SYB Posted July 10, 2008 Share Posted July 10, 2008 Can I send analogue signal down an SDI musa connector? Also going to buy some musa connectors how many different types are there? Thanks in advance Link to comment Share on other sites More sharing options...
broadcast_techie Posted July 10, 2008 Share Posted July 10, 2008 Yes - is the short answer.The long answer is that SDI was designed to be used within existing analogue infrastructures. Kris Link to comment Share on other sites More sharing options...
boatman Posted July 10, 2008 Share Posted July 10, 2008 ... Also going to buy some musa connectors how many different types are there? It's more years than I care to think about since I worked in the BBC P&ID. Back then there were only two female MUSA connectors; for PSF1/2 & PSF1/3 coax cables and of course U-links for video jackfields. However, there was quite a variety of male panel mount connectors and barrels. Be aware that the MUSA was developed in the 1930s as a rotatable connector for RADAR installations and has a 50 ohm characteristic impedence. This wasn't usually a problem for baseband video but did prove to be a problem when we were developing the Eureka 1250 line HDTV system in the 80s. I don't know how well it handles the SDI signal. Link to comment Share on other sites More sharing options...
broadcast_techie Posted July 10, 2008 Share Posted July 10, 2008 Musa connectors only vary to fit the type of cable they are being connected to. ie, if you have cable type X you need musa Y. There is no difference with regard to the actual musa side. One solution may be to buy BNC/Musa adaptors and use existing BNC cabling... As I said, SDI is fine over musa... Kris Link to comment Share on other sites More sharing options...
peternewman Posted July 10, 2008 Share Posted July 10, 2008 Be aware that the MUSA was developed in the 1930s as a rotatable connector for RADAR installations and has a 50 ohm characteristic impedence.Fascinating, you learn something new every day. Regarding the characteristic impedance, certainly Canford and some of the other suppliers offer 75 ohm MUSAs, their newer ranges claim to have redesinged connectors for 75 ohm that will suit SDI and HD well (although I guess some of that may just be marketing). I don't know and I'd be interested when or if most video MUSAs became 75 ohm impedance. To second what Kris has said, yes analogue will work fine over SDI MUSAs and SDI will also work over analogue MUSAs. Link to comment Share on other sites More sharing options...
david.elsbury Posted July 11, 2008 Share Posted July 11, 2008 Is the Musa connector related to the car radio antenna connector? The look rather similar ?!? Link to comment Share on other sites More sharing options...
Brian Posted July 11, 2008 Share Posted July 11, 2008 Be aware that the MUSA was developed in the 1930s as a rotatable connector for RADAR installationsMUSA = Multiple Unit Steerable Array ...claim to have redesinged connectors for 75 ohm that will suit SDI and HD well (although I guess some of that may just be marketing). :) You can never design a true 75 ohm MUSA as long as you want it mate with existing connectors. Link to comment Share on other sites More sharing options...
peternewman Posted July 11, 2008 Share Posted July 11, 2008 Be aware that the MUSA was developed in the 1930s as a rotatable connector for RADAR installationsI kind of made an assumption before, but was the connector designed for mounting at the pivot and providing a slip ring style arrangement, only with move of the characteristics of a coaxial cable than a pair of slip rings would provide? You can never design a true 75 ohm MUSA as long as you want it mate with existing connectors.Presumably this is because the characteristic impedance is defined by the spacing primarily, so you'd have to have a different sized pin or shell? Obviously neither of which would mate properly. I guess it just goes to show quite how resilient composite and particularly SDI really is, or perhaps just how we make an unnecessary fuss about characteristic impedance (DMX over mic cable anyone? :)). Link to comment Share on other sites More sharing options...
boatman Posted July 11, 2008 Share Posted July 11, 2008 Be aware that the MUSA was developed in the 1930s as a rotatable connector for RADAR installationsI kind of made an assumption before, but was the connector designed for mounting at the pivot and providing a slip ring style arrangement, only with move of the characteristics of a coaxial cable than a pair of slip rings would provide? Yes, that was what it was used for. When I attended my first course at Wood Norton as a graduate engineer back in the 1960s most of the equipment in use there then was still of 1940s & 50s vintage and the staff were always keen to talk about the history of it all. Link to comment Share on other sites More sharing options...
Brian Posted July 12, 2008 Share Posted July 12, 2008 Presumably this is because the characteristic impedance is defined by the spacing primarily, so you'd have to have a different sized pin or shell?Exactly. The problem with some 'analogue' MUSA was that the reflections caused by the 50/75 mismatch were exactly at multiples of the 270 MHz fundamental of the SDI signal. Link to comment Share on other sites More sharing options...
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