Sourcing development or product, Servo control Pan/Tilt 2.4 GHz antenna 2

[CcanDo]

The device BOM will include two of our proprietary 8 Embit rolling custom code 802.15.4 transceivers. One transceiver will be attached to the mobile target, the other will be located at the antenna. Range between the two will be from antenna base to 200 feet LOS. The antenna will then pan/tilt within a reasonable aperture to track the target. RF only will be the primary control, though 802.15.4a, a roof mounted daughter antenna, embedded GPS, IR or another stacked scheme will be considered.

 

[VEBill]

I assume that you're looking for suggestions.

For 200 foot range, why not switch to a slightly different data comms standard that could easily span that sort of distance using simpler (non-moving) antennas?

Another thing to consider is that you might be able to stand-off far enough away from the target's play area to have the entire range of target movement within the main beam of a fixed high gain antenna, while not so far that it's too far.

Another option is two antennas covering each side of the play area. And a simple switch of two-port transceiver.

 

[VEBill]

Typo: "a simple switch OR two-port transceiver."

 

[IRstuff]

Too many missing parameters:
> Angular coverage required?
> Speed of mobile platform?
> Size of antennas?
> Link budget margin?
> Angular accuracy/resolution of tracker?

Generally, a minimum of a 2-quadrant receiver is needed to be able to accurately track a target constrained in 1-dimensional space.

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[CcanDo]

Both the antenna carrier and target may travel in opposite directions, each up to a maximum speed of 25'/s. (16 MPH), and/or in synchronization with each other. The antenna will rotate only 180* from the X axis. (90* left-90* right of a right angle tangent from X) The scheme may be complimented by a MEMS, but complicated because of calibration required due to environment, operator training and maintenance.

The robust form factor will be under 20 lbs., and considering inertia, and aerodynamics, small. Accuracy is considered relative to latency. Centerline of the antenna (s) will be within a 10* aperture from CL (target(20* total window)

The transceiver latency is 10ms, each Embit. Each of the 8 Embits is dedicated to its own 10A. SS relay. However, an additional transceiver is not an issue, but thought unnecessary.

I'm sourcing for a shelf item or a "turn key design contract" that includes proof of concept using our transceivers. I offer, propagation when the two radios are within a couple feet of each other to be the greatest challenge. Gain can be adjusted down, but not so much to adversely effect the time to time 200' maximum separation between radios.

 

[VEBill]

Any normal radio system should have a dynamic range that far exceeds (200:1)^2 - the inverse square law applied to a range ratio of 200 feet to 1 foot (even zero). Several orders of magnitude better. So the only issue might be that you've selected, or been forced to use, a radio modem set that isn't very good (from the radio comms point of view).

Is the antenna tracking for purposes of closing the link with a directional antenna (as I have assumed, based on the short range mentioned when I looked up 802.15.4), or for location tracking as IRstuff has assumed? You had mentioned embedded GPS and IR, so I had assumed the only goal here was to aim the antenna. If it's for location tracking, in the real world one would just walk over and pick up the mobile gadget.

How does aerodynamics enter into it?

If the range is only 200', I still think there's a dozen ways to close the loop without invoking a complicated tracking systems.

One might arrange two high gain antennas, one pointing in each direction (covering the 180 degrees). The middle bit might be closer (depending on your geometry), so it would still work with the antennas not pointed in that direction.

If this is an RFQ, it's a fairly limited audience. And we all have day-jobs. You might get lucky.

 

[Comcokid]

Sounds like a problem solved by simple antenna diversity techniques, either passive or active. Passive being two antennas and a power splitter/combiner. Active when you use a switch between two antennas and use the 802.15.4 MAC level signal strength information.

 

[MikeHalloran]

Or just run a 500' cable with an aerostat suspending the middle.


Mike Halloran
Pembroke Pines, FL, USA

 

[IRstuff]

are the motions synchronized, or indeterminant?

Gimbal motion is really two-part; the physical and commanding of the gimbal itself, and what determines the command and control. As for the latter. something like a Kinect or equivalent, can extract the motion of the opposing antenna and use that information to generate the commands for the gimbal.


Some other questions:
> minimum distance: "from antenna base" is likely to be WAY too close --> 50 rad/s is too fast for almost all commercial gimbals. something like:

https://www.youtube.com/watch?v=72Ig_Dk9pbA

only does 12 rad/s
> weight of payloads?
> how much money you got? There are military-related gimbals:

http://www.gd-imaging.com/Documents...ucts/GDGIT-HS-Two-Axis-Gimbal-DS3-0312-2a.pdf

TTFN
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