Production BLog

RF Remote Frequency Selection

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Sunday, December 15, 2013

In the past few months, I have been tasked with some larger shows, in which there is a strong RF component, with either onsite time constrictions, or simply, a lot of task loading in other areas in the limited time available.

One of the first shows this summer with such objectives was a local (televised) benefit festival, with numerous A list Canadian artists in a very short period of time (1 day). The requirements of the event were a large stage (SAM550), 4 Hangs of PA, Large 'house' monitor world with 'guest' monitor worlds, Multiple consoles at FOH (SL100Mix), and an extensive RF world.

Traditionally (not the hugest fan on large shows such as this - just like Com falling on the audio department in theatre), RF falls onto the Monitor Tech. On smaller scale shows, with 20-30 channels, it is easily manageable. When you get to this level with over 60 'house' production channels, plus additional band RF, things get filled up pretty quickly.

So with having ample time (2 days) to prep the complete audio rig, with several bodies in the shop to pull gear, I spent 1 day prepping just the wireless.

This involved in finding out what other 'house' production wireless were to be used (such as Truck/Production Com and UHF Radio, Truck Traffic RF) and possibly try to advance blocks of spectrum to guest RF/Monitor techs with artists carrying their own wireless.

It also involved pulling, racking, RF distribution, control networking all of the RF equipment. As well as setting up the transmission characteristics of the Tx and Rx (Levels [AF, RF, I/O], Syncs, displays, etc). In addition, starting the RF frequency coordination.

Since we were bringing in 40+ channels (and another 20 channels from various Trucks), coordination is key. With having our warehouse within 10KM of the festival site, I decided to try an experiment. Scanning and coordinating all the RF from our warehouse environment, and seeing if it transfers to the festival site, on the other side of downtown Calgary, right next to several big RF players (Universities, Hospitals and various high end office units).

Using my R&S FSH3 Spectrum Analyzer and IAS Intermod Software, I was able to coordinate the 60 channels of production RF (with spares), program our units and pass on frequencies to the other suppliers (trucks) for their RF.

One other thing I included into the coordination band plan, was to leave at least some 6mHz blocks of space in each of the 'popular' RF units for the incoming band RF.

On site, once the PA was out of the way, Patch Land and Monitor Beaches were established, we started in on RF World. Sparking up the receivers showed that 2-3 units were too close to an in use frequency, and in a matter of moments, a spare was deployed. When war gaming the whole system, I think only 1 unit had an issue within the system.

One of the acts brought their own RF tech. After a quick chat about 'wow thats alot of RF' and other typical chit chat, he went on to coordinate his RF (roughly 30 channels IRRC) to play nicely with ours. In addition, when he was doing our scans, picked up on the 6mHz holes I left out, and with IAS, marked the TV channels I was operating in as DTV (which just happened to be how I planned it in my head). He did have everything working with all of our units in operation, but the customary, I'll turn off my stuff when not required if you turn off your stuff when not required was in effect.

So fast forward a few months of onsite coordinations, to last weekend. We had a typical show for us, load in early morning, hang a bunch of PA in a convention center, start sound checks after lunch, and do a show.

The requirements of this party band, had 10 wireless IEM and 13 RF mics (plus a few RF for other show elements). With our small time frame to setup and coordinate 30 channels of RF from scratch, I decided to try this approach again. The venue was closer than the first time at the benefit, but downtown Calgary.

With this particular venue, in the right time of year, there are a lot of smaller ballroom/board meeting spaces in a small area, and you can easily pickup each others wireless fairly well. Even in this venue, there is a separate hotel ballroom on top of the second floor loading dock, that shares a common wall with the convention hall, and across the street is another building with several dozen smaller ballroom/meeting spaces.

In this instance, the difference (aside from less RF), was that the units weren't programmed before showing up on site, just the RF coordination was performed. When we initially turned on the Rx programmed from various shows prior, it was nothing short of a christmas tree display of various RF sources! Kind of fitting for a christmas party.

Once we started programming the Rx and Tx, in all, 2 Tx needed to be adjusted due to system interference (and even that was probably due to the gain stages in the UA870 and UA845 antennal/distro system in conjunction with the close distance of the Tx).

In short, it worked out on several occasions to pre program large RF shows from the warehouse, and perform onsite coordination changes for larger shows on an as needed basis.