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now I´m having issues with my video splitter, when I turn on my glasses and my archos, the image in the glasses are worst than connected directly to the receiver, and archos records on black & white.

Loss of color usually means that the color burst is low level. So, the last thing to do is add resistors to load the video signal down. The best thing to do is to put a o-scope on the video while everything is connected to check it all out. Then you will be able to determine what to fix.

I tried adding a 75 ohms resistor to the receiver without success.
The Airwave Rx already has the equivalent of a 75 ohm series resistor inside it.

Yes I do have a 470 uF cap on the video signal path.

Any chance it is installed backwards?

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Any chance it is installed backwards?

Originally was installed with the negative pointing towards the rca final conector (that´s the way I think it goes) I even tried to reverse it getting a worst picture.

Seems that something´s happening with my video splitter. Even if I only plug the receiver to the archos through it, the black&white screen appears.

Sadly I don´t have access to an o-scope :(

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Sadly I don´t have access to an o-scope

With common video issues, an o-scope is your best solution. Try to find someone that will let you use theirs. Keep in mind that without a scope, it will be difficult to correctly adjust the video levels. I couldn't imagine doing it without one.

I'm curious, what splitter are you using? Does it have a video level pot on it?

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Do you have a schematic or a block diagram or a pict of your setup (signal flow overview) which you can post?

The schematic is exactly the same as airwave´s datasheet.

I'm curious, what splitter are you using? Does it have a video level pot on it?

Don´t have a level pot, it´s this one (PC-122)

http://www.conectrol.com/ELECTRONICA/SEGUR.../ACCESVIDEO.htm

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More test done on this, plugged through my archos, with av in & av out and the image is perfect. What I don´t like is that has some lag that could be dangerous in some situations. I think I´ll end up buying another video splitter.

Going to stage 2 of this proyect, making a proper pcb with macthed impedance for mounting the sma on it.

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  • 3 weeks later...

Well I ordered this scope couple of weeks ago:

Velleman Personal Scope

I think is more than enough for what I want to do with it.

Today I received and did some testings with my 2 receivers. Here´s a summary of what I have found:

For all the cases I build a rca terminator with a 75 ohm resistor soldered across it

1)Airwave, video out directly conected to the scope: The VPP varies quite a few and the voltage goes in a range from 0'78-1'2 VPP.

2)Airwave receiver+ video amplifier out 1+glasses: VPP goes from 0.5-0.8

3) Airwave receiver+video amplifier out 2+glasses: VPP goes from 0.3-0.5

4)Lawmate receiver+video amplifier out1+glasses: VPP goesf from 0.25-1VPP

5)Lawmate receiver+video amplifier out2+glasses: VPP goes from 0.25-0.35

6)Lawmate receiver+video amplifier out1+archos: VPP goes from 0.03-0.5VPP

7)Lawmate receiver+video amplifer out2+archos: >VPP is almost no signal max 0.032

8)Lawmate directly plugged to the scope: no VPP.

After this figures war, I´m more confused than I´d hope, and really don´t understand anything. My problems were with airwave receiver connected to my amplifier, I loose color in my archos. What is quite clear is that something is happening with my amplifier´s video out 2. What I´ve seen too is that VPP varies a lot from a wide range, all this values where obtained wihtout a white saturated screen, the camera was focusing my backyard. Also trigger was set up automatic

So any thoughts to where should I move foward?

I´d post some scope´s screenshots later on

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1)Airwave, video out directly connected to the scope: The VPP varies quite a few and the voltage goes in a range from 0'78-1'2 VPP.

I'm not sure what you mean when you say the Vpp varies. If you mean it varies when you change the camera's scenery, then yes, that is what video does. But if the scenery is fixed, then the peak amplitude will remain the same. Not all parts of the video will be at the same level. Just observe the highest value, which represents white. Lowest values (above the sync porches) are black. Everything in between are all the intermediate intensities.

With the video source setup to show saturated bright whites, you should see some parts of the video signal that are 1.0Vpk-pk. If you are seeing 1.2Vpk-pk, then you definitely don't have a low amplitude (it is a little bit high).

2)Airwave receiver+ video amplifier out 1+glasses: VPP goes from 0.5-0.8

That sounds like your amp needs help.

3) Airwave receiver+video amplifier out 2+glasses: VPP goes from 0.3-0.5

I'm not sure how you are connecting the two glasses, but they should not share the same output (not parallel connected). Each pair should have their own dedicated buffered amp output jack. If they are not sharing the same output then the amp needs attention.

8)Lawmate directly plugged to the scope: no VPP.

You might want to check that again. :)

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I'm not sure what you mean when you say the Vpp varies. If you mean it varies when you change the camera's scenery, then yes, that is what video does. But if the scenery is fixed, then the peak amplitude will remain the same. Not all parts of the video will be at the same level. Just observe the highest value, which represents white. Lowest values (above the sync porches) are black. Everything in between are all the intermediate intensities.

With the video source setup to show saturated bright whites, you should see some parts of the video signal that are 1.0Vpk-pk. If you are seeing 1.2Vpk-pk, then you definitely don't have a low amplitude (it is a little bit high).

That sounds like your amp needs help.

I'm not sure how you are connecting the two glasses, but they should not share the same output (not parallel connected). Each pair should have their own dedicated buffered amp output jack. If they are not sharing the same output then the amp needs attention.

You might want to check that again. :)

I'm not sure what you mean when you say the Vpp varies. If you mean it varies when you change the camera's scenery, then yes, that is what video does. But if the scenery is fixed, then the peak amplitude will remain the same. Not all parts of the video will be at the same level. Just observe the highest value, which represents white. Lowest values (above the sync porches) are black. Everything in between are all the intermediate intensities.

With the video source setup to show saturated bright whites, you should see some parts of the video signal that are 1.0Vpk-pk. If you are seeing 1.2Vpk-pk, then you definitely don't have a low amplitude (it is a little bit high).

Well the camera was pointing at the same scenary somewhere of my backyard, and the VPK-pk varies those figures.

That sounds like your amp needs help.

definitively but the strange thing is that with lawmate receiver I don´t see any loss of quality or black & white screen.

I'm not sure how you are connecting the two glasses, but they should not share the same output (not parallel connected). Each pair should have their own dedicated buffered amp output jack. If they are not sharing the same output then the amp needs attention.

Well my mistake, I was trying to say that I measured with receiver to the amplifier´s video in. Then conected and runing my glasses to amplifier´s video out 1 and rca 75 ohm terminal to video out 2.

You might want to check that again. 

I know this didn´t make sense at all, but I didn´t want to lie and the scope was displaying 0 VPP jejeje :lol:

So, at all measures the VPk-Pk fluctuates from those values I posted before, in all the cases where focusing the same scenary. Does it something to do that I set up the scope to automatic trigger? Should I do it manually for example for upwards slope? (Sorry I don´t really know how to say this in english).

I guess the conclusion could be, just go to adjust the tx with a white saturated screen, and get rid of the amplifier. But how do I stabilize those VPk-pk values?

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But how do I stabilize those VPk-pk values?

I suspect it has something to do with the oscope. If the Video levels were indeed changing, then you would see the effect on the video monitor. Its brightness would flicker at the same rate.

Just so there is no confusion, you are saying that the video level *at the same horiz time location* is bouncing around when the camera is not moving? Or, do you just see that the levels are different at different horiz times?

For some help with understanding video behavior, just watch the video levels as you scan the camera at different scenery. In your case, you only care to observe the brightest whites. Those determine the max pk-pk, which your want to be 1.0Vpk-pk or so. If necessary, ignore getting it to sync (if your scope does not have a TV sync feature then sync is often not possible). Just look at the overall scope image instead.

EDIT:

Well my mistake, I was trying to say that I measured with receiver to the amplifier´s video in. Then connected and running my glasses to amplifier´s video out 1 and RCA 75 ohm terminal to video out 2.

I'm not really sure how you are performing the measurements. Measure the video levels coming *out* of the amp when the outputs are terminated with 75 ohm resistor terminators (don't connect your glasses or monitor at this time). The brightest white levels should be at 1.0Vp-pk. That is what you are looking for. BTW, if the video amp is a good design, the Rx's output amplitude will match the Amp's output amplitude {when properly terminated}.

Edited by Mr.RC-Cam
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Well I think an image worth more than 1000 words :) . Here I go with some atachements:

Airwave directly conected with the scope without amp See the VPP diference between next pic

21608301486.jpg

Airwave directly conected with the scope without amp See the VPP diference between upper pic

21608301351.jpg

Airwave connected to the amp and measured amp´s video out 1

p><p> <a  href=http://img2.putfile.com/thumb/8/21608301457.jpg' alt='a>'>

Airwave connected to the amp and measured amp´s video out 2

21608301471.jpg

Lawmate directly conected to scope VPP much more stable than with airwave

21608301377.jpg

Lawmate connected to the amp and measured amp´s video out 1

21608301467.jpg

Lawmate connected to the amp and measured ampa´s video out 2

21608301426.jpg

This time all measures where only with the rca 75 ohm terminator plugged in.

All the measures are not white saturated screen, but the camera is focusing at the same frame. Do you see now the VPPK difference between the first 2 pictures? They are under the same condition but taken time apart.

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Do you see now the VPPK difference between the first 2 pictures? They are under the same condition but taken time apart.

These two are different because the waveforms are from different video lines (each PAL video field has ~625 of them). The top example looks like it is from a line's scene area that doesn't have saturated whites. The bottom one does, as if it is showing a video line that has white OSD text or a image that has characteristics that are bright white. In other words, they are just different horiz lines in the video field.

Using a simple digital scope can be a bit strange if you are measuring video. Just observe the max Vpk-pk values (which represent the whitest whites). The measurements taken in the second photo would do fine for this, if those peaks are the max you ever see. Don't worry about syncing on one specific horizontal video line. Just ignore the ones that don't have the max peaks in them.

Or, you can do as I suggest in the Lawmate Tricks web page and just illuminate the entire camera view with a bright light source so that it is evenly saturated. This will help ensure that all video lines are the same, which may reduce the measurement confusion. BTW, if there is an OSD being used, then turn if off too.

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I´ll go with the saturated white screen. Should I go with a white fluorescent light? Another thing that is crossing my mind is that if I tune my transmitter with the airwave receiver, probably the lawmate receiver is going to be a little bit off.

Now a little update, I made a new 2 sided PCB with a quality FR4 1mm. The rf width is exactly 68.5 mils. Also did almost every 5 mm ground vias to attach the ground opposite side. The result is quite satisfaying

21703184796.jpg

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I´ll go with the saturated white screen. Should I go with a white fluorescent light?

I use a little battery operated flashlite.

Another thing that is crossing my mind is that if I tune my transmitter with the airwave receiver, probably the lawmate receiver is going to be a little bit off.

That is often the case. Maybe try to adjust for the best compromise between them all.

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Well here it´s my 2nd airwave receiver. This time the sma is soldered to the PCB, I have tried hard to achieve 50ohm line with a quality pcb. After this picture I improved the soldering on the sma conector and pin, I think right now it only has the necessary lead. The problems with the lawmate transmitter and airwave rx + video amplifier are still there. I have to adjust the transmitter white level and see, hopefuly this week will do it and some range test between lawmate rx, and the 2 airwaves. Then if I get rid of these problems would try the Oracle Diversity Receiver and post a video. At this time I´m only doing electronics, have a brand new plane waiting for me and don´t have time for it :(

22316214967.jpg

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  • 3 weeks later...

Hi again, I´m going to adjust my VPk-Pk in my transmitter, but I want to make sure where it is. It´s a lawmate 600 mW, I attach a pic of it, is it right the one I have draw?

BTW do you think the sma is correctly soldered? I see too many lead on the center pin.

24117225358.jpg

Edited by Wavess
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Well this is the neverending story. Tried my lawmate transmitter I soldered the cables again after the crash, and did check the inside, does not seem to have any damage in it. If I move the transmitter from horizontal to vertical, and really close to the receiver (aprox 3m) I loose signal an got a snow screen. I doubt this could be caused by interference, this is a 600 mW transmitter and is really close to the receiver in order to loose signal. I´m also begining to think that there was something wrong with it in the Oracle´s test. I have never lost signal at all so fast like the other day. What do u guys think about it?

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Thanks terry, I changed the aerial and now doesn´t seem to do it any more. Have to test it more though.

I did the video signal adjustment and now I can see on my 3 receivers 1.012VPK-PK :) with a nice saturated video waveform. The video pot is extremely sensitive to turn it. Within a 1/10000 degrees of turn voltage could change from 0.2 to 2VPk-PK. Now it´s time to try all this on the real world. B)

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