Calgary Amateur Radio Association
Enjoy Amateur Radio | Serve Our Community
If you haven't tried it yet a powerful multipath modeling program is "PATHLOSS".
Very steep learning curve but the best out there. My copy is out of subscription and on an old pc, so not useable. But I believe Joel VE6EI may still use it.
Hello everybody -
Repeaters and Propagation and Multipath - oh my..
Looking for any direction finding aficionados who'd like a challenge on 2 meters.
The signal from VE6RYC is reflected from one or more mountains before it reaches the Powderface Trail in Kananaskis. We haven't found a propagation model that is able to account for this and predict the performance that we see in the area.
These reflections manifest as multipath fading - making reception for a 'typical' mobile very sensitive to antenna positioning.
We'd like know the name(s) of the mountain(s) that the signal from VE6RYC is reflecting from to reach the Powderface Trail (actually the location of the reflecting surfaces).
Direction finding seems like the way to figure it out empirically - but the reflections and multipath make it a challenge. Being able to identify the reflecting mountains will help with knowing whether directional antennas could help with the multipath, and which way(s) to point them.
One of the control points at the upcoming rally is in an area where the interference pattern from the multipath is really tight, reception was EXTREMELY sensitive to antenna positioning. The tight pattern means that small changes in conditions will have a significant effect on the mobile's reception.
This is not desirable, especially at a control point where opportunities to reposition can be frustrated by congestion in the area.
The historical approach for dealing with the multipath has been careful positioning of the mobile in the morning, and then when conditions change (usually early in the afternoon), reposition the mobile until it works again.
It is a tried approach, and it works. But it begs the question of whether we can do better, and what would it take to do better?
At the moment, all we have for ideas is to try out some directional antennas and hope the reflections aren't from points that are too close together. Other ideas are welcome.
A visit out to Kananaskis
Some time in the next couple weeks we'll be heading out into the area (tentatively Friday 7th).
There was a previous trip where we assembled some reception information about different repeaters to locations on the road.
There are still a number of points we wish to collect - and this will be an opportunity to finish that off as well as collect some simplex path qualities between points of interest.
We could use a couple more individuals in the area for this.
There are a few roles to remain mostly static, and a few to be mobile.
You'll need a mobile installation - ideally capable of both 2m and 70cm operation, but no experience needed.
We're going to try to have the task fairly well defined, and there will be a bit of an orientation about the task ahead of time (zoom meeting).
You can contact me va6djh_rally @ oneharding.com