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Old Mar 24, 2012, 10:55 AM
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Dennis Frie's Avatar
Denmark, Capital Region of Denmark, Naerum
Joined Feb 2011
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Quote:
Originally Posted by rimshotcopter View Post
Dennis, may I ask you to post a picture of your FPV Transmitter Antenna and what Frequency used to transmit on?

Thank you.
I use a standard 500mw 2.4 ghz lawmate video-tx and the normal rubber-duck antenna. Works pretty well with good antennas on ground.

This is the plane I have been flying and experimenting with the most, but I have a new one ready very soon (with clean installation)
This picture is a bit old, but it looks pretty much the same (except UHF receiver)
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Old Mar 24, 2012, 11:02 AM
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rimshotcopter's Avatar
United States, CA, Los Angeles
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Thank you Dennis, do you have a problem with reception flying over head in a small radius? I know you can get pretty high.
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Old Mar 24, 2012, 11:09 AM
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Dennis Frie's Avatar
Denmark, Capital Region of Denmark, Naerum
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Originally Posted by rimshotcopter View Post
Thank you Dennis, do you have a problem with reception flying over head in a small radius? I know you can get pretty high.
It all depends on your altitude and antenna
With the antenna placed as seen on the picture and 8 dbi CP on the ground 1.5 km just above your head should be doable - but don't expect crystal clear video.

If you plan to fly high above yourself, you are better off pointing the video-tx antenna horisontal. I have done it a few times, and it does give you a lot better reception when flying just above yourself.
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Old Mar 24, 2012, 11:14 AM
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Bingo and Thank you Dennis. This is the information I need. Let me explain, I am not looking for distant but altitude. I would like to be able to take off from a small space, climb to an attitude X, hover, then return to home.
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Old Mar 24, 2012, 11:16 AM
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Dennis Frie's Avatar
Denmark, Capital Region of Denmark, Naerum
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Quote:
Originally Posted by rimshotcopter View Post
Bingo and Thank you Dennis. This is the information I need. Let me explain, I am not looking for distant but altitude. I would like to be able to take off from a small space, climb to an attitude X, hover, then return to home.
In that case I would just let the tx-antenna point horisontal. What kinda altitudes are we talking about?
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Old Mar 24, 2012, 11:20 AM
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Originally Posted by Dennis Frie View Post
In that case I would just let the tx-antenna point horisontal. What kinda altitudes are we talking about?
400 Feet Max because of the present guide lines, but if I should get the opportunity to head out to a remote unpopulated area, maybe more if possible.

FYI, I fly in city parks and never would attempt more than 100 feet but knowing I could do more is a comfort.
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Old Mar 24, 2012, 11:51 AM
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Dennis Frie's Avatar
Denmark, Capital Region of Denmark, Naerum
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Originally Posted by rimshotcopter View Post
400 Feet Max because of the present guide lines, but if I should get the opportunity to head out to a remote unpopulated area, maybe more if possible.

FYI, I fly in city parks and never would attempt more than 100 feet but knowing I could do more is a comfort.
400 feet shouldn't be any problem at all
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Old Mar 24, 2012, 11:35 PM
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Россия, Москва, город Москва
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Hello Dennis
what current sensor is used by you?
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Old Mar 25, 2012, 05:20 PM
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Originally Posted by alex57russ View Post
Hello Dennis
what current sensor is used by you?
Hello,

I have a similar question. I want to use the ACS709 as current sensor. Unfortunately it gives an output in the 0 - 5V range for -75 - 75A, namely 28mV/A. How can I cancel the offset? As far as I understood the code there is no offset taken into account for the current input. Probably I need to change the line
Code:
          // Current calibration.           if (loopcount==3) {
            current_num=ADCreal*current_cal;
to something like:
Code:
          // Current calibration.           if (loopcount==3) {
            current_num=(ADCreal-512)*current_cal;
Would this be correct?

Thank you very much,
Nils

EDIT: Found the offset_ variable and set it to 512, hope this is correct.
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Old Mar 26, 2012, 05:10 AM
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Dennis Frie's Avatar
Denmark, Capital Region of Denmark, Naerum
Joined Feb 2011
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Quote:
Originally Posted by alex57russ View Post
Hello Dennis
what current sensor is used by you?
I use the current sensors from flytron. They are not that expensive, lightweight and have worked flawless so far. But you should be able to use more or less all current sensors.

Quote:
Originally Posted by nils1982ks View Post
Hello,

I have a similar question. I want to use the ACS709 as current sensor. Unfortunately it gives an output in the 0 - 5V range for -75 - 75A, namely 28mV/A. How can I cancel the offset? As far as I understood the code there is no offset taken into account for the current input. Probably I need to change the line
Code:
          // Current calibration.           if (loopcount==3) {
            current_num=ADCreal*current_cal;
to something like:
Code:
          // Current calibration.           if (loopcount==3) {
            current_num=(ADCreal-512)*current_cal;
Would this be correct?

Thank you very much,
Nils

EDIT: Found the offset_ variable and set it to 512, hope this is correct.
I suppose you have solved it yourself
But yes, just add 512 as offset and calibrate it as a 150 A current-sensor.
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Old Mar 26, 2012, 10:58 AM
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Dennis what are your thoughts on using openlrs's telemetry protocol for antenna tracking?
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Old Mar 26, 2012, 11:36 AM
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Dennis Frie's Avatar
Denmark, Capital Region of Denmark, Naerum
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Originally Posted by msev View Post
Dennis what are your thoughts on using openlrs's telemetry protocol for antenna tracking?
It's probably easy to implement, but you will be limited to 100mw RF-power. While it should be enough for quite a few kilometers, it doesn't make much sense, unless you use a directional antenna for the RC-system as well. That could be an option, but it's probably not a solution I would use myself for long-range.
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Old Mar 26, 2012, 11:48 AM
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Indeed...thanks for the explanation. ...
It might be of use only if you were going in a rather straight line..So the tracker would "set" in its "last good position" and then using the osd one would try to stay as best as possible in the 0 degree range ..
But kinda defeats the purpose of an antenna tracker which is to constantly try and find the ideal ground antenna position..

Have you had any tests on your tracking solution ?
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Old Mar 27, 2012, 09:46 AM
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Here is a picture of my newest DIY build less the IC chips. It has a voltage selector to supply 5 or 12 volts to the camera port and the power to the TX can be enable/disabled for ground testing. I know building these things are not for everyone and there are many cheap alternatives available but I just Love Building things.

Now I can force on the Software now that I have all of the ports available. Dennis, I would like to incorporate the Telemetry protocol on this board while I am working on it. By chance, did you do any more work the development?

Thank you.

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Old Mar 27, 2012, 09:59 AM
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Dennis Frie's Avatar
Denmark, Capital Region of Denmark, Naerum
Joined Feb 2011
761 Posts
Looks very nice.
What is the coil-formed copper in top-right? It looks a bit like an aircoil as part of the input-filter.

I finished a telemetry test that was able to send a string of data - and another sketch able to receive the data. But while testing I realized how bad the audio is on Lawmate and never really got any further. I have the sketch if you want to use it for anything.
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