Pharos matches a dynamic directional (beam shaping) radio on the air with another on the ground, with the two tracking each other for multi-mile range for video and telemetry. Coming to Kickstarter in 2-3 weeks.
The Pharos is a newly-developed smart antenna. Unlike conventional omni-directional antennas that waste energy in all directions, the Pharos concentrates the available power where you need it most. Working in conjunction with the Pixhawk autopilot (a version with its own autopilot is being also developed), the antenna activates the side facing your UAV, boosting reception and range. A second Pharos can also be used on the aircraft, quadrocopter or UAV, keeping ground control in aim at all times. The Pharos is also circular-polarized, granting immunity to polarization losses and multipathing signals, an optimum choice for challenging environments.
Air:
Ground:
Comments
Here is a thought! With this type of antenna you might be able to get a vector you could use for navigation in case of LOS of GPS or compass? I understand right now it does not work that way but it could be made to do so?
@ Andy Little, Thanks. We think we just touched the surface of the solid state antenna trackers. These circuits can be found on sophisticated equipment so far i.e. airborne radar antennas, so our goal was to bring this technology to the consumer level and especially the drones. The small size and low power consumption of the solid state antenna trackers makes it possible to equip drones with tracking antennas as this was a privilege of only the Ground Station units up until now.
About your consideration of the antenna size Vs your smaller airframe:
You can try to disassemble the antenna enclosure (4 screws) and take the antenna elements apart. Then place each antenna element at the 4 cardinal points of your airframe i.e. nose, tail, left wing, right wing and the antenna controller at the middle of the airframe, connected with your radio. You will need 4 extension coaxial cables to do so. With this hack you can save some space (and weight) and have a more customized solution that will boost your 5.8GHz range.
Some of our drones are modified as described above so the antennas and controller are integral part of the airframe.
@Magnet Systems
It certainly looks interesting. I can see a use for the solid state ground Antenna tracker part, though a traditional higher gain antenna should give better range, but is more bulky and fragile. For the airborne part, at least for the size of aircraft I fly, it is a little bulky, but for larger aircraft I am sure it will be very useful.
I think you have an interesting product!
@ Andy Little The total losses are low (0.8dB) as we have been using a 4-layer PCB with Rogers material for the antenna controller circuitry, ideal for this specific design.
We thought of Phased array but this wouldn’t solve the problem of 360 coverage as you would still need 4 antennas. So we end up to the switching technique which is simpler but when combined with the X-air antenna (perfect axial ratio) does not leave any blind regions a.k.a. the RHCP is retained in the whole BW of the antenna. Combining this with the rapid antenna switching time (5 microsec) you get a 360 coverage with the gain of the X-air (10 dBi). You can call that Hybrid-omni as this is what it actually is.
For example, look at the previous page video on sec 4:52. At that point we issue a “point camera here” command to the right of the drone and the whole drone yaws 90 degrees to the right (we use a 2-axis gimbal so the drone needs to yaw). This is the point when the antenna switching happens. You will see no fluctuations on the video streaming or telemetry quality. This is a result of the rapid switching time.
The antenna dimensions are 7x7x7 cm which is actually a cube with a side equal to the surface of an X-air antenna.
Yes, we considered the mechanical gimbal and we have been using a mechanical tracking antenna unit for quite some time integrated to our Ground Station. Take a look here: http://www.adcormagnetsystems.com/gcs.html But this is not the optimal set up especially for the drone due to weight, complexity and power requirements. The Pharos antenna is a motorized antenna replacement with no moving parts, 65 gr of weight and only 20mA of current draw. At the picture below, you can see the Pharos antenna attached to the tablet GS tablet (White Pharos with blue LED) and on the drone a black Pharos is attached underneath. Actually the one attached to the drone is a modified Pharos that includes a camera producing the spherical vision that you can see on the big screen at the back.
Looks interesting. I have been waiting for a phased array antenna but this doesnt look to be it.
There are some switching losses I presume?
Did you consider a single antenna on a gimbal?
What are the dimensions?
@Spencer Yes, this is how the Pharos antenna works. Everything is based on code running on the Pixhawk that defines the bearing from the drone to the GCS (and vice versa) and RF switching circuitry used inside the Pharos that activates the corresponding antenna within a few microseconds.
Please see the video posted in the previous page. It shows our drone flying at 350 ft, reaching a range of 10.6Km. It was streaming uninterrupted video to the GS and 2-way MAVLink telemetry the whole time. You can see the RSSI at the top right, just below the artificial horizon to get an idea of the quality of the link.
The set up used was a microhard modem connected to the Pixhawk directly through its TTL level serial port and an IP camera directly connected to the modem through the modem’s IP port. Very straight forward set up. The Pharos Antenna was used on both ends of the link (drone and GS) but with a single Pharos you should also get the range you seek for as Hugo mentioned.
It can be done using just one Pharos on either GS or aerial vehicle.
-Hugo
If I understand this correctly one of the 4 antennas that points to the ground station (when the antenna is carried by the drone) activates each time and in this way you get the full 10dB gain of this antenna?
We are using drones for mapping applications and we need to go beyond 5Km with our quadcopters but so far we are not able to reach more than around 2.2 Km for video and telemetry. Is it possible to reach 5Km with the pharos antenna and the set up you describe with the microhard modems?
The goal of the Pharos antenna is to support not only aerial vehicles but any robotic platform that employs a 5.8GHz video streaming wireless data link. The outcome is that instead of getting a gain of (max. 1-1.5dBi) with your current omni 5.8GHz antenna (i.e. cloverleaf) you now get a gain of 10dBi. An additional outcome is that you can also stream telemetry through the same miniaturized modem (if you use the microhard modems) but this is optional.
Can it be used with ArduBoat or ArduRover?
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