No Towers? No Problem: Satellite Connectivity for IoT

Webinar Summary

The following summary is auto-generated from the webinar recording.

Satellite connectivity promises coverage where no cell tower reaches, but it comes with real constraints. It is slow, bandwidth-limited, and billed by the byte, so it works best for sending small amounts of valuable data, infrequently.

In this webinar, Rob Lauer, TJ VanToll, and Alex Bucknall introduced non-terrestrial network (NTN) connectivity, compared the Skylo and Iridium networks that Blues supports, walked through the hardware options, and showed three working projects.

Five Concepts Behind Satellite IoT

• NTN covers any connectivity that isn't ground-based. Here it means satellite: the device's RF link goes to a satellite instead of a cell tower.
• GEO vs LEO. Geostationary (GEO) satellites appear fixed in the sky and provide large, persistent coverage footprints. Low Earth orbit (LEO) satellites orbit much closer, move relative to the device, and operate as a constellation.
• MTU, or maximum transmission unit, is how much data a single transmission can carry. It differs sharply between networks, so payload size shapes both your firmware and your data model.
• RF constraints. Long distances and low-power devices make antenna placement, sky visibility, power, latency, and throughput matter far more than they do on cellular.
• End-to-end data flow. A GEO satellite relays traffic straight to a ground station, while traffic in a LEO constellation can hop between satellites before it reaches the ground.

Skylo vs Iridium

The webinar's side-by-side comparison of the two satellite networks Blues supports.

Skylo uses geostationary satellites operated by partners, while Iridium owns and operates a global LEO constellation. That difference drives most of the tradeoffs:

• Coverage. Skylo covers a growing set of regions, including North America, Europe, and near-shore waters. Iridium is truly global, including open ocean and the poles.
• Packet size. Skylo packets range from 50 to 256 bytes, and Iridium's from 10 to 10,000 bytes. If your messages fit in 256 bytes, either network works.
• Sky view. Skylo's satellites don't move, so a fixed device needs a clear line of sight toward them. In the northern hemisphere that means facing south, which is why TJ keeps his Skylo device on the south-facing side of his house. Iridium's satellites cross the sky, so a device may wait for one to come into view.
• Data. Every Blues satellite product includes 10 KB of prepaid satellite data, and usage beyond that is billed at the same per-byte rate on either network.

The webinar's rule of thumb: Skylo suits land-based sensors, agriculture, utilities, and environmental monitoring inside its coverage. Iridium is the choice for blue-ocean, polar, and international asset tracking. The Choosing Between Skylo and Iridium guide covers these tradeoffs in more depth.

Choosing the Hardware

Blues offers four satellite hardware options:

• Notecard for Skylo puts cellular, satellite, and WiFi on a single 30 × 42 mm Notecard, so it works with any Notecarrier or with a carrier board you design.
• Starnote for Skylo pairs with an existing Notecard (Cellular, Cell+WiFi, or WiFi) on a Notecarrier XS. It comes in two versions, one with onboard antennas and one with connectors for external antennas.
• Starnote for Iridium also pairs with an existing Notecard, on a Notecarrier XI whose supercapacitors handle the Iridium modem's brief, intense power surges while it transmits. It ships as a kit with a Notecard Cell+WiFi, Notecarrier XI, antenna, and LiPo battery.

The network settles most of the hardware choice. If you need Iridium, Starnote for Iridium is the option. If Skylo fits, TJ recommended Notecard for Skylo as the default for most projects: it's one module instead of two, it's smaller, and it costs less. The tradeoff is that its cellular side is narrowband (LTE-M and NB-IoT), because a single modem handles both narrowband cellular and Skylo's satellite network. Choose Starnote for Skylo when your product needs a mid-band or wideband cellular Notecard for normal operation and satellite only as a fallback.

Whichever you choose, all of these options use the same Notecard API, and each has a starter kit with a matching quickstart.

Demo: Notecard for Skylo on a Back Deck

TJ's project pairs Notecard for Skylo with a Notecarrier F, a LiPo battery, and a solar panel inside an enclosure, with one antenna for GPS and another for cellular and satellite. It reports temperature from his back deck, configured with a handful of requests:

The requests behind TJ's demo. Forcing the ntn transport is for testing only.

• hub.set with outbound set to 300 syncs with Notehub every five hours. A large inbound value saves power, since this device receives nothing from the cloud.
• card.temp with minutes set to 60 records the temperature every hour.
• hub.sync followed by hub.sync.status runs one sync and waits for it to complete.
• card.transport with method set to ntn forces satellite-only communication.

That sync matters. Over satellite, Blues optimizes every byte by sending data in a structure Notehub already knows, so each device needs one sync over cellular or WiFi before it relies on satellite. The satellite best practices cover this and other NTN-specific advice.

Forcing ntn is not a best practice. In production, use a fallback mode such as wifi-cell-ntn, which tries WiFi, then cellular, and uses satellite only when neither is available. The connection retry and fallback behaviors guide explains exactly how Notecard moves between them.

In Notehub, each event's captured time was hourly while the upload times arrived in five-hour batches. Sampling and transmitting are separate decisions, and Notecard stores readings between syncs, so a satellite product can keep fine-grained data without connecting often.

TJ's events in Notehub, next to the week of temperature readings that Claude charted with Notehub IQ.

To look at the data beyond the events table, TJ used Notehub IQ from Claude Desktop to chart a week of temperature readings, with no dashboard to build.

Demo: A Hostless Starnote for Iridium Project

Rob's hostless Iridium deployment, which has been running outside for several weeks.

Rob's project is the Iridium equivalent: Starnote for Iridium paired with a Notecard Cell+WiFi, plus a Blues Mojo coulomb counter for power readings, a BME280 environmental sensor, and a LiPo battery. There is no host microcontroller, because Notecard handles all of the logic. The configuration mirrors TJ's, with a six-hour outbound sync, card.power logging the Mojo's readings, and card.temp readings that the BME280 supplements automatically.

Rather than scroll through events, Rob asked Notehub IQ how much data the device was using. It found that the device averaged about 77 bytes per satellite sync, far less than its cellular syncs, which carried the initial setup traffic. At that size, the bundled 10 KB goes a long way. A follow-up question revealed that solar charging wasn't keeping up with the load, and that the voltage pattern pointed to a worn-out LiPo.

Demo: Finding the Satellites

Alex built a proof-of-concept phone web app, with help from Claude, that overlays satellite positions on the camera view to show where to point an antenna. For Iridium, it shows satellites moving across the sky in real time. For Skylo, it highlights the most likely target, although those positions are inferred, because Skylo doesn't publish which partner satellites carry its traffic. The app isn't public yet, but it shows how much antenna placement matters for satellite deployments.

Answers from the Q&A

• GPS is free. Notecard's GPS receives location without using satellite data, so location fixes aren't billed. Only the data you transmit is.
• Use the certified antennas. Skylo and Iridium certify specific antennas and can remove devices that use others from their networks. For custom antenna needs, contact the network.
• Go outside. Satellite links need open sky. Iridium can sometimes connect through a window as a satellite passes, but Skylo almost always needs a direct view of its satellite.

Get Started

The quickest way to try satellite connectivity is a starter kit and its quickstart: the Notecard for Skylo Starter Kit, the Starnote for Skylo Starter Kit, or the Starnote for Iridium Starter Kit. Each one includes the hardware you need and 10 KB of satellite data.