"Wireless Toslink" - Page 1
Forum section: electronics / beginners

author: mayor
author_rank: Regular Contributor
timestamp: January 07, 2015, 01:42:04 am
content: Hey there,I am looking to create a wireless link between a TV's toslink output and a receiver's input.I am thinking of using toslink receiver and transmitter modules (they produce TTL level "serial" data). I've also looked at TI's 2564 BT chip, which packs a bunch of features, and isn't necessarily straightforward to use.I want to have as simple a BOM as possible, and it seems to me this should be achievable, since I don't need to do any sort of data conversion, encoding or decoding. Basically, I just need a wireless carrier for an arbitrary digital "serial" signal...right?I'd be glad to hear suggestions, or whether I am missing something. Mayber others have gone down a similar route and can suggest simple-to-use ICs for wireless transmission.TIA!

author: tggzzz
author_rank: Super Contributor
timestamp: January 07, 2015, 09:28:26 am
content: If you are looking for a one-off project then...Find the bitrate, range, power and decide which RF band you can legally use. In an ISM band you have to accept inteference from other users.Look in catalogs to find pre-existing modules (not chips) and use them as the basis for your project.Do not hack something RF together unless you understand RF design and have the equipment to measure the level of spurious out-of-band transmissions. If you do transmit illegally then you may well screw up other people/equipment, and have The Authorities make you an offer you can't refuse.Light is unregulated, but be careful of your eyes;neveruse the easily available high power lasers (i.e. >1mW) for free space comms unless you reallyreallyknow what you're doing. It only takes less than the blink of an eye to blind yourself or, more importantly, someone else.

author: tszaboo
author_rank: Super Contributor
timestamp: January 07, 2015, 10:01:38 am
content: Quote from: mayor on January 07, 2015, 01:42:04 amYeah, No. You need a reliable transmission, which carries a timebase over radio waves. Data rate is 1Mbit even for 48 Khz 16 bit. That could take years and a lab at IBM to do. And in the end it doesnt provide any real life benefit over wifi.On the other hand you can probably hack/use these cheap Miracast dongles or a Chromecast, and use a HDMI-SPDIF converter/extractor, and the whole project could cost something like 50 bucks.

author: Jeroen3
author_rank: Super Contributor
timestamp: January 07, 2015, 10:11:44 am
content: You'll need a 125 Mbit/s wireless connection for full toslink. (according tot wikipedia)Since a single 2.4 GHz channel for WiFi is 54 Mbit/s I would assume you would need multiple of those. Or a higher carrier.Or you should accept the lower audio bitrate per channel / maximum channel count. Which is probably cheaper.You would probably want to avoid 2.4ghz due to it being rather busy. And if you use the 802.11 protocols you will have lag.Both are unwanted. Search for something in the higher ghz for short range radio. I've seen news on prototype laptop docks working on 60 GHz? for average-desk-width distances. There are a lot of bands free to use without license.

author: fcb
author_rank: Super Contributor
timestamp: January 07, 2015, 11:38:55 am
content: I'd use an radar module. Like those built by RFbeam, fairly cheap and stupidly wideband.

author: ConKbot
author_rank: Super Contributor
timestamp: January 07, 2015, 01:37:13 pm
content: Quote from: Jeroen3 on January 07, 2015, 10:11:44 amNot sure where they got that, but even at 192 KHz sample rate, 32 bit samples, 8 channels, thats only ~46 MbpsPlus I'm sure consumer grade equipment will have and ENOB > 24 bits

author: macboy
author_rank: Super Contributor
timestamp: January 07, 2015, 01:43:41 pm
content: Quote from: ConKbot on January 07, 2015, 01:37:13 pmTOSLINK, or more generically, S/PDIF, uses 64 bits per sample regardless of bit depth of the audio. Only two channels are supported, not eight. Multi-channel is only possible using encoding like dts or DD. So the minimum data rate is just under 3 Mbps for a 44.1 kHz sampling rate. (Using DD or dts does not change this; the data is put in place of the samples, and a non-audio data flag is set). The official maximum for TOSLINK is 96 kHz, so around 6 Mbps, but 192 kHz works on most modern equipment at around 12 Mbps. The clocks used for the audio processing and DACs on the receive end come from the clock recovered by the S/PDIF receiver. If you add to the clock substantial jitter (in engineering terms, so nanoseconds of jitter, not picoseconds like the audiophools talk about) in the process of transmitting it, then you will mess up that clock and fidelity will measurably decrease.I would try a low power laser (red laser pointer), driven by the TTL S/PDIF signal, pointed literally directly into a TOSLINK receiver. Maybe you would want a lens to increase the size of the target, and/or some ambient light filtering like a black tube and red filter, etc. But this should work. TOSLINK just uses a red LED; you are simply substituting a collimated LED and forgoing the cheap plastic fiber.

author: ConKbot
author_rank: Super Contributor
timestamp: January 07, 2015, 02:45:59 pm
content: Oooo optical wirelss, I like that. Omni transmitter placed somewhere good, feed it from coax toslink with a DC bias, NIR laser diode into a difuser, and a somewhat directional reciever with a selective filter on it.