Maxim's Loss-of-Video-Sync Alarm IC

411 posts in this topic

Posted

my black box is off to you. I agree that it's sort of a dead product, but was hoping to use it untill I made the jump into another OSD. $$$. I figure that it might be usefull to know what is wrong with it, so that the problem dosn't reapear later in a new osd design.

It's esp odd, since the video looks fine on the screen.

Ken

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Posted

I figure that it might be useful to know what is wrong with it, so that the problem doesn't reappear later in a new osd design.

Lupy, I received your Blackbox OSD today. One major issue is that its video level is too low. The OSD effectively attenuates the incoming video by nearly 50%. Its overlayed OSD pixels levels are driven decently high (to about 0.8V), but all important levels are definitely incorrect.

Short of having the mfg tells you how to change the video gain, a schematic would probably be needed. I thought of attempting to "fix" it using a bit of reverse-engineering, but there is a chance I would destroy the little fellow in the process. Plus, I am short on time for such fun. So, I left it as-is.

It's esp odd, since the video looks fine on the screen.

One clue was that the colors and contrast is less vibrant when the OSD is in the loop. At least that is what I see on my equipment. Incorrect video levels are often hard to detect -- a monitor's AGC, and the manual contrast controls, can mask it. But the net effect is less dynamic range in the image, regardless of the standard band-aids the monitoring equipment applies.

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Posted

ah, I never actually flew it, just tested it in the yard and such. I didn't look at it closely enough to see the color/cantrast change. Did you notice that the switching seemed to start off fairly normal, then increase untill it's almost constant?

Thanks for taking a look.

Ken

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Posted

For me, the switching is nearly constant. Variability in the random switching could come from the video Tx and Rx; Perhaps yours experiences a tiny video level shift as it warms up.

I'll box up the OSD and get it back to you. Do I use the address on the bubble envelope?

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Posted

Hi Mr Rc-Cam,

and of course my question comes up about the hitt consulting propeller based OSD, that uses a missing sync detector chip also. will this work with the oracle?

http://forums.parallax.com/forums/default....=181370#m181370

about half way down on page schematic in expresspcb as an attachment.

will be hopefully ordering an oracle today

gwen

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Posted (edited)

Hi Mr Rc-Cam,

and of course my question comes up about the hitt consulting propeller based OSD, that uses a missing sync detector chip also. will this work with the oracle?

http://forums.parallax.com/forums/default....=181370#m181370

about half way down on page schematic in expresspcb as an attachment.

will be hopefully ordering an oracle today

gwen

ps what about using a 900mhz 7db omni/tilted on its axis and a 900mhz panel as the 2 diversity antennas?

Edited by gwenhastings

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Posted

my question comes up about the hitt consulting propeller based OSD, that uses a missing sync detector chip also. will this work with the oracle?

If it uses industry standard NTSC or PAL signals then it will work. If it has cheated on these, then compatibility will be uncertain.

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Posted

haven't been keeping up with this thread, but yes use that address, I got the BB back fine a while back.

Not really inderstanding the chip you are using, this might not work, but could you have the oracle take a sample of the current video quality, and then do a switch baised on a decrease from that level? The user could select from a set of allowable decreases in quality.

This problem with the BB video out levels might also explain why the mobicom 900mhz video tx I had been playing with didn't work if the video went through the BB first.

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Posted

I got the BB back fine a while back.

That is good to know. I was wondering about that.

... but could you have the oracle take a sample of the current video quality, and then do a switch based on a decrease from that level? The user could select from a set of allowable decreases in quality.

Such things can be done. But, I hate to add hardware costs to the design in order to accommodate such wayward issues.

In my opinion, the low video levels from the Blackbox OSD are not doing you any favors. Even though it may look fine to you, the image's dynamic range is affected. Fortunately, the display device's AGC does a fair job of masking these problems. However, for best video quality the best fix is to restore the video amplitude to standard levels. Perhaps you could try re-tweaking your Video Tx's level pot until you obtained industry standard 1V video from the Rx's (when the BB OSD is installed).

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Posted (edited)

Hi again.

This last 2 months I´ve playing and full testing the Oracle Diversity System. I didn´t like my beta tester video at all, it was a very bad day when everything turned wrong. So I´ve edited this new video, that has the most relevant 5 flights that I´ve done. I also wen to a small lake the other day but that would be another story and another vid.

Usually Oracle in my flights is quiet , I´ve improved a lot with my new Airwave, but today Oracle began to do repeatedly chirps, I didn´t know what was going on, so I didn´t have much flight time enough and I landed. I realized that my ground battery was running out, and 1 receiver didn´t have signal at all, Oracle was alarming low battery and did stay with the valid receiver all the time.

In this video you hard would notice the video source changing, my two receivers are now adjusted to 1 VPK-PK and have adjusted white balancing on Oracle too.

So no more words, here´s my final video test of this great device.

Testing Oracle

Edited by Wavess

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Posted

Hi, very cool video!

I noticed the good quality of the video: it appears that you use a good camera with higher resolution than many other setups I have seen.

Would you mind recommending a low cost and high quality camera that I could purchase as of today (2009).

I am working on a setup for use this summer (I am hooked already):

Easy Star plane

IMU based Autopilot

Airwave TX (2,4GHz)

Camera ??? (need advice)

OSD system (need advice)

Diversity RX (oracle + 2 x Airwave)

Regards

UFO-MAN

Hi again.

This last 2 months I´ve playing and full testing the Oracle Diversity System. I didn´t like my beta tester video at all, it was a very bad day when everything turned wrong. So I´ve edited this new video, that has the most relevant 5 flights that I´ve done. I also wen to a small lake the other day but that would be another story and another vid.

Usually Oracle in my flights is quiet , I´ve improved a lot with my new Airwave, but today Oracle began to do repeatedly chirps, I didn´t know what was going on, so I didn´t have much flight time enough and I landed. I realized that my ground battery was running out, and 1 receiver didn´t have signal at all, Oracle was alarming low battery and did stay with the valid receiver all the time.

In this video you hard would notice the video source changing, my two receivers are now adjusted to 1 VPK-PK and have adjusted white balancing on Oracle too.

So no more words, here´s my final video test of this great device.

Testing Oracle

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