long HD SDI cables

at the last job we experienced problems with long SDI cables (75m and 100m)
connecting a camera direct to a monitor worked fine, but as soon we used any of blackmagic gear we had no or a weak signal. we used 1080i signal, with SD everything worked also with the BM gear.
we used ATEM 2 M/E and Miniconverter SDI>HDMI
what are the tested cable lengths for HDSDI cables from blackmagic.
could it be that the output level of BM gear is lower than it is on other devices?

Hello, I have a problem similar with HDMI cables (20m).
It works in SD but only on input 1 in HD (no on input 2,3 or HDMI 4)...
It works on program output HD.

Gerarld,

That is to be expected. Unless the device re-clocks the signal, every loop degrades the signal strength. What you should be using is a Distribution Amplifier to split the source.

There are a lot of factors that go into the maximum length. It depends on the type of signal and wire gauge. You should follow your cable manufacturer guide.

Just FYI,

I run 200ft 1694a HD-SDI AWG:18 cables to a Videohub with no issues.

smpte has pretty much laid out the guidelines for this and 100 meters is what they say the limit is ... and that is using a good quality rg6 or better with appropriate connectors and that means also no patches etc in between ... this can be substantially less with lesser coax products or patches in between no gender changers barrels etc ... now we like to say 200 ft is the limit because it gives us some acceptable tolerance for cabling

sd sdi on the other hand can go upwards of 300 meters on even rg59 much lower data rate which is probably why everything worked in sd ...

as far as hdmi goes i wouldn't trust anything over 15/20 ft not meters as a zero failure distance for hdmi.

smpte standards have nothing to do with bm vs aja vs gvg etc ... if a product is smpte 292 then you can expect 100 meters +- given best conditions ... that said i'd stick with a lesser distance and if more is needed use a device that can reclock the signal ...

all cable is not created equal. In the US, a roll of Belden 1505A HD-SDI cable is about $450 for a 1000' roll (384 meters). It's expensive. If you are not using double shielded cable rated at 75 ohms, it's not going to work.
Alternates to Belden 1505A are products like Gepco VPM2000, or Canare L-4CFB. And of course, as stated in this thread, if you are willing to run with the thick Belden 1694A, you can go more than 100 meters without issue.

So, rule # 1 - no cheap cable (or connectors.
rule # 2 (as also stated in this thread) - if you are using Copper cable - at some point, you need to reclock the video with a DA - made by Blackmagic, AJA, Cobalt Digital, and so many others. The Blackmagic product is called the Mini Converter SDI Distributor.

But the real answer is STOP USING COPPER CABLE. Blackmagic makes the Mini Converter Optical Fibre, which will run your camera signal with an LC-LC fibre cable for as long as you want - a lot longer than 100 meters. Of course, if you are not in an indoor controlled enviornment, you will need expensive tactical fibre cable.

And when you say "gee, my TV sees it, but these damn converters won't work" - if you have an expensive HD-SDI waveform monitor from Tektronix or Leader, than have an EYE pattern, you can see the square wave breaking down, and the converter, which expects a nice clean square wave, can't recognize the signal. That is why people still buy the expensive scopes (maybe that's coming next for Ultrascope !).

Bob Zelin

actually relatively speaking fiber optic cable is very inexpensive ... we buy tac-4 for less than .75c a ft so aprox 1000 bucks for 1000 ft which is a high estimate ... you can buy it pre-terminated with whatever connectors you want ... compare that to 4 lines of 1694a at about 600 bucks a 1000 ft ... you have spent 2400 on copper that can't even get you as far as you need to go ...

use that extra 1400 bucks to get you some converters ...

fiber is the way to go and it is 1/10 the weight ... when was the last time anyone hulked up 4 1000 ft rolls of coax ?!?

it took us a while to make the move to fiber because so many people were scared about "how expensive" fiber was but when you look at the roi and flexibility and reliability it provides its the way to go for sure !!! copper should really only be used for the "last mile" so to speak let the glass to the heavy lifting !!!

Hi all,

Can't agree to all, first of all there is a good document to figure out what kind of copper cable you may need.
search the internet for " Maximum Transmission Distance at 3Gb/s" it is a pdf from draka cable.
There should be similar from belden canare etc. too....

Yes optical cable are really inexpensive today, and you can really go long ways, and I like optical cable.
But you have some knowledge about optical cable to work with securely, so that you will have an proper link.
There are multimode and singlemode cable. You should not mix them. If a cable is broken, you can't repair it like a copper cable (simple tools for crimping BNC..50 Euros? maybe 100! )
Try this with fibre optic.....

So optical fibre is cool, but not always necessary,

regards Nils

i just got a mic with a xlr 1\4 male mono cable and i want to connect it to my pc i have no idea how to do so is there something i can attach to it ? i really nead an answer fast because if i can't connect it i'll return it back to the store

___________
XLR Cables

I use a heavy duty HDSDI cable from VDC and we often use 90m runs with HD Barrels joining the 30m lengths. This works really well. NOTE that they must be HD BNC barrels and that SD ones do not work. We have 30m 6 way multi which carry normally 3 cameras and 3 sets of sync to Genlock everything. Waveform is fine and output has passed BBC Technical Spec in HD.

Would love to use fibre but price is still too high. Normally 90m is OK but some rigs have had control room positions in funny places. You could have the ATEM in the hall itself and remote it all back on Cat 5 and a multiview if needed.

Hope this helps you

Regards,

John

Best thing we ever did is swap to Fibre for runs like this. You need to keep the tips clean and not tie the cable in knots but it's not rocket science. Yes, breaks are harder to fix but any decent local data cabling company can fit LC, SC or ST connectors or even make a joining splice. Most fibre cable runs redundant pairs and an added bonus is you can use the cable for both data and SDI/HDSDI.

Another plus is you eliminate earth loop potential problems. We blew an output in our trucks HDSDI router driving a copper run to a remote building - we all think of digital as immune to earth loop but it isnt. Fibre fixes that too.

And it isnt expensive once you factor long lengths in.

Pat