SpaceX Starlink tests direct-to-cell work when 500 satellites are enabled. There are some times when service may be delayed by 5-7 minutes.
Only 300 satellites may be fully operational and in place. By the end of the year, more satellites will be needed to provide reliable voice and Internet service. Signal power is 8x higher. The connection will be 3-4 bars almost anywhere on Earth.
This video shows how to text. Satellites have not been fully installed. Power upgrade has not yet begun.
Starlink – How can we get it everywhere? Starlink is a combination of more satellites, a better spectrum, passive and powered antennas.
Cellular signals, such as those from 4G, are often transmitted at frequencies lower than 700 MHz, or even 1.9GHz depending on the provider. The lower frequencies can penetrate walls, windows and other obstacles because their longer wavelengths are able to bend or pass through the materials. Starlink Direct-to Cell service uses the PCS bands, frequencies around 1.9-2 GHz. This is higher than what cell towers typically use. The higher frequencies have a harder time penetrating because the shorter wavelengths are absorbed by concrete, bricks, and even dense vegetation.
Does cranking the 8X power solve this problem? It’s important to have power, but that is not all. Increased PFD can help overcome signal losses caused by obstructions. Imagine turning up your speaker volume to better hear through walls. It’s not just the power that matters; it’s how the signal reacts to materials. Starlink signals are still at significant risk of being degraded (weakened) by materials indoors, even at 1.9-2 GHz. A typical brick wall can reduce the signal by 10-30 dB. Concrete walls could also do this. A power boost of 8X translates into about 9 dB (10 log(8) 9), a good increase but not sufficient to compensate for losses caused by thick walls and multi-story building.
The passive antenna is built into the phone or case.
The passive antenna does not generate any power. It is simply a metal piece or circuitry that captures and focuses radio waves better than the tiny antenna built into your phone. Imagine it as a funnel that focuses signals. It could improve the ability of the phone to “hear”, or to receive, satellite signals if it is small enough to be integrated in the case.
It helps by adding 3-6dB gain to Starlink frequencies of 1.9-2GHz, depending on the antenna design. This is like quadrupling or doubling the strength of signal your phone receives. This 8X boost in power from the satellite would result in a gain of between 12-15dB. It could compensate for light-obstructions such as a wooden wall (10-15dB), or even a thin layer of brick (5-10dB). This would make it easier to get a good signal in an open room or near a window.
There are limits: This won’t do miracles. Signals can be killed by a concrete wall (with a loss of 20-30dB) or an underground basement without glare. The gain of passive antennas is also heavily dependent on the orientation. If the phone is not aligned to the beam from the satellite, then the gain will drop. The phone manufacturers would also need to optimize them for Starlink frequencies and angles of satellites, as these are not yet standard.
The real-world perspective: A passive antenna might allow you to make a phone call, or even load a website, in your suburban home, near a large window. But it won’t be able to reach as far inside the house as a cell site.
Antennas with a Low Power (0.1-1 Watt)
Let’s now add some power. You could build a powered antenna into your phone or case. It’s not just about capturing the signals, but also amplifying before they reach your phone’s reception. It’s low power enough at 0.1 watts to not fry your phone battery, or break FCC regulations. 1 watt is pushing the limits but still feasible for small devices.
It helps by adding 10-20dB gain depending on the power and design of an active antenna. Add the satellite boost of 8X (9 dB) and you get a total gain between 19-29dB. This is enough power to break through more difficult barriers, such as a brick wall (15dB), or even concrete (20-25dB), if you are lucky. In a typical house, at 0.1 watts you can get a reliable phone call and internet speeds of 1-5 Mbps. At 1 watt you will be able to reach 10 Mbps, or even more in tricky spots, like the corner in a basement near an external wall.
The power draw of the battery is the deciding factor. One watt can drain the battery quickly (think 500 mA) if it is 0.1 watts. One watt of power in the phone’s case could get hot. The FCC limits the uplink power of phones to 0.2-1 watts. A 1-watt amplifier would have to be carefully tuned in order for it not cause interference with other devices.
The passive antenna is a small, thin device that can be attached to a mobile phone case or phone. It boosts the signal by 3-6 decibels. In lighter, near-window buildings you’d have voice and spotty Internet. Think suburban homes instead of concrete jungles.
Antenna Powered (0.1-1 watt): Increases sound by 10-20 decibels. It’s useful for indoor calls and data, but battery life is affected. Sky access is still needed.
A deal for 700 MHz spectrum or any other spectrum could also make a huge difference.
If you plug your phone into a wall outlet, 1 watt will drain the battery of your mobile in just 2-4 hours. You can use a higher-power, longer battery life device inside the phone satellite modem to get 10+mbps speeds. Your cellphone can be plugged into a docking station or in a power outlet to get the daily 20 watts.
If Starlink makes deals with lower spectrum bands or has access to them, then the transmission will be better into buildings. This would be acceptable to a phone company, or a country partner to save on capex and operating costs by not having to build 80-90% cell towers.
Brian Wang, a Futurist and Science Blogger with over 1,000,000 monthly readers is one of the most popular Futurists. Nextbigfuture.com, his blog is the #1 Science News Blog. The blog covers a wide range of disruptive technologies and trends, including Space, Robotics and Artificial Intelligence. It also includes Medicine, Antiaging Biotechnology and Nanotechnology.
He is known for his ability to identify cutting-edge technologies. He currently serves as a co-founder of a company and a fundraiser for early stage companies with high potential. He is Head of Research for Allocations for Deep Technology Investments and an Angel investor at Space Angels.
He is a frequent corporate speaker. In addition, he’s been a TEDx Speaker, a Singularity University Speaker, and a guest on numerous radio interviews and podcasts. He accepts public speaking engagements and advisory roles.
