From left: Greg Riggs, Moderator, Gary Stigall, Criss Niemann, Karl Winkler
On Tuesday night, May 29, 2018, the Audio Engineering Society Los Angeles Section met at the School for Audio Engineering (SAE) Hollywood. Greg Riggs, AESLA Executive Board member and Manager of Private Brands for Guitar Center, moderated a lively discussion on the changing landscape of wireless communications, the challenges of frequency coordination, and the impact on the entertainment and news industries. The panel was comprised of Criss Niemann, Senior Market Development Specialist for Shure, Karl Winkler, Vice President of Sales & Service for Lectrosonics, and Gary Stigall, frequency coordinator for the LA Chargers and LA Rams. Among the topics, the panelists covered FCC spectrum allocation, negotiating frequencies with your neighbors in a crowded environment, what you can do when your wireless transceivers become obsolete, and what changed when analog shifted to digital.
Gary Stigall opened by noting that "it's going to be a very interesting year for us. TV channels are going to be disappearing and reappearing throughout the band, and it's going to be up to us to keep track of who's up and who's not." Through congressional acts and FCC actions, the 600 MHz VHF band that was formerly allocated to television stations has been auctioned off, much of which was purchased by T-Mobile, who is using these frequencies, starting with low-populated rural areas such as Cheyenne, Wyoming. As bandwidth disappears, the demand for wireless mic frequencies continues to rise, with events like the Super Bowl using over 4000 frequencies. Gary noted it took twenty people just coordinate all the users, saying, "It's a big effort."
Karl Winkler, who originally trained as a violinist and violist, expressed his appreciation for the complexities of the field: "Wireless mics are really where the rubber meets the road. You know, you've got your transducers, but then you've got the whole radio element and all the extra points of gain structure with radio and audio so there's a lot to it, and for me, it's been a fascinating journey to learn about it." The simplest applications of wireless audio might be in a television studio, and may involve a couple of dozen channels when you include on-air talent and IFB (interruptible fold-back, used for cuing and intra-studio communications). A mid-level application might be a Broad-way theater, with perhaps a 100 active channels, but that particular example is more challenging that it might seem, given that there are dozens of theaters in a few blocks, and so the coordination problem becomes acute.
Greg asked Criss Niemann how Audio/Video integration, typically in a corporate setting, differed from these entertainment and broadcasting applications. Criss replied, "There's a hospital nearby that I worked on that has two channels per room, but seventy-five rooms. It's almost easier to coordinate knowing everything is going to be in one space, because with a situation like that, you don't know how much attenuation between floor to floor or building to building." He also noted that the trend has been to use as little power as possible for any application, in order to allow a greater number of discrete channels, and not impact your neighbors, and the newer digital systems allow this. Furthermore, in these corporate applications he generally will lock down the equipment's settings, as an unaware user could easily change to frequencies not cleared for use and create problems for their wireless-using neighbors.
Criss also spoke of his experience with touring bands, where he has seen a guitarist use up to forty transmitters, just so that every guitar on the stage can be picked up and played as desired. Interestingly enough, he has found one of the biggest RF challenges with a touring band can be the LED wall, individual panels which are tested for leakage, but when assembled as an array often produce quite a bit of noise, all of the panelists nodding in agreement.
Gary remarked on how the exploding use of wireless is impacting long-time wireless users. He described a situation at Minneapolis's Mall of America this year where he was coordinating frequencies in advance of the Superbowl, and suddenly found a huge source of RF. As it turned out, it was the Today Show creating some material for the following day. Gary had to convince this crew to go wired until they could be coordinated, but it took some persuasion because their work methods had never be-fore affected anyone else. The three panelists noted that the FCC does not have any enforcement officers, and so following the law and enforcing regulations requires a good amount of finesse and politeness to steward the spectrum in a fair and effective way.
Certain parts of the spectrum are unlicensed by the FCC and can be used by anyone, such as 1.9, 2.4 and 5.8 GHz. Wireless cameras operating in the 5.8 GHz range have become popular, so popular in fact that these camera crews are frequently running into each other. While these bands can have profession-al applications, the panelists did not recommend using them for more than one or two non-critical channels.
Greg noted that in the days of analog TV, it was possible to transmit wireless audio in spaces between the television channels, where the television signal would "basically have three hotspots," but digital television uses the spectrum in a much more expansive way, leaving no gaps for this kind of use. Greg also noted the problem of intermodulation, or the creation phantom signals caused by the close proximity of two real signals and their interaction, and how that can prevent a fuller utilization of the available spectrum.
Karl and Criss went on to discuss some of the reasons for the FCC spectrum sale and television repack. "It's practical antenna size. Very typical antenna geometry is one quarter wavelength and for these UHF frequencies that's a few inches. Something that can fit into a portable battery powered device and have good reception." In contrast, television channel 2 requires an approximately 9 foot antenna. These 600 MHz frequencies penetrate walls relatively well while still allowing for devices of manageable size, and thus are highly attractive to all potential users, including the cell phone companies.
Ron Streicher in the audience raised the question of compensation for the loss of use of equipment he had purchased. The panel replied that Japan had in fact done just that as they were going through their own spectrum reallocation, and that they had lobbied for a $500 million fund to purchase and upgrade equipment for wireless users, but in the U.S. the idea had received no traction. The panelists spoke of their efforts to make the FCC aware of the needs of the three million wireless microphone users in the U.S., but had been hampered by the fact that up until recently, there had been only 914 licenses granted for these uses, and so the FCC greatly underestimated the impact the loss of these frequencies might entail. The recommended reaching out to our elected representatives to make sure we are heard, and to respond to any FCC requests for comments.
The AES-Los Angeles wishes to thank Criss Niemann, Gary Stigall, and Karl Winkler for a fascinating and informative evening.
