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RUDICS vs Certus 100: Is it time to make the switch?
What is Iridium RUDICS?
Iridium RUDICS (Router-Based Unrestricted Digital Internetworking Connectivity) was devised in the early 2000s as a means of allowing remote devices to connect to internet-connected servers using TCP/IP. The previous system, dial-up data, had a hefty overhead every time the service was activated, as a series of checks needed to take place before data could be transmitted.
RUDICS improved upon this by connecting the call to a predefined IP address, dispensing with the checks, and making connection much faster. This had the advantage of requiring less power at the remote transmitter end, lowering latency, and generally being a more efficient means of accessing the Iridium system.
RUDICS was, and still is, used for solutions that have multiple remote units in the field reporting back to an end point. Data buoys, water level stations, Unmanned Surface Vessels (USVs), ocean gliders, geotechnical and structural monitoring solutions, weather stations and many more applications have relied upon RUDICS for two way communication for over two decades.
The technology underneath it hasn’t changed in that time, though. And the data needs of those applications have.
Where does Iridium Certus fit in?
Iridium Certus leverages the advanced technology on the latest generation of Iridium satellites, and is available in three speed classes: Certus 100, which is intended for IoT applications; Certus 200, which is good for basic internet and voice; and Certus 700, which delivers the fastest L-band internet broadband speeds currently available, up to 704 kbps.
When we’re comparing RUDICS to Certus, we’re exclusively talking about Iridium Certus 100. They’re both aimed at the same use case of connecting remote devices to servers using TCP/IP (although Certus 100 devices have an alternative option here; more on that later).
Like RUDICS, Certus 100 runs over Iridium’s 66 cross-linked Low Earth Orbit satellites, so you keep the pole-to-pole coverage, low latency and small antennae you’re used to.
Certus 100 has faster data speeds
RUDICS transmits data at 2.4 Kbps; Certus 100 transmits data at 22 Kbps, and the downlink is 88 Kbps. That’s around nine times faster sending data from the field, and over 35 times faster receiving it. This means that you can transmit more data, more frequently, and push commands, configuration changes and firmware back to your remote units far more quickly.
Costs / billing mechanism
RUDICS is charged per minute, rather than the Certus 100 charging model of per byte of data transmitted. This makes RUDICS more expensive than Certus 100 for many applications; it’s possible, even probable, that you’re paying for connectivity time you don’t need. That matters more as your end users ask for more data: on RUDICS, more data means longer calls, and longer calls mean higher OPEX.
RUDICS is circuit-switched
RUDICS is circuit-switched, which means the ‘call’ between the remote device and the server has to be maintained. It’s not fault tolerant if your view of the satellite is temporarily obscured, or the server goes offline.
Certus 100 is packet-switched
Certus 100 is a packet-switched network, sending data in small and optimized packets which are much less likely to be ‘dropped’ mid-transmission.
In our view, there are very few instances where Certus 100 will not present a more reliable, cost-effective and scalable solution for remote data transfer than RUDICS.
Do you need IP at all? Meet Iridium Messaging Transport
It doesn’t stop there: while Certus 100 supports TCP/IP-based connectivity, Certus devices also offer users the ability to send data via Iridium Messaging Transport (IMT). This is a message-based transmission protocol which allows you to send and receive messages of up to 100,000 bytes.
This could facilitate additional sensor readings, greater data resolution, photographs or even audio files. Just as importantly, sending data via IMT will substantially lower the cost of data transmission because there’s no TCP/IP overhead in a message-based service; you’re only billed for your (successfully delivered) data payload. You’ll use far less power, too.
IP is fantastic for real time, two way communication with your application, but a lot of RUDICS deployments don’t really need it. If your units wake up, send a batch of readings and go back to sleep, a message-based service is likely a better fit.
There are two Iridium modules that access IMT:
- The 9770 gives you both Certus 100 and IMT, so you can switch between IP and messaging depending on the type of transmission. The trade-off is that it’s larger, more power hungry and more expensive.
- The 9704 only accesses IMT. It’s a small, light, and energy-efficient Iridium module, drawing just 2.5W at peak, and it’s lower cost. It’s ideal for projects with size, weight and power constraints, such as buoys, gliders and battery-powered sensors.
Which device should replace my RUDICS unit?
The right replacement depends on whether your application needs a live IP connection, and how tight your size, weight and power budget is. Here’s where we’d start:
 RockREMOTE Mini
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 RockREMOTE Mini OEM
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 RockBLOCK Pro
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 RockBLOCK Plus 9704
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 RockBLOCK 9704
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|---|---|---|---|---|---|
| Service | Certus 100 (22/88 Kbps) + IMT | Certus 100 (22/88 Kbps) + IMT | IMT, up to 100 KB per message | IMT, up to 100 KB per message | IMT, up to 100 KB per message |
| Best For | Externally mounted units that need IP, with messaging for routine data | Integrators embedding IP and messaging into their own hardware | Rugged, externally mounted messaging with GNSS | Rugged IP67 messaging with integrated GNSS for outdoor IoT | Integrators with tight size, weight and power constraints |
| View Device | View Device | View Device | View Device | View Device |
All of them are managed through Cloudloop, our satellite IoT platform. Cloudloop Subscription Manager handles activations, airtime and billing, and Cloudloop Data routes your data to where you need it: AWS, Azure, Google Cloud, MQTT, REST API, webhooks or email. Both are included free of charge with any Ground Control airtime plan.
What does switching look like in practice?
We’re already helping RUDICS users make the move. A manufacturer of ocean gliders needed to upgrade its fleet from RUDICS to Certus 100 to meet growing end user data needs without runaway OPEX. Ground Control completed the firmware and hardware modifications needed to meet the Certus 100 specification, giving them a manufacturer-ready upgrade path that works at fleet scale.
In another case, an ocean monitoring customer was seeing its RUDICS operating costs rise as end users demanded more data. We ran joint workshops to confirm compatibility with the RockREMOTE Mini and agree a test plan, and they’re now working through the test cycle.
Get in touch
If you’re currently using RUDICS, let’s talk: based on your current data usage we’ll be able to advise if you can save money by switching to Certus 100 or IMT, and we can work through any technical implications of doing so.
We’ve been Iridium partners since 2005, so we’re well placed to provide you with an experienced, objective perspective on the right connectivity solution for you.