What’s the use of oscilloscopes (scopes) and other testing gear? Don’t you already have a broadcast monitor or laptop with everything in it?
Yes and no.
Rule of thumb: If you’re doing a project for the web or DVD, then expensive testing gear is probably overkill, not to mention financially nonviable.
What if you have a multicam setup in a broadcast environment?
What if you’re streaming or broadcasting live?
What if you have many monitors and devices along with switchers and other gear?
What if color and signal accuracy is paramount (as in film, scientific, medical or broadcast work?)
You see, when you have one monitor, you have no option but to trust it. When you have two, showing dissimilar images, which one do you believe? This happens more often than not. The more the devices, the worse it gets.
For these reasons, when a lot of signal is flowing around on set, the only way to keep everything under control, is with signal testing equipment.
This rigging guide is for the novice filmmaker or videographer, so there’s no point going into details. Only a trained engineer can operate and fully utilize all the information a scope provides. For everyone else, let’s stick to the basics, as outlined earlier.
These are some important tools that comprise a testing system:
- Digital Oscilloscope
- Signal Generator (with Sync Pulse Generator)
- Digital Multimeter
Note: All the cameras used in this guide are digital in nature, but analog signals are still found on some broadcast cameras.
For a single SDI feed, with a laptop for display, the ideal solution is a Blackmagic Design Pocket UltraScope:
If you want a PC setup for your data station, you could use the Blackmagic Design Ultrascope Card instead.
These are okay tools, and probably good enough for simple testing. When everything is hunky-dory, they work. But when signals misbehave, they are lost. Personally, I find it more beneficial to trust the in-camera monitors over cheap solutions.
Scopes are the bread and butter of a video signal testing system. Waveforms, vectorscopes, you name it. If you’re feeling adventurous, download one of the manuals and try reading.
Take a look at the Leader LV5382. This is a top-of-the-line product that gives you the best of everything, and a whole lot more:
Note: HDMI is a difficult standard to monitor, simply because it only specifies ‘how’ a signal should be packaged, not ‘what’ that signal should be – unlike HD-SDI. In fact, it is surprising that technology has gone miles ahead, while those making the standards are still scratching their heads. Can’t blame them. It’s changing too fast!
Take a look at the Tektronix WFM2200. The more the systems, the more running around an engineer might have to do.
Try the Tektronix PQA600 system.
What if you’re shooting RAW?
RAW means the signal only contains data in a specific format. There is no color space or ISO attached to it, even though it will have a gamut (which is defined by the sensor-sampling system within the camera).
Furthermore, RAW might also be compressed, as in the case of Redcode. For these reasons and more, RAW monitoring needs software to interpret the signals correctly. Here’s a list of some software for the cameras chosen in this guide:
Signal Pulse Generators
You need these to test systems against a standard known type of signal (a good generator will give you many options), and to generate a pulse to synchronize systems perfectly, like in the case of live broadcast switching or stereoscopy.
Check out these signal pulse generators from Tektronix.
Tools to check other tools? If you want to keep your testing system sane and healthy, and have the knowledge to do so, you should always have a multimeter in hand.
What I’ve outlined here barely scratches the surface. Testing signals, be it in file form (RAW or otherwise) or signal form (HD-SDI, HDMI, etc.), is not an activity to be taken lightly. It is a good idea to rigorously test products often, so that you know they are performing to their utmost.
For further research, I highly recommend the Tektronix Learning Center.
Next we’ll look at accessories for external monitors.