Plot data
Plot average as a line
Plot ~1/10th second running average
All on same graph
Looking for smallest length of time that gets as close to the avg as possible
Ask Lisa about transmitter
Range testing
Turn the mountain sideways
Look for somewhere that will give consistent blockage
I conducted some basic RSSI testing at Maalwyk park. Managed to get two useful positions before the weather didn’t cooperate anymore.
This was my initial testing plan:
I started with the far right corner, and it promptly started to rain so I only managed to get the far right point. Both points are ~35 degrees off the centerline and ~800 feet away from the receiver.
I conducted 6 tests in total. One with no transmitter, one with the transmitter one yard in front of the receiver, both run for 45 seconds, and two for each side of the field with the antennas at 60 and 100 degrees, run for 2 minutes. The results are below:
The data, taken with a grain of salt as I don’t have enough points to make a real conclusion, shows that in general there is a detectable difference between having a transmitter on the different angles from the receiver, and the difference is larger with a larger angle between the antennas. This isn’t really a useful conclusion, but the test itself proves that I can collect useful data and it can be done fairly quickly.
Everything but the FrSky DJT module has arrived.
I can now test the video relay in its entirety as well as start developing on the XBee radios.
Radio tests:
Check strength is going down as square of distance (inverse square law)
Antenna angles:
Angle 90-105 for localization
Look up radiation pattern
Optimization between distance and angle resolution
Remove transmitter from quad
Check mouser order time
I have submitted a parts list to Lisa as of Tuesday night. Most of the parts have short shipping time so hopefully by next week I can start to assemble and run actual tests of the first level of relay using just off-the-shelf components.
I now have a complete setup to begin running tests of RSSI differences between two helical antennas. I attempted to run a proof-of-concept indoors (yes I know you told me specifically not to do that, but it was raining outside and I procrastinated. So I guess I have no real excuse…). The values were noisy, but it was easy to see that the RSSI output reacted to which antenna the transmitter was near. I started off by using “pit mode,” a feature that greatly minimizes the tx power of the transmitter. There is no official power level other than “2-3 meters” so regardless it is very small.
Moving up to 25mW, I could still see a reaction when moving parallel to the two antennas which were angled about 30° from each other. I tested also with 200mW. I haven’t included any data because it was difficult to interpret live and I saw no way that I could get usable info from it because I was inside, and it was erratic enough to not be worth the effort.
Proper testing will be done this week outside on a field. I will carry my phone with me when moving the transmitter around to record a GPS track so I can easily correlate (or not correlate) RSSI data with position.
Didn’t get done.
Tinfoil? The internet says it works. They are always right.
A simple 3D printed enclosure lined with tinfoil on the inside would make for a cheap and easy shielding cover.
Aero has quite a few XBee radios that appear to be close to the same as the ones I am purchasing. If the order takes longer than expected I can use these as stand-ins but I doubt they will take longer than it will take for me to finish testing other components.