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Thread: Skyzone googles / Problem with ImmersionRC 600mW transmitters

  1. #1
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    Skyzone googles / Problem with ImmersionRC 600mW transmitters

    Hi,

    I am experiencing the following problem with my new Skyzone goggles:

    - If I use a 250mW ImmersionRC transmitter, the quality of the video image in the goggles is just perfect, tested on two different aircrafts with different FPV (PAL) cameras

    - If I use 600mW ImmersionRC transmitters, the quality of the video image has problems, as bad colors as well as deformations of some areas of the video image appear (area changes during flight). This again was tested with two different 600mW transmitters, on two different aircrafts with different FPV cameras, on different frequencies.

    So the effect is reproducible, as soon as I am using the 600mW ImmersionRC transmitters Iím experiencing problems with the video image in the Skyzone goggles (also visible on an external monitor, connected to the Skyzones video out - so not a problem of the internal displays), while using the 250mW transmitter everything is fine.

    To sort out problems with the transmitters in general:

    Using the ImmersionRC 600mW transmitters with an ImmersionRC Duo 5800V3 receiver and a Fatshark Base SD goggle, again the video image quality is just perfect. So it's neither a problem of the 600mW transmitters, or the FPV cameras in general.


    Iím really happy with the goggles (Camera, DiversityRX, size, weight, quality of the internal displays, FOV, ...), but together with the ImmersionRC 600mW transmitters at least mine is not usable.


    Anybody else experiencing this?

    Sascha

    Edit: typos and the 250mW is a Fatshark VTx
    Last edited by Sam; 16th December 2013 at 12:30 PM.

  2. #2
    His Royal Sassiness ssassen's Avatar
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    That's because their receiver just isn't compatible, the same applies to the multistandard LCDs sold by the Chinese. Just because the frequency matches doesn't mean it'll produce a good image and/or offer good range, if only it was that simple. The receiver needs to properly demodulate the baseband signal and have matching de-emphasis curves for the audio/video, if not, audio/video quality and/or range will suffer.

    Yet another prime example of a Chinese company wanting to cut corners and make a quick buck on a flawed product. The only way this could work is that the receiver has different, selectable, baseband demodulators for each brand of Vtx they want to tune to. That however entails a lot more than just tuning to the proper frequency and simply ignoring the rest.

    Oh, and for the record, there is no 250mW ImmersionRC transmitter, that's a Fatshark branded product using a slightly different design.
    Last edited by ssassen; 15th December 2013 at 03:03 PM.
    Purveyor of the FPV secret sauce at ImmersionRC

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    Hi Sander,

    thanks for your reply, even if it's in "foreign terrain" ;-) Just checked the 250mW TX I borrowed from a friend, indeed it's a Fatshark (had to remove a mouting-sticker first to be able to see that). Until yet I only noticed the slightly different design compared to my 600mW.

    I'm using several systems, so not only my Duo5800V3/Immersion VTx. Of course I was also interested to see if the new goggles are able to tune my Immersion VTx, but I have to admit Foxtech didn't state in their product description that the goggles are able to do so (no word of "ImmersionRC support"). Of course somebody could expect this by only looking at the frequencies they support, and yes - that was also what I thought. So thanks for enlightening me and probably others!

    Sascha
    Last edited by Sam; 16th December 2013 at 12:31 PM.

  4. #4
    Engineer for Jesus Christ IBCrazy's Avatar
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    Quote Originally Posted by ssassen View Post
    That's because their receiver just isn't compatible, the same applies to the multistandard LCDs sold by the Chinese. Just because the frequency matches doesn't mean it'll produce a good image and/or offer good range, if only it was that simple. The receiver needs to properly demodulate the baseband signal and have matching de-emphasis curves for the audio/video, if not, audio/video quality and/or range will suffer.

    Yet another prime example of a Chinese company wanting to cut corners and make a quick buck on a flawed product. The only way this could work is that the receiver has different, selectable, baseband demodulators for each brand of Vtx they want to tune to. That however entails a lot more than just tuning to the proper frequency and simply ignoring the rest.

    Oh, and for the record, there is no 250mW ImmersionRC transmitter, that's a Fatshark branded product using a slightly different design.
    So basically you put a small signal amplifier on it with a 2.8V DC bias and it works. Seems simple enough to me.

    -Alex
    If it is broken, fix it. if it isn't broken, I'll soon fix that.

    videoaerialsystems.com - Performance video piloting

  5. #5
    His Royal Sassiness ssassen's Avatar
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    Quote Originally Posted by IBCrazy View Post
    So basically you put a small signal amplifier on it with a 2.8V DC bias and it works. Seems simple enough to me.

    -Alex
    That indicates a sync tip clamping and/or DC shift issue, somebody didn't do their homework!
    Purveyor of the FPV secret sauce at ImmersionRC

  6. #6
    now you are both just making it up.

  7. #7
    There are only 10 people that understand binary in this world, IBCrazy and Sander.

  8. #8
    Engineer for Jesus Christ IBCrazy's Avatar
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    ^LOL! I love it.

    I got one of the "alternative" receivers for the Dominators and did a little homework. What's funny is that I did my tests on an oscilloscope that was so old that it has vacuum tubes in it as transistors weren't even invented at the time of it's construction (circa 1948). It's my old trusty O-scope from college. I have better ones, but this one is just my favorite.

    I found that the alternative module had 1 V P-P wave varying from ~1.1 to .1volts with a clamped sync pulse for the top and bottom line data transfer. The NextWave had a 3.8-4V wave (1.2V P-P) with a similar clamp for sync check.

    -Alex
    If it is broken, fix it. if it isn't broken, I'll soon fix that.

    videoaerialsystems.com - Performance video piloting

  9. #9
    Engineer for Jesus Christ IBCrazy's Avatar
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    Quote Originally Posted by ssassen View Post
    That indicates a sync tip clamping and/or DC shift issue, somebody didn't do their homework!
    I think it has to do with the voltage zero reference. I'm not sure whether the signal is AC coupled or DC coupled (I would guess AC, but I don't have any schematics to verify). However we both know that ground reference is not easily achieved in semiconductors (as they usually only drop to .2V unless there is significant load on them). I think the tearing of the image is the ground reference issue.

    It just shows how much of this stuff is made without proper testing. It's no wonder many people have issues getting this stuff to work when they buy pieces from different manufacturers.
    If it is broken, fix it. if it isn't broken, I'll soon fix that.

    videoaerialsystems.com - Performance video piloting

  10. #10
    Hi, I am using the Skyzone goggles with the TS832 AV TX included in the combo from fox tech with the foxteck circular polarised antenna and can't get any further away than about 50 meters without the video drop out. Anybody else having any problems?

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