Description
BAL SDI VIDEO CABLE CLONES
The BAL SC75A Series SDI cable clone range provides practical emulation of coaxial cable from 5m of up to 500m length, for use when testing and aligning SDI video systems.
All BAL SC75A Series Cable Clones use BNC connectors and are 75 ohm impedance to match the cable. They use high-quality switches for selection of simulated cable lengths and require no power. The bandwidth of 360MHz preserves waveform shape. They are enclosed in compact, rugged die-cast aluminium boxes, 116 x 38.5 x 31mm for the four- switch and 138 x 95 x 49mm for the eight-switch versions. Conversion factors for industry standards of coaxial cable are provided.
Specifications:
|
Cable-Clone type | Switches | Cable types | Simulated lengths |
|---|
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SC75A045B-B | Four | BBC PSF 1/2M | 5 + 10 + 10 + 20m |
|
SC75A375C-A | Four | Belden 1505A | 25 + 50 + 100 + 200m |
|
SC75A1694A | Four | Belden 1694A | 25 + 50 + 100 + 200m |
|
|
BAL SC75A375B-A | Four | Belden 8281 | 25 + 50 + 100 + 200m |
|
BAL SC75A375B-B | Four | BBC PSF 1/2M | 25 + 50 + 100 + 200m |
|
|
BAL SC75A37B | Four | BBC PSF 1/2M | 23 + 58 + 115 + 230m |
|
| | Belden 8281 | 23 + 58 + 115 + 230m |
|
| | BBC PSF1/3M | 18 + 45 + 89 + 179m |
|
| | RG59 | 17 + 42 + 83 + 116m |
|
|
BAL SC75A510B-A | Eight | Belden 8281 | 5 + 10 + 10 + 20 + |
|
|
BAL SC75A800B-G | Four (i) | BBC PSF 1/2M | 25 + 50 + 100 + 200m |
|
| | Belden 8281 | 25 + 50 + 100 + 200m |
|
| | BBC PSF1/3M | 19 + 39 + 78 + 156m |
Note: (i) Eight switch Size.
Technical Note:
The SDI, serial digital video interface, SMPTE RP259M and EBU Tech 3267 standard defines characteristics of the protocol and the electrical interface. The SDI signal is transported via coaxial cable from one piece of equipment to another. Characteristics of coaxial cable are well known in terms of delay and loss. In a well-designed system using studio quality cable, lengths of 300m are possible. The SDI signal operates at a data rate of 270Mbits per second, with frequency components in excess of 270MHz, and is transmitted at an amplitude of 800mV. To ensure reliable reception, the best possible transmission of the original waveform is required at the receiving equipment and automatic equalisation is used to optimise performance. Unlike analogue systems, which degrade progressively with worsening signals, the SDI system works well until a practical “knee” in performance is reached. At this point the system fails rapidly. SDI test equipment is used to measure error rates on the system, as well as “jitter”, the accuracy with which a crossing point can be detected by SDI receiving circuitry. The quality of this is determined by the state of the signal sent and low-pass filtering effect of cable. It is essential to know that all parts of the system are operating well below the critical point. One way to do this is simply to add a length of cable and check that the signal is unaffected. The BAL SC75A SDI cable clone range provides a very convenient replacement of bulky lengths of cable. The unit is connected into the signal line and simulated cable lengths switched in until the signal shows errors. In this way a very accurate assessment of headroom is achieved.