[Bruce]

I am thinking

 

[Thermos]

The duty cycle is limited to 11% to comply w/ RF limits, but a more realistic duty cycle is probably around 1%.

That's an excellent reference document, thanks for finding the real duty cycle!

Just curious, why do you think a more realistic duty cycle would be 1 percent?

Cheers,

Dave

 

[noahhl]

That's an excellent reference document, thanks for finding the real duty cycle!

Just curious, why do you think a more realistic duty cycle would be 1 percent?

Cheers,

Dave

Just based on network traffic -- you wouldn't be constantly uplinking, particularly while in flight. If you were streaming video off the plane you might hit a higher duty cycle, but not for the sort of typical network traffic I'd expect -- sending a text message, etc.

My best reference for that specific to Starlink is this report that examined the impact of Starlink on the Very Large Array radio telescope in NM. This study examined duty cycles over WiFi for typical applications -- at the 50 Mbps+ range that Starlink will deliver, even a Skype call is really only around 1% duty cycle. I'm pretty sure that's both sides of the transmission too -- the uplink is probably a smaller share.

 

[bjdecker]

RF safety is not my specialty and authoritative safe distance numbers should come from SpaceX. But as an engineering exercise I did some resarch and ran some numbers.

SpaceX says in their FCC filing that the effective transmit power (transmitter power plus antenna gain) at 14 GHz is 33.2 dBW, or around 2 kilowatts, at when the beam is pointing directly away from the antenna face. It’s a little less when the beam is pointing off-broadside.

In the absence of any distance numbers from SpaceX, plugging the above numbers into an RF exposure calculator says that the minimum safe distance in the beam is around 5 to 11 feet assuming an always-on transmit duty cycle. Because this is a phased array antenna there’s likely to be a lot less RF outside of the transmit beam but to know exactly how much, you’d need information that SpaceX didn’t provide.

Perhaps a Mini owner on this thread can look in the user manual and see if it lists anything about RF safety.

HTH

Dave

I guess when hair & teeth start falling out we'll understand the root cause ...

 

[PilotjohnS]

Can't really argue with the Starlink website.....

View attachment 69063

Starlink review was by Walter White from New Mexico

 

[Snowflake]

The only limit in consumer facing Starlink materials that i could find was an 11" limit between radiator and body, but that's actually for the wifi signal, not the uplink.

That's another consideration as well. If it's generating a WiFi hotspot, it's probably intending that to work over a range sufficient to cover an area a lot larger than the cockpit of an RV, and not with a focused beam.

Of course I say that typing on my laptop with my cell phone sitting next to me on the table. Both are >12" away from my body, so who knows.

 

[avrojockey]

Well, actually, there have been... This is older information, but the lesson is still true today; what you're seeing may be older than you think, and using Wx radar to try to dodge trouble can be a bad idea.

Nexrad Weather Radar Linked to Small Plane Crash Deaths

Federal transportation experts are warning that a weather radar system used in many small planes may have caused the deaths of at least two pilots who

www.aboutlawsuits.com

Even with airborne weather radar you can get into trouble. It's not the tool, it's the monkey. I've flown with a lot of professional pilots who don't understand storms, radar, tilt management and ultimately risk.

For anyone considering using these tools for mitigating weather risk, I highly recommend watching Archie Trammell's videos:

https://www.radar4pilots.com

 

[Thermos]

Of course I say that typing on my laptop with my cell phone sitting next to me on the table. Both are >12" away from my body, so who knows.

Even with noahhl's better analysis, I have to admit that I'm reluctant to put either the satellite RF or wifi RF that close to my head in the RV-7 cockpit. It's not necessarily rational, it just is.

I wonder if I can make a tinfoil hat that will fit under my headset? Or maybe I paint my head with this stuff or wear one of these...



Dave

 

[bkervaski]

I have a mini on the roam plan, it's great, we use it at the airport and plan to throw it in the back of the plane for trips, but no plans to try to use it in flight. It's going to let me/us take longer trips from work into more remote areas and fly-ins and still be able to have an effective internet connection for work. It's frankly just what we've been waiting for.

 

[cjs]

I have a mini on the roam plan, it's great, we use it at the airport and plan to throw it in the back of the plane for trips, but no plans to try to use it in flight. It's going to let me/us take longer trips from work into more remote areas and fly-ins and still be able to have an effective internet connection for work. It's frankly just what we've been waiting for.

Same here. I'm axiously awaitingMusk's cell phone (satellite-based) service for all the same reasons.

 

[dmattmul]

How much power does this thing transmit with? Is it safe that close to your head?

Looks like 13.4 inches is needed.

 

[SkyDweller]

I thought the mini was designed to stop working when it detects motion to keep users from using it mobile. Trent Palmer installed Starlink in his Kitfox with the antenna mounted in the skylight.

I remember him in that video mentioning that he does not run it while he is in the plane due to concerns with being directly under/near it during operation as a potential health concern. He basically said he powers it on after landing to get service while in a remote location. I’m not educated enough on the topic to give an opinion on whether it being in your immediate vicinity while operating is harmful to your health, but I’m sure someone here may have some input.

 

[Kuhtenia]

Looks like 13.4 inches is needed.

Part of the snip you nicely attached states "Users must not operate the Starlink Kit within the safety zone of an airport."

This would seem to be relevant to the use case being discussed here - i.e., are those using these things really going to have them in the "off" position at all times inside the proverbial fence?

In any event, can anyone indicate what the actual specific issue is/might be for such a "must not operate" statement?

 

[Thermos]

In any event, can anyone indicate what the actual specific issue is/might be for such a "must not operate" statement?

My educated guess is that the perceived issue is with 2.4 GHz/5 GHz wifi signal interference with GPS, TCAS, ATC radar, ADS-B, and most importantly, aircraft radar altimeters that operate around those frequencies. For example, existing radar altimeters have such poor RF filtering that they're vulnerable to RF interference several hundred megahertz away from their operating frequencies; that's the reason for all those 5G RADALT NOTAMs you see in your preflight briefings.

I've never heard of a limitation like this being stated or enforced in the US. If this is an EU approval, can someone in Europe can help with a better definition of "airport safety zone" or clarify the reason for this language?

Dave

 

[PilotjohnS]

RF safety is not my specialty and authoritative safe distance numbers should come from SpaceX. But as an engineering exercise I did some resarch and ran some numbers.

SpaceX says in their FCC filing that the effective transmit power (transmitter power plus antenna gain) at 14 GHz is 33.2 dBW, or around 2 kilowatts, at when the beam is pointing directly away from the antenna face. It’s a little less when the beam is pointing off-broadside.

In the absence of any distance numbers from SpaceX, plugging the above numbers into an RF exposure calculator says that the minimum safe distance in the beam is around 5 to 11 feet assuming an always-on transmit duty cycle. Because this is a phased array antenna there’s likely to be a lot less RF outside of the transmit beam but to know exactly how much, you’d need information that SpaceX didn’t provide.

Perhaps a Mini owner on this thread can look in the user manual and see if it lists anything about RF safety.

HTH

Dave

OK now we are finally talking about something in my wheel house.

Given the small size of the antenna, there will probably be considerable side lobes. This means that there will be considerable radiaition directed to your head. I would put a small metal shield between the antenna and your head. (Tin foil hat, seriously)
It one gets head aches, or prone to cancer or starts seeing red areas of the skin on the back of thier neck, then this is too much exposure. Unfortunately, the worst problem will be cancer from the exposure, and this is not detectable until its too late. I would heed the Starlink warning and put it in a wing tip. Gosh, cant believe there are people putting this in the baggage compartment.

 

[Pdp7427]

OK now we are finally talking about something in my wheel house.

Given the small size of the antenna, there will probably be considerable side lobes. This means that there will be considerable radiaition directed to your head. I would put a small metal shield between the antenna and your head. (Tin foil hat, seriously)
It one gets head aches, or prone to cancer or starts seeing red areas of the skin on the back of thier neck, then this is too much exposure. Unfortunately, the worst problem will be cancer from the exposure, and this is not detectable until its too late. I would heed the Starlink warning and put it in a wing tip. Gosh, cant believe there are people putting this in the baggage compartment.

Do you want to quantify this assessment based on the published numbers? Starlink does have radiation warnings on their larger more powerful antennas, though not on the smaller consumer oriented terminals.

I haven’t done the math but I’d be shocked if this was any more of a concern than holding your cellphone to your head.

 

[dmattmul]

This is a temporary location but wanted to get some numbers at difference orientations. This is in the back of a 14A. I did comply with the minimum body distance warning. Downloads at the 4 compass points where 141, 132, 71, and 109 Mbps with around 12 Mbps upload and 26 - 30 latency. Tried 2 USB C to 5.5-2.1 plug and no joy. Even my 5.1-2.1 cigarette socket adapter would light the led on the antenna but would not connect. At rest my ships power is at 13.4 volts and with voltage drops was concerned this would be an issue. Units draws ~ 4 amps and the 5.5 mm jack and wiring looked pretty small. I might have been able to get it to work once the alternator comes alive and outputs 14.2 volts but decided to try and fix the issue so made-up jumpers using 16 awg wire and my own socket and 5.5 plug and this worked fine even at resting voltage. As others have mentioned don't try the Amazon cables using USB C technology with the mini.

I made these tests at 4,000 ft turned off the cell coverage even though it appeared I would not get a signal. Sirius XM came in fine and even made a quick video call and that also worked well. Eventually this will go into a wingtip or the tailcone (I have a Showplnes fiberglass tailcone) of my 10.