Vhf Video Transmission

[sir diggy]

Ok here's my idea:

I want to make the GP32 a handheld able to transmit to a television wirelessly.

[A similar example is the Top Guy portable that is exceedingly rare]

Like the Top Guy, I want to use a small low power transmitter that has a signal between 54 to 88 MHz (VHF CH 2-6 ) and has its own power source. I found one here (http://www.northcountryradio.com/Kitpages/lptvx.htm). The only problem is that the standard NTSC video and audio signal (coming from the GamePark) needs to be converted into AV outputs before being transmitted.

This being said, one would need to convert the signal from the GP to an AV output before plugging into the transmitter.

The only solution I can think of is refurbishing an AV jack from a GameAXe and getting an AV cable (http://www.lik-sang.com/info.php?category=182&products_id=1446)

that would then plug into the transmitter.

Is this worth my time?

 

[cozmic]

Sound difficult but cool.

 

[GBA_lover]

yeah go for it. i would love to see the gp being played on the tv it would be soo cool.

the beev

 

[Octavious]

dude
that would be the coolest ever!
I would proboly have to get/do that
play NES and more one TV!
cool

luck to ya

~Octavious

PS where can I get more info on Top Guy, where do you think I could pick one up, how big is it ( its dimensions ), how many batteries does it use, and how much average does it cost??
This could be a good base for my RetroPortables project!

here for top guy summary

 

[sir diggy]

OK. Wish me luck.

I'll post my progress...


Oh and the likelihood of finding a Top Guy is slim to none since only 1ooo were made. You can google it and find a couple pages that mention it.

 

[project-2501]

I'd really like to see an av in with possible recording to be honest. Then I could use it with a PSOne or this little wireless camera I've got.

 

[Octavious]

well, once we get the TV thing, more progies wil come from it
I just hope this works for you
they have similar Idea the GP32 and the topguy
the GP32 has a LCD , so does the Topguy
now we just have to incorporate the video out, and the topguywill be like a guide I guess
hey,now I have a portable movie watcher on TV's also
sweet!

~Octavious

 

[aapje89]

cool , could it also be reversed (then I can watch tv on my gp32 )

 

[sir diggy]

I think you already can use any handhled with AV inputs (Game Axe etc.) as a portable monitor with the help of this little contraption.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...8154844656&rd=1

I just need an output for the GamePark so I can plug into the transmitter. :blink:

Any suggestion on how to wire this up?
Could the USB work? Probably not?
Wire it at the currently available RF transmitter link?

 

[Robster]

OK, maybe I'm missing something here: you want to transmit the GP32 screen to a TV? So you can sit in front of your TV and play DrMD or such?

If that's the case, I'm afraid you're out of luck. The display signals inside the GP32 are never in a suitable form for output to a television. It's been discussed before, I believe you could replace the LCD driver chip with a TV encoder but it would be a lot of work and require a lot of electronics knowledge! Not to mention completely disassembling your GP32 and modifying it so that it will never work with LCD again...

 

[trooper]

OK, maybe I'm missing something here: you want to transmit the GP32 screen to a TV? So you can sit in front of your TV and play DrMD or such?

If that's the case, I'm afraid you're out of luck. The display signals inside the GP32 are never in a suitable form for output to a television. It's been discussed before, I believe you could replace the LCD driver chip with a TV encoder but it would be a lot of work and require a lot of electronics knowledge! Not to mention completely disassembling your GP32 and modifying it so that it will never work with LCD again...

​

How is it possible for the nomad to do it and a number of other handhelds, But no the GP32 ???.
I`ve not been following the nomad tread too closely, So not too sure what has already been discussed.

Trooper

 

[Tobriand]

Basically, its because the Nomad uses, unless I'm much mistaken, a CRT as a display. That means the signals sent to its screen are pretty much identical to those sent to a TV monitor (which will also be CRT). A GP32 uses an LCD, which has a completely different sort of signal. I don't see, personally, quite why it should be that - with the correct hardware - it shouldn't be possible to convert the one into the other. But as Rob says, I suspect making that equipment would be extremely hard, and probably somewhat pricey too.

Of course, this does get somewhat complicated as an idea (LCD signal <> CRT signal) when you start looking at flatscreen LCD TVs, but I think its safe to suggest that they include the hardware you'd need to include in a Gamepark (but the other way round) to convert TV signals to LCD ones. Quite what that involves, I haven't a clue, but I know it'd be damnably complicated.

However, that said and done, if you're still interested in giving it a try, the best of luck to you - if you can get it to work, and it wouldn't cost a bomb and a half please do tell us how. I imagine it might become a fairly popular bit of modification for those of us who enjoy fine soldering and such (not me, I fear, but still)

 

[sir diggy]

Well let me give it a try with my GameAxe first since the AV output peripheral is already there.


My father is an electrical engineer so I'm not worried about the fine soldering, but this signal issue does open up a new can of worms.

More to come...keep thinkin fellas!!

 

[EvilDragon]

Well, creating a cable which goes from an A/V out to a TV is easy.
Problem is - the GP32 doesn't have an A/V out.

As already said, older handhelds like GameGear or Nomad have a CRT display in - which uses normal TV A/V inputs (that's why the TV Tuner was possible without any problems).
So you could just grab the line going to the CRT display and plug it into a TV. Pretty simple.
A/V, by the way, is an analogue signal.

Now, the GP32 uses a TFT display.
This display is digital and uses 20-30 wires to run, as the GP32 uses a Matrix to control every single dot on the screen, unlike a display with A/V input, where it just gets an analogue signal. In that case, the display converts these signals into the matrix and puts the picture on the screen.

So I'm sorry, but there's no chance of getting a TV signal out of the GP32...

BTW:
If the signal ways in the GP32 to the screen would be TV signals, we wouldn't have the problem with the BLU+
And we could exchange the LCD with every other LCD with A/V input...

BUT it would be pretty blurred, as the analogue signal doesn't drive the LCD dotwise.

 

[frolik]

dude
that would be the coolest ever!
I would proboly have to get/do that
play NES and more one TV!

man that is just SO retro!!

 

[sir diggy]

I was doing some research and you are correct. The signal is digitized from an analog signal into a digital one when being presented on a TFT display.

I just thought people may be curious as to why this project seems to be losing hope and why.

Here's an article on CRT versus TFT if you are interested.
Sharp LCD Apllication Note


Would there be any way to intercept the signal before it reached the "sampler/quantizer" and use that pre-existing analog CRT signal?

Or perhaps any video graphics adapter with LCD in to CRT out?

 

[Winterkid]

I would think since the LCD display technology is based on VGA drivers a VGA to Composite video device would be the place to start researching. The display circuittry in the GP32, is there an analog source before it hits the DAC? I think that would be the place to tap for the signal to hook a second DAC to switch over to in order to pass through such a VGA to RGB composite adapter. Then again, my speciality is digital circuitry.

 

[EvilDragon]

I was doing some research and you are correct. The signal is digitized from an analog signal into a digital one when being presented on a TFT display.

Would there be any way to intercept the signal before it reached the "sampler/quantizer" and use that pre-existing analog CRT signal?

No, because this signal doesn't exist in the GP32.
You probably looked up how TFT displays for computers work.
They've got a VGA input (which is analog), since all computers had
VGA output when they came out (that time, you still had CRT displays).
So the converter and driver for analog > digital sits in the TFT monitor.
As the GP32 doesn't need to convert the signal from digital to analog and back
to digital, this wouldn't make sense.

For computer TFTs, there's now the new DVI connector, which sends the
digital data directly to the display.
They defined a standard for that connector, so that EVERY DVI TFT works
with. However, this standard only applies to DVI devices, so...

Or perhaps any video graphics adapter with LCD in to CRT out?

​

... this wouldn't also be possible, since ALL LCDs work differently and have a different driver.
It's part of the hardware / software to set the correct timings, etc.

This is also the problem with the new LCDs in the BLU+:
They need different timing settings. If the software doesn't use them, you get the white bar.

So there cannot be a universal LCD in to CRT out adapter, it has to be a specific one for the LCD you're using.

I would think since the LCD display technology is based on VGA drivers a VGA to Composite video device would be the place to start researching. The display circuittry in the GP32, is there an analog source before it hits the DAC? I think that would be the place to tap for the signal to hook a second DAC to switch over to in order to pass through such a VGA to RGB composite adapter. Then again, my speciality is digital circuitry.

​

Again, the LCD display technology is NOT based on VGA drivers.
ALL LCDs use a specific driver and a digitally driven matrix.
The TFTs for computers just have a converter from VGA to their own LCD. You wouldn't have been able to connect them if they wouldn't have it.

But as the GP32 is a digitally device giving out digitally signals, it's managing the whole LCD stuff itself.
Wouldn't make any sense if the GP32 would convert his digital data to analog, just to digitize it again for the LCD.

 

[sir diggy]

Thanks for all your help guys!!!

Much appreciated.