Unidata Newsline No. 20 - Unidata and Technology

Communications Networks don’t last Forever

Over the last couple of years, we have been reminded that communications networks do not last forever, and we should plan for the expected life of networks we use for data collection/ telemetry / IoT. The closure of the Globalstar Duplex Low Earth Orbit satellite data network in Australia and the soon-to-be-closed 3G Cellular networks in Australia are good examples of network closures. Both networks have served us well for about 15 years, but their closure reminds us that we need to plan for the operational life of the networks we use.

We should consider a five year forward look at the networks we use and plan for the updating of these networks based on their projected life. Cellular networks worldwide continue to have new additions, and we have seen this in the recent introduction of the Narrow Band services (NB IoT). There is bound to be new technology introduced in the next 5 to 10 years, so we need to keep a watch on the technologies as they emerge and remember to plan for obsolescence. Satellite networks tend to last longer than cellular and other ground-based networks; however, satellite providers like Inmarsat and Iridium add new satellites to their networks from time to time.

Inmarsat has a smaller number of high-capacity equatorial satellites in its equatorial orbit system. We note the introduction of the first of the newer model Inmarsat I-6 satellites in the Indian Ocean region this year. That new satellite has significantly improved performance when compared to the older model Inmarsat I-4 satellites. When customers move to the newer Inmarsat Satellites, they may need to slightly adjust the antenna pointing angle. Iridium has many satellites in its low earth orbit system, and it can retire old satellites and add new satellites easily, and there is no noticeable change to the service.

Starlink is now available, but it requires a 240-volt power source. It provides an excellent service for installations where there is 240-volt power, for example, remote farms. The need for this power supply makes it inappropriate for remote telemetry applications.

Iridium Certus Arrives

This year, we have a new service to use, the Iridium Low Earth Orbit Certus 100, with an 88 kb data rate service, and it is an excellent choice for telemetry / IoT. It is a great replacement for the obsoleted older Globalstar. Iridium Certus is a flexible satellite service platform using the L-band frequency and Iridium’s constellation of 66 satellites in Low Earth Orbit (LEO). It was commercially launched in 2019, which makes it Iridium’s newest capability. The new satellites are called Iridium NEXT. It is interesting to note that SpaceX was contracted to launch all the Iridium NEXT satellites. All the Iridium NEXT launches have taken place using a Falcon 9 rocket launch from Vandenberg Air Force Base in California. Because the Iridium Certus is a Low Earth Orbit system, there is no need to point the antenna. The installation procedure is easier than equatorial Earth Satellite Systems.

There are also different modem choices, The Rock Remote and the Blue-Sky networks, both of which have the Iridium Radio Module component inside. Unidata has used both models of modems, and both work very well. The Blue-Sky Networks modems are smaller and more suited to outdoor applications, while the Rock remote is less expensive and more suited to be mounted inside a separate enclosure. Unidata will investigate building a system based on the base Iridium 9970 Radio Module over the next year. The Iridium Certus service complements the current Iridium Short Burst data service (SBD), which Unidata has used for some time, especially with Groundwater applications where the data load is less.

Globalstar Satellite and Cell Phone 3G Replacement Systems

This year, the older Globalstar Satellite Network and the older 3G Cell Phone systems are being phased out and replaced with up-to-date communications networks. Unidata is involved in several customer projects to achieve this objective, and we have had a very busty factory over the last year as a result. We have supplied several customers with upgrade options. The new Iridium Certus satellite products, with Rock Remote and Blue-Sky modem components and the new NB-IoT cell technology. NB IoT provides increased cell tower range and also lower power than the standard 4G and 5G, which provide very high speed and higher power, which is not needed for telemetry and IoT applications. The Inmarsat BGAN modems from Hughes 9502 and the Add Value Sabre Ranger remain popular as well. The emphasis has been on manufacturing to allow for ease of installation in the field. More work in the factory means less work on-site, and that saves time and money for our customers.

How to Choose an IoT Satellite Service

There are many different satellite services, and how do you choose the one that is best for IoT / telemetry applications? This article highlights some important considerations.

1. Consider your data budget – Different applications need a different data budget
If you are monitoring groundwater, for example, perhaps you need to read the sensors for water depth, perhaps water conductivity, and temperature four times a day and send that data once per day. For groundwater monitoring applications, perhaps a short burst data / message-based service is better, for example, the Iridium SBD service. For weather monitoring or river monitoring, perhaps you need to read several sensors once per minute and send that data every 5 minutes. This is a much higher data load and data transmission frequency; hence, a higher-end full IP service such as Inmarsat BGAN or iridium Certus may be best.

2. Consider a shared data plan

Most satellite providers offer either a single-unit data tariff plan or a shared/group plan over many units. Shared/group plans are always less expensive than single-unit plans. Data usage is across all units in the plan; some units may have small data, and other units may have large data.

3. Consider your financial budget trade-off with installation convenience

Different satellite providers have different ways of charging for services; some providers allow for an always-on service because their network topology (such as an equatorial satellite network provider) allows for that. Other providers, while allowing for an always-on service, charge regular session fees (such as low earth orbit satellite network providers) because they need to pass data calls from one satellite to another satellite, and that requires additional satellite management bandwidth. Some low earth orbit providers may simply drop the connection as satellites pass out of view. They do not attempt to transfer the data call between satellites, which is less convenient and less expensive.

4. Consider your antenna Installation requirements – Different satellite providers have different antenna requirements

Some antenna installations are more convenient, and some are less convenient. Equatorial satellite providers have a plate antenna, which requires the installer to point the antenna towards the satellite in azimuth and elevation. While that is not difficult, it is another process an installer must do. Low-earth orbit satellite providers have a more convenient omnidirectional modem antenna. There is no need to do any antenna pointing during the installation process for these services.

5. Consider your installation location – Different satellite providers do or do not have requirements for the location of the satellite modem antenna

The location for an equatorial satellite installation needs to be reviewed to ensure that the location has an unrestricted line of sight to the satellite they are seeking to use. In deep valleys, they may have that line of sight blocked by a hill. On flat plains, they are unlikely to have the line of sight to the satellite blocked. For low-earth orbit satellite providers, that is not a consideration because the satellites in that low-earth orbit constellation essentially pass over the antenna on the ground, and they can penetrate deep valleys; they can “see” both sides of the mountain when passing the antenna location on the ground. There is no need to review the Installation location before installation.

6. Consider the way you plan to power the site

A small groundwater monitoring site with Iridium SBD satellite service can survive on a lithium battery for 2 to 5 years, while a larger river monitoring site may need a 20 to 50-watt solar panel and battery. Power requirements need to be considered when choosing an appropriate service. Starlink requires a 240-volt power source, which is okay in a remote homestead but not practical for most remote installations.

7. Consider the likely longevity of the satellite provider

Mainstream providers such as Inmarsat and Iridium are likely to be around for many years, while some of the low earth orbit and microsatellite providers may not have the financial resources to continue service for a ten-year period, which is generally considered the minimum life for commercial satellite services.

Unidata has a Technical White Paper on Satellite Airtime Models, which is on our website, and it would be useful when comparing different satellite systems.