Starlink gets FCC nod for space calls, but can't dial up full power Despite granting Starlink conditional authorization for direct-to-cell satellite-based phone services, the Federal Communications Commission (FCC) has deferred a request to operate at signal strengths beyond those allowed. SpaceX's satellite operations biz can, according to the US comms regulator, operate its constellation of …
Yes, the places where you would need to rely on satellite communications are exactly the places you would find a payphone. Though I wonder if the places you are going to find a payphone are the most rural out of the way places where you might not find terrestrial cellular service.
...in contrast, here in Australia, Telstra (BT's Aussie historical incumbent equivalent) decided to not only provide free wi-fi for anyone in range of their payphones, they've also now made calls to AU landlines and mobiles FREE from all phone boxes.
Also noting that, being Australia, Telstra's public phones aren't housed in the same kind of fully enclosed "phone box" street furniture like the UK. So you're effectively just standing on the street with a small roof over your head and a half-height or full-height narrow wall in front of you. Also not much space to post those "massage" advertisements!
Consequences to ground based cellular in adjacent bands be damned.
The limits they have chosen have been carefully chosen for a reason. First of all note that this is out of band interference. They are talking about RF signals that are outside of the bands Starlink/T-mobile are licensed use. The -120 dbm figure makes sense because if you look at your phone's db readings (via whatever method is appropriate for it) when you are at the extreme edge of cell reception, in the territory where it will show 1 bar but attempting to actually use that bar for anything is likely to fail you will probably be in the area of -121 to -123 dbm.
If they let Musk crank up the power, that bumps up the noise floor in adjacent bands. I'm not sure how much he wants them to crank it up, but if they let him do -10 db more power for instance then the "shows 1 bar but is actually useless" territory (when your phone is using one of the adjacent bands) will be hit around -110 dbm, currently solidly within the range where your cell phone will function pretty normally. Slow if you try to use data, but adequate for calls (though they may be dropped occasionally) and messaging. Basically making more people reliant on satellite by reducing the effective range of cellular towers in areas where they are sparse.
All this is because Musk either was a cheapskate and deliberately chose to equip his satellites without the proper bandpass filters to keep the out of band interference within acceptable limits and assumed he could bully the FCC into doing what he wanted, or Starlink's engineers just screwed up and Musk figured he could bully the FCC instead of fixing the design for subsequent launches.
Starlink is trying to increase that limit to -110.6 dBW/m2/MHz. It appears it's mostly because their satellites weren't originally intended for phone use and they bolted it onto ones they originally designed for home internet, as opposed to competitors who see the phone market as a core business and designed specifically for that.
Yes, that is why I was careful to get the units from their request rather than risking mistaking one unit with another. The dBW to dBm conversion I can do: -110.6 dBW/m2/MHz = -80.6 dBm/m2/MHz. Working out how much of that signal you would receive on average on the surface is harder.
their satellites weren't originally intended for phone use and they bolted it onto ones they originally designed for home internet
Doesn't matter. They knew the FCC limitations for terrestrial cell phones and could have equipped their satellites with better bandpass filters, but chose not to. So either their engineers are incompetant and screwed up thinking that inadequate filters were adequate, or they thought they could use inadequate filters and bully the FCC into allowing them bypass limits the FCC set for a very good reason.
It isn't as if bandpass filtering is some exotic technology. They have existed since the early days of radio, but better filters cost more money and add more weight, and they thought they could get by without them either because they're dumb or they're evil.
Or….or the engineering team had primarily designed for the Starlink signal format, which has looser requirements . And had correctly forward-planned for flexibility of implementation. And were thus able, with a considerable amount of smart work, to reconfigure an existing set of orbiting satellites to transmit LTE instead of Starlink signal. But because hardware is fixed, can only transmit at the lower power given the LTE requirements.
Which they were aware of, from day #1, but they believe there is margin in the spec. And because it’s a total different system concept than when the rules were originally written, have calculated that the actual impact of the combined effect of hundreds of satellites transmitting in-view, is less than the naive worst-case as if it all came from one satellite which the rules assume. So they’ve re-done the systems modelling to show why they believe it should be acceptable, which may or may not be water-tight reasoning, but anyway is going to be re-analysed by FCC.And if the FCC say no, all that happens is that they transmit at low power = low capacity on day #1; and if and only if the market of direct-to-cell proves out, upgrades the v3 satellites so they can provide more capacity direct-to-cell in 3 years time - which it will take at least that length of time to build up customers.
I mean either that, or the entire engineering team should automatically be assumed to be Nazi Zombies, just because of the political views of their boss.
Radios aren't perfect. When they get really "not perfect" and are in space, they aren't serviceable so hopefully there's a way to shut them down/off. Onboard monitoring systems will be important too so they'll shut themselves down rather than spew noise if they can't be commanded from the ground. The Starlink sats are build on an assembly line that's just cranking them out. These aren't birds built at JPL where everything from the components up to the completed craft are meticulously scrutinized. That level of inspection is important when the budgets are close to the $1bn mark and there's no way to get a do-over. The "what-if" that has to be heavily considered for space to mobile comms is how much damage could be done if just one or two sats were broken and blanking comms as they passed by. Many emergency service providers are relying on mobiles (yeah, not too bright) so the seriousness can ratchet up very quickly.
1915Mhz in the UK has the entry
1.9149 - 1.92 GHz Mobile Spectrum Access Hutchison 3G
in the OFCOM allocation tables.
I'm sure there would be similar allocations in other countries that the Musklink uplinks would interfere with (or that would interfere with the uplink)
The satellites don't cover enough of the surface to interfere with UK signals since the LTE parts would be disabled when not in view of countries where they are licensed to use them. Canada and Mexico, at least those parts near the border would be less fortunate.
"Lack of mobile coverage is nice."
I agree. The places I don't get coverage are extremely out of the way and me being there is so infrequent that I'm not bothered. If I wanted something along for emergencies, I'd take my amateur radio and a long (and simple) dipole antenna. The local club teaches about making those sorts of antenna which are nothing more than a long stretch of wire that can be wound up on a stick for storage. Building one for 146.52 MHz is easy. There are other sorts of rescue beacons that can be had if you are worried about summoning emergency services while out in the forest. I just read a news article today about a guy that was "lost" for 5 weeks, but had enough skills to survive. He wasn't that bright as his car was found much sooner and he should have never left it since it is easier to find. He was also out in the boonies by himself. Apparently he was never a Boy Scout. We were taught to travel in at least 3's. Somebody injured could be carried out by the other two or one could stay with the injured person while the other sought help. It's also easier to keep a watch overnight with 3 people.
It is not just mobile phones... All our vehicles are rolling mobile devices now. Sure, there is satellite -> vehicle coms today with things like satellite radio. What worries me is the privacy loss of vehicle -> satellite coms, reporting my every movement and in-vehicle conversations.
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