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Comment by morpheuskafka | Hacker News Reader

So these are using LoRa (902-928MHz) as the actual frequency for text transmissions? This is really an exciting frequency that's been around for a while and has a lot of potential for disruption.

Fun fact--there is a completed WiFi standard for this frequency (802.11ah / WiFi HaLow), but as far as I know, there have never been any chipsets made for it.

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There are 802.11ah chipsets advertised, but I've never seen one in action. See e.g. https://www.newracom.com/product/nrc7292/

Ubiquiti's Rocket M900 and AFAR are also "wifi" over 900 MHz ISM band solutions as well, though I'm not sure what if any standards they use.

edit: looks like you can actually purchase a chip that uses 802.11ah: https://www.mouser.com/ProductDetail/Silex-Technology/SX-NEW...

along with a rpi compatible dev board: https://www.mouser.com/ProductDetail/Silex-Technology/SX-NEW...

There is so much crap (e.g. cordless phones) over the 900 MHz band that using this probably only makes sense in remote environments though.

Especially for cost--my group recently picked up a pair of 900 MHz Ethernet radio modems which acts basically like a 40km long line-of-sight Ethernet cable. Super useful for field research, but at US$900 per pair, they're above the "let's see what happens" budget for true experimentation. A $90 pair, on the other hand, even with a slightly lower range, would put them comfortably at about the price of a Raspberry Pi or other SBC, opening up a lot more possibilities.

I looked at the same thing for a project a couple years ago. We wound up writing a simple script using the TUN interface to send the IP packets over Digi's XBee radios (there's a 900MHz edition). Of course, sending all the packets through a userspace Python script was by no means efficient and the radios had only a 100K RF data rate to begin with, so the data rate was like 800bytes/second or something like that IIRC. Probably would be enough to cause some applications to timeout or give up on the network, but it was good enough for SSH and simple REST APIs.

There's no way 802.11ah will deliver 15Mbps, but if the standard is designed with that kind of data rate its gonna be a lot faster than what we were using (main reason is Wi-Fi is direct sequence spread spectrum while the XBees are frequency hopping, allowing a larger RF bandwidth). The one thing that is good about the XBees is they will support repeating messages for each other and they have a nice mesh functionality as opposed to Wi-Fi's client-AP model. Additionally, we were just using the small wire antenna on the XBee, which only outputs a fourth of the legal maximum power to begin with, limiting the range. The chipsets OP linked support the full 1 Watt output power.

As an aside, I also saw a serial modem using MURS that you could theoretically run a dialup program over. Also ridiculously expensive.

Yes to “LoRa”, but not necessarily on the 900MHz band. I have a few all using boards with 433MHz LoRa radios, most of the hardware supported is available in 433/815/915MHz variants. (In fact, I’m fairly sure most of the chipsets are capable of all those frequencies, and the only real difference if you buy the 433MHz version is the antenna they include.)

Yeah, this has been my experience too. Generally you use the frequency that has been legalised for use in the region you operate it in. I wonder if this automatically switches to the suitable frequency based off coordinates (when using a gps’d board) I’m sure it would be trivial to implement. Ah good ole opensource. This really is a great solution, riding around New Zealand the only solution is a SPOT tracker which charges like a wounded bull so I love that this is disrupting this space (and using clever tech - heck might throw one of these on the moto just to use it for security)

For Meshtastic, you upload a country/frequency specific firmware.

It’s perfectly happy running on devices without gps, so it’d be a maybe nice to have but not a thing the project could rely on to meet regulatory frequency compliance.

For your motorcycle use case, keep in mind this is a small group of people mesh thing, not something where one device can expect to connect to unknown other people. The SPOT tracker is still the solution you want if you’re looking for safety/emergency contact.

What meshtastic might be useful for on motorcycles (and I’m considering building some of these) is a medium range mesh network between you and your riding group, with super simple super limited Comms UI. I’m thinking 3 or 4 different colour old school video game type buttons that you can mash wearing gloves, that light up a bright-enough rgb led to see in the sun, with 3 or 4 agreed meanings for the colours. “Pull over and check messages”, “Wait for me”, “I’ve crashed”, “Cops!” type messages, that can be sent/understood without needing to read a text message on a phone screen (but still having that text messaging available as well).

> keep in mind this is a small group of people mesh thing, not something where one device can expect to connect to unknown other people.

I'm curious why you say this. Can a network not support, say, 500 nodes? 5000?

Also, (for a smaller-group use case obviously), is voice over the network completely out of the question?

The low bandwidth and the mesh topology put a hard upper limit on the number of nodes in a channel. From memory its limited to 250 nodes in the default settings.

https://meshtastic.discourse.group/t/theoretical-mesh-stats/...

"I suspect up to about 30 nodes per channel would be fine, I bet the channel will be almost unusable once you reach 100 nodes."

As for voice - I think in default "very long range mode" the mesh bandwidth is down around 20 bytes per second. It's possible to get higher bandwidth at the expense of range, but it's really not what you're looking for if you want voice comms.

Presumably this is all using one channel as well, so scalability will be limited by the amount of airtime per device.

I suppose you could send voice very slowly at very high latency if you wanted to... but it would not be very efficient.

Right, it uses that in Europe as they don't have 900MHz. I think in the US there's some periodic use only requirements for 433.

Australia only has half the regular international ISM 915 band, we sold the top half to telcos. (Meshtastic knows and deals with that if you select the 915MHz _au firmware.)

There are few standard compliant options, here's another one: https://www.morsemicro.com/ from Morse Micro.

That being said, if you spring for 900mhz WiFi, you can kiss that 8-day battery life goodbye.

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