Is mobile data (EVDO) already a part of your remote news gathering operation?  Here is a discussion of how you can use that resource as a low cost backup system for your IFB system.

IFB for EVDO requires only three components:

• A PC with at least two USB-2 ports
• An EVDO USB “stick” with activated service (caution: both the service and the stick must be REV. A)
• A Voice Over Internet Protocol (VOIP) USB module

Just connect everything together and call into your news room cell home interface.  If it works, you have just created a very low cost backup system.

Why should EVDO only be used as a backup system?

1. The viability of IFB over EVDO is highly dependent on how heavily loaded the EVDO network is.  Operation in the suburbs may be acceptable, but use in an urban business area in mid or late afternoon will likely include a disastrous combination of long latency, drop outs and choppy audio.
2. In addition to long latency (up to seconds), expect a loaded EVDO system to have large ssecond to second variations in latency.  This highly distracting artifact is engineered out of cell phone service - latency typically only  changes when cell sites hand off.  EVDO, designed for data, has no such protection.
3. IFB via EVDO only remains a bargain if 5 GB (approx. 10 hours of IFB) of data per month is not exceeded.  Depending on your carrier, the cost can skyrocket to as much as $1.50 per minute thereafter.
4. The rates and terms of service of EVDO are not regulated, and are subject to changes at the discretion of the carrier.
5. Like cell phones, EVDO depends on an external infrastructure NOT under the control of your station.  EVDO relies on the same cell towers and hardware that cell phones do, and depends on limited emergency power, including the same interconnect into either the internet or the public switched telephone network (PSTN).
6. Use of EVDEO when airborn (helicopter use) will undoubtedly face the same fate as use of a cell phone when in the air - nearly immediate shutdown.  This is not a matter of FCC or FAA rules, but self preservation on the part of the cellular carriers.  The cellular control software swiftly recognizes when too many cell sites are lit up and immediately sends the offending transmitter a signal to shutdown.

At this time EVDO is not subject to Priority Access Service (PAS) preemption by emeregency workers, which makes it a valuable backup to cell phone usage.

If mobile data is already a part of your remote news gathering operation, then why not create this low cost BACKUP system?

Recently mobile data has been suggested as a method for delivering IFB to ENG talent.

Many broadcasters are familiar with mobile data (formally known as EV-DO Rev A).  It is the email and internet link for BlackBerry and iPhone.  I’ve used EVDO for years to provide connectivity for my laptop.  It works most everywhere cell phones do.  Mobile data is especially useful in avoiding the often $15 a night hotel charge for internet access sometimes demanded.  Significantly, an informal survey of our ENG customers revealed that most have EVDO in their live-trucks.  It provides inexpensive internet and email access for the crew.

As proponents of IFB via transport stream (a digital version of “pro channel”) the possibility of using EVDO for IFB was intriguing; so a trial seemed in order.  Putting together an EVDO IFB system was simple and inexpensive.  Only three items were needed; an EVDO stick, a laptop computer and a voice over internet (VoIP) module.

The preliminary test produced a “mixed bag.”  On the plus side, EVDO shows value as a backup to other ways to get IFB into the field – you can never have too many backups, especially ones as inexpensive as EVDO IFB. 

However, as a primary means of delivering IFB to live trucks, EVDO seems a poor choice.  It is a weak alternative even to cell phones.  And cell phones remain an unwise choice for IFB with their frequent drop outs and difficulty in getting a connection at major incident scenes.

Mainly, EVDO is unreliable.  In areas of even moderate EVDO usage it develops problems that will drive an on-air reporter crazy.  The delay (latency) can grow to more than half a second, and even worse, it varies widely from second to second.  Another issue is “holes.”  Because EVDO is intended for data, the carriers make no special effort to insure steady, uninterrupted transmission.  A pause of a second or two in the flow of data is hardly noticeable.  The same hole in IFB during a live segment could be devastating to a reporter.  Finally, because EVDO is part of the cell phone infrastructure, sharing the same towers, antennas, interconnects and power, it can never be more reliable than the cellular network.

While the hardware costs for IFB EVDO are insignificant and the monthly basic charges very modest, use for more than five to ten hours a month for IFB can generate BIG overtime bills.  Most EVDO contracts (Verizon and Sprint) provide 5 GB per month of data.  For web surfing that is a lot of data, but for IFB audio it is less than ten hours.  News operations people say that it takes one to two hours of IFB per live segment.  If the 5 GB limit is exceeded, the charge can be as much as twenty-five cents per additional MB (an MB is one-thousandth of a GB or about 25 cents per 10 seconds of IFB).

There are more test results and other issues in evaluating EVDO for IFB.  Modulation Sciences is preparing some more papers with those details as well as instructions on how set up your own system for doing IFB EVDO inexpensively.  Check back here in a week or so for the next installment.

The Problem

As stations switch off their analog signals they find themselves facing an unexpected crisis – actual digital coverage falling dramatically short of expectations.  Some viewers, even with unobstructed paths to the station towers, are unable to receive the station reliably. 

Failure to achieve predicted coverage impacts many homes, not just a few isolated viewers. This is a wide area problem.  Whole pieces of DMAs that once received a fine analog picture now report no digital reception.  These were areas predicted to retain full coverage after digital conversion.

The Difference between Analog and Digital Coverage

Generations of television broadcasters since the birth of the medium learned to equate coverage with “millivolts per meter.”  Managers and salesmen might not know a millivolt per meter from a klystron, but they knew if they didn’t have enough millivolts in an area, they didn’t have any audience.

Signal strength was king.  All the other transmitter stuff that the engineers spent time and money making perfect – SNR, the waveform, differential phase, etc, etc all affected the quality of the picture.  And most mere mortals, as opposed to engineers, could see little difference in the picture one way or the other.

The trouble is digital television really is different — very different.  Many engineers, and even the FCC don’t realize how different digital coverage issues really are.  A mistake in adjusting the transmitter or the drift of some setting over time does not degrade quality the way it would for an analog station; for digital it trashes coverage.

And since the FCC recently released coverage maps for all full power digital stations in the country, everyone has a copy of their predicted coverage.  More to the point, these maps showed the gain or loss of digital coverage against what analog had delivered.  The trouble is, these maps are based on signal strength and interference.  They fail to take into account all the factors unique to DTV that impact coverage.

Put in analog terms, the impact of an out of adjustment DTV transmitter is the same as if an analog transmitter were reduced in power twenty times – from, say, 100 kilowatts to 5 kW.

The Cliff Effect

Digital TV reception is an all or nothing affair.  It is both a strength and weakness of DTV.  The picture is either perfect, or there is no picture. If the picture is gone, it has “fallen off the cliff.”  Contrast this with analog TV, where the quality of the picture gradually degrades with the distance viewers are from the transmitter.  There is no such thing as a DTV picture with snow or ghosts; it is always either perfect or just not there.  The problem is that a lot more factors affect when the signal falls off the cliff than just distance from the transmitter (signal strength).

In a footnote to the report that accompanied the publication by the FCC of the digital verses analog coverage maps, the FCC stated,

“ We recognize that the digital cliff effect can also occur at the fringe areas of coverage. However, this cannot be quantified and for purposes of this report we apply the term “digital cliff effect” only to losses within the service area that can be quantified.”

With that footnote, the FCC dismisses issues that can reduce the coverage of a station by as much as 50%.

The Key is Margin

Rather than signal strength, gauging the coverage of a digital TV station is a matter of figuring out margins.

Let’s say that a perfect transmitted digital TV signal has a margin of 100%.  A typical digital TV will receive a perfect picture if the signal at its antenna terminals has a margin of 30%.  At 29% the picture fails (falls off the cliff).  Depending on the TV set, failure means the picture will freeze, go blank, or break into random blocks.

Decreasing signal strength reduces the margin only by a small amount until it falls below a critical level (a very low level) and then the picture fails.  However, if nothing else consumes much of the margin, the distance to the point where the picture fails is typically MUCH further away than the point where an analog picture would be unappealing to watch and much further than the predicted coverage.

In predicting the coverage performance of a digital TV system, its designers assumed that the 70% margin between a perfect signal and the point where a typical TV set fails would be used to deal with degrading influences like multipath.  Multipath is when the signal bounces off objects like buildings and mountains.  These reflections create additional paths of different lengths between the transmitter and the TV set.  In analog TV, multipath caused ghosts.  The designers of our digital system expected that multipath would consume the most margin and would control coverage.  Other things that consume margin are rabbit ear TV antennas and people moving around the room near the rabbit ears.

Weather sometimes consumes a good chunk of margin.  Surprising, it is not often severe weather that interferes with DVT pictures, but rather inversions in coastal areas and hot humid weather on the plains.  The good news is that the problems only affect a small area at a time and usually last for seconds to tens of minutes, although they often occur in clusters.  It is more of a problem when a cable head-end or a translator is affected, since either of them may be providing signal for tens of thousands of homes.

Margin is a Systems Parameter.  It is the sum of the entire signal – what is transmitted by the station, the propagation path between the transmitter and receiver (including any multipath), the receiver antenna, and the digital technology used in the receiver. 

Loss of Coverage

The designers of DTV assumed that the DTV picture that the broadcaster sends out would have a near perfect margin, 99 to 100%.  In many cases this has proven incorrect.

The consequences can be devastating.  Defects in the transmitted signal can eat up 50 to 60% of the margin.  With so much of the margin gone before the signal leaves the station’s tower, only viewers in near ideal situations will get a picture. This has proven to be the case for many of the stations that have recently shut off their analog signal.

With many stations having been on-air in digital for more than five years, how could this have gone unnoticed for so long?  The answer is, so long as there was an analog signal, no one noticed.  If the digital signal was not usable, the viewers stayed with the analog.  A number of coverage studies were performed by stations and interested organizations.  Some of the studies relied only on signal strength, assuming a perfect transmitted signal.  The studies that did check to be sure that there was a usable picture, also usually had an experienced engineer first verify the transmitted signal to insure that it was near perfect.  If it wasn’t, it was fixed before the tests were run.

So how do so many stations, maintained by conscientious engineers, transmit such substandard signals? 

Education and Economics

It’s difficult to explain to a non-engineer the magnitude of the shift in thinking required to make the transition from analog to digital TV transmission.  Everything is different, even the acronyms.  It is a whole new bowl of alphabet soup.

With everyone in the same boat – manufacturers, suppliers and consultants – learning as they went along, the station engineer had few places to turn for education.  One great resource was Gary Strongly, one of the inventors of ATSC DTV.  After he left Zenith, Gary went on the road doing seminars about the “nuts and bolts” of making DTV work.  Gary correctly realized that no matter how good the technology, if the people who had to make it work on a day-to-day basis didn’t understand it, DTV would not succeed.

I am certain that Gary’s heroic effort helped, but not everyone could attended his seminars.  And those who did attend encountered another hurdle when they got back to their stations – budget.

The million or so dollars that most stations had to spend to go digital  offered no promise of return on investment for several years, so the request for many tens of thousands of dollars needed for test equipment to insure that full coverage could be realized was largely not forthcoming.  Even today, few stations own the basic test equipment needed to insure full coverage, although a few suppliers, my company (MSI) among them, have introduced much low cost test gear.

The situation remains grave today.  The bottom line is that many stations are transmitting signals so deficient that they are reducing their effective coverage by 50% or more.  This not only puts the station at risk, but it places the entire medium in jeopardy.

Solutions

Money needs to be found to purchase test equipment.  This must be 8vsb transmission test gear.  PSIP analyzers or transport stream analyzers, although important, will not help resolve coverage problems.

Beyond the test gear, many station engineers need help in first understanding what the data from their test equipment means, then in how to apply that information in adjusting or repairing their transmitter systems.

In an effort to deal with this crisis, my company is now offering a block of free telephone consulting time with each transmitter analyzer sold.  This time can be used to learn to interpret the analyzer’s readings, or to relate those readings to transmitter adjustments, or some of both.

For broadcasters, the earthquake and the disruption of cell service should serve as a reminder that the cell phone is an unreliable means for IFB links with reporters in the field, especially during emergencies.

Most TV stations spend hundreds of thousands of dollars — perhaps millions — preparing for a power blackout, but little money or thought about what they would do if their cell phone suddenly became useless.

Loss of IFB with reporters could prove costly, not only to a station’s ability to report the news, but also to its viewers who rely on that news in a time of crisis.

The cell phone has a number of problems.

If blockage doesn’t deprive you of cell phone service during a major “incident,” Priority Access Service (PAS) will. The FCC encourages cellular carriers to provide PAS to emergency services personnel at all times. PAS ensures that emergency workers will get the next available wireless circuit, regardless of how many non-priority users are waiting. With most cellular companies offering PAS, the chances of an ENG crew getting wireless circuits for IFB or any other use during a major news story is very low.

Random disconnects are also a problem. We’ve all experienced them. It often seems that the longer a cell call is, the more likely it is to suffer a “random” disconnect. While it’s denied by the cell phone carriers, many people believe that the cell phone system is programmed to disconnect long calls during busy usage times. Whether that’s the case or not, it’s a common occurrence and losing IFB during a live ENG segment is a sure way to ruin a reporter’s day.

Also, long and variable transmission delays are common to cell phone calls. This is the delay between when you say “hello” and when the person you’re speaking to hears it. Engineers call this latency and it’s the reason that people find themselves “talking over” each other during some cell calls. On some cell phone systems, latency can sometimes reach as much as three-quarters of a second.

Cost, in the form of time charges, is another disadvantage of using cell phones for IFB. Thirty or 45 minutes of IFB connect time often precedes even a brief live shot. Multiply each of those shots by two or three news shows a day, times the number of ENG vans, by five or six news days a week and it comes to a lot of cell phone minutes. As a result, it’s not unusual to run up cell phone bills of thousands of dollars a month for news departments.

And remember, cell phone usage while airborne in any type of aircraft is prohibited. Just in case you think that you can “get away with it,” you can’t. The cell systems can detect that you’re in the air and turn off your phone, usually within the first 30 seconds of placing or receiving a call.

To make matters worse, Analog PRO Channel, another popular technology for IFB, will not function after the analog shutdown on Feb. 17, 2009.
There are three alternatives to cell phone for IFB available.

Two-way radio. The original carrier for IFB and still a viable one, if you can get private channel allocated. The problem is that few frequencies are assigned for broadcast operations and in all but the smallest markets the frequencies must be shared. If you’re lucky, you share them with another broadcaster, if not, maybe the local fuel oil delivery company. Either way, half-hour IFB feeds are out of the question.

DRL. When the FCC “refarmed” the 2 GHz ENG band, it allocated 40 channels for IFB service in the new band. My company, Modulation Sciences, built equipment for this band and obtained an experimental license from the FCC to conduct a test. Our test results were positive. Unfortunately, the DRL channels are located within the video channels of the existing band. Because the 2 GHz relocation is behind schedule, it will not be until some time after the analog shutdown that DRL channels will be available to broadcasters.

In addition, DRL requires the construction of infrastructure-steerable antennas, receivers and transmitters suitable for mounting outdoors on a tower. My guess is that it will take three to five years for DRL to become a useful technology for news operations.

IFB on the digital transport stream. This technology places IFB audio in the transport steam (the main signal) of your station. It is much like a digital version of Analog PRO Channel. The system would be as reliable as your station’s signal. After Modulation Sciences realized that DRL would not be usable in time to replace Analog PRO Channel, we selected this technology as an immediate solution to providing IFB after analog shutdown. We expect to begin delivery of a Digital Proceiver by the end of the third quarter.

Most of the time, the cell phone will work just fine. But when you need it the most you may discover it may not work at all.

Consider the alternatives.