Author: bajabi

The 10 Most Frequent Questions

1) Why should I consider fiber optic connections instead of coaxial copper connectivity?

In the world of UltraHD and 4K you can’t use traditional coaxial cable to run distances longer than 60, maybe 80 meters. With fiber there’s virtually limitless bandwidth available over very long distances. Also, fiber is insensitive to electromagnetic fields, and no interferences can deteriorate the signal in any way. The same holds for ethernet connectivity. You can’t run more than 100 meters over copper without special extenders, but with fiber you can go IP at virtually any bandwidth and at any cable length.

2) Do I need single mode or multimode fiber cable to connect to AJA & Blackmagic Design products?

AJA & Blackmagic Design have deliberately chosen for single mode connectivity. Single mode cable can bridge much longer distances than multimode cable, and at considerably lower cost per meter. They implements highest quality single mode SFP units, in order to guarantee signal integrity at whatever cable length.

3) What is the difference between single mode and multimode?

Light travels through the core of a fiber cable, and it cannot escape because there’s a layer around this core, the cladding, that has a lower refractive index than the core and by consequence acts as a mirror. The light traveling through the core is guided through a reflective tunnel. The diameter of both types of fiber is the same, 125 microns, but a single mode core is only 9 microns, where the core of multimode is 50 microns or more. It’s a historical thing. With multimode it’s easier to send enough light into the core, and lower cost light sources like LEDs can be used, sending multiple ‘modes’ of light into this larger core. With single mode more expensive light sources like laser diodes have to be used, because they have to be able to send only one concentrated ‘mode’ of light straight into the smaller core. Multimode can’t be used at longer distances because of dispersion effects, single mode however uses more coherent light and can go over very long distances without deterioration. Today the differences in costs between light sources have become smaller, and in professional video single mode is being preferred by almost all manufacturers. If we had to choose today, we most probably would decide to go single mode and get rid of multimode altogether, leaving a lot of confusions behind us.

4) How do cables connect to each other and how do they connect to transmitters and receivers?

There are many different connector standards, but they all use the same basic way of connecting. The head ends of the fiber cables are carefully fixed, aligned, and polished and when a connection is made, these head ends are contacting each other very precisely, and the light can pass without reflecting back and without escaping the light tunnel. Good quality connectors don’t introduce much attenuation, provided they are not damaged and are kept clean. Needless to say, dust and dirt are the greatest enemies of light passing these tiny contact surfaces.

5) What type of physical fiber connection is being used by AJA & Blackmagic Design?

Blackmagic Design uses standard LC Duplex connectivity on all equipment. These are the well known blue colored LC connectors, neatly fitting into almost any SFP in the market. The word duplex simply means ‘double’, twofold.
As a matter of fact, all Blackmagic Design equipment uses Duplex, where one of the connections (connector A) is for device input, the other one (connector B) for device output. By consequence the cable has to be ‘crossed’ cable, in order to correctly connect inputs to outputs, and prevent connecting inputs to inputs and outputs to outputs. Most of AJA equipment is using LC duplex connector, but the FiDO series has the basic versions with SC and ST connectors as well.

6) In a single mode setup, can I still use multimode cable instead of single mode cable?

When using multimode cable (orange or aqua colored) things might work at smaller distances, however this definitely is not recommendable. The core diameter is plain wrong for the type of transmitter and receiver being used. Single mode SFPs ask for single mode (yellow colored) cable. And don’t confuse multimode with multiplexing or multiple signals! As explained, the difference between single mode and multimode only pertains to characteristics of the light beam and the fiber string, and has nothing to do with data structure.

7) Can I use low cost patch cable to make the fiber optic connection?

Yes you can, no problem. And you don’t have to worry about signal integrity at all. The actual fiber strings are similar, whatever cable you choose. If you strip a thin patch cable, a thicker cable on a drum, or even s very thick armored cable laying at the bottom of the ocean connecting two continents, you will end up with the very same string(s) of single mode or multimode fiber. So, a single mode fiber string is a single mode fiber string, 125 microns in diameter, with a core of 5 microns, whatever the ultimate form factor of the cable assembly.

8) So why would I go for FieldCast cabling instead of patch cable?

It’s all about the strength of the cable, the robustness of the connectors and the quality of the connection, nothing more nothing less. Patch cable is very vulnerable, and LC connectors can easily break, furthermore they are only guaranteed for 500 mating cycles. So, in the field and even in the studio you need sturdy, easy to use cabling that does not break down or wear out. This is where FieldCast comes in. FieldCast does not add anything to the quality of the signal, it simply changes fiber optics into something very useable, even more useable than coaxial copper cable. And, most importantly, FieldCast is the first fiber optic product to be available from stock, and at a price level that is in balance with the prices of AJA & Blackmagic Design products.

9) Why doesn’t Blackmagic Design use robust connectors instead of LC connectivity?

Transmitters and receivers with LC and SC connectivity as well as SFP housings can be soldered straight to a PCB. However, it is very difficult if not impossible to do this with robust fiber optic chassis connectors of whatever brand. They generally don’t carry the transmitter or receiver part, and cannot house transmitters or receivers. Furthermore, these robust chassis connectors tend to be pretty expensive, raising the costs of the basic product, forcing the end user into investing in high cost cable systems. This is why Blackmagic Design sticks to the low cost standard connectors, keeping the prices down and leaving it up to third parties to come up with adaptive products and offering alternatives to the end user.

10) What third party adapters are available for connecting FieldCast cables to AJA & Blackmagic Design products?

FieldCast offers adapters for both Camera Converter and Studio Camera, called Adapter One and Adapter Two. Both products contain a FieldCast 2Core SM (single mode) chassis connector, so you can directly connect FieldCast 2Core SM Main Cable to it. Adapter One can simply be mounted to the back of Camera Converter and completely protects the vulnerable LC Duplex connection. Adapter Two can be mounted to the right side of Studio Camera, and connects to the LC Duplex SFP with a special short patch cable FiberBrik Two can also be used in combination with AJA FiDO for CION camera. For Blackmagic’s Studio Converter and AJA’s FS1-X FieldCast offers a FielCast Panel containing four FieldCast 2Core SM chassis connectors in a row. At the back these connectors have patch outlets with LC Duplex connectors that tap straight into the SFPs of Studio Converter and FS1-X.