Just a little announcement of an alternative build and maintenance method for RPi plus ic880a based on ttn-zh’s build.
As most of the build guides I’ve found stop with just the larger components, but I’ve gone to the extreme, and tried to specify exactly all of the components that will build to a full, IP67 rated, externally mountable gateway.
Not just that, but I’ve also set up an ansible script to be able to do remote deployment and remote updating of a fleet of gateways (again from the great ttn-zh install script). There’s still the provisioning of plain raspbian images, and the control of a internet accessible grafana host for remote monitoring to do.
The gateway script already includes:
ttn-gateway
ssh direct access via tor hidden service (for NAT punching),
prometheus.io and node_exporter for remote system monitor via graphana,
autossh connection back to an internet accessible “jump-host” with:
local port forwarding for ssh,
local port forwarding for prometheus monitoring via graphana.
And all with a nice: ansible-deploy -i production site.yml from a local machine
On the page you write larger diameter coax would be overkill, which is the case when considering transmission power, however the coax you specify has quite a high loss for each meter of cable. Larger diameter cable usually has less loss and would be preferable if a significant (>2m) length of cable is to be used.
I was assuming that as the link budget for LoRa is quite large, and the antenna option 1 I’ve chosen comes with a 2.5m RG58 coax; then signal loss over a that kind of distance isn’t too critical. (And the install I have with this cable + antenna gets 2km in a city)
As I’m not a specialist with RF equipment, and having a list is so that someone following doesn’t have to know all the in’s and out’s of RF, is there a guideline distance where we can say “It is preferred to use LRM400 cable if the coaxial lead is more than x meters from antenna connection to gateway”?
In general use the shortest cable possible. I’ve seen professional installations and never seen over 1.5 meter of antenna cable and even for those short distances they’re using something like ecoflex 15 which has a third of the loss LRM200 has. The specs for LRM400 are comparable to ecoflex.