SD-SDI HD-SDI Dev Boards ? - Page 1
Forum section: electronics / projects

author: chris_leyson
author_rank: Super Contributor
timestamp: October 27, 2017, 11:27:00 am
content: Hi, anybody know of any SDI development boards or application notes either for standard or high definition SDI ? I would like try SD-SDI SMPTE 259M at 270Mbit/s or 360Mbit/s to start with and monochrome only. Ideally power over SDI with a back channel would be nice.EDIT: Found some Eqcologic now Microchip app notes so that's a good startChris

author: dmills
author_rank: Super Contributor
timestamp: October 27, 2017, 11:51:18 am
content: Power over SDI??!New one on me, SDI has an annoying (by todays standards) misfeature in that it is NOT DC balanced so it has a lot of low frequency content, in fact one of the standard tests is a so called SDI Pathological signal that seeks to break it by stressing exactly this.I would expect any power over that link (never mind a back channel) to enough jitter to cause a problem for meeting spec.There is no 8B10 or anything of that sort, hence the need for (typically) 4.7uF coupling caps in a signal that can have GHz of bandwidth, it is annoying that way.The standard dev board is a modest FPGA, and for SD you don't even really need transceivers (You do for 1080 based modes), Quite a few of the xilinx boards have SDI capability on board, but that is usually designed for 3G which gets you into oversampling shennanigans for SD as the transceiver clocks do not go slow enough.Regards, Dan.

author: chris_leyson
author_rank: Super Contributor
timestamp: October 27, 2017, 12:43:39 pm
content: Hi Dan, after a bit of searching I think I should change the the title to CoaXpress. Microchip aquired Eqcologic and now sell the EQCO30R5 and EQCO30T5 chips for either end of the link, power over coax and a 20Mbit/s backchannel included. You're right, the link is not SDI but SDI with extra bit stuffing. Microchip have some very basic data sheets on the EQCO30T5 and EQCO30R5 and no application notes so I would probably need to join the CoaXpress consortium to get any useful information. On the other hand I could reverse engineer an EQCO-SDI-30-7502 repeater.

author: dmills
author_rank: Super Contributor
timestamp: October 27, 2017, 02:54:08 pm
content: Distinct shades of the old AMD 'TAXI' bidirectional link over coax chips that MADI audio was based around back in the day.I would be nervous around single sourcing issues with these, as they do not output SDI on the wire side in any form that anything else (Including things like waveform monitors) will really understand.These just scream CCTV industry to me.Regards, Dan.

author: Scrts
author_rank: Frequent Contributor
timestamp: October 27, 2017, 03:34:18 pm
content: You can check DekTec and Blackmagic equipment, but it is expensive. I've done SD-SDI on FPGA on regular LVDS. Altera Cyclone II was capable of that.

author: dmills
author_rank: Super Contributor
timestamp: October 27, 2017, 04:57:05 pm
content: Not sure I would call BMD expensive, it is all at the very, very cheap end of the market (But then nobody does SD any more, or at most does it as an afterthought).But yea, SD is well within the capacity of any semi modern FPGAs LVDS IO, given a suitable line driver and equaliser.The elephant in the room is that good gear for physical layer examination of SDI is expensive and slightly uncommon, Tek, Leader, Omnitek and Phabrix have product but most so called SDI vectorscopes will not actually draw you an eye, they work in the video domain not the physical layer, the physical layer eye and jitter option usually costs real money.Regards, Dan.

author: chris_leyson
author_rank: Super Contributor
timestamp: October 27, 2017, 05:07:48 pm
content: QuoteThere are quite a few machine vision companies selling cameras with CoaXpress or CXP interfaces and mostly PoCXP. The standard is maintained by Japan Industrial Imaging Association and is free to download. Physical layer is 8B/10B and that is as far as I got spending most of the afternoon reading the standard. The Microchip EQCO30T5.2 is pin compatable with TI LMH0303 cable driver for data in/out and supply pins, why Microchip would even bother to mention that is behond me because the functionality is completely different, but yeah it's a cable driver.QuoteThe machine vision cameras I've looked at are a bit cheaper but still very expensive.I was looking for solutions for the physical interface at each end of the cable and I think I've found just enough information from the Microchip datasheets to have a stab at something. SDI cameras with RS485 control are cheap and available from China but not sure about the other end. Damn, going to have to borrow a high speed scope for this

author: Richard Crowley
author_rank: Super Contributor
timestamp: October 27, 2017, 05:17:18 pm
content: I kept meaning to ask that question: Are there no DIY hacks for viewing eye patterns on HD-SDI? (or HDMI, for that matter)

author: chris_leyson
author_rank: Super Contributor
timestamp: October 27, 2017, 05:36:42 pm
content: QuoteGood question, if I stick with SD-SDI I can use my HP 54610B, it's got enough bandwidth. For HD-SDI maybe a higher speed phase locked sampler.

author: dmills
author_rank: Super Contributor
timestamp: October 27, 2017, 08:48:22 pm
content: Phase locked sampler and a lower speed ADC is the usual way, but you are looking at 20GHz bandwidth at the input to get a decent eye, and just calibrating that kind of thing is a headache.Some kind of diode switch would be my guess, but it is all going to be painfully compact and probably on duroid or similar.Regards, Dan.

author: chris_leyson
author_rank: Super Contributor
timestamp: October 28, 2017, 12:57:40 am
content: Thanks for all the sugestions guys, looks like I've opened a can of worms, a $10 solution in silicon costs $100,000 to design and test. It's no wonder that there are not many players in the CXP camera game. From a machine vision physical layer point of view, a bit of RG6 and it's job done.

author: dexters_lab
author_rank: Unknown
timestamp: October 29, 2017, 10:19:41 am
content: I have a sd-sdi analyser, pretty sure it did eye diagrams, pass/fail analysis etc, it's a synthesys research dva-184cIt is pretty old but then so is sdiI can loan it if you cover postage to/from me

author: dmills
author_rank: Super Contributor
timestamp: October 29, 2017, 01:45:59 pm
content: That thing is a blast from the past, but quite adequate for 270Mb, just not the modern quick stuff.I had forgotten all about synthesis research.Regards, Dan.