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  1. #1
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    3DR radios, telemetry discussion and help

    So Santa brought me a 3DR radio for Christmas. I know this can hook up to an Eggtimer, Quark, and RRC3. I am looking into that and will work the details with Chris or Jim when I get to that.

    For now I just want to play with the thing and get it set up. I had a USB cable lying around that I should be able to use to supply the 5 volts to the "Air" unit. And of course power to the Ground is via USB.


    Here are the specs I found for a 3DR radio.
    Power
    Supply voltage: 3.7-6 VDC (from USB or DF13)
    Transmit current: 100 mA at 30 dBm
    Receive current: 25 mA
    Serial interface: 3.3 V UART

    I found some simple boards for about a dollar each. One has output of 5 volts at 500 Ma, the other is 800 mA. Yes I know, why not opt for the larger one and be done with it? I like the layout and formfactor of the 500 Ma better. Adjustable ones can be found all the way up to 3 amps, but I don't think that would be necessary. Either of these boards should run it just fine from a 2S or 9v battery?

    I need to do some heavy updates on my computer in order to get Mission Planner or Q Ground Control to work. So I will have to come back to all that.

    Mikey D

    Nothing is foolproof to a sufficiently talented fool.
    TRA #16513
    Level 1: Danger Close ---AT H123W to 1240'--- 29 OCT 2016
    Level 2: Binder Design Tyrannosaur ---AT J315R to 2148'--- 30 SEP 2017

  2. #2
    Join Date
    26th October 2016
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    I'm using these radios for various UAV projects and they seem pretty stable and easy to setup. If you want to power one of these with a 2S or 9V battery, I'd look at using a BEC. I've had luck with this one, for other applications, in the past.

    US Ship Hobbywing 5V/6V 3A Switch-mode UBEC, Max 5A Lowest RF https://www.amazon.com/dp/B008ZNWOYY..._DrTrAb4YWWWBN

    NAR level 2: Mad Cow Super DX3

  3. #3
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    Thanks.
    I didn't know what the heck that thing was, I had to research it. From what I read it looks like a switching power supply with a fancy R/C term for it, but I could be wrong. There is probably more to it that I'm not seeing.

    Something like this is what I had in mind:
    https://www.amazon.com/gp/aw/d/B01N1...volt+regulator
    Nothing is foolproof to a sufficiently talented fool.
    TRA #16513
    Level 1: Danger Close ---AT H123W to 1240'--- 29 OCT 2016
    Level 2: Binder Design Tyrannosaur ---AT J315R to 2148'--- 30 SEP 2017

  4. #4
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    Switching BECs for R/C typically supply enough current to drive servos under heavy load. Your radio will probably be fine with the linear regulators you found on Amazon, since they don't need a lot of current. A switching BEC will be more efficient, though.

  5. #5
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    26th October 2016
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    Quote Originally Posted by mikec View Post
    Switching BECs for R/C typically supply enough current to drive servos under heavy load. Your radio will probably be fine with the linear regulators you found on Amazon, since they don't need a lot of current. A switching BEC will be more efficient, though.
    What he said....

    That said, I like those little boards you found and they have made it to my Amazon cart
    NAR level 2: Mad Cow Super DX3

  6. #6
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    Quote Originally Posted by mikec View Post
    Switching BECs for R/C typically supply enough current to drive servos under heavy load. Your radio will probably be fine with the linear regulators you found on Amazon, since they don't need a lot of current. A switching BEC will be more efficient, though.
    Good deal.

    Quote Originally Posted by tHoagland View Post
    What he said....

    That said, I like those little boards you found and they have made it to my Amazon cart
    LOL Amazing how things do that. Glad I could enable, I mean help. These are the ones I am leaning toward. I like the form factor better:
    https://www.getfpv.com/diatone-5v-50...yABEgKw4fD_BwE
    I can probably dig around on that site and come up with enough stuff to qualify for free shipping.

    Amazon has them for 10 bucks a piece.
    Nothing is foolproof to a sufficiently talented fool.
    TRA #16513
    Level 1: Danger Close ---AT H123W to 1240'--- 29 OCT 2016
    Level 2: Binder Design Tyrannosaur ---AT J315R to 2148'--- 30 SEP 2017

  7. #7
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    10th July 2007
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    I didn't know what the heck that thing was, I had to research it. From what I read it looks like a switching power supply with a fancy R/C term for it, but I could be wrong.
    Exactly.

    SBEC units are more efficient than linear regs, as has been said. That means you get more life out of the same size battery. You can even get tiny 1A and 2A versions that would be much lighter and more suited to the 3DR radio setup. The PCB for those are about 1/2" x 1/2".
    TRA 13430, Level 3

    "Everybody's simulation model is guilty until proven innocent" (Thomas H. Lawrence 1994)

  8. #8
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    Okay, this may seem a silly question, but referring to the BEC referred to in post #2. Is that green ring some sort of noise filter? Like I say, never heard of a BEC before today.

    And I keep reading these "loud" and have "noise". I understand (mostly) noise and such, I'm guessing since these are made for R/C then the noise problem has been dealt with. Wouldn't want anything jacking with my altimeters. Do the simple linear regs produce less noise?
    Nothing is foolproof to a sufficiently talented fool.
    TRA #16513
    Level 1: Danger Close ---AT H123W to 1240'--- 29 OCT 2016
    Level 2: Binder Design Tyrannosaur ---AT J315R to 2148'--- 30 SEP 2017

  9. #9
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    BEC (battery eliminator circuit) is usually linear. SBEC is switch-mode and chops up the high voltage to make it lower (typically). If an SBEC is not done properly it can emit more EMI (electromagnetic interference) but if designed properly the can quite happily coexist with sensitive electionics. I have a design that has a 5A 24V switchmode converter sharing the PCB with a microvolt sensitive analog front-end. Most of the SBECs you will find are designed for the RC crowd. If a company had a product that produced interference with the receivers they would have customers leaving them in droves. I have no hesitation in fitting a SBEC to a rocket if needed. The answer is to GROUND TEST THE SYSTEM.

    The ferrite toroid on the wires keeps any electrical noise from the SBEC getting along the wires (antennas!) and radiating out into other electronics. Sometimes not needed, sometimes needed. Think of the toriod tying the two wires together so any signals going out on once preferably want to come back on the other.
    TRA 13430, Level 3

    "Everybody's simulation model is guilty until proven innocent" (Thomas H. Lawrence 1994)

  10. #10
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    Quote Originally Posted by MikeyDSlagle View Post
    Okay, this may seem a silly question, but referring to the BEC referred to in post #2. Is that green ring some sort of noise filter? Like I say, never heard of a BEC before today.
    Yes, it's commonly referred to as a choke. Does the same thing as those 'bulges' you often see at one or both ends of computer cords (data cords and/or power cords), it suppresses high-frequency noise that may be generated by something, which would otherwise continue down the wires, using them as an antenna to radiate noise outwards and/or couple it directly into the next thing down the line. They're frequency-dependent resistors (known as inductors), at higher frequencies they appear more resistive, so they block higher frequencies while having less of an impact on lower frequencies. The number of 'turns' (wire loops through the toroid) affects the inductance, which is why you'll sometimes see those cable bulges have the cable loop through them a second time (saves them from having to make the bulge twice as long, roughly speaking).

    Quote Originally Posted by MikeyDSlagle
    And I keep reading these "loud" and have "noise". I understand (mostly) noise and such, I'm guessing since these are made for R/C then the noise problem has been dealt with. Wouldn't want anything jacking with my altimeters. Do the simple linear regs produce less noise?
    In the world of electronics, much as everything else, there are trade-offs. The two main types of voltage converters are linear regulators and switching regulators. Linear regulators produce less noise, but are effectively resistors. Current-in is current-out, all they do is reduce the voltage. So if you're turning a 2S battery into 5V you're converting ~7-8.4V into 5V at the current being drawn by the load, and all of that extra power (P = V I) is being burned in the linear itself. So the linear can get hot depending on how much current is drawn and the delta in the input & output voltages, this is why linears typically have lower maximum currents, because the inefficiency produces more heat and there's only so much heat they can handle without adding heatsinks, etc. Switchers (ignoring some inherent loss that depends on the design and parts used) are power-in-power-out devices, so they can be much more efficient than linear regulators, but, as the name suggests, they do this via switches (MOSFETs typically), which introduces ripple (noise) in the output voltage because some part of the time they're 'charging' the output from the input and the rest of the time they aren't so the output is dropping (this switched load can introduce noise back into the sourced voltage as well). The choke doesn't eliminate all of this noise (they're only effective at high frequencies, lower-frequency noise is reduced using capacitors or by increasing the frequency that the switching occurs [which reduces the efficiency due to dynamic losses]), but it's a quick way to tackle the higher frequencies. Another common trade-off is that switchers often require a larger delta between the input and output voltage to work properly, while linears can often deal with a smaller delta (they're commonly referred to as LDOs, Low Drop-Out regulators, the drop-out voltage being the minimum delta between the input and output).

    I've used the same UBEC pictured in post #2, to power a Raspberry Pi Zero to be flown as a camera / data recorder (haven't flown it yet). Works well to power the Pi, though I haven't tested it in a noise-sensitive environment yet. In my case I cut the shrink wrap back a bit and unsoldered the jumper block, just sorting those two pins together on the board, to reduce the size a bit and to ensure the jumper didn't come out, as the output will malfunction (and likely destroy anything down-stream of it) should that jumper ever come off during flight. The Pi expects 5V so I'd never need the 6V option, anyway. I'd suggest at least gluing the jumper in place, or removing the jumper and putting a good solder blob between the pins instead, or removing it entirely and shorting on the PCB as I did, depending on your skill and willingness to hack up electronics.
    Will Ferry (Launches & Videos) NAR #96512 (L2) / TRA #15328 (L2) / LUNAR #2759
    L1: 9/2013 @ XPRS, GLR T-Bolt "Thunderbolt" (R.I.P.), H148R
    L2: 4/2016 @ TCC Helm, Binder Design Excel w/DD "dd2.xls", J315R
    Impulse flown (flights): 2013: 767Ns (2), 2014: 4298Ns (8), 2015: 7486Ns (16), 2016: 11693Ns (18), 2017: 11138Ns (16)

  11. #11
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    Have you looked at this thread yet? http://www.rocketryforum.com/showthr...5-GPS-Solution

    I ran out of time and used a 1amp 5V voltage regulator https://www.pololu.com/category/84/r...power-supplies to feed the radio and the GPS chipset. You get what you pay for when investing in a GPS. I used a Ublox chipset -8N and the Ucenter utility. When I tried to shrink tube the GPS on the radio, the GPS suffered an attenuation of the satellite signal. It was worse on the 433Mhz radios than the 900Mhz jobs. Read the entire thread above and it goes into programming and recovery of the settings on the "airborne" tracker if one screws up the settings. If I kept the GPS a few inches away from the radio on a cable, it was fine.

    I didn't get around to testing the ground unit as a "dedicated" receiver and the airborne unit as a "dedicated" tracker. The fact that a 2-way link is maintained I suspect there may be some decreased range as opposed to some of the dedicated rocket
    trackers out there. You might want to read the programming page on the 3DR and see if the settings might be optimized to improve the range. DO NOT change your 9600bps communication speed or you'll have to reset the rig with a USB serial card
    like shown in the thread. Kurt

  12. #12
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    Good info guys. I think I am going to grab a few of the linears and try them first. I'll see how much run time I can get out of a standard 9 volt and one of my 2S LiPos. And see how hot the linear gets. Then may step up to the BEC later if I need to.

    I did look at the thread you mentioned. Well I actually followed it for quite a while. Thought I might would try it. Then everything started getting way out of my know-how and progress slowed to a crawl at one time, I simply stopped following. I'll peek back at it again one day.

    I don't really need this for tracking. I have an Eggfinder for that. I just wanted a 3DR to play around with and get real time speed and altitude. It's not really necessary as I can get all that info after touch down, but it's pretty cool tech (to me) and I want to play around with it.

    As far as the programming page on the 3DR, you talking about in Mission Planner or something similar?
    Nothing is foolproof to a sufficiently talented fool.
    TRA #16513
    Level 1: Danger Close ---AT H123W to 1240'--- 29 OCT 2016
    Level 2: Binder Design Tyrannosaur ---AT J315R to 2148'--- 30 SEP 2017

  13. #13
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    No, not MP. There is programmer for the 3DR alone. I think the link is in that thread. You will certainly have to be familiar with a lot of the discussion that went on in that thread in order to be able to use these radios effectively. That was the learning curve I had to climb in order to get some rudimentary use out of them. It's not easy. Also the cost of these devices have gone up since the start of that thread. Kurt

  14. #14
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    Could you throw me a bone? All I am seeing is reference to MP and U-Center. But I'll keep looking. I am gonna read back through the thread when I get time. It's quite lengthy now.

    *Edit: Found it by sheer chance. Someone mentioned a 3dr tool and I finally found it on a page from a google search.:

    http://www.ardupilot.co.uk/ardupilot-software.html
    http://vps.oborne.me/3drradioconfig.zip


    I think this is where I dropped off last time: LOL

    Quote Originally Posted by ksaves2 View Post
    Thank you. Folks this is really suckee. If you don't have any hacking experience stay away until this thread gets easier. I was able to get the left side of the screen to come up with ecarsons instructions.
    Thanks. Couldn't get the right side to come up. I gave up R/C years ago with the gold Futaba transmitters as I originally had a flying field in my back yard. Hacking this drone stuff is hard for the neophyte.
    going to shutdown and start over. I don't have a GPS attached yet and just trying to get the programming software to connect. Again, I'm a total neophyte here myself. Kurt Savegnago

    Quote Originally Posted by ksaves2 View Post
    For anyone who thinks they can save money and time with this modality, stay away unless they are totally familiar with the drone hardware.
    I was able to get the radio to connect once to a Winblows 7 home premium system. Close but no cigar. I will continue to keep working with it
    because 500mW on the 70cm band with an NMEA tracker should be very useful. The Ham APRS stuff comes across once every 5 seconds and will
    get one's rocket back but a little more Rf output will help for live tracking. Again, unless you are familar with this stuff, don't waste the $20.00 or more
    until morons like me can get it up. I hate when others say it's easy but in reality if one isn't in the know, it can be a challenge. Kurt
    Last edited by MikeyDSlagle; 31st December 2017 at 07:29 AM.
    Nothing is foolproof to a sufficiently talented fool.
    TRA #16513
    Level 1: Danger Close ---AT H123W to 1240'--- 29 OCT 2016
    Level 2: Binder Design Tyrannosaur ---AT J315R to 2148'--- 30 SEP 2017

  15. #15
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    You got the 3dr programmer up there that I was talking about. Just use the radio programmer not MP. Sorry I didn't remember the link. Go to the Ublox website
    And look for the u - Center utility it's out in the open. Be aware that this works only with the u-blox GPS chipsets and you need to get a Serial USB interface board. Make sure it is 5V. This is only needed if you wish to monitor the performance of the GPS chipset that you're using. It is also used to change the parameters of the u-blox GPS chipset that you are using. You can also take the strings off the receiver and pipe them through U-center and you can see the tracker on the map and do various manipulations with the data. I have a picture of the USB serial board on that other thread. U-center can reprogram a Ublox GPS or it can monitor the strings (and signal strength for that matter.). Please be aware that only the top dollar GPS chips are completely
    programmable. The $7 to $25 chips one can probably only change the Port speed.

    With this discussion of voltage regulators, part of my problem might be due to the unit I chose and I might try to seek out a battery Eliminator circuit and experiment with that. It might be quieter though it might be bulkier to make a slightly larger package. The small cables provided don't lend themselves to the addition of a toroid very easily. Kurt
    Last edited by ksaves2; 31st December 2017 at 04:09 PM.

  16. #16
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    What the hay. I'm going to try one of those BEC and see what it does as far as performance. If I could shrink tube it to the radio and the GPS signal is not interfered with, this might be a reasonable route to go.
    Only problem I see potentially is the Chinese (at least according to the FPV blogs) grossly over estimate
    the power output of these things. Also it might be easy to convert to get the data output like altitude feed over the air but I don't find that enlightening. Once one finds the rocket they can always download that data so I doesn't matter. Kurt


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