Calling all satellite-channel engineers ...

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ChrisGreaves
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Calling all satellite-channel engineers ...

Post by ChrisGreaves »

Forum?
I would appreciate a layman's explanation of what I think of as "Satellite telephone channels".
Back in the Good Old Days (say early 70s) we used a landline to chat from Australia to/with parents in the UK. It was "like in the next room" clarity.
Then satellite connections came into vogue, and we learned not to say "Go Ahead" at the same time at each end.
That is my total knowledge of satellites for telephone calls.

I read online news reports and listen to news podcasts, and get the impression that while local phone service is being restored within Tonga, people overseas (Australia, New Zealand) cannot yet communicate by telephone.

It seems to me that mobile phones reach up to satellites and so it ought to be possible to talk via smartphones via satellite.

Now I can understand that these existing "via satellite" channels might be overburdened ("bandwidth") if every man and his dog decided to get a minute-by-minute account from every relative in Tonga, but how is it that, say, Government Relief Organizations can't get through? I think of digital telephony as software, and so figure that, surely, major relief organizations could climb aboard a dedicated emergency channel.

I understand that little-old-me might be blocked from asking a neighbour to rinse volcanic ash off my pet aspidistra, but wouldn't it be simple to have, say, a password protected channel for governments and agencies?

Thanks
Chris
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PJ_in_FL
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Re: Calling all satellite-channel engineers ...

Post by PJ_in_FL »

Just a clarification for you Chris:

Mobile phones are very low powered and can only reach a few miles to a cellular node (AKA tower). To reach a satellite requires a completely different handset or transceiver, much higher power and significantly different antenna array because of the different carrier frequencies/bands.

If Tonga has their cellular and land-line infrastructure tied to the physical cable, then when the cable breaks the phones are out. They would need to purchase, import and integrate a satellite transceiver into their system, pay the fees for maintenance and bandwidth, and have that as primary or backup to their existing (working-just-find-until-Earth-shattering-event-happens) system. But other than said events, if it ain't broke, no one is going to fork over the dough to fix it.
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Re: Calling all satellite-channel engineers ...

Post by ChrisGreaves »

PJ_in_FL wrote:
21 Jan 2022, 14:27
Mobile phones are very low powered and can only reach a few miles to a cellular node (AKA tower).
Got it! This is why every murder-mystery novel I consume has the heroine out-of-signal when she is dumped at the side of a highway in a forested area. :thumbup:
... Tonga ... would need to purchase, import and integrate a satellite transceiver into their system,
Understood as "If every national government bought a satellite phone service as a channel for international communication in the event of a disaster, then they could receive assistance from other nations much sooner"
Is that correct?

My mis-understanding then came from SmartPhones (which are really only local as far as the next microwave tower is concerned) and satellite phones.
I remember now, 20 years ago, when my sister was on a boat off the coast of Queensland, my parents could send only a short signal "Phone Home!" via the satellite phone, then had to wait until she and Geoff could get to a port, tie up, and find the local phone.

It sounds as if Tonga depended on a cable rather than a satellite, so a tectonic event ruptured the cable and that, as we say, was that.
Thanks PJ. :innocent:
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Re: Calling all satellite-channel engineers ...

Post by BobH »

Elon Musk is systematically inserting satellites into low orbits for the purpose of providing wireless Internet service without land lines and reaching into areas that have not been served due to the costs of land lines. Smartphones work over the Internet. The limited range of smartphones will not be an issue when the global coverage of Musk's satellites is complete.

Even now, there are effective satellite telephones. Are there none in Tonga? If not it should be fairly easy to get some there by airplane.
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Re: Calling all satellite-channel engineers ...

Post by ChrisGreaves »

BobH wrote:
21 Jan 2022, 18:56
Elon Musk is systematically inserting satellites into low orbits
But, but, according to Wikipedia The term LEO region is also used for the area of space below an altitude of 2,000 km (1,200 mi) (about one-third of Earth's radius.
Folks here claim that they "lose signal" between Bonavista and Clarenville, a distance of about 100Km, so it looks as if smart phones are limited to half that distance, that is, 50Km.

LEO satellites would seem to be well beyond the range of smart phones. :scratch: :scratch:
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Re: Calling all satellite-channel engineers ...

Post by BobH »

I can use my smartphone connecting to my wifi network to connect to the Internet. My wifi network is created by my router. I bypass the cell tower. If I connect my router to Musk's low orbit satellite network, then a cell tower becomes moot.
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Re: Calling all satellite-channel engineers ...

Post by ChrisGreaves »

BobH wrote:
22 Jan 2022, 00:28
I can use my smartphone connecting to my wifi network to connect to the Internet. My wifi network is created by my router. I bypass the cell tower. If I connect my router to Musk's low orbit satellite network, then a cell tower becomes moot.
Understood, but if you were on the (sadly very) wet ground in Tonga, wouldn't the router and cell tower be out of action? Especially if they were connected to the undersea cable?
I was looking for something immediately direct, a virtual wire running from a handset waaaaay up in the sky to a satellite, with no earth-based infrastructure to get in the way.
:scratch:
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Re: Calling all satellite-channel engineers ...

Post by BobH »

^^^
Don't forget to post pics when you find one. :evilgrin: :flee:
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Re: Calling all satellite-channel engineers ...

Post by ChrisGreaves »

BobH wrote:
22 Jan 2022, 17:23
^^^
Don't forget to post pics when you find one. :evilgrin: :flee:
Here you go!
Cheers, Chris
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Re: Calling all satellite-channel engineers ...

Post by BobH »

:rofl:
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Re: Calling all satellite-channel engineers ...

Post by ChrisGreaves »

Now we're getting somewhere!
How will Tonga's broken internet cable be mended?

"A 2G wireless connection has been established on the main island, using a satellite dish from the University of the South Pacific. But the service is patchy, and internet services run slowly."

I was wondering why, in this day and age, a government-only satellite service could not be established as a vital communication channel. Somewhere in there I mentioned my sister's boat off the Queensland coast, which suggests that a satellite phone was not beyond the reach of an individual. I understand that 2G is probably classed as "slow" nowadays, but it ought to be enough to co-ordinate emergency communications "Send Drinking Water" and that kind of message.

"It will take time to get a cable repair boat to the archipelago and the closest one is currently stationed in Port Moresby, Papua New Guinea - about 4,700km (2,900 miles) away."
And of course in the end it is shipping logistics that are on the critical path.

There is a fascinating map which shows amongst other things:-
(1) A cable linking two Western Australian Iron Ore ports; presumably it is cheaper to have a ship lay cable than send a team of engineers across the land.
(2) A cute little cable linking Newfoundland to Greenland. Who Knew? But there again it is probably just a link in the chain between New York and London.


"Around the world it is estimated there are more than 430 cables, spanning distances of 1.3 million km (800,000 miles)."
I had not realized the extent of the cables nowadays.

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Chris
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Re: Calling all satellite-channel engineers ...

Post by ChrisGreaves »

ChrisGreaves wrote:
19 Jan 2022, 00:48
I would appreciate a layman's explanation of what I think of as "Satellite telephone channels".
"Senior Sergeant Potts said it was lucky she had a new phone model, which could link up to satellite systems to provide an SOS function." from this ABC news article Nurse stranded in desert without food, water after Google Maps gave her wrong directions

:whisper: (In my opinion she was not too bright and set herself up for getting lost)
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Re: Calling all satellite-channel engineers ...

Post by BobH »

I must confess to having scanned that article rather quickly. Did I miss seeing what sort of phone the young lady had?
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Re: Calling all satellite-channel engineers ...

Post by ChrisGreaves »

BobH wrote:
16 Aug 2023, 17:31
I must confess to having scanned that article rather quickly. Did I miss seeing what sort of phone the young lady had?
No, you didn't miss it. It was just " a new phone model "

If I had any free time I'd write a short essay on her series of ineptitudinous decisions. Where is Darwin when we need him?(1)
Cheers, Chris

(1) No Guys. do NOT whip out Google Maps and search for Darwin. It's in The Northern Territory. C
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Re: Calling all satellite-channel engineers ...

Post by ChrisGreaves »

ChrisGreaves wrote:
19 Jan 2022, 00:48
I would appreciate a layman's explanation of what I think of as "Satellite telephone channels".
Little by little data drifts in.
This morning from the ABC news "Regional police cars to get high-speed internet access anywhere in Western Australia"

To get an idea of remoteness, picture the USA; visualize a North-South line just off the west coast, then move that line inland until you feel you have passed one-third of the contiguous states. That's W.A.
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Now populate that area thinly. "As of 2021, the state has 2.76 million inhabitants—11 percent of the national total.[5] The vast majority (92 percent) live in the south-west corner; 79 percent of the population lives in the Perth area, leaving the remainder of the state sparsely populated" Basically everyone lives south of Perth-Kalgoorlie and West of Kalgoorlie. Wipe out a part of San Francisco and every other town and city in that marked area and you're getting close. (Check out a map of Newfoundland; there are cell-phone dead zones between Bonavista and Clarenville).

This is my background and the basis for my original query about satellite phones. So many travellers in Western Australia get bogged or stranded and suddenly cannot call for help.

The ABC news article suggests that Elon Musk's Starlink is coming to the aid, which satellite network upsets serious and amateur astronomers alike. It solves a problem that is basically of tourists own makings: thinking that cars never break down, it won't get that hot, we'll buy more drinking water at the next gas station etc.

My eye was caught by the data "The square is a phased array antenna that talks to Starlink's low orbit satellites, which are found about 550 kilometres above the planet's surface. Historically, communications have been enabled by satellites much higher up at 35,000km from the ground. The shorter distance covered by Starlink satellites makes it easier to get high-speed internet coverage in remote parts of the country."

I don't understand why a lower orbit gives better coverage; I would have thought that the density of satellites would give more coverage, and as well that a higher-orbit satellite would be visible over a wider area.

I grant that the higher the orbit the longer the delay, but we were used to that with international telephone calls fifty years ago.

Cheers, Chris
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Re: Calling all satellite-channel engineers ...

Post by William »

ChrisGreaves wrote:
16 Aug 2023, 20:15

If I had any free time I'd write a short essay on her series of ineptitudinous decisions. Where is Darwin when we need him?(1)
Cheers, Chris

I dunno about that. It seems she was well prepared in a typical Aussie way:

"having an esky of 18 beers to keep her going"

:cheers: