Welcome to the fourth instalment of our Shure Whiteboard Sessions, we hope you’re enjoying the new series thus far. In this week’s video, we get stuck into some wireless microphone best practice with our explanation of how to coordinate a wireless system (or frequency coordination as it’s otherwise known).
Some basics to consider
The first fundamental to understand when coordinating a multi-system setup is that each receiver can only receive signal from one radio transmitter at a time. For this reason, if you’re running two transmitters, you’re going to need two receivers tuned to separate frequencies. If you don’t set up your system in this manner, and you assign two transmitters to the same receiver, you’re bound to experience interference. Additionally, if you tune two receivers to the same frequency as one transmitter, then both receivers would pick up the same audio. The long and short of it is this: always pair one transmitter to one dedicated receiver.
Once you’re comfortable each system is accounted for with its own dedicated transmitter and receiver, it’s important to always adhere to minimum frequency separation. The graph below represents a typical RF transition from a wireless system; the amount of these transmissions we can fit next to each other will depend partly on the quality of the wireless system. Typically, lower-end systems have a larger RF footprint than higher-end systems – meaning they take up more space, which makes safely stacking many systems next to each other more difficult.
Now on to the tuning process…
During any wireless tuning process, it’s important to ensure there is a clean noise-floor, and that you’re operating in a nice clean portion of RF spectrum. The graph below illustrates how a typical spectrum landscape might look having completed a quick scan. In the scan, we can clearly see the RF noise floor; a selection of digital TV channels; and a handful of existing radio mics in the local area. The gaps you can see in-between TV and other radio mics represent white spaces where we can potentially deploy our wireless channels.
Many entry-level systems will perform a scan and deploy the system onto a clean channel automatically. More advanced systems, on the other hand, are capable of scanning the entire tunable bandwidth – building up a bigger picture of the RF landscape and performing spot checks to determine the best operational frequency. Also, all Shure systems have built-in pre-set groups and channels. These carefully harmonised groups are designed to make coordinating a multi-channel system easier by removing much of the guesswork. Without them, tuning a ten channel system (as demonstrated in the video) would be more susceptible to risk.
All of the pre-set channels within a given groups are designed to be compatible; again, observing minimum frequency separation and avoiding intermodulation distortion. In a completely ideal RF environment (say a desert for example) we could tune all ten of our systems onto different channels within group one and be guaranteed a clean setup. In the real world, it’s not quite that simple – but you get the point. The group(s) you choose to operate in will depend on application and the equipment in use. Bear in mind, though, if you choose to operate across multiple groups, a clean set of compatible frequencies is not guaranteed.
Using Multiple System Types
Tuning our system to multiple channels within a single group works great if we’re only using one type of system and brand, but what if we’re presented with a mix?
For example, if we take our ten system rack of radio mics from the example above, and then introduce a rack of in-ear monitor systems to run side-by-side, things get a little more complicated. Both systems will have multiple groups of channels, with no guaranteed compatibility between them. In fact, group one channel one could be the same frequency on both systems. In this instance, you will need to perform a custom frequency coordination using specialist software, such as Shure Wireless Workbench. This software allows you to intelligently scan the RF environment and deploy wireless systems based on your custom inventory list. The software understands the relationship between the groups and channels of each system before scanning the environment for a clean and compatible set of frequencies. These frequencies might spread across multiple groups, but we can still guarantee compatibility; because, in this instance, the software has performed the calculations for you.
We hope you found this introduction helpful. To learn more about how to successfully coordinate wireless systems, consider attending one of our Wireless Mastered or Wireless Workbench training sessions. To ensure you don’t miss our next whiteboard session video, please subscribe at LosingYourVoice.co.uk or simply enter your details below. If you missed last week’s video, check it out, here. See you next week!