Charging matters - the Samsung Galaxy S6

What does it take to capture attention at a packed trade show amidst all the hustle and bustle? In my case it was a single slide that promised a charge time of no less than ten minutes for a new smartphone due to be released. I stopped dead in my tracks whilst passing the Samsung booth at the 2015 Mobile World Congress - the specs of Samsung’s new flagship smartphone, the Galaxy S6, were being unveiled.

Battery life and charge time

Charging is a nuisance and battery life still ranks at the top of most people’s preferences when selecting a new device. The paradigm from my perspective had always been “How much time do you get from a single charge?” But passing Samsung’s booth it occurred to me that by dramatically reducing the time needed for a full charge is another way to skin the cat. The nuisance factor of charging drops and influences the acceptance of shorter “battery life”. Device selection by scrutinizing the energy metric then becomes a trade off between the time needed to fully power the phone and the ensuing endurance of its charge.

At the Mobile World Congress: Samsung compares the charge
time needed for their new flagship Galaxy S6 versus the iPhone 6

At the MWC, Samsung claimed that their Galaxy S6 (due for release on 10 April 2015) will provide four hours of operation on a 10-minute charge. Oops. I initially thought 10 minutes would mean a full charge. Besides, does being operational mean making calls, browsing the web or just being idle in standby? This is where things gets confusing.

4 versus 3 hours?

Back home I quickly checked what my iPhone 6 plus gets me on a ten-minute charge from an empty battery. It’s battery status indicated a 5 % charge. It lasted for around 3 hours during which I spent roughly one hour surfing the Internet using a 802.11 ac WiFi connection. Sure, that’s comparing apples with oranges. Battery endurance should accurately measure the split of time spent on making calls, browsing the web or just being idle in standby as well as taking the wireless connection into account. But 4 versus 3 hours? Is that a quantum leap as Samsung suggests, or just another case of marketing interpreting basic physics in new ways?

Copying: the sincerest form of flattery

In its comparative marathon, Samsung claimed its new flagship phone charges in half the time of an iPhone 6. The jury is out on that one and certainly phone review websites will seize the opportunity as soon as the device is available. Keep watching this space. It’s clear that Samsung has done much with its new device to match Apple’s latest smartphone models: use of superior materials lead to a higher appreciation of quality; the battery is now built into the device and can no longer be removed; the phone no longer accepts memory cards. Some of these new features are bound to annoy Samsung aficionados who have cherished this differentiation from the iconic smartphone inventor. On the other hand, new features such as wireless charging with its support of both WMC and PMA standards means Samsung is one lap ahead of the field.

Keep your eyes peeled

Fast charging is a prized feature for power-hungry phones. I’m curious to find out what it takes in battery technology, semiconductor devices and the chargers as such to offer incremental improvements for decreasing the time it takes to “fill up a phone” as we move forward.

MWC 2015 and the Connected Car

Ready for the self-driving car? With all the hoopla surrounding this hot topic during January's CES in Las Vegas, many observers have been foiled to believe we're almost there. 

With this in mind, I traversed the exhibition halls of last week's record-breaking Mobile World Congress (MWC 2015) in search of the automotive industry's latest answer to its autonomous future. On the Connected Car front, this is what I found at the show which was frequented by over 93000 visitors and featured almost 2000 exhibitors.

Into the Conceptual Future

The Tesla always stops attendees in their tracks and NXP Semiconductors stashed a range of boards and modules feautring their automotive ICs in its trunk. More than anything, NXP paints a conceptual picture of the car's future if you connect the dots of new and existing functions that their silicon addresses.

Automotive solutions from NXP include:

- a single-chip radar front-end transmitter for ADAS (Advanced Driver Assistance Systems) and collision avoidance

- car-to-car (C2C) and car-to-Infrastructure (C2I) communication based upon the IEEE 802.11p automotive WiFi standard

- a single-chip FM/AM/satellite radio with tuner plus further ICs that support digital radio such as DAB (+), T-DMB, HD radio and DRM

- in-vehicle networking using automotive-grade Ethernet PHY that complements existing technologies like CAN, FlexRay etc.

- a wireless "smart car key" using NFC hidden in an iPhone cover

Replacing mirrors with cameras and screens

Qualcomm and QNX showcase the future of automotive in a Maserati that uses cameras and displays where we usually find mirrors. The video feeds are delivered by two front cameras, one at the back, and one on the roof of the car. 

The development platform embedded in the car uses Qualcomm ICs built around its automotive grade Snapdragon 602A quadcore processor and the QNX operating system. The 602A integrates four Krait CPUs, one Adreno graphics engine, a Hexagon DSP, WiFi, Bluetooth, GPS, three USB ports and support for four camera connections by way of the MIPI standard. At the center of the driver's console is a large 12-inch infotainment display that reacts to touch, voice and gestures. Qualcomm's Gobi 3G/4G modem connects to the cellular network for communications and media streaming. It further serves the WiFi hotspot in the car for passenger entertainment. The center console also features a surface to wirelessly charge your cell phone based Qualcomm's WiPower solution based on the Rezense standard.

Connect to and control your e-vehicle

Porsche's Car Connect service is not a future concept but is something real and available today.

The Panamera e-hybrid vehicle is equipped with a telematics unit from Italian company Cobra, which Vodafone recently acquired. By way of a cellular "machine to machine" connection (M2M), the service features vehicle tracking, remote monitoring & assistance, as well as usage-based insurance. 

The smartphone app controls the electric charging of the Panamera and can also detect the car's location. Vodafone is the operator providing the cellular connection. The service's annual pricing ranges from € 145 to € 289. When buying a Panamera, the first year of service is free.

The best ager's dream come true

On Ford's booth visitors saw what is more akin to a connected bike than the Connected Car: an e-bike that folds and stows easily into the back of the car, with an accompanying smartphone app that finds bike-friendly roads, calculates the best route, and suggests convenient parking.

The MoDe:Me e-bike targets urban commuters who are wary of congested city traffic and thus decide to park on the city outskirts and use their 200-watt e-bike to travel to their final destination.

A carrier's automotive focus

From 2016 onwards, AT&T will provide all US Audi models featuring their Connect infotainment system with 4G LTE or 3G coverage allowing drivers to enjoy navigation, streaming and high-speed access to the Internet. 

An AT&T SIM card will be pre-installed in the telematics unit for customers who purchase a new Audi in the USA next year, enabling on-board Internet access for up to 8 devices.

AT&T works together with car manufacturers in its 5,000-square-foot innovation center in Atlanta called Drive Studio to create new technologies and services for the Connected Car ecosystem.

Something simple for the automotive after-market

Visitors perusing this year's MWC showgrounds will have noticed the VIP shuttles with a banner of Huawei's simple yet neat product called CarFi on them.

That's the Connected Car in its most basic form. CarFi plugs into a 12-volt cigarette lighter socket and allows any car to become a WiFi hotspot for up to 10 devices using a LTE connection that supports up to 150 Mbit/s. The device retails for roughly € 160.

Bold visionaries see the autonomous car traveling on public roads by 2017. That's hard to imagine right now. For the moment most of us will be able to get Internet into their car in one way or another.

4K Smartphones - Stand and Deliver

In my last post I ventured to predict that 4K displays will become mainstream on high-end smartphones at some point even though they’re unlikely to deliver a better viewing experience for the mobile user on average. To become a game changer, it takes more than just adding a impressive new feature to a device to attain that immersive cinematic experience. What about 4K video content? Is enough readily available? Are the wireless networks and mobile infrastructure in place to transport high-resolution content? What are the effects of 4K displays on the smartphone itself? It’s a tall order to provide a comprehensive picture in a blog, so I’ll attempt providing some vignettes of insight in a question and answer style. We’ll shortly probe the ecosystem from production through to transfer and finally consumption of 4K content to arrive at the bigger picture.

"Looks pretty much like 4K to me"

Seeing the difference

Spicing up the quality of images or video is not only a case of increasing resolution. It’s technical and personal matter at the same time.

What parameters influence the perceived quality of a display?

A combination of technical factors such as the screen size, display resolution, frame rate, color depth, dynamic range, viewing distance and other parameters make up for the quality of the viewing experience. In addition, your own eyesight plays an important role, in particular its ability to distinquish fine details, known as visual acuity. The resulting mix of objective and subjective factors makes it extremely difficult to pinpoint a single metric as being paramount in providing a superior viewing experience.

What does it take to produce 4K broadcast quality content?

Producing 4K content dictates a four times higher resolution than the prevalent HD (high-definition) standard, resulting in 4x the amount of data too. That translates to very expensive equipment in the production chain (cameras, lenses, switchers, encoders, storage disks, editing workstations) so that only a trickle of material is currently shot in 4K. Over time equipment pricing will erode and options will increase. Shooting in 4K will ultimately ensure that content is future proof, spurring on its adoption.

What content is available in 4K resolution to date?

YouTube Netflix, Amazon, Sony, DirectTV, Comcast are just some of the names who boast 4K UHD movies, TV shows, or video clips, all of which have caveats of sorts. A good overview of 4K UHD programming available in the USA currently (December 2014) can be found at Digital Trends. Indeed, it’s quite a limited offering but it’s an incoming tide that’s rising.

Squeezing 4K data

Getting 4K content to the end-user requires high-bandwidth transmission paths. 4K codecs that efficiently compress the material when it is captured (encoder) and decompress it again when viewed (decoder) play a pivotal role in easing bandwidth requirements and the cost of transfer.

What are the transport requirements for 4K video?

As can be seen from the listing of offerings at Digital Trends, most 4K content is streamed over the Internet and requires a 25 Mbps channel. Many experts contend that 36 Mbps is the best channel bandwidth for delivering Ultra HD, whilst others purport that 15 Mbps is sufficient for a decent 4K experience that is also commercially viable. Whatever the case, that’s certainly a lot more compared to delivering a HD (1K) stream at 3 Mbps. It also costs approximately 5x more.

	SD (720 x 576)	HD (1920 x 1080)	UHD (3840 x 2160)
Recommended Internet Speed	3 Mbps	5 Mbps	25 Mbps

Netflix’s recommendations on Internet speed for viewing their movies and TV shows

Why are differing minimum 4K bandwidth requirements quoted by experts?

This depends on the type of content and the codec used for compressing the video footage. For example live sports events with fast moving action will require higher frame rates (more data to encode) for a fluid viewing experience. In addition the encoder used to reduce the data must compress at a faster rate due the live nature of the event. Stated in simple terms, the more time a codec has available, the more it can squeeze the data without sacrificing quality. So it stands to reason that films shot and compressed in the studio require less transport bandwidth than live sports events broadcast on the fly.

What codecs are available for 4K video compression and do they differ in the quality and bit-rate?

Of late there’s been a pitting of solutions between Google’s VP9 that follows an open source approach, and MPEG / ITU groups’ HEVC (High Efficiency Video Codec, also known as H.265). The latter’s previous H.264 (MPEG) codec has been the defacto standard for HD content in the past, but Google is hot on the heels to change this for 4K. Then there’s another initiative from Mozilla and Xiph.org called Daala that claims it will beat both on technical merit. In a future post I’ll attempt to uncover some of the key differences of these codecs in their complexity, delivered quality, achievable bit-rate reduction, available content offerings and devices that support each.

Please, no frame freezes or fallouts

Many of us know how annoying a sudden and unexpected throttling of bandwidth can be, especially when enjoying streamed video or audio. Consistent channel bandwidth is of the essence, so let’s take a look at the options.

What channels are available for transmitting 4K Ultra-HD content?

Several options are available such as satellite, microwave, cellular and fixed networks using cable or DSL. Currently the majority of 4K content is available as video-on-demand (VoD) that is stored and then streamed through fixed networks (cable/DSL) to the end user. On the broadcast TV front, satellite providers like DirectTV and BSkyB will lead the 4K race. Terrestial TV broadcasting will require more time for standards to come into place and availability will largely depend on country initiatives in transitioning to newer technology with Japan and Korea at the forefront.

Will mobile networks have sufficient bandwidth to transmit 4K content?
4G cellular networks typically support download rates of up to 150 Mbps for LTE Cat 5 smartphones that are prevalent on the market . More than enough for one UHD channel at 25 Mbps one would think. Keep in mind though, the cellular broadband network is being shared by many people at the same time. In fact we’re dealing with a top theoretical download speed that most of us won’t ever witness in the real world. Even worse, the data rate may change unexpectedly depending on network usage, and your 4K video may suddenly freeze.

Can Wi-Fi reliably stream 4K video content?

The more recent WiFi standards that employ 40 MHz channel bands (802.11n or 802.11ac) provide sufficient data throughput to support 4K video transmission in theory. In practice however, performance is unpredictable as those of us who have tried streaming HD video at home will know. This is largely due to contention between neighbouring WiFi networks whose data rates start sagging as they counter the chatter of next-door access points on the same frequencies. In addition WiFi microwaves, especially those operating in the 5 MHz band, are attenuated by walls and floors, leading to a 80 - 90 % drop in peak rate compared to the access point being in the same room. In short, uninterrupted video delivery is simply not reliable enough.

What other wireless standards can handle 4K streaming and when will they become available?

Two new standards, WiGig and WirelessHD, are out there and both operate in the 60 GHz band. They are much faster than Wi-Fi 802.11ac or LTE mobile broadband technologies. Their formidable throughput rates (7.5 Gbps for WiGig) are targeted at the wireless delivery of high-definition content. Yet the 60 GHz signals they use cannot penetrate walls. It’s all about connecting computing and entertainment devices in the same room without cables. The idea is to turn mobile devices into media stations that wirelessly dispatch streams to 4K TVs and displays. Devices supporting the new standards are expected to start shipping this year and they will allow uninterrupted wireless streaming of 4K content, albeit in the same room.

Expensive power hogs

Smartphone innovation happens at a mindboggling rate and users often wait for announced models to be released before replacement. Even if 4K is one of those desirable new features, there are other factors to observe.

What are the drawbacks of smartphones with 4K displays?

Power and cost are two inhibitors in the uptake of 4K displays on smartphones. The display is one of the major culprits in draining the battery on a mobile phone and the amount of power consumed is directly related to the size of the display. 4K also means four times more data to store and process. More memory and busier units on the SoC (system-on-chip) will sap precious juice from your phone’s battery even faster. In addition, the display is the component that costs the most in a smartphone. Paying more and having to charge your phone more often don’t speak for a runaway market success.

Can smartphones record 4K video?

The minimum requirement for a smartphone camera to capture 4K content is a camera with at least 8 megapixels (MP) of resolution. Most mid-range devices already sport such pixel magic. But can available smartphones capture and encode 4K video? Suprisingly yes, even though most don’t feature 4K displays. For example, both Apple’s iPhone 6 and 6 Plus models (8 MP camera) support 4K video recording; Samsung’s Galaxy S5 (16 MP camera) and Sony’s Xperia Z2 (20.7 MP camera) both use Qualcomm’s Snapdragon 801 that supports video capture and playback using the HEVC / H.265 codec. In fact, an impressive list of smartphones supporting HEVC can be found at phoneArena.com which are able to record 4K videos.

A nascent technology gaining momentum

What do you do if 4K content is limited, seamless transfer paths still patchy, the first smartphones with 4K displays just around corner, yet many featuring 4K capture available right now? 4K’s marketing machine has the answer and is harping that user-generated 4K content on mobiles will bridge the gap. Smartphones will be the force to bring 4K into the limelight as users record 4K footage and either watch it on 4K TVs or upload it to YouTube. A bulletproof business model or high hopes on an act of faith? Whatever the case, it is apparent that the industry is working its fingers to the bone towards a single new display standard. At some point the law of large numbers will bring down costs and herald in the age of 4K phablets, one way or another, sooner or later. The market research company ABI Research forecasts almost 500 million 4K display-enabled mobile phones to be sold in 2019.

It’s still an HD world out there and will be for quite some time, but 4K UHD is on the move.

4K on Mobile - splash, bang or thud?

The new year has just begun and the mobile industry is bracing for the splash of 4K displays in the smartphone market. Will smartphones with Ultra-High-Definition (UHD - the acronym denoting 4K resolution) become a runaway success? They promise a four times higher resolution than the current high-end of small screen technology. They also require four times the amount of data to transfer and a lot more processing muscle to handle the extra workload in tasks such as compression and image enhancement .

 
Rumours have it that Samsung’s Galaxy Note 5 (to be released mid 2015) will feature a 4K screen resolution of 2160 x 3840 pixels on a 5.9 inch display delivering an astonishing pixel density of 746 ppi (pixels per inch). What does this all mean and does it make sense, or is it just one more superlative being added to the spec list of megapixels, octacores etc. to dazzle the consumer?

10-fold increase in 4K smartphone unit shipments

Not if you believe Qualcomm, the Nr. 1 chip supplier in the mobile handset world with a market share of over 50 % for baseband modems in cell phones according to Forward Concepts . A quick look at 4K support in their Snapdragon 805 system-on-chip reveals an unshakeable commitment and formidable investment in this latest display technology.

Smart Phone Display Trend – Source: IHS DisplaySearch, 2015 IHS DisplaySearch expect a 10-fold increase in annual shipments of 4K displays on smartphones by 2017. A modest 6 million units are forecast to ship this year (2015).

Why the 4K smartphone market differs from its TV counterpart

Most of us have witnessed how TV formats battled in moving from PAL/NTSC to high-definition HDTV and the time it took for content and broadcasting in this format to become common. Seers from the mobile world expect the change to 4K to be a completely different kettle of fish. Uptake of this superior technology will be swift . The premise is that mobile devices such as smartphones don’t need to wait for 4K content to become available on a large scale as they are already equipped with cameras and codecs that generate 4K video which can be shared with like-minded. The breakthrough will be further fueled by the fact that consumers buy new mobiles every other year. That’s a very different replacement cycle to PCs or TVs, driving down the cost of high resolution handsets at a much quicker rate. 

Your best viewing distance

 The proposition of enjoying an immersive cinematic experience, viewing an image in fine detail, or simply reading crisp text are undeniably attractive. Does 4K on a handheld deliver on this promise and improve the user experience compared to lower resolution displays? Image quality is an extremely subjective experience and its perception depends on a multitude of factors, not the least of which being the condition of your eyesight. Objectively speaking however, a higher resolution always makes perfect sense the closer you get to the screen or the bigger the screen gets. At some point your eyesight will notice the edges of rasterized text or displayed objects. But how close is close and how big is big? Smartphones are getting bigger by the day - sometimes that small hand can barely hold newer models. In addition, the phone, or shall we call it phablet (phone + tablet) , is at most an arm’s length away from your eyes, usually viewed less than elbow’s length away or some 40 cm / 16 inches. Experts from the display market rely on a simple but reliable rule of thumb for the “best” viewing distance based on screen resolution and size for 16:9 aspect ratios:

• for UHD (2160 x 3840) it’s 1.5 x height of the display
• for Full HD (1080 x 1920) it’s 3 x height of the display

Even the best-sighted of us will no longer be able to distinguish differences to the next lower-resolution display beyond this measure.

So, how does this translate to the latest phablets?

 

	Screen Diagonal	Screen Size	Resolution In pixels	Pixels-per-Inch (PPI)	Best Viewing Distance (landscape)
SAMSUNG Galaxy Note 5 **	15 cm 5.9 "	13.1. x 7.4 cm 5.2 x 2.9 "	3840 x 2160 UHD	746	11 cm 4.3 "
SAMSUNG Galaxy Note 4	14.5 cm 5.7 "	12.6 x 7.1 cm 5.0 x 2.8 "	2560 x 1450 WQHD	515	16 cm 6.3 "
Apple iPhone 6 Plus	14 cm 5.5 "	12.2 x 6.9 cm 4.8 x 2.7 "	1920 x 1080 Full HD	401	21 cm 8.3 "
Apple iPhone 6	12 cm 4.7 "	10.4 x 5.9 cm 4.1 x 2.3 "	1334 x 750	326	31 cm 12.2 "

       ** estimated release is mid 2015

As the table suggests, a cinema quality movie on a 4K smartphone will deliver a better user experience if viewed from a distance of less than 11 cm / 4.3  inches (landscape mode). That’s really close in front of the eyes. Of course, zooming ever further into a hi-res photo by pinching the touchscreen remains an attractive side benefit of 4K content on 4K displays. The “best viewing distance” matches Qualcomm’s affirmation on the average person being able to immediately appreciate the superior quality of a 344 ppi display if viewed closer than 10 inches (25 cm). However note, 344 ppi is not even Full HD resolution.

Notwithstanding, the mobile future is 4K

In the mid nineties when browsing the Internet and Search were at their genesis, I remember contending with technology peers that the future of the medium would remain text-based, more than enough for the emerging knowledge-based, networked society at the time. My rationale was that pictures, let alone videos, would never break through because of bandwidth and cost considerations. How wrong could I have been! As the saying goes “a picture says more than 1000 words”. And if a picture actually sells more than 1000 words, the dynamics of retail and commerce will drive adoption for certain. So, with this in mind and unencumbered by conventional wisdom, 4K on smartphones are destined to break in and break through, even if their added value may not be apparent to the mobile user at first glance.

The Charm of Personal Medical Electronics

Last week I attended the Medica right on my doorstep here in Düsseldorf. My goal was to investigate the state of mobile healthcare - mHealth - with a focus on personal medical electronics. We’ve seen lots of fitness devices becoming mainstream over the past years, but what about personal devices for those who have a chronic ailment? For the uninitiated: Medica is the world’s largest event in the medical sector and attracts over 130 000 visitors each year to see products and services from some 5000 exhibitors.

Photo courtesy of Messe Düsseldorf GmbH

Having steered well clear of pavilions covering surgical devices (not for the faint of heart), one thing that immediately caught my eye was the large number of country booths in each hall inhabited by many smaller companies with innovative products. After visiting around 10 of these, I was surprised to often find the conversation steering towards regulation, compliance and the lobbying power of large incumbents in the medical and pharmaceutical field. It quickly became clear that mHealth has an armoury of jaw dropping technology at its disposal to propel the industry forward, yet security, privacy concerns, slow regulation & legislation and the interests of industry heavyweights curb and constrain enthusiasm and progress in adopting new technologies. Mobile health (mHealth) technology circumvents the technical challenges of existing health systems and provides a more flexible way of enhancing patient self-care. mHealth ultimately equips the patient with completely new 24/7 self-monitoring capabilities that change the dynamics of the doctor-patient relationship.

A second observation from my visit was the number of “cloud based” solutions on offer. In particular for establishing new electronic medical record systems to receive and process information from mobile devices, moving them to “the cloud” so that physicians and other experts have “anytime” and “anywhere” access to a patient’s health status.

The smartphone is a welcome hub for many mHealth solutions. It records incoming data from specialized sensors monitoring a patient’s condition, and wirelessly moves this data to “the cloud”. Often the device’s display provides insightful visual feedback. If necessary, acoustic alarms or haptic prompts notify the patient to take a corresponding course of action.
On the sensor front there are a plethora of exciting solutions around, many if the form of “wearables” and some as “implants”. Two examples from my Medica visit, both from companies who license their technology, give an idea of what’s round the corner. The Israeli company Healthwatch Technologies showcased T-shirt-like garments with interwoven textile electrodes that enable hospital-grade ECG (electrocardiogram) monitoring for patients with heart arrhythmia or palpitations. The garments are comfortable and machine washable.

Photo courtesy of Healthwatch Technologies

The Swiss company Biovotion, award winner in Nokia’s recent Sensing X Challenge, demonstrated a device worn on the upper arm loaded with specialized sensors that monitor physiological parameters. The current version measures five parameters and the next-gen device expands this to thirteen.

Photo courtesy of biovotion

Future versions will also allow measurement of blood glucose levels for diabetes patients using patented dielectric and optical spectroscopy techniques. Non-invasively of course, meaning no piercing of the skin and no blood. Present day self-monitoring of glucose is mostly done using test strips and readers. Pharmaceutical incumbents in this multi-billion dollar “strip” market will certainly raise their eyebrows once such technology reaches the street.

The two examples above demonstrate what novel personal medical electronics can achieve based on available technology.

In general, personal monitoring of the following vital metrics is certain to provide telemedicine  with a fresh impetus going forward:

• heart rate
• body and/or skin temperature
• respiratory rate
• ECG (heart arrhythmia)
• blood pressure (hypertension)
• blood glucose levels (diabetes)
• lung volume/spirometry (asthma, COPD)
• oxygen level in blood (asthma, COPD, sleep apnea)
• sleep patterns (sleep apnea)
• sweat (anxiety and stress)

Health insurers will love this technology because it keeps patients out of hospitals or reduces the time they need to spend in hospital, saving costs where it hurts most.

Privacy and security concerns are among the greatest barriers hampering mHealth adoption. They slow down innovation in this field. Understandably. Who wants their health monitored by a smartphone app if the data could be purchased by an insurance company or other third party covertly. Their interest in optimizing profit or increasing revenue might well rank higher than the patient’s well-being. So long as no clear legislation is in place on both national and international fronts that ascribes such abuse as a criminal offense, this promising area of the medical industry will not be able to fully take advantage of the opportunities offered by consumer electronics and match the fast cycle of innovation in the latter field. mHealth is at an important intersection right now. The technology has the potential to radically and effectively change the treatment of many lifestyle diseases which plague industrial societies.

Sensor Hub, Motion Coprocessor or DSP?

In my last blog I referred to the return of digital signal processing in the form of a discrete, low-power chip that acts as co-processor to the main applications processor of a smartphone or mobile device. Taking this one step further raises some fundamental questions. How complex are these helping hands in terms of their signal processing capabilities?

Determining motion

Let’s take the iPhone as an example. The latest iPhone 6 uses the newer M8 motion coprocessor (an NXP Semiconductor LPC18B1 chip) in combination with Apple’s very own A8 / APL1011 applications processor as outlined in a recent teardown by TechInsights. The word motion provides the first clue regarding the primary purpose of the chip: monitoring movement to determine if the user is sitting, running, walking, cycling or driving. In fact iPhone apps interrogate this user activity status from the CMMotionActivity class offered by the iOS operating system. To determine user activity, the motion co-processor will most likely take acceleration readings in three axes (x, y and z) from the accelerometer sensor. Repetitively calculating the max and min values will enable distinction between sitting and running/cycling and driving, regardless if the user is holding the phone, has it stashed in a trouser pocket or nestled in a car’s device cradle.

However it’s far more difficult to distinguish between running or cycling as the acceleration in all three axes is quite similar for both activities. This is where measuring yaw (rotation) using the gyroscope sensor comes into play. Cycling has a smoother repetitive motion than jogging. By calculating the spectrum of the yaw rate using an FFT (Fast Fourier Transform), cycling will show a single dominant frequency as determined by the cadence of the cyclist. Of course calculations can be further relaxed if likelihoods are taken into consideration. For example, a measurement showing an impromptu change of states from cycling to driving is somewhat implausible. Statistical models as offered by Bayesian probability inference or Markov chains come to the rescue here. And if all goes wrong and a confident activity guess is out of question, iOS luckily provides the state unknown.

The M8 LPC18B1UK chip is based on ARM’s Cortex M3 core. In contrast to the follow-up Cortex M4 core, the M3 does not include a DSP instruction set. So, it ’s plausible that activity tracking calculations are performed at a low frequency. In fact the chip is clocked at only 0.15 GHz. That in turn makes it battery efficient so it can run constantly without ever taking a break. Even in the iPhone’s standby mode it collects, calculates and caches sensor data. The iPhone stores results for a maximum period of seven days in the LPC18B1UK’s on-chip flash of 1 MByte. Sampling rates of 14-bit accelerometer data are thus probably in the 1 to 2 Hz range. In other words, really slow.

From lightweight processing to heavy lifting

As the iPhone 6 example above underlines, motion detection is all about lightweight processing. Similarly Atmel’s sensor hub solution as found in several smartphones from Samsung (see Wikipedia) use Atmel’s SAM D20 which features an ARM Cortex M0+ core on-chip and no DSP functionality. However Atmel’s sensor hub roadmap points to the follow-up SAM G51/53 which is based on the DSP-rich ARM Cortex 4 core. Sensor hubs are evidently transitioning from lightweight DSP processing to heavy DSP lifting. Recent smartphones from HTC, Nokia, Samsung and Sony confirm this trend: they use Qualcomm’s Snapdragon 800 SoC (system-on-chip) family with an on-chip sensor engine based on their powerful 32-bit Hexagon DSP core that also offers floating-point support. Next-generation smartphones, wearables and other mobile electronics will thus not only capture both user and environmental sensor data but also combine these streams in an eclectic signal processing mix to provide never-seen-before smarts for the user.

Sensors and the Rebirth of the DSP

Back in the nineties the digital signal processor (DSP) had its heyday. It was a completely different beast compared with CISCs (complex instruction set computers) like Intel’s Pentium or RISCs (reduced instruction set computer) like ARM’s IP cores. DSPs allowed complex mathematical algorithms to be processed in real-time based on the fundamental mutliplier-accumulator structure of their internal architecture. Mostly these signal processors had a 16-bit fixed-point word length with a very basic feature set. Their distinctive clout was speed combined with low power - a boon for all types of embedded applications requiring real-time response. Yet their restricted word length made programming them an art, something for maths whizz kids who could work with integers just as well as with floating point numbers. And then at some point, stand-alone DSPs simply disappeared off the processor map. What happened?

Layed off by semiconductor advances

With each reduction in size of semiconductor processing nodes, clock speeds moved into the gigahertz range whilst supply voltages and power consumption dropped dramatically. Lower power levels and longer word lengths enabled newer processor types and categories to extend their reach into the domain of rigorous real-time requirements, formerly a unique terrain for digital signal processors. Multiple cores on the same dice were suddenly feasible and the stand-alone DSP simply got gobbled up in the process. What was once a stand-alone math starlet enjoying the limelight became reduced to a common (and essential) block on a larger system-on-chip (SoC).

Smartphones and their sensors

Recently I’ve noticed the term “DSP” appearing more frequently again in the semiconductor world. The trail leads back to sensors; in particular, sensors as they are used in smartphones. First -generation devices featured three or four sensors to ensure fluid interaction with their touch screens: a proximity sensor to turn off the display during a call for saving power and preventing contact with the ear or face; an ambient light sensor for the best reading experience under all types of lighting conditions; an accelerometer to sense the orientation of the phone and switch between portrait and landscape modes accordingly. With each new device generation, further sensors joined the fold. Recent smartphones are often blessed with over ten such environment watchdogs.

Each new smartphone generation features more sensors

Sensors provide information on what the user is currently doing. Combined with location intelligence, smartphones can react intelligently to the user’s activity and current surroundings. Continuous sampling, storage and processing of sensor data is necessary in order to keep track of what is happening to the device, its user and whereabouts. Keeping the phone’s main processor- one of the battery hogs - on all the time, makes no sense. Enter the power efficient coprocessor, often termed sensor hub, or motion processor and sometimes even DSP.

Fusing sensor data to predict location

By adding an additional processor with scanty energy demands operating separately from the main, power-hungry applications processor, the continuous flow of sensor data can be analyzed all the time, even when the phone itself is asleep. Sharp readers will contest why use a processor geared towards blistering speed (read DSP) if sensor data, like readings of the temperature or magnetic field, arrive at a snail’s pace? Yet most calculations are all about sensor fusion, or using multiple sensors inputs to determine something really useful. Take indoor navigation as an example. The usual satellite GPS signal may not be available yet seamless navigation might still be required. Using combined data from the accelerometer, gyroscope, magnetometer and pressure sensor, the DSP implements a mathematically complex Kalman filter to accurately estimate the user’s position from previous bearings (dead reckoning algorithm) and simultaneously compensates for a number of tricky sensor anomalies such as offset, gain, non-linearity and noise. Such an intelligent sensor hub provides rich soil for further smartphone differentiation to take root as algorithms and smartphone apps combine motion, physiological (e.g. heart rate, voice analysis, …) and environmental data in completely new ways. This new trend brings the digital signal processor (DSP) back into the spotlight, reestablishing it prowess from its former glory days as a highly power-efficient mathematical engine.