I already have 3 base nodes (with power and high gain antennas) and 10 mobile nodes, forming a group A. I want to use another 8 nodes to form another group B with these 3 bases, so that I can fully utilize the existing relay equipment. Mesh mainly carries position information and sends text information. May I ask how to configure channels? In which channel will position messages and text messages be carried?
A node will send it routine nodeinfo and postion packets to its ‘primary’ or first channel. (technically via web client can configure any channel as primary, but generally best to stick to convention of first channel as primary)
But it may reply with its nodeinfo, or position packets on other channels (if the channel is configured for position!) it has. Ie if receives a message on those other channels, it can reply.
Providing the devices have the same lora/modem settings, the devices should all forward messages, even if they don’t have the same ‘meshtastic’ channel locally
ie the base nodes, should ‘relay’ the messages for group B, even if they dont actully have the B channel. (they can forward/relay message without being able to decode it!)
So could have the 10 A mobile nodes, use one common channel. If its the primary they will all share their location between each other.
The other 8 B Nodes, could also have their own common primary channel which is private for them.
The 3 base nodes (and the 10 mobile nodes) would all relay B’s messages.
And similarly 8 B nodes (as well 3 base nodes), would all relay A’s messages.
You could even have A’s channel and B’s Channel on the same node. So can commiucate with either group. But would be ‘primary’ - the first one would be the one it would normally share its own location with.
For someone on the secondary channel to knows its positon would have to specificall ‘ask’.
Oh, but forgot one point. Some regions/presets (eg the US) there are actually multiple ‘Frequency Slots’ available. And the default frequency slot may be based on the primary channel name. LoRa Configuration | Meshtastic
… so if just leave frequency slot as default might find devices with different primary channels (despite having the other channel as secondary) are unable to communicate. Because they end up inadvertantly having differnt Frequency Slot being configured.
Ie in the US, your A nodes, and B nodes (because have different primary channel) - end up not communicating. Ie the base nodes DONT forward B messages.
… in such regions would have to make sure set a specific and common frequency slot for interaction. (would have to work out what slot A using, so can set B to the same!)
(I think frequency slot also used to be referred to as ‘channel’. Now generally known as slot to differnate the frequency slot from the actual ‘meshtastic’ channel)
Find out if if slots with your preset+region combo: https://meshtastic.org/docs/overview/radio-settings/#frequency-slot-calculator
Thank you for your reply. Are you saying that both groups will set lora to LongFast, and the nodeinfo and position messages of both groups will be forwarded by these three relays? But it won’t be decoded?
OK。 Because the construction cost of base stations is high and the performance is good. When adding new groups, it is best to use these base stations to cover the signal further
Are you saying that both groups will set lora to LongFast, and the nodeinfo and position messages of both groups will be forwarded by these three relays?
Yes.
Subject to the amendum, about frequency slot. Depends on region, if there multiple slots in play.
The auto hashing, of the frequency slot from primary channel name, would be good in that different networks, use different radio frequency, so they don’t interfere. But would also mean they dont forward each others packets.
Only other relevant point, is Rebroadcast mode CAN be configured, Device Configuration | Meshtastic
ie you COULD set ‘LOCAL_ONLY’ on the base nodes, so they DONT rebroadcast messages in B’s mesh.
All nodes with this left on the default ALL, should forward all backets, even if belong to ‘other’ messes.
Periodic position messages and telemetry messages are only interpreted within one’s own group？
Yes. In your example, Group B (for example) does not have either of the psk’s for A’s channels. So nodes in group A won’t be ‘seen’ by Group B (because can’t decode the packets)
(note however nodes in B, may still list nodes from A as ‘unknown’. Will just appears a base node in nodelist, without any name/position/telemetry info. Knows of the other nodes, just no details)
The two should forward each others messages (subject to the limitations with frequency slot above) - even can’t directly communicate.
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Will this increase channel utilization?
Umm, yes I think. As all the devices are communicating on the same frequency.
ie the base nodes, will be retransmitting A and B’s packets on the same frequency. The ultilization is measured by each node, by the packets it sends out.
The base nodes would be doing most transmitting, so most likely to run into duty cycle issues.
(that been said, am a bit hazy on exactly how the utilization is calculated. much more confident on how the channels work!)
Should Max Hopps be adjusted?
Shouldn’t need to as such.
In theory messages should still be taking similar amount of hops.
Eg messages still going A1 → base1 → A2, or B1 → base1 → B2
Although I suppose, because tehre are ‘more’ mobile nodes (18, vs 10) in the expanded network, messages MIGHT end up taking a more ‘convoluted’ route as there are more paths.
Eg while messages might go A1-> base1 ->A2 ->A3 for example,
Now might get A1->B3->A2->B2->A3 which is a longer route
In that regard, suggest not changing it, unless the expanded mesh has issues with deliverablity.
How to configure MQTT gateway? Do the two groups have independent gateways?