—To receive TV broadcasts, you need some sort of antenna. And that
antenna can’t just be a paper clip or coat hanger, although both can
work sometimes. The antenna must have some physical relationship to the
wavelength of the signal being received. If it does, it approaches
resonance and transfers the maximum level of signal to a receiver.
We know the relationship between wavelength and frequency. They’re
inversely proportional to each other, and a quick way to determine the
wavelength is to divide the frequency into 300. Example: The wavelength of a TV broadcast
signal on Ch. 2, broadcasting at about 55 MHz, is about
5.45 meters. If you could actually see the radio wave, one complete
cycle of the signal would measure 5.45 meters, or almost 18 feet.
In order for our antenna to resonate—i.e., have gain at the desired
frequency—it needs to have some fractional relationship to the
wavelength. So, a full-wave loop for Ch. 2 would measure 18 feet. A
½-wave dipole would then measure 9 feet, while a ¼-wave whip antenna
would measure about 4.5 – about 54 inches.
That’s not to say that our Ch. 2 antenna wouldn’t work at other
frequencies. It could also pull in signals at Ch. 3, or 4, or even 5
and 6. But it wouldn’t be as efficient at those frequencies as it would
on Ch. 2.
The same principle holds true for high-band VHF Ch. (7-13). To
pull in Ch. 7, broadcasting at about 176 MHz, we’d like to have an
antenna with a full wavelength of 5.6 feet. A ½- wave antenna would then
measure about 2.8 feet, and a ¼-wave whip antenna would measure about
1.4 feet, or 17 inches.
For UHF TV channels, let’s pick 600 MHz (TV Ch. 36) for our
example. A full wavelength here is 1/2 meter, or about 19 inches. A
½-wave antenna would then be 9.5 inches and a ¼-wave whip antenna, such
as you’d find on wireless microphone systems, would measure slightly
less than 5 inches.
Again, that’s not to say the ¼-wave or ½-wave antennas mentioned
wouldn’t work on higher or lower UHF TV channels. It’s just that they’re
most efficient at 600 MHz. All of this is just basic physics and innate
knowledge to anyone who has worked with RF antenna and transmission
systems, amateur or professional.
Each individual “antenna” in the Aereo system is about the size of a dime.
Here is a cross-sectional view of the tiny antenna elements in place.
Now, let’s look at the Aereo antenna. It’s about the size of a dime
and resembles a small loop antenna. Just looking at it in a photo and
keeping in mind the science you just read, it would be impossible for
such a small antenna to have any resonance or gain on low-band VHF TV
channels, let alone high-band TV channels.
Yet, that is precisely what Aereo seems to be claiming: One
subscriber can activate one of these antennas to watch WABC on Ch. 7
in New York, or WNET on Ch. 13. And I don’t see how these tiny
little pieces of metal can even work on UHF TV channels: They’re just
Granted, if they were close enough to the transmitting antenna atop
the Empire State Building—like a few hundred feet away – the signal
levels would be so strong that they would “brute force” their way
through the antenna system. But functioning as standalone antennas a few
miles away? Not very likely.
Now, here’s where things get tricky and the boundaries between
engineering and law become blurred. Aereo installs these tiny antennas
in close-spaced arrays on circuit boards. Thanks to the laws of antenna
physics, that close spacing guarantees that adjacent antennas interact
with each other. That’s due to the principles of inductive and
And that means the thousands of smaller, individual antennas couple
energy together to act like a larger antenna; one that will approach
resonance and have some gain at the desired reception frequencies.
No matter how you switch the antennas, they do interact; it is simple
science. And that appears to be the secret sauce behind what Aereo is
doing: Creating large “virtual” antenna arrays made up of thousands of
tiny, individual antenna elements that, taken together, make up a large,
directional antenna array.
According to the patent application, the individual antennas can be
switched on the fly to individual receivers, depending on which ones are
in use and which aren’t. So the company can claim that each tiny
segment of the antenna is actually a stand-alone antenna, assigned to
one subscriber. (Note that, in some earlier Aereo press releases and
news stories, they do mention that subscribers can “lease” one or more
antennas as needed to pull in a signal. )
THE BASICS – RF, VIDEO, AND MPEG DISTRIBUTION SYSTEMS
Now, if all Aereo was doing was providing thousands of tiny antennas
that actually interact to form a large, steerable antenna array, that
would be interesting enough. But an Aereo subscription also comes with a
“personal” cloud DVR, sitting on a server somewhere on Aereo property.
That means the following must happen for you and me to watch Aereo’s
service on our iPhones. (a) A signal must be received from a TV station –
say, WABC on Ch. 7 in New York. (b) That RF signal on Ch. 7
must then be demodulated by a receiver and converted from the 8-VSB
modulation format to a baseband video signal, or at least an MPEG-2
stream with video, audio, and metadata. (c) The baseband video signal or
MPEG-2 stream has to be re-encoded or transcoded to MPEG4 H.264 for
transport. (d) The H.264 signal is then encapsulated with IP headers and
travels to your home network and device.
That takes a lot of hardware. In a conventional master antenna TV
system (MATV), one or more antennas are installed on an apartment
building or office and one or more amplifiers go with it to distribute
the RF signals from the antenna to multiple users. Is this a public
performance? From my perspective, no, as the antenna system is merely
passing along whatever channels can be received with it. The end-user
determines what channels to watch and when. This is a perfect example of
a “rented” or “leased” antenna system.
In contrast, a community antenna TV system (CATV, or cable TV) uses
large antennas to capture broadcast signals and subsequently demodulates
then to baseband video or MPEG, then re-broadcasts them on the same or
different channels with a new program guide. In today’s digital world,
your cable TV provider has encrypted these local channels, meaning you
must lease or buy a compatible set-top box to watch them.
That is indeed a retransmission and a “public performance” in the
eyes of copyright law. The CATV company charges for its service and
sometimes inserts local ads on those channels. So they provide not only a
remote antenna system, they also add in a DVR service, their own
program guide, and encryption.
This is why broadcast TV stations and networks have largely given up
on the old FCC “must carry” rules and now demand a retransmission fee
for their content, just the same way HBO, Showtime, and ESPN do. It’s
today’s business model, and it is threatened by what Aereo is doing.
For Aereo to have a 100 percent, true-blue, subscriber-controlled “antenna
system,” they would need individual antennas, receiver/decoders, and
encoders for every subscriber. That would amount to thousands of
discrete pieces of hardware and an enormous capital outlay they’d never
hope to recover at $8 per month. Their patent describes a way to assign
each antenna to a separate tuner to demodulate the video stream to
MPEG2. That might work fine for a handful of viewers. But what if
10,000, 20,000, or 100,000 subscribers are watching at once?
There’s a reason why cable TV companies use single receivers for each
channel at their head ends: It’s the only cost-effective way to provide
service. And they use multiplexers to route more than one IP video
stream to customers for the same reason. It is a classic “one serving
many” model and a cash cow for the likes of Comcast, Time Warner and
diagram from the Aereo patent filing clearly shows that, at some point,
multiple streams of decoded MPEG-2 video programs are mixed together and
transmitted from the rooftop antenna systems to the MPEG-4 transcoders
in the basement.
OK, so let’s buy the argument that Aereo uses a few receivers as
needed for each subscriber to pull in TV channels and perform the usual
RF-to-video-MPEG conversion. But then, according to their patent
application, they combine multiple MPEG-2 streams into a multiplex (or
“mux”) to send them from the roof of the building to the basement for
transcoding to MPEG4 H.264 and ultimately, transmission to each
subscriber over an Internet connection.
Combining those MPEG-2 streams is really no different than
multiplexing TV channels in a piece of coaxial cable delivered to your
home. Note that, unlike our MATV example, the TV channels don’t exist in
their original 8-VSB format. They’ve been converted (altered) to another
format for delivery to the viewer.
Note also, in the area between the MPEG-2 Mux and Demux, the words
“Antenna Transport (N x 10GBase).” Here is where Aereo’s entire argument
falls apart: You can’t receive an MPEG-2 stream with an antenna; only a
modulated RF channel. Calling a 10 Gigabit Ethernet connection that
streams MPEG-2 digital video an “antenna transport” is disingenuous. The
signal has to be converted to a new format to travel over this part of
the network, and as I just pointed out, it is now a bunch of MPEG-2 video
programs combined together in one stream for efficiency…just like a
CATV or DBS service provider would do at their head end.
In contrast, an MATV system simply receives, amplifies, and
distributes RF channels intact to two or more viewers. Those RF signals
aren’t demodulated or transcoded – they are delivered in their original
state to the viewer. The actual demodulation and decoding happens in
each individual TV set.
What’s even stranger is that Aereo is now calling everything ahead of
the mux an “antenna.” Horsefeathers! Antennas are antennas; receivers
and demodulators are receivers and demodulators. Separate and distinct.
That’s as absurd as calling a car an “engine,” or a house a “roof.”
For Aereo to truly provide the service they claim they do, they’d
need individual hardware and software processing for every subscriber.
No more than one TV channel could travel at the same time to a tuner,
and no more than one video program at a time could pass to an encoder,
especially not in a multiplexed stream. That improbable and wildly
expensive set-up would be a true “leased” antenna and reception system,
controlled by the subscriber.
If at any time TV channels, baseband video, or MPEG streams are
combined together during the process, then it’s a a CATV system. Pure
Again, let me say that I don’t want to delve into the copyright and
business model issues with regards to Aereo. I’ll leave that to the
lawyers. Instead, I’m solely focusing on the science of what Aereo does,
and to me, it’s overly clever engineering, attempting to re-define the
term “antenna” and parse legal terminology.
Their entire argument for getting away with retransmitting broadcast
TV content rests on those thousands of individual antennas, which as
we’ve learned, unquestionably interact with each other and are separate
antennas in name only. The rest of the system appears to be more
conventional, with receivers, MPEG streams mixed together, and MPEG
transcoding – just like a cable TV does, or even an IPTV multichannel
provider, like AT&Ts U-Verse.
The puzzler is why the plaintiffs—TV stations and networks—didn’t
pursue this technical angle more aggressively in the first place. In the
first court case, at least one judge—
Denny Chin of the U.S. Court
of Appeals for the Second Circuit—called Aereo’s system a “Rube Goldberg” approach, cleverly
designed to circumvent copyright law. He hit the nail on the head. There
was some testimony from an RF expert at the first hearing, but either
the testimony wasn’t presented correctly or contained technical flaws.
So the copyright violation angle has been pursued exclusively by
plaintiffs since then.
The judge for the 10th Circuit in Salt Lake City, Dale Kimball, stated in his February decision that “Aereo’s retransmission of plaintiffs’ copyrighted programs is indistinguishable from a cable company.” Kimball got it right as well, as did the three-judge panel that subsequently upheld Kimball’s injunction.
See Pete’s original post, including his pedigree, at HDExpert.com
See Aereo’s patent application