna dishes is a well established technology and they will know to good accuracy where the satellites are. Also, at the high frequencies that will be used, a narrow beam phased array wouldn't be all that big and would have slow and predictable aiming requirements.

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But, a "standard" O3b "terminal" requires two fairly large (3m) antennas (one tracking a satellite, plus one ready to pick up the next satellite when it pokes it's head above the horizon) plus all of the motors, gearing etc in order to slew them. If any part of the slewing system breaks, that antenna is out of action, and a terminal with only antenna cannot give an unbroken service. Note that the slewing system is in use practically all of the time, so there is going to be significant wear and tear there. A "high availability" terminal requires 3 antennas, basically two working plus one in standby. You also need the concrete foundations for the antennas, support buildings, frequency converters, filters, LNAs/HPAs, etc - all this makes even a standard terminal an expensive option, and a high-availability one much more so.

The high frequencies allow good data rates, I totally agree, but they are also really prone to rain/dust fade. O3b have had to incorporate Active Gain Control loops into their modems to handle this - makes them even more complex and expensive.

Oh yes, I am speaking from personal knowledge here having done a considerable amount of work for O3b.

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Anonymous Coward

Good answer, cheers.

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So perfect for an ISP in a remote location not served by fibre?

Rather than a fibre you have a trio of dishes, then a local distribution (3G/4G/WiFi/cables???)

That sounds like a good solution for much of Africa. Probably add some DNS caches and Squid proxies for best effect...

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Go

Most large antennas (+3m) generally have tracking motors on them anyway and those motors tend to do nudge movements which are relatively high torque. I have yet to see an in-service motor fail on a commercial antenna, but I've only worked with a dozen or so large motorised dishes.

The counter argument is that the antennas I used are expensive and thus the motors are made of tougher stuff, but I would hope that someone building the kit for O3b would be planning a decent MTBF. Plus these dishes would be moving on a 50% duty cycle, so they only need to work every 6h (360min) or 4.8h (288min) when they increase capacity. Plus you have a short but sweet maintenance window of some hours if you need to swap out a motor/gearbox. You can always have a spare gearbox and if you can accept a small downtime you can use one antenna to give you a full working day with just one break of service. Being pragmatic fundamentally this kit won't be domestic because it is about back-haul for entire islands, cities, states, however if it is all you can get then you'll be grateful for it.

I still remember when I noticed my office had more peering connectivity than the whole of Pakistan, it was a revelation. I like O3b, seems like a good step forward for the developing world.

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Requires a motorized antenna

Yes, MEO has all of the advantages you mention. In addition, since the satellite is closer, you need less power per bit to send the signal to the satellite from the ground.

However, there is one drawback. With GEO, you can point your antenna at the satellite and then lock it in place: no motors required. With MEO, the satellite crosses the sky, and your antenna must track it. Furthermore, unless you have a second antenna, you lose the signal for a few seconds every 20 minutes or so. One satellite sets in the east and another rises in the west (yes, opposite of the sun) and you must swing your antenna to the new satellite.

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Boffin

Re: Requires a motorized antenna

The Beeb says that the ground stations will all have 3 antennas. So for switchover, they can have one antenna pointed at the old satellite and one at the new one, so there's no break in coverage. The third antenna is a spare, presumably for when the motors on one of the dishes break.

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Re: Requires a motorized antenna

It's not as though there with be 1000's of ground terminals, How many ISP's or Mobile networks are we talking about that are going to need steerable dishes?

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Happy

Re: Requires a motorized antenna

O3b's own ground stations that uplink and downlink the signal have three antennas, one active, one slewing to pick up the next bird and one hot spare. The far end terminals would typically have two (one active, one slewing).

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Pint

"Not that many of us will be able to benefit..."

False in the sense that you're writing only for a northern European audience, perhaps forgetting that el Reg is popular around the world.

True in the sense that if someone doesn't have access to the Internet, then they're not reading this article anyway.

False again in the sense that perhaps they're reading it over a link that can be improved by O3b.

True again that that's probably "not that many of us".

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Bronze badge
Pint

OMG - moving satellites!!

Relax. The Ruskies have been using Molniya orbit birds for many, many, many years. O3b is a different (simpler) orbit, but it's all very well established technology. Every objection raised above is rebutted by the long history of moving antennas.

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Thumb Up

I'm curious: ground station cost?

@alannorthhants - thanks for your earlier well-informed post with some of the technical details. Does your knowledge of O3B include an estimate of what a ground station would cost and what environmental considerations there are in establishing one? Thanks!

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Re: I'm curious: ground station cost?

There were only ball park "finger in the air" costs, but the minimum price tag was several million US$. Has probably changed since the last time I looked.

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Stop

Re: I'm curious: ground station cost?

Millions of dollars? Really? Because I would be surprised if the entire rig cost more than $500,000?

A few thousands for the modem? call it $100k for the antenna? $15k for the amps?

It's been too long since I priced these things, but earth stations aren't *that* expensive!

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Re: I'm curious: ground station cost?

... plus foundations, buildings, cables, customer equipment located at O3b's anchor stations, the ground you need, etc. These are not your normal terminals, they are lot bigger (practically a small ground station in the case of the high-availability configuration) and a lot more complex.

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Holmes

Re: I'm curious: ground station cost?

A quick look around shows me what General Dynamics are offering as an O3b earth station: http://www.gdsatcom.com/Antennas/Data_Sheets/2.4M_GDST-O3b.pdf

I should suspect that the primary back-haul nodes which connect to Tier-1 internet fibre would probably cost a fair bit because you are going to want at least a 5.6m Ka-band, but the field earth stations shouldn't be so expensive.

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Megaphone

Very important point for all future stories on providers: In what countries does Ob3 have facilities

A very important question should be answered in all future stories on service providers: "In what countries does the service provider have facilities?"

GCHQ, NSA, etc., which intelligence agencies will be recording and analyzing the traffic? A very important question that should always be answered now.

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Bronze badge

This isn't new by any means.

Just look at Globalstar & Iridium as a couple of examples. Sure these are telephone based things, but data is data even if it is voice data, or internet data. Just give me a big pipe to push the data through.

As with any system of this type, the biggest concern is capacity. Will the system have anough to satisfy all of its users as a reasonable speed.

Wish them well in any event. Nice being below 45 degrees (more like 37.5 or so).

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Happy

Re: This isn't new by any means.

This is new because the ground antennas are physically pointing at and tracking the 'moving' satellites. This is to get both low latency and high bandwidth using high frequencies (Ka band) . Globalstar and Iridium use L-band, which doesn't require a directional antenna, therefore no need to track, but the datarates are very low.

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Mushroom

Rocket went up after a delay, satellites were kicked out, commentator had a minor brainfart and said the rocket was moving at a couple of km/h instead of km/s, lots of cloud.

Given where they're selling the service to, I'd say it'd take a lot of cost for a ground station to be more expensive, even over the long run, than layout cable/fibre plus its upkeep and chance-of-being-stolen-or-destroyededness (technical term there).

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