@glyn.hudson is there a limit on the number of emonTx6 that can communicate with the Pi3? I seem to remember there might have been with the Tx4, but can.t see any reference to that here.
I’m considering using these for a farm project I’m looking at where there are up to 6 remote locations. Most of these are around 50m away, but one is about 150m (open air, no obstacles). It seems like this latter one might be on the limit for 433MHz?
Rachel
Hi Rachel, there’s a limit of 255 RF nodes per system. This is the same as for the Tx4/5. We’ve never tested this many! In practice, I think there could be some RF collision issues with this many nodes.
6 is no problem, obviously they will need to have unique RF node IDs. This can be set using the serial configuration, or we can do this for you when they are first purchased.
We usually state that 100m is about the maximum in free air, in most cases this is usually a bit optimistic since there’s often at least a wall or two in the way. I think 150m is pushing it for 433Mhz.
Is this the case even with the Tx power at maximum? There is also an option to turn on the LNA for on the Rx side, but that can saturate the receiver for stronger sources (which you could of course reduce Tx power for) and lead to more susceptibility to interference. It’s also possible to reduce the bitrate.
I’ve seen reports of the RFM going out to 500 m in free air, so 150 m doesn’t seem unreasonable 
One thing to consider is that the Pi3 and the TX6 are essentially the same thing, just one has a Pi in it. As long as you have an internet connection for the Pi, any of them can be the Pi that acts as the base station.
No, this is just the default setting. Until now, with the emonPi3/Tx6 we’ve not had the option to easily charge the RF power. I’ve yet experimented with higher power.
Correct, the only hardware difference is the LCD and push button. Now with the emonPi3/Tx6, they both share the same FW. At startup it will autodetect if a Raspberry Pi is present, if a RaspberryPi is not detected it goes into emonTx6 mode e.gf transmitting data via RF
I’ve been doing a bit of google earth measuring - going to the farm tomorrow. But actually, I think the best option is to put the base station in the building where the main switchboard is rather than the office as I’d originally planned. I can either run a cable or Wifi bridge to get the LAN to there and then I’m about 90m from the furthest building we want to monitor.