If you're building such a massive infrastructure project, why not just run fiber along its length?
If you have a tiny low-energy sensor that only wakes up for a few milliseconds out of every hour and can be powered by something like a little peltier element or turbine or pile-driven geothermal shaft, what's likely to go wrong besides someone stealing it? And with the design worked out, how much would a unit cost, $100 even with a rugged enclosure and special pricing for government jobs?
You'd only have to maintain a handful of base stations as opposed to umpteen dozen fiber terminations, and you could freely move sensor nodes or install new ones depending on what you learn or changes to the program.
But that said, it sounds like these sensors are A) along an existing infrastructure project like you said and I misunderstood, and B) also need to monitor for intruders which presumably also involves general surveillance. So...yeah, what gives?
Well, whatever, it looks cool.
- Maintenance: It could be very difficult to find and fix a fiber break. AFAIK, there's no easy way to determine where a break in the fiber is, you generally end up replacing the entire broken segment, which in this case could be miles.
- Reliability: If the fiber breaks, all the upstream sensors go down. Especially since a fiber break could also mean a pipeline break, you just handicapped yourself at the most critical time.
- Cost: Hundreds of miles of fiber, properly shielded from the elements, must cost a lot. (Of course, getting wireless signal to thousands of sensor stations would also be pricey, and I can't say how they'd compare.)
IIRC, the materials cost for building long haul fiber is a couple dollar per meter or less, especially in China.
If you're already building a massive structure like a canal, embedding conduits into the infrastructure is a tiny marginal cost. And Fiber maintenance is very, very low in protected environments (such as the electric-fence protected canal).
Not only that, you could easily build two conduits, one on each side of the canal, creating route diversity.
So for laying hundreds of miles (let's say 1000km) of fiber where construction is already happening, the total cost would be a few million USD.
They list the maximum range as 100 Km, with accuracy of +/- (0.8 m + 0.001% x Distance). So measuring to a break at maximum range, you'll be within 1.8 meters.
I'm not saying don't have some other way of transmitting data...just rather than worrying about "how do we relay connectivity between senors using a wireless protocol", and/or "How do we connect sensors that aren't in cell coverage areas to the broader internet", fiber can be used to connect sensors in relays. Put a cellular chip every 10 miles, say, and then connect those, with sensors, with fiber. So basically cell chip -> sensor -> sensor -> ... -> cell chip -> repeat. Any single split of one of those 10 mile stretches, and you have lost nothing (as communication can still go the other way, that is, the sensor north of the split can still send data north, the sensor south of the split can still send data south, say). And you know where the split happened.
"Workers will just cut the fiber" - err, really? I assume installing oil pipelines, given the mechanical complexity of it, involves more than just sticking it together and welding it shut (and removing it involves more than just slicing it open and dropping a new one in its place). An extra step or two to ensure the fiber line is properly hooked up hardly seems any more complex than what they're already doing.
The project is still innovative though.
It’s almost like some kind of system for supervisory control and data acquisition...
I'm guessing they called it IoT so more people would click on the title.
>> “The Smart Gateway can learn the availability of the connection to the cloud. After a successful transmission, it will follow that network next time. Otherwise, it will try another one,” says Zhang.
>> Video cameras were spaced every 500 meters along the entire structure.
>> Yang and his team developed the so-called Smart Gateway to receive data continuously from local sensors and then transmit it to a cloud server using whatever signal was available at the moment. That could include fiber, Ethernet, 2G, 3G, 4G, Wi-Fi, or Zigbee.
I'd be interested to see how their network holds up when streaming video to a gateway via Zigbee or video to the cloud over 2G (or even 3G). Considering the system is supposed to go into "continuous stream" mode during a natural disaster or other emergency, I'd guess this is also when the network would collapse. Oof.
I helped build similar devices (custom S100 based systems) 30 years ago at BHR group for remotely monitoring experiments at remote sites and using sensors to monitor pipelines was standard back then.
Wish I had suggested we build our own modems out of BYTE for £30 instead of paying £300 for answer and £600 for answer originate.
is there some reason this was not undertaken at the time of construction?