On 25/03/18 13:00, Dean H (KC4KSU) wrote: > It’s good to hear someone else is looking at applying 6LoWPAN to amateur > radio. > > I’ve studied 802.15.4 a fair bit. I find the standard is growing beyond > an individual’s ability to manage. So I distilled the 802.15.4 frame to > the essential pieces. My result <https://github.com/dwhall/HeyMac> is > not 802.15.4 compliant, but it’s much more manageable for an individual > to understand and write code. My frame format will support RFC6282 > (header compress and UDP compression).
I don't think 6LoWPAN over Bluetooth Low Energy confirms to 802.15.4 either. To be honest, a IEEE 802.15.4 is never going to be practical on amateur radio bands, and there's nothing to say we have to confirm. :-) > My target radio is the Semtech SX127X running in LoRa > <https://en.wikipedia.org/wiki/LoRa> mode. That’s a Chirp Spread > Spectrum modulation with selectable bandwidth from 7.8 to 500 KHz. It > has built-in FEC and supports payloads up to 255 Bytes. Not enormous > paylods, but twice that of 802.15.4. My first LoRa configuration is > (Bandwidth=250KHz, FEC code rate: 4/6, spread factor: 128). This > results is a data rate around 9000 bps. > > My current status is that I have a physical layer driver working and I’m > building the MAC layer. It’s time-slotted, but not channel hopping. > Time slots are 250ms to allow a full frame and an ack. The radio > boards <https://www.tindie.com/products/edwin/loragps-hat/> have a GPS > chip and synchronize to its Pulse-Per-Second (PPS). Ahh, so 433MHz. Over 1kB/sec data rates is nothing to be snorted at to be honest, even if it does take 250kHz of spectrum. My reasoning for using AX.25 equipment is largely because there's a lot of infrastructure already around. I have two stations capable of operating with it, and it's widely understood. I recognise that it's sub-optimal in terms of noise performance. A "FreeDV 1200" modem could conceivably run just as fast, and provide the long-distance hops between isolated networks via HF links. There's no reason why we can't route between such networks… or even the 433MHz system you're proposing -- it's all IP after all. :-) > In the MAC layer, I have an extended Beacon working. I’m experimenting > with what to put in the beacon at the moment. My next endeavor is to > create a MAC command for simple text messages. This is all still in > prototype stage. I’m coding in Python3 on a Raspberry Pi 3. Yes, I’m > getting millisecond-level accuracy with Python. I start range-testing > the 1/10th Watt radio modules this weekend. There are 1W modules if > this protocol proves promising. Sounds good. Nothing wrong with Python, especially at the prototyping stage. -- Stuart Longland (aka Redhatter, VK4MSL) I haven't lost my mind... ...it's backed up on a tape somewhere. ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Freetel-codec2 mailing list Freetel-codec2@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freetel-codec2
