Patch panel cables

I am working on building a new rack system, and it is my first time. The system will consist of two racks. I'm coming out from a Sony Optical Multiplexer (HD-SDI) and into a pass-thru patch panel. The second rack will have the SmartHub Router, and will be connected to a pass-thru patch panel. When at a job the two will be connected with a short (hd-sdi) connecting cable. My question is, will having the three short (18" connecting and 8" patch) patch cables affect performance?

You will be WAY more then fine. If you were stringing 4 cheap 100' cables together I'd start to worry but under 50' even the wire doesn't make much difference most if the time. Also remember that digital signal make it or don't there is no "sort of works".

That's good to know, thanks for the info

Depending on which connectors and patch panels you use, there may be +/- 3 dB of loss in each connector. Doesn't really matter with the cable lengths you're talking about.

Is there a formula for loss per connection or cable length?

That is individual for the cables and connectors. You'll find it in the data sheet for the specific cable or connector.

Well good connectors will not really have enough loss to get excited over unless you have a lot of them in the line. Cable will have a specified loss per 100ft given my the manufacturer at many different frequencies. An example is at the bottom of this page http://www.gepco.com/products/proav_cab ... _sdi_F.htm
Please remember that the equipment we use has been designed to cope with line loss so don't go crazy with the numbers 20-30dB of loss should still be fine.