Why 100 meter sdi cable not get (send) 1080 50p at the other

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Lakshmikant

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Why 100 meter sdi cable not get (send) 1080 50p at the other

PostWed Sep 22, 2021 5:27 pm

Only Hope From You Sir all over the world

i am using micro converter HDMI to SDI (Updated)and SDI to HDMI (Updated) from my camera to my display (OR recorder). i am getting only 1080 50i, 720 50p, 1080 25p at the other end of 100 meter (328 Feet) sdi cable. when i use 1 (3.2 Feet) meter to 10 meter (32 feet) sdi cable i get 1080 50p. i have not 50 meter (165 Feet) sdi cable so i could not test to 50 meter sdi cable but i think it (1080 50p) should work up to 50 meter (164 feet)

i am using Belden 1505F (it is a rg59 standard sdi cable) (a Very high quality 100 meter sdi cable with very high quality connector)

Please See Picture Here
https://e.pcloud.link/publink/show?code ... PggScbylD7

so my question is
Why 100 meter sdi cable not get (send) 1080 50p at the other end
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Asgeir Hustad

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Re: Why 100 meter sdi cable not get (send) 1080 50p at the o

PostWed Sep 22, 2021 11:02 pm

100 meters 1080p50 SDI is right at the limit with very good cable. 1505F is good cable, but it's a compromise between flex (good handling) and good signal quality.

To find cable lengths, you should look at the attenuation of a cable at half the video frequency. 1080p50 is 3G-SDI, which means you need to look at 1500MHz in the spec sheet.

1505F has an attenuation of of 13.6dB/100ft at 1500MHz. The SDI spec sets a limit of 20dB attenuation before the signal can be lost, which implies a max length of 150ft => 50m. Newer receiver chips may offer better performance, but nothing's guaranteed.

If you instead take a look at 1694F, it's specced as 10.6dB/100ft => ~60m
1694A, 7.8dB/100ft => ~80m.

I have sent 1080p50 100meters with proper 1694a-cable, but it's hit and miss with different gear.
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Lakshmikant

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Re: Why 100 meter sdi cable not get (send) 1080 50p at the o

PostThu Sep 23, 2021 7:01 am

Thankyou so so much for reply
this helped me
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Lakshmikant

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Re: Why 100 meter sdi cable not get (send) 1080 50p at the o

PostThu Sep 23, 2021 7:39 am

Dear Asgeir Hustad Can you please reply here

viewtopic.php?f=4&t=147786
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Dave Del Vecchio

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Re: Why 100 meter sdi cable not get (send) 1080 50p at the o

PostThu Sep 23, 2021 11:42 am

Belden has a maximum cable length chart for different cable types and video signal bandwidths: https://info.belden.com/hubfs/resources ... lletin.pdf

So for 1505F, Belden recommends a maximum cable length of 46m with 3G SDI signals.

In order to support higher bandwidth 4K/Ultra HD video (up to 12G SDI), Belden has introduced a range of cables with better attenuation specs. These typically have product numbers starting with 4xxx and should result in better performance for lower bandwidth signals as well.

So with Belden 4505R which is a similar thickness RG-59 type cable, Belden claims you should be able to do up to 66m @ 3G SDI which is actually a bit better than some of the thicker cables of older design (1694F or 1695A, for example). One other thing you might notice is that the flexible versions of the cable like 1505F or 1694F tend to perform a bit worse than the stiffer equivalents (1505A or 1694A). One other factor is that well used cables that have been flexed or bent multiple times will often not perform as well as brand new cables.

One other note is that in newer versions of the SDI specifications (SMPTE ST 425, 2081, & 2082) used for 6G and 12G SDI, they changed the maximum insertion loss threshold to 40 dB loss at 1/2 the clock frequency (up from 20 dB in the older HD and 3G SDI standards). The bottom half of the Belden cable distance chart uses this threshold, which are why the maximum cable lengths are longer for the same signal type.

So in theory, 6G and 12G SDI hardware designed to meet these newer standards should also perform better with 3G or HD SDI signals as well. And occasionally I have found this to be the case, and a cable that didn't work with a 3G-only input receiver did work carrying the same 3G SDI signal into a 6G or 12G SDI capable input receiver. So sometimes you can put a 6G SDI to HDMI converter (with the loop through output) or a 6G SDI distribution amplifier at the end of a long cable run, followed by a shorter run to the actual 3G destination. This doesn't always work of course, but can sometimes be worth trying if it's difficult to swap out the cable.
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Lakshmikant

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Re: Why 100 meter sdi cable not get (send) 1080 50p at the o

PostThu Sep 23, 2021 4:33 pm

thankyou all for helping me

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