TV Broadcast using TV_Text

tatatom

I am This close to using the TV broadcast option but no matter what I try I can't get it any better than the attached image. It works perfectly with just a cable and composite input to the TV but no matter what TV or what settings I try this is as close as it comes.

I'm using a homemade board modeled after the Demo board.
Below are the TV_Params settings from TV.spin. Any help or suggestions would be most appreciated because at this point I'm stumped.

Thanks
Tom
++++++++++++++++++++++++++++++++++++++++

tv_params long 0 'status
long 1 'enable
long %10100 'pins
long %10010 'mode
long 0 'screen
long 0 'colors
long cols 'hc
long rows 'vc
long 4 'hx
long 1 'vx
long 0 'ho
long 0 'vo
long 55_250_000 'broadcast
long 0 'auralcog

Mike Cook

See if this thread helps:

http://forums.parallax.com/showthread.php?p=593861

I'll be trying this in the next few weeks, so keep us posted on your results. Also there was another thread that talked about using a 6 MHz crystal:

http://forums.parallax.com/showthread.php?p=651266




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Mike

Post Edited (Mike Cook) : 6/3/2007 1:30:01 PM GMT

Anubisbot

Hi tatatom,
i have the same problem.
I tryed all the settings, and only got a picture like you.

I almost think that it has some to do with the tv.

Do you use a TV antenna.

Anubisbot

tatatom

Hi Mike & Anubisbot

Yes I have antenna on both the TV and the Prop board.
I changed the mode to %11110 as per Mike Green for colour suppressing
I changed the freq to 60_000_000 (and many variations between 55_250_000 and 60)
I tried on 4 different TVs
and no difference.

As for 6 mhz crystals I don't have any and it seems like it does work for some with the standard 5 mhz

So what's next to try?

Tom

Newzed

Tom, do you have an RCA patch cord from the Prop TV out to the TV you are using, and is·your TV set to Games?

Sid

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Yesterday is history, tomorrow is a mystery, and today is a gift.

That is why they call it the present.

Don't have VGA?
Newzed@aol.com
·

Anubisbot

Or maybe it has some thing to do with our boards we use, since i use a home made testboard, im not sure if it can has something to do with it, but tomorrow i get a difrent board, still self designed but not self made. i will check it with the new board then again. And i orderd some 6 MHZ crystals to see if it gets better.

Do you have a photo of your board, specialy where the antenna and the 3to4 resistors are..

@newzed
we try to broadcast

Anubisbot

Mike Cook

Yup Same results here, using the following:

P12 - 1.2K
P13 = 560
P14 - 270
P15 - 560

Tried both 5 and 10 MHz crystals, don't have a 6 MHz on hand,

Set Mode to %11010

Tried 55_250_000, 60_000_000, 61_250_000 for Broadcast, using a Parallax ProtoBoard, Stock#: 32212.

Only way I can get a picture is to wrap the antenna wire around the TV's antenna. Boy thought this would be easy!

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Mike

tatatom

I use a RCA cord for composite output to TV. I disconnect it and connect the antenna to the signal for broadcast. I have tried different Prop chips too. Seeing that Mike is using a Parallax proto board and having the same results I sorta doubt that it is the fault of the board. Below is an image of my board.

So now where does all this leave us?

Tom

ThePenguinMaster

hmm.. this is interesting.. i did a custom board using the tv text too and i used an rca cable. i made it at my house and everythng worked great. but i took it to my parents house and plugged it into their tv and got a result simular to the pictures you have posted.. weird colors and all. now it turns out the solution to my problem was i was plugging into an·RF modulator (i think thats what you call it.) and there was a frequency setting on the back that i had to switch. so basically their tv was old and only took antenna input. i was using an an av cable. when it was converted from what is normally output to the av cable to what their tv could take, it was converted using the wrong frequency. now if your broadcasting the viedo from your board, it is probibally having a simular problem where the broadcast frequeny is not compatible with your tv. so maybe theirs a setting you need to double check? just thought that might help.

tatatom

Mine works great using a cable to the composite input of a TV. Using the video in or the VCR adapter it is perfect on all 4 TVs I have tested. The problem lies in trying to broadcast with an antenna which doesn't work on any. All get the results pictured previously

Tom

Newzed

Tom, I have a little color TV camera out in the garage that looks down the driveway.· It is controlled by a Stamp and the camera output is broadcast by a little cube I think I got from Ramsey Electronics.· What the camera sees is sent to the TV in my office on Channel 59.· Maybe that is what you need.· It is about 40 feet away and goes thru three walls.· 100% dependable.

Sid

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Yesterday is history, tomorrow is a mystery, and today is a gift.

That is why they call it the present.

Don't have VGA?
Newzed@aol.com
·

Mike Cook

Sid,

I would have to agree that a video transmitter, to transmit the Propellers composite output, for longer distances would be the way to go.

However according to the data sheet for the Propeller and the documentation provided in the TV.spin object, it states "Wireless video transmission (NTSC or PAL)", directly from the chip, that's what we are trying to accomplish.

My needs are for short range transmission, 2 to 6 feet would be adequate, with out any additional hardware, besides the resistors needed for the broadcast output, and maybe substituting a different crystal than what's·provided with the Propeller ProtoBoard.


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Mike

Post Edited (Mike Cook) : 6/3/2007 7:05:35 PM GMT

tatatom

Yes I have both a Ramsey video transmitter as well as a more powerful transmitter and they work. But the robot I'm working on would really benefit from using only a Propeller for a transmitter and not other devices because of space and power requirements. So I'll keep on trying and keep my fingers crossed. Any other ideas anyone?

Tom

tatatom

Has anyone out there been successful with TV broadcast using a home made board? Maybe there is something unique that you did to get it to work where others (like me) have failed? Since there are several others having the same problem I don't feel quite so bad, but I'd (we) would feel much better if we could get it to work.

Tom

BTX

tatatom.

Your picture in the top of this thread, seems to have the horizontal sync pulses inverted.
Check this inside the TV with a oscilloscope.
Perhaps your video signal is correct, but your broadcast signal is not..[noparse]:)[/noparse], check this please ("luminance signal").
Maybe an incorrect channel syntonized could do that too. Maybe you're syntonizing an 'armonic' of the RF signal.

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Regards.

Alberto.

Paul Baker

Since it seems a few people are having difficulty with the broadcast mode, I'll start working on this tommorrow to see if I cant get you guys up and running. I do remember that setting the output to 60MHz and using channel 3 got the best results, and using portable TVs with a scanning dial work much better that ordinary TVs.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

Newzed

How do I set the output to 60MHz?

Sid

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Yesterday is history, tomorrow is a mystery, and today is a gift.

That is why they call it the present.

Don't have VGA?
Newzed@aol.com
·

Mike Cook

I've been setting it in the TV_Text.spin object, in the DAT section, tv_params, next to last value commented as broadcast.

In the unmodified file (TV_Text.spin)·it is set to 0, I·tried the following values:

Channel      Frequency
-------      ---------
2            55_250_000
             60_000_000
3            61_250_000
4            67_250_000

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Mike

Post Edited (Mike Cook) : 6/5/2007 12:43:00 PM GMT

Newzed

Mike, I don't have a copy of tv_text.spin.· Could you please post one?

Sid

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Yesterday is history, tomorrow is a mystery, and today is a gift.

That is why they call it the present.

Don't have VGA?
Newzed@aol.com
·

Mike Cook

Should be in your Propeller Tool folder, but here it is attached, this one is from the 1.0 Propeller Tool

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Mike

Mike Cook

Paul,

FYI:
The TV I'm using to receive the signal with is a cheap Walmart 13" color TV about 4 years or so old. It has a whip antenna that can be attached to the TV's RF 'F' connector. In the TV's menu option, I have it programmed for OFF AIR, instead of CATV, actually tried both settings. I have a little B&W 'tunable' 5" TV at work, I'll bring that home and try with that TV. But to be 'usable' I really need it to work with about any, off the shelf, modern TV.

Thanks for looking into this, have you had a chance to read my PM?

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Mike

ThePenguinMaster

im pretty surte like i said in an earlyier post there is a problem with the frequency the tv is recieving.. transmitting through an rca and having it converted into a antenna signal through a modulator showed the same results. i know you guys are broadcasting, but i had the same effect through an rca modulator on a tv, and i think its related. and the reason i think that is because on my old tv im going from rca on my board, to an antenna hookup.. two different signals.. an rf modulator translates it to an antemma signal for you.. i believe i hat to switch the modulator to 45mhz (not 100% sure) now i know your not using a modulator to translate it.. i know your broadcasting through the chip.. but what im saying is that during modulation you can set a frequency and i had to change the frequency. the satelight dish also goes from rca through the modulator to antenna. the dish used a different hz setting. im not offering a solution to the problem, but clues that might help. im sure its the broadcast frequenct thats incorrect.. ill see if i can check what setting i was on to get it to work.. so maybe you can set your broadcast frequency to what i had and maybe that will work.

i dont know how the modulation works on the chip but id imagine you can change the frequency.

Paul Baker

OK I have just run the test and I dont have any issues with broadcasting to channel 3. The demo board and it's antenna (a hooked test probe lead) is roughly 2 meters away from the television antenna (a 24" length of wire stuck into the coaxial hole).

Attached is a picture of the TV and the file used in conjunction with the TV_Text_Demo.spin

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

Mike Cook

Paul,

If possible, can you:

1. Try it on a Proto Board

or

2. Using the demo board, Install the three resistors that make up the TV interface on the Demo Board's plastic bread board area, and then change the pins that the object uses? I'd do this but have never purchased a demo board, just have chips and Proto Boards.

I opened another NEW Proto Board and installed the three resistors.

P12 = 1.2

P13 = 560

P14 = 270

Still have the same quality picture as Tom's as shown in his first post. However no picture on channel 3 but have a torn, somewhat color picture on channel 2,.

The Demo Board schematic has the resistor for P12 as a 1.1K, could that be causing the issue? I would like to see this work on the Parallax Propeller Proto Boards.

Thanks for your help.


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Mike

Post Edited (Mike Cook) : 6/5/2007 11:17:04 PM GMT

Paul Baker

Mike did you conduct your test using my TV_text?

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

Mike Cook

Paul,

Yes I did, used your TV_TEXT.spin, the TV.Spin from the Propeller Tool 1.05.5, and a simple top file that I created. Archive attached along with a few photos.

The TV has a whip antenna, I used an insulated wire, on the Propeller Proto Board as it's antenna, about 24" long, this was connected to the junction of the three resistors that would normally connect to the center pin of a RCA jack. Only way I can get any picture is to wrap the insulated antenna wire coming from the Propeller Proto Board around the TV's whip antenna. Nothing displayed on channel 3, but got the picture as attached, on channel 2.

I changed the line in your TV_TEXT.spin from:

······················· long··· 60_000_000·············· 'broadcast

to

······················· long··· 0·············· 'broadcast

Recompiled, connected to the composite input of the TV and a perfect picture as I expected.

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Mike

Post Edited (Mike Cook) : 6/5/2007 11:46:15 PM GMT

Paul Baker

Well I replicated your setup, demoboard, 3 resistors of the values you specified and a wire (6"), still get a pretty good picture. Based on the screen shot of your TV I would say that your TV has a very narrow range of allowed variance of timing signals. That would explain the offset of the scan lines you are seeing.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

Mike Cook

Paul,

Well since 60 MHz not a 'real' TV frequency, I tried with 61_250_00 (61.250Mhz) picture is some what better on this board. Is there anything different about your TV_TEXT.spin besides the parameter in the tv_params section?

On the first NEW Propeller Proto Board I tried this on, I used all 4 resistors, and could never get it to work properly using broadcast, but it would work well in composite mode.

P12 - 1.2

P13 - 560

P14 - 270

P15 - 560

The first NEW Propeller Proto Board I tried this on, failed with in 30 minutes, it will identify and program but no TV output, composite or broadcast. Looks to be a PLL failure,·I sent you the details in a PM. Hope this second board will run longer than 30 minutes!

I'll keep tinkering with the frequency, I tried the Incremental Video frequency for channel 3 (61.2625MHz) and this did clean up the picture, not as good as a direct connect but looks like I can get a few feet with it now.

Actual TV looks a little better in 'real life' than the photos, TV's don't photograph very well!


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Mike

Post Edited (Mike Cook) : 6/6/2007 1:38:30 AM GMT

tatatom

Paul

I downloaded and ran your TV_Text and get the same garbled results on either channel 2 or 3.


Tom

Newzed

Paul, my TV Start pin is 0 - what do I have to change to get your program to work?

Sid

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Yesterday is history, tomorrow is a mystery, and today is a gift.

That is why they call it the present.

Don't have VGA?
Newzed@aol.com
·

Mike Cook

Sid,

In your top file, for example: TV_Text_Demo.spin located in your:

C:\Program Files\Parallax Inc\Propeller Tool v1.0\Examples\Library

Directory, if you installed the Propeller Tool with the defaults.

In the method PUB start, change:

text.start(12)

To

text.start(0)

To have the TV interface starting on pins 0..3. Then the value of resistors should be:

P0 - 1.1K

P1 - 560

P2 - 270

P3 - 560 (optional)

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Mike