Category Archives: Technology

Articles about general technology – illustrative but not necessarily about farm networking.

WiFi standards – 802.11a to 802.11z

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It seems like every time you look around there’s a new crop of WiFi routers offering unbelievable speeds and ranges due to the use of a new WiFi standard. Years ago, WiFi started out with 802.11a (back in the last millenium) and then 802.11b, which gave way to 802.11g, which was replaced by 802.11n, and new routers use 802.11ac. And, if you’re wondering, yes, of course there’s a new one on the way, currently called “802.11ax.”

There are also many ancillary standards associated with these, even an 802.11z standard (having to do with extensions to Direct Link Setup, whatever that means). The “a,” “b,” and, to some degree, “g” standards are, for all intents and purposes, obsolete, because nobody has built equipment using those standards for a long time. On the other hand, all the standards are “backwards-compatible,” so the newest equipment can still interoperate with the oldest “a” and “b” equipment.

For us here in the Ayrstone labs, the amusing thing about all these advancements since 802.11g in 2003 is that they are squarely centered on one thing: improving indoor WiFi performance. The reason that amuses us, of course, is that it’s exactly the opposite of what we’re trying to do, improve outdoor WiFi performance. There has been almost nothing done to improve outdoor long-distance WiFi since the 802.11g standard.

Here’s a quick rundown of the various WiFi standards:

  • 802.11 – 1997 – up to 2 Mbps on 2.4 GHz and InfraRed with WEP encryption
  • 802.11a – 1999 – up to 54 Mbps on 5 GHz
  • 802.11b – 1999 – up to 11 Mbps on 2.4 GHz
  • 802.11g – 2003 – up to 54 Mbps on 2.4 GHz, WPA/TKIP encryption
  • 802.11n – 2009 – up to 600 Mbps using both 5 Ghz and 2.4 GHz, MIMO, WPA2/AES-CCMP encryption, wide channels
  • 802.11ac – 2013 – over 1 Gbps using both 5 GHz and 2.4 GHz and extra-wide channels, MU-MIMO

802.11g was the standard that made WiFi useful (effective data rates of over 20 Mbps) and safe. The original WEP encryption standard in 802.11b was fatally flawed and easily broken – we now consider it “anti-security,” because it gives the uninitiated the illusion of security but does not actually deliver any, much like having a door made of paper painted to look like steel. WPA/TKIP encryption is still considered unbreakable (when used with strong passwords), so 802.11g WiFi devices are still perfectly useful.

802.11n added even more unbreakable security (WPA2/AES-CCMP), which is designed for large networks and organizations. It also added MIMO (Multiple Input, Multiple Output), a way of using multiple antennae to increase the bandwidth and increase the range of the WiFi signal, especially indoors. A single antenna senses “multipath” (signals bouncing off the walls and other solid objects) as noise, because they are slightly out of synchronization with signals coming directly from the other station. MIMO antennas can “correct” and re-synchronize those multipath signals, improving indoor performance dramatically in some cases. 802.11n also introduced dual-band capability, using both the 2.4 GHz and 5.8 GHz bands to increase throughput, and “wide” channels – increasing the amount of electromagnetic spectrum used from 20 MHz per channel to 40 MHz. Wide channels increase bandwidth, but at the sacrifice of range. So you can get faster data speeds close to the WiFi Access Point, but speeds will drop off quickly as you move away.

802.11ac is the latest standard, and it adds on top of 802.11n. Specifically, it allows for extra-wide channels (80 or even 160 MHz in the 5 GHz band) and MIMO improvements. In particular, it adds “MU-MIMO” or Multiple-User MIMO to expand the advantages of MIMO to multiple users of a WiFi access point, as well as increasing the number of spatial streams (from 4 to 8) and offering improved modulation techniques on the wider channels (256-QAM).

So the improvements to WiFi since 2003 can be roughly broken down into 3 areas:

  1. 5 GHz – The higher the frequency of a radio signal, the more it behaves like light, so the more it is affected by solid objects. 5 GHz. signals disperse more in air, and pass through solids even more poorly than 2.4 GHz. signals (which don’t do very well). So, with some notable exceptions (very focused point-to-point links with very clear line-of-sight), 5 GHz is only useful indoors and for very short distances.
  2. MIMO – MIMO is one of the most exciting improvements to WiFi, because it can dramatically improve indoor performance. Of course, both the access point (e.g. wireless router) and the client device (e.g. laptop) have to have MIMO to make the best use of it, but can really improve both range and throughput indoors. Outdoors, however, where there aren’t walls that signals can bounce off of, the value of MIMO is very limited.
  3. Wide channels – I sometimes explain that radio signals are a lot like plumbing. If you have a water hose with a constant pressure, you can put a narrow nozzle on it and push a little water a long ways, or you can put a wide nozzle on it and push a lot of water a little ways. Wide channels are like a wider nozzle: more bandwidth that doesn’t travel as far.

The key to getting maximum range outdoors is to “squeeze” the stream down as much as possible to force it out toward the horizon. The AyrMesh Hubs do this by going somewhat against the “trend” in WiFi:

  1. 2.4 GHz only – for lower dispersion and best penetration of solid objects
  2. SISO – focusing the radio signal (the spectral density) into a single beam for maximum range
  3. Narrow channels – focusing the radio signal into the smallest channel width for maximum range

When we introduced the AyrMesh Hub2n, we noted that it uses 802.11n technology. However, while it does comply with the 802.11n standard, it is, essentially, using the 802.11g features present in 802.11n and almost nothing unique to the 802.11n standard.

That’s not to say that we’re not keeping close tabs on the improvements to WiFi and trying to figure out ways to improve our products. By moving to 802.11n, we picked up WPA2/AES-CCMP encryption, which is actually more efficient on many WiFi radios equipped with hardware encryption, and new modulation methods which may provide marginally better performance. Right now we don’t see any improvements from MIMO, for instance, but we may yet find a way to make use of it. We also have hope that new, more efficient modulation methods could provide us new ways to increase the range and throughput of outdoor WiFi.

We also made use of another WiFi standard in the Hub2n: 802.11s, the new WiFi meshing standard. Time will tell, of course, but we hope that adopting this standard will enable us to introduce new Hub models and other equipment without changing the meshing, effectively “future-proofing” the Hubs.

What this means is that now is the perfect time to build your Wireless Farm Network using WiFi: the technology is extremely well-proven, inexpensive, and reliable. There are lots of contenders to take the place of WiFi for outdoor connectivity, from Super-High-Frequency radio to “White Space” radios (using the unused frequencies in the Television band). None of them are going to offer anything close to the price/performance you can get today out of outdoor WiFi, at least for a very long time. So you can build your network well-assured that there isn’t something waiting in the wings to make your investment obsolete. There will never be a better time to build out your Wireless Farm Network.

Getting the most out of your router – part 2

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The ASUS RT-N66U – a modern, high-end home wireless router

In the last article in this series, I discussed what a home router is and a little bit about how it works, as well as providing guidance on how to set up the DHCP server.

IP addresses on your LAN are assigned one of two ways: either by the router’s DHCP server, which provides them out of the DHCP address pool (which I suggested should be 192.168.1.50 to 192.168.1.254) or by statically assigning them yourself (which I suggested should be out of the remaining 192.168.1.2 to 192.168.1.49 addresses). Assigning static addresses is very seldom necessary on modern routers, however, because most modern routers have a feature called “DHCP Reservations.” This allows you to specify the MAC address of a device and make sure it is assigned the exact same address via DHCP every time it is connected to the router. Using DHCP reservations, you can ensure that your laptop always gets the same IP address without having to configure a static address for it (which is a pain, since you’d have to re-configure it every time you go to the coffee shop).

Using either static addressing or DHCP reservations, you may want to make sure that “infrastructure” on your home network, like file servers, entertainment systems, or security devices always have the same IP address.

Your router’s NAT usually automatically closes off all the ports on your public IP address, making it impossible to access anything on your LAN from the Internet. In most cases, that’s a good thing – you don’t want the Internet able to reach your private network. But, in some cases, you want to make devices on your network available from the Internet (ALWAYS protected with strong passwords, of course!). The classic example is the IP camera set to watch something important on the farm – it could be the front drive, livestock, or your machine shed – you want to be able to access it from wherever you are so you can check up on it. But you might also want to be able to check and operate machinery like your grain dryer, pumps, irrigation systems, HVAC systems, etc. from a distance.

The IP camera has a webserver that uses port 80 (usually) for its interface, so the trick of port forwarding is to open one port on your public IP address and tell your router to “forward” all packets coming to that port automatically to port 80 (or whatever port you configure) on the camera. So you “knock a brick” out of the router’s firewall by specifying one port on the public side (I like to use ports 7001-7099, because very few services use these ports) and forward that public port to a port on your camera.

The way you do this varies from router to router, but the drill usually entails going to the “port forwarding” interface on your router and specifying the incoming or public port (7001), the device that’s receiving the packets (your camera’s IP address – 192.169.1.something), and the port on the device that will receive the packets (port 80). Then, if your public IP address is 101.102.103.104, you can access your camera on the Internet at http://101.102.103.104:7001 (the IP address, a colon, and the port number). Some routers allow you to specify only certain incoming IP addresses that can access the camera, but that’s usually not a good idea because, for instance, if you want to look at the camera from your smartphone, you won’t know the IP address of the smartphone.

NOTE: some routers (stupidly, in my opinion) require that the port numbers on the public side and the private side be the same – they won’t forward port 7001 on the public side to port 80 on your camera. If you have a router like that, you’ll need to reconfigure your camera (or whatever device you have) to the appropriate port (e.g. 7001) port before you can do the port forward. You shouldn’t forward ports under 1024 unless you know exactly what you’re doing, because you might be disabling something your router needs to function properly. Forwarding extremely popular ports like 80, 20, 21, 22, 23, 25, etc. can also attract password crackers and other undesirable elements to your network.

Let me emphasize at this point the importance of a strong password on anything that’s exposed to the Internet – if you can access it, so can anyone else, so make sure it’s locked down.

On my own home network, I have several ports forwarded to different IP cameras around my property, as well as ports forwarded to my desktop Windows machine (using VNC so I can access it easily when I’m away) and my Linux development machine (using SSH). I can actually access any of those devices using my smartphone, so I can stay on top of things anywhere I have an Internet connection.

Click here to go to Part 3

Getting the most out of your router – part 1

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The venerable Linksys WRT54G – Courtesy of Linksys

The world of networking is complex, including that little bundle of technology sitting on your shelf – your router. It is actually a pretty amazing little device that can probably do more than you realize. In truth, the typical “consumer” router is a combination of three devices:

  1. A router – a router is a device with two or more ports that is used to connect two or more networks together. Typically, the consumer router has a “WAN” port that connects to the “Wide Area Network” of your Internet Service provider and “LAN” ports for your Local Area Network.
  2. An Ethernet switch – you may have noticed that your router doesn’t have two ports; most actually have five: one WAN port and four LAN ports. Inside the box is an Ethernet switch that turns the LAN port of the router into 4 LAN ports to which you can connect wired computers, servers, and even additional Ethernet switches if needed. Actually, it’s 5 LAN ports, because the fifth one is connected to…
  3. A WiFi Access Point – this is simply a wireless radio connected to an internal LAN port that provides a WiFi signal for computers, tablets, smartphones, IP cameras, entertainment systems, and all kinds of other things. This WiFi radio is usually optimized for short-range, indoor use, providing maximum throughput for a short distance.

One of the odd and important facts about a router is that it has two Internet Protocol (IP) addresses: one on the network to which its WAN port is connected (which should be a public IP address, visible from the Internet – e.g. 108.162.198.52, ayrstone.com’s address), and one on the LAN port, the network it creates for you (a private address, not usable from the Internet, e.g. 192.168.1.1). Its job is to take data packets from each network and move them to their destination network. So, if your computer is at 192.168.1.50 on the LAN, and it receives a packet on its WAN port destined for 192.168.1.50, it passes it to the LAN port where it finds its way to your computer. Similarly, if your computer creates a connection to 108.162.198.52, the router receives packets from your computer on its LAN port and routes them to the WAN port. When you print to your networked printer (at, say, 192.168.1.100), it receives packets from your computer and then just turns them around and sends them back down the LAN port, since they are not destined for the Internet.

The ability of the router to accept traffic on a single public IP address and enable several different computers at private IP addresses to have separate “conversations” with the Internet is called “Network Address Translation” or NAT. The way it does this is by using “ports” – simply numbers associated with every IP address.

Each IP address has 65,535 possible ports. Some ports have pre-assigned purposes, some are available for use by applications, and some are ephemeral – here’s a good explanation of which are which. NAT uses those ephemeral ports to keep the conversations between your network and the Internet straight; for instance, your computer’s conversation with this website might be using your public IP address’s port 55135, while another computer on your network might be having a conversation with another website on port 61234. To the two websites, it looks like the traffic is coming from a single computer, specifically your router. Your router then routes the responses from the websites to the correct computer based on the port on which the data comes in.

The private IP addresses on your network are usually assigned by your router using Dynamic Host Configuration Protocol or DHCP. When a computer connects to your network, it will ask the router for an address via DHCP, and the router will provide it one (assuming it has one to provide). The address is referred to as a “lease,” because it will expire at some point after the device leaves the network, so it can be used by another device. However, note that you can simply assign a static IP address to a device in your network, as long as (1) it is an IP address inside your network (usually meaning it has the same three first numbers as everything else on your local network, e.g. 192.168.1.x) and (2) it does not interfere with the DHCP settings on your router (if your DHCP server begins at 192.168.1.50 and your router is at 192.168.1.1, use static addresses between 192.168.1.2 and 192.168.1.49, and KEEP TRACK OF THEM WHEN YOU ASSIGN THEM!!!)

The first tip for getting the most out of your router is this: set up your router’s DHCP server carefully. I suggest setting your router’s IP address as 192.168.1.1 and setting your router’s DHCP range from 192.168.1.50 to 192.168.1.254 (204 addresses). The reason for this particular range is that, first, it allows for a large number of devices to automatically use your router, getting private IP addresses via DHCP (204) but still leaves you 48 addresses you can use for devices you want to statically assign. This gives you the flexibility to maintain, expand, and control your home network.

Alternately, most modern routers support DHCP Reservations, which allow you to ensure that the router ALWAYS provides the same IP address to a device on the network. That way you get the advantage of a static IP address (knowing where a device is at all times) with the advantage of DHCP (ease of configuring devices and the IP addresses being managed by the router).

Click here to go to part 2

Myths about Wireless Farm Networking

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Myths are fun, but this guy won’t help you get the work done.

We have been talking about the myths of Wireless Farm Networking lately, and I wanted to add my own two cents worth here.

The article about the myths is excellent and stands on its own – I strongly suggest you read it. I thought I’d add a little about the topic here, by focusing on three aspects: Wireless, Farm, and Networking.

Wireless – I have seen “wired” farm networks – a number of livestock producers have trenched and buried fiber lines to their livestock buildings (Ethernet can only go 100 yards) for monitoring and control. However, it’s much cheaper now to go wireless, and it gives you much more flexibility. To build a good wireless network on your farm, you have to learn about “line of sight” (or, more correctly, Fresnel Zones) and position equipment so it has both power available and good radio signal from the rest of the network. It used to be that having a private wireless network across your farm was either technically impossible or cost-prohibitive, but we are proving that wrong every day.

Farm – A farm is pretty much defined as being in a rural area, and we’ve all seen that what works in town doesn’t necessarily work on the Farm, and vice-versa. The AyrMesh network is designed for farm use – relatively few people and machines spread out over a relatively large area. There are lots of good solutions for networking in town, where there are a lot of people in a small area, but they will never work as well as a solution designed specifically for the farm.

Network – The Internet Protocol (IP) network is the single, unified data communications medium for this century. I have seen farms that had a wireless link for their weather station, another wireless link for their GPS corrections, a home WiFI system and cellular coverage. Getting rid of the “point-to-point” solutions and putting everything on the network enables you to collect and transmit the data you need more easily, deliver what you need over the Internet, and gives you the option of adding new technologies to your operation quickly and easily.

Some people think this is revolutionary, but I would argue nothing could be further from the truth: this is the result of a clear evolution over time. In the 1970s academicians started tying computers together and transferring data over the first networks. In the 1980s networks came out of academia and started being used for business and even personal purposes; in the meantime, ham radio operators and researchers were starting to send digital data over radio waves. In the 1990s companies started to network their offices to share files and printers, as well as sending emails. Building-to-building microwave links became relatively common, and Industrial Automation moved to IP networks. In the 2000s the consumer internet became a reality, as did WiFi for wireless data, and we all got “on the net.” Now, in the 2010s, we have the Internet of Things and the low cost of high-power wireless networking, making this the decade of Wireless Farm Networking. The ability to monitor farm data and even control farm operations using a local network connected to the global internet will change agriculture forever.

Unmanned Aerial Vehicles (“Drones”) and Wireless Farm Networks

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One of the hottest topics in “Ag Tech” at the moment is Unmanned Aerial Vehicles (UAVs, also known as drones) and the role they can play for the farmer. Drones are hot right now, in Ag and other industries, because technology has made them much more adaptable and much lower in cost.

The possible benefits are tantalizing: an automatic, self-flying platform that can loft things into the air, take them where you need them, and take actions you prescribe. Just a few of the things drones can conceivably do for you:

  1. Take visible-light, near-infrared, and infrared photographs of all your fields at much higher resolution and in less time than satellite
  2. Get instant thermocline and other weather data (pop up 1000′ and check the temperature, wind speed, barometric pressure, etc.)
  3. “Run and get it” service for small items (see the beer drone and Amazon Prime Air)

When I was at the World Ag Expo a few weeks ago, there were several companies showing off drones and talking about drone-based ag services. Please make note of the distinction between drones and drone-based services, because, at the moment, it’s important. Or maybe not. I’ll explain as well as possible.

The Federal Aviation Administration has had a long-standing rule against the use of UAVs for “commercial purposes” – anything involving making money. Now, you can buy model airplanes with very sophisticated self-flying and video systems for fun or research, but not for any money-making purpose. However, a number of people couldn’t help themselves in making use of these amazing machines to enhance their businesses, and they have been getting “cease and desist” letters from the FAA. One guy named Raphael Pirker actually was fined by the FAA, giving him the opportunity to challenge the fine. He appealed to the National Transit Safety Board, and the administrative judge there ruled that the FAA did not have in place any actual regulations for the use of UAVs in non-navigable airspace, and therefore could not enforce the fine against Pirker. There’s a good article about this in Scientific American.

So, apparently, one currently can use UAVs for commercial pursuits, with some (not entirely clear) limitations. I’ll bet if you take your drone anywhere near a commercial airfield, for instance, you’ll get to meet some members of law enforcement and spend time with them. I’ll bet if you take your drone near any government installation, you will get to spend a serious amount of time with members of law enforcement and/or the military. In either case I’ll wager you’ll get to contribute a good amount of money to the government. And there are undoubtedly some private citizens who will happily shotgun your UAV out of the sky on sight.

I’ll also wager that the FAA (or some other part of the government) will create some rules about UAVs to protect people from stuff falling out of the sky on top of people and property, and having our neighbors peeking in 2nd (or 102nd)-story windows. But, for the moment, it looks like the skies are open, particularly out in the rural areas, and I expect farmers to be the first to benefit from UAVs. Some people like Chad Colby are already talking publicly about the opportunities.

Honestly, I think the current “state of the art” is mostly a plaything: the drones that are currently available are mostly manually radio-controlled and focused on live picture-taking. UAVs I have seen that might be put to use on the farm must be charged, taken to the field, flown around the field, and then the pictures (or other data) downloaded off the UAV (by bluetooth, WiFi, or transfer from some kind of flash card). This is a significant commitment of time, which limits how often you can really use the drone. A crop scout may be able to save a lot of the time he would normally spend by using a UAV to survey fields, but there’s benefit to the grower having a drone or drones that would continually survey fields.

The reason I am particularly interested in Ag Drones is because I believe they can become an important part of the day-to-day information-gathering apparatus. To be truly useful, however, I believe they must be:

  • Autonomous: flying over your fields automatically without intervention. Ideally, they would have a “home” out in the field where they would stay, and they would do their flying at specific times with no human interaction needed.
  • Smart: able to recognize problems and take appropriate action – recognize if there is something different in the fields, avoid danger, and report back
  • Connected: automatically uploading data collected and sending alerts to you as needed. For instance, a drone flying over your fields taking infrared photos might use the wireless farm network to automatically upload the pictures to a service that automatically scans them for anomalies indicating crop stress.
  • Self-maintaining: self-charging and self-monitoring, needing little maintenance and letting you know when it needs “help”

My own vision is that an Ag drone should be programmed with pre-configured flight paths and connected via WiFi with a wireless farm network for constant (or at least mostly constant) communication. It should be able to download changes to its schedule and pre-configured flight paths off the network, and It should also be able to land on a platform that will automatically charge the drone’s batteries for the next flight. Set up this way:

  • The grower, scout, or agronomist doesn’t have to go out and mess around with the drone – it can just do its thing as often as it needs to (pending charging of the batteries)
  • The data can be automatically collected on the grower’s PC or on a central server (on the farm or on the Internet) – it can even be automatically processed and problems (plant stress, aberrant weather conditions, etc.) can be automatically reported to the grower
  • The drone works for the farmer, not the other way around.

All the pieces exist today to create drones that can meet these criteria, but I’m not aware of any pre-built planes or copters that are ready-to-use. However, there are open-source software projects that have built auto-pilot systems for drones and other robots (e.g. the ArduCopter), and there is discussion of induction charging of quadcopters in the “DIY” forums. And heavier-lift copters (capable of picking up fairly heavy items and transporting them) are also in the works. Imagine being able to get out your cellphone and “tell” your copter to bring you the parts you forgot back at the workshop, then hearing it whirring its way toward you a few minutes later. And then, when it delivers them, it DOESN’T TELL YOU YOU’RE AN IDIOT for forgetting the parts. For me, that would be nearly priceless.

In short, I think there are a lot of possible benefits from using UAVs on the farm, and I’m eager to see them start to deliver those benefits. However, I think a lot of the benefits are greatly enhanced by having the UAVs connected to a wireless farm network – I believe the two technologies will work hand-in-hand, each enhancing the value of the other.