Mesh Myths, Half-Truths, Caveats, and Unconventional Wisdom

Antennas

• Stock Antennas  — Nearly all of the antennas that are provided with Meshtastic devices are, for lack of a better term, garbage. That doesn’t mean they don’t work, but it generally means they don’twork all that well. For a typical pocket/on-person node, they come with the cheapest possible 915mhz-capable antenna. That usually means either a tiny PCB (printed circuit board) antenna, or a very short SMA-based plastic antenna, usually no more than 2-3 inches in length. While that CAN function, they tend to be able to hear some mesh traffic, but generally are not successful transmitting mesh traffic unless another node is extremely close-by — generally within about a city block or so.
  • TL;DR: Expect to buy a new antenna for your pocket node unless you know it comes with a decent one.
• dBi/gain — [caution: oversimplifications ahead!] dBi is a way of comparing the “beam concentration” of an antenna. Not just in how it transmits but also in how it receives signal. “dBi” means “Deicbels above Isotropic”. Decibel (“dB”) is the unit of measure, and “Isotropic” (“i”) represents a perfect sphere of sending and receiving capability. As dBi increases (such as 5.8dBi, 8dBi)  the sphere shape becomes more and more of a donut, and if you get to the much higher dBi numbers like 10, or 12dBi the sphere becomes practically a frisbee. What that means is that the same transmitted energy from your node is concentrated into that shape. None of the signal power is wasted on broadcasting up into the sky, or straight into the ground. As dBi increases, the concentrated signal is more likely to penetrate things like tree leaves, smoke, humidity in the air, buildings, etc. Now…why bring this dBi stuff up at all? Because the evidence from our real-world experience on the MSP Mesh indicates contrary to conventional radio wisdom might normally suggest about antenna gain. The vast majority of nodes on the network are near or below the tree/roof line — the signal effectively has to cut through foliage and buildings taller than that node’s location to be able to send message.
  
  Conventional radio advice might be to just use more wattage to penetrate the blockages, but we don’t often have that option given the power regulations of the ISM band (902-928mhz) that the mesh utilizes. We enjoy the penetration qualities of higher dBi antennas, and our experience at any antenna elevation has been that the typical drawback of higher dBi antennas – not being able to hear things above or below the signal lobe (the “donut” or “frisbee” shape of signal) – doesn’t pose much of an issue for the sensitive listening capabilities of most mesh devices. Thus, most stationary nodes tend to use a 5dBi or higher gain antenna.
  • TL;DR: save yourself an extra antenna purchase and start with a higher gain antenna for your stationary node. … and on that note, the next item is 100% related to this one:
• Beware of cheap junk! — The mesh shares radio frequencies with at least one cryptocurrency mining platform. There is an entire market of people using the same radio frequencies as the mesh — and thus the same kind of antennas — but attached to the promise of easy money. While that may seem great (hey,more options on the market!) the Mesh’s experience has been that most online retailers sell toward that market, not the mesh networking market and wildly exaggerate specifications of antennas and cables to make a quick buck from the crypto miners. Often the antennas or cables will be a few dollars cheaper than getting an actual decent field-proven product, but you have no idea the quality of what you’re going to get. We highly recommend only buying antennas and cables from community-vetted sources. TRUSTED VENDORS PAGE
  • TL;DR: You might spend an extra $10 on a vetted antenna… but you won’t have to buy it again. The peace-of-mind is worth it.

Batteries

• Cheap Batteries — Most mesh devices operate on some sort of rechargeable lithium-ion or lithium-polymer battery. Most of the LiPo “pouch” or “pack” style batteries seem to be of reasonable quality and specification accuracy for their price. Where things start to require community vetting is when you get into the cylindrical batteries like the ubiquitous 18650 or 21700 type cells. Because flashlights and vape pens (among other devices) use this type of cell, the market is flooded with fakes, exaggerated claims of mAh (power storage) capacity, and downright unsafe batteries.  Don’t be fooled by unreasonable mAh claims. You will not find an 18650 that can hold more than 4,000 mAh or a 21700 that can hold more than 6,000 mAh that is actually real. No matter how cool the wrapper on the battery looks, it’s not real.
  • TL;DR: only buy batteries from trusted, vetted vendors.
• Temperature Concerns — A common misconception about batteries used in outdoor Mesh nodes is that extreme heat or extreme cold will greatly impact battery performance. While this may be true for many other applications, the overwhelming evidence from years of outdoor nodes on the MSP Mesh is that extreme heat and extreme cold have a negligible effect on the capacity or longevity of good quality battery cells. As long as an outdoor node is using quality cells, and in enough parallel capacity (generally 10,000 or more mAh) heat and cold are not issues to worry about. Passive ventilation is recommended (often as simple as a small hole in the bottom of an enclosure, etc) but not required. To our knowledge there is no need to externally heat or even insulate battery cells from ambient temperature, whatever that temperature is. The secret formula is: lots of capacity.
  • TL;DR: Mesh devices typically use such a tiny amount of current that charging and discharging in any ambient temperature is ok without extra attention to the batteries.

Novel node concepts

• Solar LED Light Conversions — One of the most popular recurring themes in Meshtastic communities is converting cheap solar-powered LED light (for sidewalks, gardens, garages, poles, etc) and converting it into Meshtastic node by taking it apart and inserting a small Meshtastic device that utilizes the existing solar panel and battery system from the LED light. On the surface this is a brilliant idea. In reality, it doesn’t work all that well in the extreme northern climates of the MSP Mesh without significant modification and improvement. The solar panels and batteries that come with these lights are generally extremely low quality, and insufficient for year-round operation in the MSP Mesh area. You can find better batteries and wire them in (or replace the ones that come with the light) and a different/better solar panel, but you can’t really increase the physical size of the enclosure, so you are generally going to be stuck with how ever many cells fit (which is usually two).  Even with two high-quality 21700 cells (which may not even fit in many LED light enclosures) you would be approaching the limits of its potential capacity/longevity in the winter months. Add to these limitations the relative lack of mounting options and heartiness/weatherproofness of the enclosure itself and you’re likely looking at a node that won’t survive long in the wild. Add to all of THAT the fact that there generally is barely enough available area to add an external antenna port such as SMA (and generally never room for N-type) …so your connectivity options are going to be limited to either a low gain SMA antenna or an even lower gain PCB antenna inside the enclosure.
  • TL;DR: It’s a fun DIY project, but generally not suitable for long-term outdoor deployment in the MSP Mesh. You’re likely to spend more money making it viable than it takes to build a much more capable node from community-vetted parts.

Expectation vs Reality

• Realistic Range — If you got into Meshtastic through the YouTube rabbit hole like many of us did, you are likely to come into the hobby expecting your pocket node to be able to communicate both ways effortlessly for miles on the first try.
  
  Well…when you get your first nodes and try it out, it’s extremely common to find that you really have a range of maybe a few blocks, and that may be generous. Don’t fret! Most people start off with a pocket node. Pocket nodes tend to have weak antennas and are usually being used in the worst possible radio situation: indoors, and low-to-the-ground.  That doesn’t mean it can’t or won’t work, but temper your range expectations, especially when it comes to being able to SEND messages.
  • TL;DR: first-try success is pretty rare. Be patient don’t be afraid to reach out for help!
• Listening vs. Broadcasting (“RX” vs “TX”) — All radios use MUCH less energy to listen for signal and translate it into useable data, music, or whatever is being broadcast. Transmitting signal (“TX”) on the other hand requires much more energy. Meshtastic devices typically transmit at about 0.25 watts of power. For reference, other communication mediums like typical home WiFi is generally broadcast at a full 1 or 2 watts (and the signal frequency can penetrate walls and floors much more easily than ours) and the cell towers that communicate with your mobile phone of choice is going to be broadcasting with anywhere from 100 to 1,000 times that power. It’s very common when getting your first Meshtastic device that you will immediately see a lot of activity – Nodes popping up in the list, chatter on the public channel, etc…. but whenever you send a message you get the sad Cloud-With-A-Slash icon (or the iOS “Max transmissions reached” status)… what’s the deal? If I can hear them, why can’t they hear me?  That’s just the nature of the beast. In order to successfully transmit to the mesh, your node will need to be within range of another node capable of hearing the message from where it was sent. That’s the big step… the barrier that we all must cross. But that’s why it’s a mesh. There are nodes all over the place in advantageous locations and altitudes that are eagerly listening for your node so that they can repeat your messages to the other nodes that they can communicate with.