BuckeyeCam Wireless Transmission

[yoderjac]

I know Bill uses BEC and John has been asking questions on other threads. I thought I'd start a thread showing an example of the evolution of a network. Everything here is using the older BEC Orion cameras. They have higher powered radios than the newer X7D and X80 series so distances may be different, but the principles all apply to those newer cameras as well.

Here is an actual example of how a network is established and evolves over time. I started by doing a signal survey. I started with the stock antennas on the PC base and one camera. I drove around on the ATV and tested the signal levels at different locations with the camera. From this I determined I needed higher power antennas and enough height to minimize attenuation from our pines.

I decided to build a pavilion to park my trailer under and I used that structure to support an antenna mast with a 13db yagi with a rotor on the mast. This allows me to adjust how where the yagi is pointing if I decided to move cameras.

The next picture is a map that shows my camera placement, and topography.

A yagi antenna move energy from one side in the horizontal direction to the other (as well as vertical). The PC base is at the SW corner of our property. The picture shows the highest power of the antenna as the dark green wedge. The light green is slightly lower power, then yellow, orange and finally red shows the lowest usable improved gain. If the antenna was 9 db instead of 13, the areas of high power would be less sharp and wider. By the way, this graphic is a bit over simplified and not actually an antenna pattern, but is instructional from a practical level.

So the first consideration was topography because ground provides total blockage compared to vegetation which will attenuate the signal. The next consideration was vegetation.

This picture shows land use. I've replace the solid wedges representing the antenna pattern with lines only so you can see the land use. The orange-ish yellow represents our hardwood riparian buffers and ridges. The brown area represents more mature pines. The dark green represents young pines and the light green is an age class of pines in between the other two. The pale green is a open pipeline.

Continued...

 

[yoderjac]

With the combination of topography and vegetation, I could not reach all the camera locations with stock antennas at the cameras. The map in the previous picture shows Camera 10 on the pipeline in red. That is because it is a camera that is performing a routing function for other cameras. The picture below was taken to show radish drilled into suppressed clover, but if you look at the rear you will see a tower stand.

It was under construction when the picture was taken but a tall antenna mast stick above the top of the picture. It has an 8 db omnidirectional antenna atop it. Because I planned for it to route pictures from a larger number of cameras, I was concerned about power use. Transmitting pictures consumes a lot of battery power. So, that stand includes a large 45 watt solar panel I got from Harbor Freight that is used to charge a 35 amp hour camera which then in turn is converted to 6 volts which charges the Orion Battery. (Unlike the new X-series, Orion cameras run on 6-volts.)

The other camera that needed a large antenna to reach the base is Camera 1 located far to the east. Again, I used a box blind to support a tall antenna mast. Since this is a terminal camera and no cameras will be routed through it, instead of using an omnidirectional antenna on it I was able to use a 13db yagi.

Continued...

 

[yoderjac]

You might notice that camera 8 is slightly out of the antenna pattern from the base. That was easily solved by simply rotating the base antenna slightly to the east since my camera placement is slightly biased in that direction.

Things are not static because of vegetation growth. Over time pines grew and my signal levels dropped. While it doesn't show on the map, there is a road way along the south and one that goes north from Camera 8, so Camera 8 had a good signal.

This map adds the initial routing I used. The light blue lines show how some cameras transmit directly to the base and others go through the repeater. As I said, as pines grew and signal levels dropped I needed to make some changes.

This map shows the first change. To reduce load on camera 10 the router and improve signal levels. I replaced the antenna on camera 8 with an 8 db omnidirectional antenna and routed camera 4 down the road through Camera 8. That worked well. Even though it looks like that path goes through more pines, because of the road, there is actually less attenuation on that path. I used a 9db antenna on Camera 4 shown here:

Continued...

 

[yoderjac]

Eventually, the pines got thick enough to make connection with Camera 3 very spotty. The high packet loss caused short battery life and from time to time I'd lose connectivity to that camera all together. While that camera is close to camera 4, it is located down the hill. That kept me from using camera 8 as a repeater. I probably could have built another antenna tower to get above the pines and put a high gain antenna on it and continue to use camera 10 as the repeater, but I knew eventually the pines will get tall enough that it would need to be quite a tall tower.

I decided it was less expensive to make Camera 4 a repeater and use 2 hops. The only problem with that was that the 9 db yagi on camera 4 was pointed directly away from Camera 3 so I had no signal when I tried. The solution was to change from a 9 db yagi on camera 4 to an 8 db omnidirectional antenna.

A drop of only one db is very small so I was sure I could still get a good signal between camera 4 and camera 8, but this allows cameras on all sides of camera 4 to access it.

I got a very good signal between cameras 3 and 4. Time will tell whether the solar panel on cameras 4 and 8 will be sufficient to handle the traffic and still allow many months between battery changes.

The ideas here was simply to show how one needs to consider both topography and vegetation along with camera placement when laying out a 900 MHz wireless network. RF transmission can be very challenging to setup, but once in place, it brings many pictures running 24/7/365 with many months between servicing cameras with no recurring monthly cost. It also allows for full resolution pictures which can be important when analyzing them.

Hope this helps folks considering the X-series.


Thanks,

Jack

 

[yoderjac]

Updated Picture Links