It was time (I was suggested) to tidy up my kit so I decided the best policy was just to use it all rather than have it “awaiting a project”. So I am experementing with three antennae, each with their own Station G2 node, in the same attic.
(a) (top of tall stack of boxes) Sirio - GP 868 C N-f | K-PO (Static attic node)
(b) (while light sabre) RAK Wireless - 868 MHz Rundstrahlantenne, 8dBi, Outdoor
(c) (white panel on left on lower stack of boxes) antennas and accessories | for wireless networks
The geometric arrangement and antenna choice is intended to avoid them interfering with each other. The directional panel (c) points away from the other two. The ground plane, height and proximity of (a) should help stop it reaching (c) or the main much flatter/narrower beam of (c). (b) hitting the metal back shield of (c) should not matter. So thinketh the novice…
Sending and receiving
To test sending and receiving I use a fourth node “house” node around the house (Heltec T114 H2C H2T - Complete Device: Heltec T114 with GPS running Meshtastic® – muzi ᴡᴏʀᴋꜱ or a RAK node Boxed solar node - glorified Bluetooth link to main nodes ... solar fail) to send messages from around the house. Most traceroutes from the house node involve the attic nodes, though sometimes the house nodes manage directly to yield traceroutes to external nodes in Munich… When close enough upstairs to be in bluetooth range, the three antenna nodes (a)-(c) can be used to send an receive too.
So far my traceroutes of house nodes and traceroutes back to the three attic nodes most surprisingly indeed essentially only contain one of the three attic nodes (a)-(c). I was not expecting this to work at all. I was expecting this to lead to to hops being wasted before signals even leave the house and to get extra hops for inward trsaceroutes and so on, or just chaos.
Advice for a novice welcome e.g. app settings. Is there any reason actually to do this, and which single antenna would you stick with for my location and environment based, based on which traceroute criteria?
So far when listing the nodes appearing in each node with each antenna, the three nodes (antennae) each receive the nodeinfo at the same time because the order is the same in “last heard” sorting and they appear at the same time after a node database reset. The picture below shows this:
There is no major difference in RSSI between any of the nodes. i.e. in the nodes list very similar RSSI is shown for all seen nodes. All nodes are detected by all three antennae.The panel antenna is not so directional that it fails to see nodes behind it…
From observing the list of nodes in the “Last Heard” mode one can see that nodeinfo appears at all three antennae at the same time - without any antenna missing the data. This shows that none of the antennae is “bad”.
Assess RSSI reliability
The computation of RSSI and SN is subject to fluctuations. With three separate systems one can see if the good values are a fluke or genuine:
Comparing traceroutes
Traceroutes out can be compared:
Fast traceroutes at all nodes simultaneously
Some traceroutes (rare) are very quick and simple and arrive simultaneously at all nodes:
which suggests to me that the node (whose location is not known) is close or high up.
But a good traceroute is no guarantee of a direct message with tick.
Study failure to get any traceroutes
If no traceroute is forthcoming then it can happen that RSSI data is not available for all antennae. But the information from the one with that info that it has an RSSI value of -130 or less might be useful to judge that that node is simply out of useful contact range. Example:
Which antenna gets the RSSI report for most nodes?
For the nodes that are high up, the RSSI is shown for those nodes by 3 antennae.
Examples of where only one particular antenna received and passed on to a neighbouring one
I was very surprised how few times I got two of the antennas (a), (b) and (c) in the same traceroute when testing away from home to see if I could reach home.
This is the only trace route so far with this
and is a traceroute from the top right to bottom left home location on the map, from a car node (Dong) (Car node with external antenna) via node MTS3 with antenna (b) to Ding with antenna (a)
from a location that was about 8 km away. This result is suggestive to me that antenna (b) only was able to receive that signal from there… who knows. The sending location lies in a region that the home node cannot reach easily, as shown here
from https://www.heywhatsthat.com/
Is my antenna directional really?
The antenna (c) (Bing) is officially very directional… but in fact can get a direct traceroutes in the opposite direction to which it is pointing.
Are fancy nodes under the roof better than a simple one on the window sill?
This node on the window sill
picks up additional node info that the ones (a) (b) and (c) fail to see at all. So those antennae (a) (b) (c) are in receive too attenuated by the roof and obviously need to be outside.
Testing a silly node design
I was testing a silly node as shown below (using the RAK system and Waveshare D solar power manager and FrSky Zipp 9 Moxon Antenna with this solar panel Polysilicon Solar Panel (18V 10W), 10Wp Power Photovoltaic Panel, High Conversion Efficiency)
and the three nodes in the attic were quite useful for this. This is because the three nodes under the attic yielded simultaneous node info arrival time and similar RSSI and SN values. That means that the node I was testing, which is in roughly the same place, can be benchmarked roughly. Benchmarked as to whether its location is any good and also what the optimal location yields for RSSI values. Then one can try to improve the node under test, or abandon the design as flawed.
The above components plus a bluetooth antenna https://amzn.eu/d/bqwkjOl went into this node design with the antenna outside …
will see how that compares with the three attic nodes. The node in the image above does not detect immediately the nodeinfo of any of the attic nodes which are only a meter above and two meters back. The updraded Bluetooth antenna dramatically increases the range and I can access the node by Bluetooth from 2 floors down.
