SAR Technology: Looking Beneath the Earth from Space
The guest on today’s show is Lauren Guy, the CTO and founder of Asterra. He has a background in Geophysics and discovered the technology on which Asterra is built while during his masters. Lauren was involved in a project that used radar sensors orbiting Mars to search for water on the planet. The Synthetic Aperture Radar (SAR) signals used penetrate the ground to give a clearer view of what lies beneath and whether there is any indication of the presence of water.
How Bad Are Water Leakages?
Most of our drinking water is transported from far-off locations like reservoirs or even desalination plants near the oceans.
About 30-40% of the water that is moved around the world is lost through leaky pipes.
It is not only water that is lost in leakages – a huge amount of energy (used to pump the water) is lost as well. Considering the growing impacts of climate change, and looming future water scarcity issues, this is incredibly significant.
How Does Synthetic Aperture Radar (SAR ) Find Water Leakages on Earth?
Different materials have varying dielectric constants and therefore, electrical conductivity. These properties cause materials to reflect SAR signals differently. Treating drinking water gives it a distinct salinity level from other makeups of water.
Since salinity affects conductivity, it reflects a distinct SAR signal that differentiates drinking water from other kinds of water sources in the ground.
The assumption made is that there is no other source of drinking water in the ground – it has to come from pipes. This makes it possible to use SAR to create an underground map illustrating leakages.
Even with the capability to accurately isolate drinking water from other kinds of water, there are still possibilities for false positives as the same water is used for a lot of different uses like watering lawns, gardens, or filling swimming pools. The isolation has to go a notch higher to be able to distinguish the drinking water that is coming from pipes.
One way to do this is by calibrating the algorithm to only show moisture in the ground that has been accumulating for more than 48 hours. The thinking behind this is that most people do not water their lawn for more than 48 hours at once. This helps to avoid wasting time on false triggers.
How Far Can SAR Penetrate into the Ground?
SAR can only penetrate a few meters into the ground, depending on the soil type, and the top covering (i.e. asphalt, pavement, etc.). Generally, the depth of SAR penetration is about 2m in cities, 5m in more rural locations, and up to 10m in very sandy soils. The penetration depth of SAR is suitable for this application since water pipes are usually laid at a depth of 1m.
Georeferencing SAR Images
Georeferencing is a critical part of working with SAR images. The images need to be georeferenced in order to figure out where they are on the surface. Finding the exact location where there is a leak as shown in a SAR image is very important to avoid sending a crew to the wrong place.
Since SAR sensors are usually pointed at Earth at an oblique angle, georeferencing SAR images can be difficult. Georeferencing algorithms have to undergo a robust training phase in order to achieve the level of accuracy required. As we continue to see the popularity of SAR technology grow, we may see this get easier.
Tackling Signal Noise in Urban Environments
Telecommunications in urban environments creates a lot of noise for SAR sensors as they use the same frequencies. Reflective surfaces also create a lot of noise. This problem can be overcome by using different polarizations. A SAR signal can be sent in three ways: Vertical, horizontal, or as an alternating combination of the two in some cases.
When the signal is bounces off different materials or noises, the polarised signal goes from vertical to horizontal and vice versa. Detecting these polarization changes, and measuring their magnitude makes it possible to identify the source of noise that caused the change of polarizations and correct for it.
Building a Business in Around SAR Tech
The problems that Asterra faced while building a business around SAR technology are quite the same for many companies that are developing new solutions in tech. Despite putting in a lot of effort to convince clients that the technology actually works, it is even more difficult to convince a client to create a new budget to buy that solution.
For Asterra, these were passive utility companies that were not actively looking for leakages in their infrastructure, but primarily relied on citizens to report suspected leakages. One of the more common ways a customer might notice a leak is a sudden spike or even gradual increase in their water bill, without having changed their habits. As utility companies did not have an existing budget for a field team that looked for leakages, it was difficult for them to justify a new expense.
Why You Should “Speak the Same Language” As Your Clients
The best kind of clients are the ones that are already solving a problem. It is easier to convince a client to buy your solution if you can acknowledge their existing ideas and solutions, and then offer your ‘new’ solution as a complement to theirs. It will not sound realistic to them to ask them to throw everything out – what is often very expensive equipment – and replace it with your solution. A general good tip in convincing anyone of something, is to make them feel like they came up with it themselves.
For Asterra, it was easier to convince utilities that already had a field team that were actively looking for leakages in their infrastructure, and already had a budget for it. The companies could just reappropriate the budget towards buying the new solution, and even save costs as Asterra’s solution is often cheaper than the original way.
There were also advanced utilities that not only have a field team, but also very expensive IoT equipment for finding leakages. Due to the high costs involved, it is not economical to install the equipment throughout an entire city. For these cases, Asterra’s solution could be adopted as a complement to these devices in order to identify the most problematic areas in the city, and shift the more costly equipment to those locations where it is needed most.
Embracing Competition in Tech Businesses
For most businesses, the thought of competitors may be dreadful, but in tech businesses, competition might just be the force that drives the business forward. Being the only player in the game may be viewed by clients and investors to mean that the market is not viable. It leaves them with many questions of why there are no other solutions in that area already if there is so much money to be made. Competition fuels more discussion around a technology, which is an opportunity for the newest solutions to gain exposure.
Other Applications of SAR Technology
SAR technology is also useful in monitoring other important infrastructure like highways and railways for potential issues. Since SAR is looking underground, the issues it identifies may not be apparent yet from ground level. Accumulated water causes most of the issues in infrastructure. Pinpointing locations with very high soil moisture can help railway companies, or a country’s Department of Transportation to identify infrastructure that may fail soon. SAR’s ability to penetrate the ground at night and in any kind of weather can be harnessed in many other applications, such as mineral explorations, defence, and identifying contaminated soils. Who will be the ones to make it happen?