Analog TV tuner and demodulator - Page 1
Forum section: electronics / beginners

author: fabiodl
author_rank: Frequent Contributor
timestamp: January 05, 2021, 10:59:15 am
content: I would like to develop a demodulator board for game consoles that output RF.I found a very nice chip,https://www.silabs.com/documents/public/data-shorts/Si2177-short.pdfIt can be purchased over digikey,etc,but they provide details only under NDA, even the i2c registers specification is not public (why?! )Do you know any more hobbyist-friendly alternative (which is not scavenging a VCR) orproducts that use it? If so, do you know if the i2c traffic can just be sniffed and replayed or if they have any pesky security protection scheme?

author: CJay
author_rank: Super Contributor
timestamp: January 05, 2021, 11:15:22 am
content: Why not ask them if you can sign the NDA or do you want to make it open source?

author: Gyro
author_rank: Super Contributor
timestamp: January 05, 2021, 11:42:43 am
content: The quality is going to be pretty bad compared to taking the composite video and sound directly at the input of the RF modulator in the console.You say "consoles". If you're planning this as a product you need to remember that the frequency accuracy of those cheap modulators they used was never great - fine tuning to match the exact frequency (as well as the specific UHF channel of course) would be needed.It would be as well to check, maybe using the 'bits scavenged from the VCR', how well the quality of an RF solution would hold up on a modern high resolution digital TV. Analogue CRT TVs were a lot more tolerant of noise and artefacts than digital ones.I don't want to be a damper, but modifying consoles might be a better strategy.

author: Benta
author_rank: Super Contributor
timestamp: January 05, 2021, 06:58:02 pm
content: I can't give you much hope.The busines model of selling TV tuners/demodulators (both as ICs or as little metal boxes) is: "How many million units do you want? Should we put them in 20' or 30' containers?"The documentation is rudimentary at best, big customers are supported directly from the supplier's design/application engineers. Supporting small customers is unwanted and there are no resources for it (not to mention application notes etc.).That parts are even available at Digikey is probably for repair/service reasons.The "scavenge a VCR" is the best option, I'm afraid.

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: January 05, 2021, 07:17:48 pm
content: How about this:https://datasheets.maximintegrated.com/en/ds/MAX3543.pdfbut it's obsoleteThere's an evaluation kit - looks like a complex project.I would rip something out of a VCR or even just pass the console RF output through a VCR.

author: fabiodl
author_rank: Frequent Contributor
timestamp: January 06, 2021, 03:33:50 am
content: Quote from: CJay on January 05, 2021, 11:15:22 amThe reply to this question is in Benta's commentQuote from: Benta on January 05, 2021, 06:58:02 pmQuote from: Gyro on January 05, 2021, 11:42:43 amI am already doing this, I just take the composite video and buffer it with a simple emitter follower and output the audio as is. But I'd like a way to connect original stuff on my PVM.Quote from: JohnnyMalaria on January 05, 2021, 07:17:48 pmThank you, yes, that' s sad, it's out of stock anywhere

author: fabiodl
author_rank: Frequent Contributor
timestamp: January 09, 2021, 04:02:55 am
content: Is there anyone who has the NDA and is willing to share under the table the minimum info to make it work with a "non-disclosure that you passed me the info" agreement?