Wireless microphone technology is a natural fit within broadcast production and TV-UHF technology brings additional reliability through dedicated frequency access.
For many decades, wireless microphones have had their firm place in broadcasting, electronic news gathering (ENG), videography, and filmmaking due to the freedom of movement, unobtrusive miking options and quick set-up they provide. This in turn has accelerated the democratisation of content creation and witnessed a leap in creativity and tools, and would suggest, blurred the lines between professional, semi-professional and amateur use of wireless microphones.
Deciding on a system – why and when it makes sense to use TV-UHF
Whether you are working as an independent one-person video team or are part of a broadcaster’s ENG crew: The choice of equipment is your starting point and may limit or expand the further development of your audio content. If we disregard “exotic” systems like Sennheiser’s AVX which works on 1.9 GHz, the market appears to be split between digital 2.4 GHz systems that promise unique ease of use and quick audio capture, and digital or analogue wireless systems that operate on TV-UHF frequencies, offering maximum transmission reliability and professional accessories.
Where can you benefit from a compact and handy 2.4 GHz system? It can be a valid choice in areas with little wi-fi activity. However, if you are in the city center, a tradeshow or a festival where there is much wi-fi activity, you will find your audio transmission interrupted, buzzing, crackling, or not working at all.
Enter TV-UHF systems, which are far more reliable. They work on a dedicated UHF frequency that you selected, maybe even on one that you paid for to use exclusively, so good audio capture is guaranteed. TV-UHF frequencies generally have better propagation properties than 2.4 GHz frequencies, which can express itself in range, less body attenuation and an ability to more easily transmit through walls, cars or people.
TV-UHF systems are physically bigger than their 2.4 GHz counterparts, but the additional size is feature-packed: they give you substantially more control of the audio and the RF. You can use them with a wide variety of professional clip-on microphones. The receiver connects both to 3.5 mm jack inputs and to the more professional XLR camera inputs. Battery life is often longer, and batteries are swappable. Regarding ease of use, a lot has happened in TV-UHF wireless, too, especially with the latest digital models.
Advantages of going digital in TV-UHF
Compared to their analogue counterparts, good digital TV-UHF wireless systems offer audio, RF and workflow advantages that may be important in your work.
Audio: Unlike analogue systems, digital wireless systems do not need a compander (compressor/expander). Therefore the associated noise is gone – and your audio will sound crisper and clearer.
RF: More sophisticated digital wireless systems hardly emit any intermodulation artifacts. These spurious frequencies clog up the available spectrum and will require some planning efforts in spaces with several wireless mics. If you are filming at or reporting from, say, a music festival or a major sporting event, it will be easier to get your digital gear included into the overall frequency plan. While analogue UHF (or lower-quality digital) requires you to calculate intermodulation products, quality digital wireless enables you to simply deploy transmission frequencies at regular intervals.
Workflow: Digital wireless microphones offer unprecedented ease of use and intuitive set-up. Let us take a look at Sennheiser’s new EW-DP system - it requires little RF or audio knowledge, and minimal attention from the videographer in general: The receiver or the associated Smart Assist app finds a free frequency, then the transmitter is synced via Bluetooth. If any issues occur, the system will guide users with Smart Notifications. It sends alerts for audio clipping, low battery (exact read-out in hours and minutes is provided, too), occupied frequencies, muted transmitters, and unlinked devices – and all come with a suggestion of how to quickly solve the issue.
Audio for video solutions will continually advance, aiming to make solutions more compact and intuitive. Digital will certainly be the route to go, as it makes workflows so much smarter and faster. Who knows, maybe there will no longer be a microphone receiver in a few years’ time?
A few practical tips when working with wireless microphones
Most shoots are done with unobtrusive clip-on microphones (also called lavalier or lapel microphones). The most widely used polar pattern is omni, as it is very forgiving when it comes to wind noise and plosives and will reliably pick up the audio even when the interviewee moves their head. In very loud environments, you may choose to go with a cardioid mic.
When working with inexperienced interviewees, a clip-on mic is probably the best choice. If you are using a handheld and need to be out of the picture, give some instructions on the ideal mic/mouth distance and ask them not to cover the mic’s antenna with their hands.
When working with clip-on mics, correct and secure positioning is key. The mic should be attached at about 25 cm from the interviewee’s mouth. Make sure that there are no scarfs, necklaces, brooches, rustling clothes or hair that could get in the way of the mic. Delicate clothes may require other mounting accessories than a clip. Make sure to bring a range of fastening accessories including tape sothat you can make sure the mic and its cable will stay in place firmly. The same goes for the transmitter – make sure it is securely attached. The last thing you want during a shoot is a transmitter that gives in to gravity or your mic sliding down a lapel! The transmitter unit should be attached such that the antenna is at a distance of about 1 cm from the body.
Gain setting is important with wireless mics: Carefully select the sensitivity at the mic (not required with EW-DP) and on the receiver/camera side. EW-DP will send smart notifications if it detects any audio clipping.
When filming outdoors, wind noise will be of major concern. Bring blimps and hairy windshields for all of your mics, including the clip-ons. Some microphones have a low-cut filter that helps reduce wind noise – make sure this is activated. Position the interviewee such that their body is a natural shield against the wind.
While you want to make sure that interviewees cannot accidentally operate any mute switches on the transmitters during the shooting, do make sure you respect their privacy and mute their transmitters during breaks.
‘Be prepared’ is the motto of every filmmaker and videographer. Take enough fresh battery packs and replacement clip-on mics with you. Gaffa tape is certainly a firm part of your kit, as well as white tape for marking camera and interviewee positions.
Always switch on the receiver first, either to listen in on a frequency you would like to use or to have the receiver do a spectrum scan for you. Be aware that your system will also be emitting intermodulation products when you are using an analogue system or a lower-quality digital system.
When filming at a large event, program your wireless system to the frequency assigned to you by the frequency coordinator before you enter the site. Never switch on transmitters whose transmission frequency you do not know during an event.
Try to keep as much distance as possible between transmitter and receiver antennas – especially inside a sound bag.