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09.19.2006
Originally featured on BroadcastEngineering.com
2GHz BAS relocation deadline will be difficult to meet

News came Sept. 13 that WGN, the Tribune Broadcasting-owned station in Chicago, and WESH, the Hearst-Argyle station in Orlando, have completed a frequency relocation agreement with Sprint Nextel as part of the ongoing 2GHz Broadcast Auxiliary Service (BAS) relocation project.

Much speculation about the shape of future HD ENG contribution swirls about in the industry, but it still seems to be too early in the game to state definitively how HD electronic newsgathering will play out; however, with the announcement of the WESH and WGN relocation agreements, Hearst-Argyle and Tribune Broadcasting appear to be one step closer to that eventuality.

HD Technology Update spoke with Ira Goldstone, chief technology officer for Tribune Broadcasting, and Martin Faubell, Hearst-Argyle vice president of engineering, Sept. 14 to learn their perspectives on the relocation project, the likelihood that it will be completed by the Sept. 7, 2007, FCC-mandated deadline and how HD ENG contribution is likely to do on the new 12MHz digital channels at 2GHz.

Their responses are presented together for your convenience, even though HD Technology Update interviewed Faubell and Goldstone separately.

HD Technology Update: Given that the BAS relocation has a September 2007 deadline, is one year a sufficient amount of time to make the conversion to the new 2GHz band plan? In terms of your station group and the industry as a whole?

Martin Faubell: For Hearst-Argyle, I think it will be difficult. As I believe you know, we have signed an agreement with Sprint Nextel. We’ve begun the process in Orlando. All of our other stations in our other markets have completed their inventories and have done so for some time. Most of the stations have submitted their inventories and completed the vetting process with Sprint Nextel, and we are prepared to march forward rather quickly. We are in the process of creating the orders with Microwave Radio. We probably have the first 10 stations lined up and ready to go in that process. We’ve identified those markets with Sprint Nextel, so it is our plan to march forward and give it our best shot to meet that deadline.

You take the 26 over the next 12 months, that’s more than two per month. That’s an extremely aggressive schedule. But, we are working with Sprint Nextel to layout that agenda and schedule, and that’s a work in progress at this point.

In terms of the industry, given what I know just of our own company, the amount of work it’s going to take internally and support by others, — tower companies, crews, modifications to trucks — I think from an industry standpoint, that deadline is going to be very difficult to meet, if not impossible.

Ira Goldstone: I don’t think it is sufficient time. I think we are all going to do the best we can, but I think it is an extremely aggressive schedule at this point.
HDTU: Could you characterize the scope of the equipment swap that is required for your group to pull this off?
MF: From an antenna-receiving standpoint, the entire chain from that point back, whether that is on a tower at 2000ft, has to be completely redone in terms of reception. Trucks, we have work to do in trucks. It is every transmitter and receiver in the 2GHz band, and for some stations, that’s 30 or 40 units.

IG: Basically, it was some of the receive antennas, site control equipment, 2GHz transmitters and receivers that are being exchanged or upgraded. The new transmitters required MPEG digital video encoding equipment as part of the transmission chain, which we didn’t have to use previously in the analog world. On the receive side, digital decoding equipment is required. So, it is really the entire RF chain.
HDTU: What have your tests revealed about the suitability of 12MHz digital channels for transmission of HD ENG contribution?
MF: I’m not sure if you remember, but we started doing digital microwave in Boston in 2001 in concert with Microwave Radio, and, at that time, TANDBERG and Wolf Coach. So, we’ve taken a longer view of this transition; since 2001, we’ve been running both analog and digital and we’ve made a lot of tests in terms of its capabilities and performance.

In many ways, it’s equal to or surpasses analog performance, and in some ways, it does not come up to that analog performance. But all in all, on balance, it is more than suitable for ENG live coverage.

We have not done extensive tests on HD microwave. CBS has tested a system and certainly some of the vendors have done so. From what I’ve seen of those test results, compression of HD to fit within the 12MHz spectrum is somewhat difficult, given the application of that microwave for live television.

It’s really come down to increasing the compression increases the latency of the signal. And for live purposes, that number has increased; so, the suitability of it is in view of the application.

IG: The problem is the DVB-compliant gear today utilizes an 8MHz pedestal, so you don’t take advantage of the entire channel. Microwave Radio came up with a proprietary solution to occupy 12MHz and Nucomm came out with a solution that was dual 6MHz pedestals, spanning those two. But neither one is a standard, so I think the answer is while in 8MHz we can accomplish HD, in an ENG environment we give up some signal robustness. As a result, an interfering signal or some multipath impairment would cause the signal to drop out or be lost.

As we transition to 12MHz modulation capability, we would now have more room to balance throughput with error correction or additional technology that enhances the reliability.

HDTU: What are your plans for HD field acquisition for news?

MF: It’s certainly on our roadmap. It’s the last phase of our planning for HD conversion, and primarily at this point, the first step in live news applications is the conversion of the 2GHz band — the completion of that with an eye toward the second half of overlaying new compression engines to accommodate and handle the HD piece. So, it is part of our roadmap. It exists. The equipment is out there and suitable to do it, it’s simply early in the game and therefore pricing of that is not in line with our thinking. So, the technology is there. The time component and the cost — we’ll ride that curve.

IG: All of the facilities as we convert to digital will have the ability to do HD once we add HD encoding equipment. We are holding off some of the HD encoding equipment decisions until we see what products are available using H.264 AVC. Again, it goes back to the available bandwidth issue and the ability to retain a certain amount of robustness.

As things fall into place, we are looking at adding HD-capable helicopters and then ground units — initially in the larger markets, and then as time goes on and the transition moves along, looking down into the smaller markets.
HDTU: What is your perspective on the long-term use of the 12MHz channels in the 2GHz plan? Do you believe you will stay there or ultimately move up to 7GHz or 13GHz for ENG shots?
MF: Well, we have always used in addition to 2GHz, 7GHz and 13GHz. I think the applications for that are still there. I think you will see more of that simply because there are fewer channels in the BAS band, and in some markets where there is an over subscription to 2GHz, that becomes a natural relief valve, but it doesn’t mean we use less of 2GHz. But, I think in the congested markets, that’s the relief valve in place.

IG: Because of the characteristics of 2GHz, ENG is going to stay in that band. There will be augmentation in the 7GHz band and a little less at 13GHz — 13GHz is more suitable for shorter hops or intercity relay. At 2GHz, based on the characteristics of that frequency, that band is a more functional one to use for ENG. So, I think again as you look at advancements in encoding technologies as we transition from MPEG-2 to H.264 AVC, along with the advancements that have occurred in modulation technology — being able to support higher-order modulations with an increased amount of error correction — the 12MHz channels, over time for high definition, become more reliable.
HDTU: Look into your crystal ball for a moment. What do you expect to happen at the first breaking news event Sept. 7, 2007, when multiple stations’ ENG vans roll up and fire up their transmitters at about the same time on the 12MHz channels set up under the 2GHz relocation plan?
MF: I think the assumption is they’ve all converted, and they are all operating digitally, and they are all operating under the new band plan. If that’s the case, I don’t expect any major failures in that regard. You know, in a fall back, as I mentioned earlier, we have been doing this in Boston for a number of years, where we’ve employed both analog and digital and tried to compare and contrast the performance, we have absolutely seen total failures of modulation when others have on older equipment as it warms up and wanders through the frequencies; it just kills it. So, it is my expectation, and I think tests in the field indicate that if everyone is digital and everyone is operating on that band plan it should not be an issue.

IG: The first statement is what we talked about earlier. The equipment utilizes an 8MHz pedestal in a 12MHz channel. So, if you center it in the channel, you probably have some room for error. Over time that may be an issue, but Day One, it may not be so much of an issue.

Secondly, CBS did a fair amount of testing in New York with multiple transmissions going to a common receive site and digital ENG held up reasonably well with a reasonable desired-to-undesired ratio of received signal. So, I think as long as stations employ transmitter power control so that we don’t have one station sitting right under the receive site blasting maximum power interfering with signals from other trucks further away from the receive site, we should be OK. Additionally, stations should have spectrum analyzers to monitor the signals, enabling them to identify potential problems if there is an interfering signal, to what side of the band that interfering signal is coming from along with the relative power of the interfering signal. If the station that is receiving signal shuts down, they’re able to see the other station is there. I think all of those things will help.

I also think the industry still has to work on our methods for identifying those other signals.

Although right now no ENG operators are encrypting the signal, Microwave Radio and Nucomm offer alternate modulation schemes as options to COFDM. As a result, not all stations in a market will be capable of decoding and identifying the transmission of another truck operated by another station that might be causing interference. Even if everyone were using COFDM, modulation operators could crank in different symbol rates and so forth, thus making identification of in interferor more difficult.

So, I think the answer is initially, I think we will be OK because of the 8MHz pedestal. I believe over time we need to add a technology standard to enable identification of signals emitted from ground and air units to insure that when there are interferers, we can manage them. I think everybody has to play nicely in the field. They have to use the amount of power they really need to get that live shot and not grossly over saturate the site, causing other people to incur interference.

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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