What frequency are you using for 33cm?

[N1IOX]

First off, this is a great project! I found out about it a few days ago, and am impressed.

I've had little success finding consensus for a frequency to use on the 33cm / 915 MHz band in the US. To try to determine what others might be using, I did a quick scan across this map, looking to see if nodes had the frequency (and/or other LoRa parameters) contained in their beacon text. Not all do, but some did. Speaking of beacon contents - many, many nodes indicate that they're using this firmware!

I've added the frequencies I saw on the map as poll options. No doubt folks are using others, too.

I'm curious what you use, or have seen used.

[richonguzman]

i can't comment much on this as this it not my QRG .... there should be a U.S.A QRG defined for sure for all to follow.
which one should be the office to define this?

[N1IOX]

In the US, frequency coordination is pretty decentralized. In my state (New Hampshire), coordination is handled by the regional New England Spectrum Management Council. They have a published bandplan for VHF and up, but the info for 33cm (902-928 here) has not been updated since 2013. Predating LoRa, methinks :) I will reach out to them, as well as the ARRL.

It would be nice if there were a single nationwide standard for this (and perhaps that can happen), like with 144.390 being the US standard for AFSK-1200 APRS. I briefly tried to find info on the process of how that frequency came to be selected, but searches turned up empty.

[N1IOX]

What started my inquiry:
I looked at the map of APRS LoRa users, noticed there was exactly one active in the entire state of New Hampshire, and by sheer dumb luck, the station is located only 2.5 miles / 4km from me. Seeing that, I decided to load the firmware, and give it a try. No luck yet; I have no idea what frequency he's using, what LoRa parameters, etc. That prompted me to ensure my beacons includes full details.

So, if KE0EHZ happens to be on here and sees this, let's chat! :)

Either way, I plan to run some tests with a ham friend a couple of towns away, and surely wanted to do so using a commonly accepted / coordinated frequency, if such a thing exists yet.

[richonguzman]

will try to get into information for you on the US for LoRa

[N1IOX]

I very much appreciate that, but I'll gladly take on that task.
I'll reach out to my regional frequency coordinator, as well as the ARRL (of which I'm a member). I'll share here what I find out.

[arizonajon1]

@N1IOX
Given the Part 15 and Part 18 uses of the 902-928 MHz band, and the amount of and different types of 3rd party interference that varies with location, I'd be wary of any "regional" or "national" band plan. The band is used extensively by utilities for remote meter reading, point to multipoint monitoring and control systems, multi-lateration systems, and so many other uses. There are slow frequency hoppers that can come and go. Part 18 ISM gear can be anywhere in the band but at least the old high power equipment tended to avoid the band edges. A reason that ham radio repeaters are on the band edges is that the cheap consumer and older high power stuff tends to use poorly controlled oscillators and so that gear favors the band center.
You may want to use a spectrum analyzer (even one of those inexpensive SDR sticks) and see how bad the 902-928 MHz spectrum is in your area. From that, find a spot that seems less awful, and use that. The handful of 902-928 MHz ham radio repeaters generally occupy 902-903 and 927-928. Don't forget Meshtastic, I've never mapped their frequencies (slots) but they can be anywhere in the band.
A neat thing about chirp spread spectrum, as LoRa uses, is that two different systems on different spreading factors can occupy the same channel, and the noise floor remains pretty constant.
Based upon the significant interference here in Phoenix from a variety of Part 18 and Part 15 industrial or commercial systems, I'm on 924.650 MHz, which seems to be generally pretty decent.
Cheers and 73 - Jon N7UV

[N1IOX]

I appreciate the input, Jon!

Aye, even in my very rural area, there is a fair amount of traffic on the band. Certainly utility meters, which I'd spent some time decoding using SDRs.

I reached out to the New England regional coordinator, but received no reply.

I did finally receive some traffic from the one other ham using LoRa APRS in New Hampshire. Still no luck directly between our respective QTHs (hilly, and thickly forested), but 'heard' him when we came nearer to me. He had a tracker module with him when out on a boat on the lake I live on; that was cool to see! I assume he noticed me on APRS.fi, etc., adjusted his frequency / LoRa params to what I was using (as noted in my beacons), and then also started including that info in his beacons.

[arizonajon1]

that's pretty sweet that you were able to hear him when a bit closer. CSS is a very robust modulation system, and part of that is that it's hard to observe if you don't know where to look and what the parameters are. Like you, I put the channel/BW/SF/CR in my beacon and it's visible on aprs.fi and other services.
There are a couple of 433 guys in San Diego, we'd been chatting via discord, I needed to drive out to SD, so once they got their parameters dialed into the same as mine, I showed up on aprs.fi! That was neat. I'm headed out there again next weekend and hope to spend a bit more time trying to map out their coverage.
When I first started pursuing this mode, I'd reached out to the local coordinators, but they really only seemed to care about 440-450 and the 420-430 link channels. I know a couple of ATVers here, and the channel I'm using is in the middle of their NTSC chroma area, but I've been at one of the guys' house and he didn't see any upsets in his signal.
Wish you the best of success in getting more stuff on the air!

[n8ik]

I have a Heltec_V3 on a randomly chosen 916.000 MHz, see http://aprs.fi/?call=n8ik-10
73, Ian N8IK
Alexandria, VA