08.05.2008 08:00 AM
HD ENG adds to long list of challenges for convention frequency coordinator

Take more than 50 TV news organizations; hundreds of wireless mics, walkie-talkies and IFBs; dozens of digital camera-back transmitters; a fleet of electronic newsgathering (ENG) and satellite newsgathering (SNG) trucks; a few news choppers; and what do you have?

Besides one enormous RF headache, you have the 2008 editions of the Democratic National Convention in Denver and the Republican National Convention in Minneapolis-St. Paul.

Louis Libin, president of Broad-Comm in Woodmere, NY, and chairman of the Political Conventions Communications Committee (POLCOMM2008), is the point person for frequency coordination of these two mammoth RF undertakings.

“HD Technology Update” spoke with Libin about these challenging RF environments (several firsts for convention spectrum use), his thoughts about HD COFDM camera-back transmitter use at the convention, and a remarkable offer he’s made to the chairman of the FCC regarding testing prototype white space devices.

HD Technology Update: For those who have never had any involvement in a political convention, could you briefly describe RF usage at a convention and the importance of frequency coordination?

Louis Libin: The political conventions are absolutely the busiest event uses of RF of any in the world. The reason is fairly simple: They’re very, very high-profile news events. But aside from just the news, we are dealing with the fact that every single organization there is considered equal rights holders. So, we just don’t have one simple setup for a single network, we have everyone of the networks, as well as many, many other organizations, all having the same rights — the same use of RF.

Additionally, it’s not just ABC, CBS, NBC; it’s FOX, CNN, C-SPAN — the list goes on and on. There are also individual stations as well. All of those stations also have RF use plans.

We’ve made guidelines for use, so we can’t have one single station come in and say they want to use eight wireless mics and three cameras.

HD Technology Update: How does the setup this year compare to past conventions?

Louis Libin: This year is the worst spectrum year ever for all different types of use. For instance, in St. Paul, we are able to use the lower UHF channels and divide them up for walkie-talkie use, IFBs and things like that. In Denver, we are stuck for spectrum because none of the channels in the lower UHF band are available. The FCC has granted us an STA to use business band, and as far as I know, this is the first time that we’ve ever used business band for broadcast-related uses.

We have made very strict, but necessary, guidelines for spectrum use that the networks and stations have all adopted. We also have other types of guidelines that have never been implemented before, such as the number of feet inside or outside that you need to separate the wireless mic from the receiver before you can use the mic. We’ve never had that before. Somebody is going to be only separated by10ft from his receiver; it’s great that they have a wireless mic, but the fact is that they are using that whole channel, and it’s actually putting a signal out that’s going far and has the potential to cause interference.

We have a lot of new guidelines, and we are in a very, very different spectrum situation than we ever have been in before.

HD Technology Update: In this political convention season, HD newsgathering will play a prominent role. Are there any special considerations or concerns on your part as the person responsible for frequency coordination with the new digital COFDM camera-back transmitters that will be used to transmit live HD shots from inside and around the convention centers in Denver and Minneapolis-St. Paul?

Louis Libin: Absolutely, we need to know exactly what they are using the link for and the bandwidth used. The bandwidth is a differentiator. If we are dealing with HD using more bandwidth, we need to figure that out so we can make the band plan. We are using so many different channels that every megahertz of spectrum matters to us. So, where we have lots of HD, it’s all new and actually it’s another nice challenge that we have. Not only now do we have analog working in the same world as digital, but now we have digital working in the same world as HD. We have so many variables this political convention season; there’s a lot that people will learn from this event.

HD Technology Update: Where do Denver and Minneapolis-St. Paul stand in terms of each city’s transition to the new 2GHz digital BAS channel relocation? Will digital channels be used for shots back to stations and/or backhaul sites?

Louis Libin: The relocation is going to happen just after the conventions. For the most part, we believe all the backhaul will be analog; however, it’s a transition and some people have their equipment already. If they can make the transition in a way that doesn’t impact anybody else, it’s interesting to do. But for us, there are so many more variables at play. For example, there will be the COFDM use outside in addition to the existing links. How does everything work together? We have to be very, very careful.

A lot of the testing was done to see what the impact would be not so much on the STLs and all the other relays, but to see what it would be on the COFDM signals being used just outside the convention centers and, in the case of Denver, also at INVESCO Field, which throws a whole other loop into the equation.

HD Technology Update: What special demands is the final day of the Democratic National Convention at INVESCO Field placing on RF usage?

Louis Libin: The last day of the Democratic Convention in Denver, everything transfers over from the Pepsi Center, about a half mile away, to INVESCO Field, the football stadium. It’s an outdoor field, and it’s a real challenge. It’s going to be a complete breakdown of equipment Wednesday night and a complete build of equipment by Thursday morning when we do our tests at noon.

We are in complete new territory. Nobody has ever done this before. We don’t even know whether all of the equipment will fit in the elevators in the allowed time to switch venues. Logistically, it’s just a nightmare, and we think it will be possible. What we will be doing is testing equipment slowly over the week. For the most part, we are using the same channels we are using in Pepsi that we’re using at INVESCO. But in some cases, we actually had to change because we’re taking interference from other cochannel links that are nearby, since we are outside.

That means that some broadcasters will have to shift channels from the ones they have been using that week. But it is a big deal if they don’t go to the correct one. Logistically, we have to make sure that everyone really understands, and it’s almost like a rehearsal. We’ve cut in a two-hour window from noon to two on Thursday to do testing. But it isn’t like testing that we are doing in Denver and in St. Paul, where we have two days of testing in three hours and three hours. The INVESCO test is a two-hour test, and it will occur as everything else is happening, so there may be bands playing as opposed to the other tests where we can control the venue; this two-hour test will be a very, very big challenge to make sure we do things right.

Frankly, there is very little room for error. If there are interference issues, and we determine that at two o’clock on Thursday, in some cases, there’s not much we can do about it.

HD Technology Update: You sent FCC Chairman Kevin Martin a letter recommending that the two conventions presented an opportunity to test prototype white space devices under consideration for use in the TV spectrum white spaces? What was your thinking behind the offer?

Louis Libin: We are moving into a new world, and there are a lot of claims being made about white spaces and white space equipment — claims that it will be able to do so many things and that it will be able to operate without any type of interference and be able to be interoperable with all of the systems that we have.

I really decided that the political conventions are the best possible scenarios, since we are dealing with the largest event where we have all different types of wireless equipment in the wireless mic bands.

HD Technology Update: How do you propose using the conventions as a venue to test these prototype white space devices?

Louis Libin: We would try to do it at first during the first two full days of testing — three hours and three hours. One would be on Wednesday prior to the convention, and the other will be on Sunday.

The tests are actually very interesting. You turn things on in an order. The cells are working with QUALCOMM on their channel 55 with the MediaFLO, and somebody is always by the switch if we have an interference problem to shut it down. The white space equipment would operate under very, very similar constraints.

After everything is up, we’d turn on the white space devices and see what happens. Then we would turn off some wireless mics and turn them back on, and let’s see if this new technology is able to do what it says.

HD Technology Update: Have you heard back from the chairman about the offer you made in your July 9 letter recommending the tests?

Louis Libin: No, not yet.

HD Technology Update: How much lead time do you need before the conventions to prepare for the white space device tests?

Louis Libin: We’d want to put it into the schedule, so we’d probably need not much more than a week prior to the testing.

HD Technology Update: Have other wireless technologies that have proliferated over the past several years presented interference challenges at live broadcast productions?

Louis Libin: We are constantly moving toward new equipment and new challenges. But in most cases, we have been able to deal nicely with them.

A typical example would be that there is a lot of 802.11 in the 2.4GHz spectrum that’s right next to the channels that we use for the cameras. Sometimes when, for example, you go to a golf event where the golf courses are completely surrounded by residential areas, you’re looking at the noise floor in that 2.4GHz spectrum that is very, very high, which impacts some of the 2.5GHz and some of the 2.3GHz, if we are using something like that.

In that respect, you have to be careful and you have to figure out what changes are. But we are also able to do different things. This time, for the first time at a political convention, we’ll be using wireless mics in the 1.4GHz band, which is a COFDM band, and we’ll be cutting out chunks of 2MHz for 10 wireless mics. So we are able to test and we are able to figure out what the interference characteristics will be. It will have the same modulation type, but we don’t really know. It’s always a challenge to figure out how things will operate once we turn on.

HD Technology Update: Is there anything else you’d like to add about the conventions, interference or preparations?

Louis Libin: We are trying to be very organized. We’re trying to make sure we won’t do any coordination, except for equipment failure, on the days of the convention. This is the first time we are trying to do this.

There are so few channels that we are able to use that we want to make sure everything is tested and signed and sealed beforehand. That’s really the big challenge, and if we’re able to do that then we have a good plan and we will have been able to implement it.

Tell us what you think! HDTU invites response from our readers. Please submit your comments to editor@broadcastengineering.com. We'll follow up with your comments in an upcoming issue.



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