Consider also simply using the physical-layer of Ethernet, using the same connectors, pair identification and pin assignment, and pulse transformer isolation at the transmitting end and the receiving end.
1. What is the signal?
2. What does the signal need to connect between, and for how long? PCBs within a single enclosure? Between enclosures in a lab? Between enclosures in an industrial setting? Between buildings or further?
3. What needs to be done about protection, filtering, error correcting, etc.? This will depend on answers to #2 (a long cable run is likely to pick up more interference and surges than one within a lab or enclosure), but also depends on how reliable and robust you need it. Likewise, how much noise the system is allowed to radiate is an important spec.
Oh, wow. I didn't know there would actually be circuitry inside an Ethernet connector. Transformeres, LEDs and the impedance matching in one package.
I guess can't use Ethernet connectors with built in transformers to carry DC through the other twisted pairs.
The reason that got me thinking about a differential connection was to not flood my studio with electromagnetic fields from the digital signal cable. There is lots of analog circuitry running through cables in the room. most of it is balanced/differential though.
I would probably use a bare jack and the transformer. Just to have direct access to the other 6 pins.
The Signal is an ADAT digital audio signal. 12.188Mbit/s is the bitrate. I have an optical TOSLINK input in the transmitting device. It gives me an output signal between 0,5V (Low) and 4,5V (High). I want to take the output of this optical reciever, make it differential and send it to another device that has an ADAT decoder/receiver.
Why not just transmit the optical signal to the other end?
I sadly don't recall the ADAT specification but I *think* it may be a NRZ (non return to zero) based single ended digital TDM representation. If you have a NRZ TDM signal that isn't guaranteed to have good short term one to zero level frequency balance then there can be low frequences, maybe even DC represented in the single ended waveform. Differential encoding by itself does not fix the DC / low frequency content of a signal, so that signal may not be suitable to be transformer coupled depending on the lowest frequency which the transformers can carry.
If you don't identify WHERE you are (by completing your user profile), then you can't really complain about suggestions you get from an international forum.
Even though it likely costs much less than copper to actually manufacture, optical fiber cable still sells for premium prices.
Yes, you're right, the lower limit of the bandwidth should be above 1MHz given a 10 bit maximum "cycle time" and 12MHz UIs. So I suspect that the 10-Base-T ethernet transformers would work though I don't recall their specific bandwidth limits it seems unlikely that such a short cable run would have problems with the bitstream.
Why not just transmit the optical signal to the other end?Because then I'd need extra cables for power. I want both power and ADAT stream in a single cable.
Why not just transmit the optical signal to the other end?Because then I'd need extra cables for power. I want both power and ADAT stream in a single cable.
Not a unique requirement... The first google result of many is
CX-Series - Deployable/Composite Copper/Fiber Cables
Applications:
Used in outdoor applications that require both optical fiber and copper wire elements for communication and power
Copper wire can power remote electronics used in fiber optic communications
Copper wire can also be used for low data rate data transmission
Deployable cables have been used in network and private broadcast applications around the world
Cables can be designed for your custom applications
Cable is designed for use with United States National Electric Code (NEC) class 2 power sources
http://www.occfiber.com/main/index.php?m=1&p=2&l=en&i=304
Why not just transmit the optical signal to the other end?Because then I'd need extra cables for power. I want both power and ADAT stream in a single cable.
Not a unique requirement... The first google result of many is
CX-Series - Deployable/Composite Copper/Fiber Cables
Applications:
Used in outdoor applications that require both optical fiber and copper wire elements for communication and power
Copper wire can power remote electronics used in fiber optic communications
Copper wire can also be used for low data rate data transmission
Deployable cables have been used in network and private broadcast applications around the world
Cables can be designed for your custom applications
Cable is designed for use with United States National Electric Code (NEC) class 2 power sources
http://www.occfiber.com/main/index.php?m=1&p=2&l=en&i=304Yeah, good luck finding anything remotely resembling that that doesn't cost the better part of $10 per foot.
Even install-grade fiber is remarkably expensive. And you don't want to know what tactical-grade fiber cabling costs.
Quite probably! I've no idea where to buy it because I'm not intertested and it isn't my problem.
My point was only that the reason given for not using optical transmission was invalid.
It is a classic time-vs-cost tradeoff. If someone simply wants the job done and dusted, it is probably simpler to grit teeth and buy it. If someone wants a "learning experience" (especially with rework) and the cost of their time is zero, then there's no reason why not to roll-your-own.