27 Nov
2016
27 Nov
'16
8:29 a.m.
I bought a pair of 900MHz 100mW LoRa modems for $20 off of tindie and wired them straight
to the SPI port on a Raspberry Pi. I wrote a driver and have them tx/rx-ing simple test
payloads. No range tests yet, still working at the bench. I would like to make a
simplified (802.15.4 + RPL)-like protocol for them to do multi-hop IPv6 with a data rate
around 10kbps. The downside is that the radios do NOT have good timing control, so
automated TDMA may need huge (milliseconds!) margins. The radios also have very tolerant
signal detection, so CRC checking is a must unless you want to wade through garbage data.
!!Dean
KC4KSU
On Nov 27, 2016, at 4:59 AM, Rob Janssen wrote:
(Please trim inclusions from previous messages)
_______________________________________________
Since we really need some other data radio
options in the hobby, I
wanted to mention LoRa.
It's a chirped spread spectrum technology
used for low power WAN
applications, with air transfer rates: 300bps-31.2Kbps. There are 433
MHz modules, as well as 900 MHz and 2.4 GHz.
Indeed it is interesting, I have looked at it as well when a local telecom
company recently announced it has deployed a country-covering network.
(by mounting LoRa equipment at all cell towers and locations)
They use 900 MHz, which is not a ham band here. But 433 could be useful.
It is unfortunate that the datarate is too low for many applications.
It could be interesting for APRS-like mobile datacomm or other telemetry,
which is also what the commercial network is for.
Rob
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