Revisiting the transmission speed

A while ago (several years, in fact) I published a post on the speed of modems, i.e., digital communication. And since I am currently involved in two fiber-to-the-home projects I felt it was time to revisit the chart. I also notice that I could not find too many graphs that have been updated the last few years.

So, the story was to understand what kinds of speed that are offered to the user (and the backbone to distinguish them). In the previous post it was briefly pointed out why the speed increased, i.e., evolution accelerated, the last twenty years. If one plots the transmission speed for a subscriber line, it does not fit to an exponential trend line, nor any good polynomial interpolations either.

Let’s get (to) the picture first. [Click on the image to get to the google spreadsheet’s chart – there might be some more points added as time passes by. WordPress does not allow embedding google charts]. All transmission speeds are in bits per second. For the sake of clarity (?) I also added the population growth (blue line) where the numbers are in Millions. (Since it is a logarithmic scale it is just a matter of moving the blue curve up and down – it looks rather flat anyway).




  • Red stars: telephone lines, teleprinters, wireline modems (POTS, ADSL, ISDN), as well as optofibres (the right-most, top-most red stars).  One could argue about the use of optofibres here, but I go by the connected-via-a-cable concept.
  • Green pyramids: Radio (and optical systems). We see the development of radio standards for subscribers: 1G through 5G, Wifi. Notice the two green dots on the left-hand side! These are the early telegraphs. One of them being the Chappe telegraph system and the other being the Swedish system developed by Edelcrantz. Fascinating stories themselves.
  • Pink bullets: Backbone speeds. Here I have bundled radio, optical, fibres, telephone lines. I have also added some of the more experimental recent results – some claiming to have reached speeds at 1.5 Pbps, i.e., 1.500. bits per second. That’s ridiculously fast – about 30000 movies … per second.
  • One could argue that some telegraph systems should be treated as backbone (pink) rather than subscriber (red). However, as long as there was no concept of frequency-division multiplexing or similar coding formats, only time-domain multiplexing, i.e., only one message sent at the time over the line, I count them as subscriber lines instead.


There is somewhat of a mess in terms of how speed is reported for all these various formats. The sources refer to measures such as: bits per second, words per minute, symbols per minute, symbols per second, baud rate, etc. For example, the Edelcrantz machinery: “A message could take 30 minutes to be sent from Stockholm to Gävle [some 200 km]”. This particular system, however, used 10 on/off shutters and we can thus translate that to 10 bits per symbol, etc.

For Morse code, there is often a words-per-minute count. In this case one has to assume an average symbol length and an average word length (in British it is 5.1 characters per word), the minute is also a bit vaguely defined since there is no standard delay between characters nor short/long beats on the key. In order to translate to bits per second, I have used what I have interpreted as best practice (various sources on the web).

Voice channels had a bandwidth of some 1 to 8 kHz in the early days and I have assumed 1 bps per Hz. Which is arguably

However, same holds for any system. Even if we say bps there might be additional overhead in terms of error correction coding, repetition, preambles, handshaking, etc.  on the line. I have reported the “raw” numbers and not cared to how much information as such is transferred. (With that said, how much information is there in a “Hi, how are you?” message?)

Notice that distances are not considered in the graph! One could argue that it is a bit unfair to compare apples and pears. I have focused a bit on the transatlantic cable as a use case. It illustrates the real challenges. The experimental Pbps optical fibres do not face the same type of challenges. Gauss first telegraphs were a couple of km. The Chappe telegraphs spanned 300 km and more. A longer cable would distort and attenuate the signal more aggressively and transmission speed would be lower. The very first transatlantic cable in the late 1850s (the notable red star at the bottom of the graph) only obtained a “few words per hour”! Horribly bad – but what an exceptional achievement?!

Curve-fitting does not work

As mentioned above – it is hard to get a polynomial interpolation to fit to the data in order to see trends. Exponential approximation do not seem to fit very well either. The R2 values are not impressive. It is quite clear that we instead should look at the graph and think in terms of distinct, paradigm-shifting scenarios. We have

  1. the arrival of the telegraph
  2. the introduction of Internet for the “masses”
  3. the arrival of the optical fibre
  4. satellite communication
  5. mobile phone
  6. etc

The telegraph (and telephony systems) shows a rather flat line from the 1820s to the 1930s. After the war, things start to roll. The launch of the SCORE satellite (1958) demonstrated communication across the globe – without cables. One could argue that Sputnik did the same, a year earlier, but it did not relay signals. The first transatlantic fiber cables were laid down in the 1980s.

Notable systems not mentioned in the graph

I did not include smoke signals nor the innovative time-coded pneumatic system used by the Greek in the fourth century.

I did not include the transmission speeds reported in the Star Trek movies (it is too far in the future and would stretch the graph too much). For the same reason I omitted the Star Wars across-the-galaxy-without-latency communication as it happened “a long time ago in a galaxy far, far away”.

The pi day … aka The Feigenbaum constant day

Ok, so the pi-day is up and running (March 14, i.e., 3-14). At approximately half past three today, some kind of pi would be served around the globe.

In an older post I found some alternative pi days for those who don’t like the date-system (Month-Day):

and we found July 19 and July 22 as more “accurate” days for the pi – at least for us in Europe. The latter internationally acknowledged as the “Pi approximation day”. (Americans might claim March 1 as an approximation according to the principle Month/Day.)

So what else do we have? Is this it? Are there no other fancy constants that we could appreciate throughout the year?

Of course there is… forza some python and loop over the most commonly  (according to Wikipedia) used constants. Standard integers aside. A euro-date below is “Day/Month” and a US-date is a “Month/Day”. I have found the best-matching date in a least-square sense.

Notice the possible benefits of celebrating some/most constants twice a year if using both Euro and US date formats! I’ve however given preference to as early dates as possible for constants approximating to the same value for several dates. For example the interesting Legendre’s constant (= 1) which could be celebrated quite a few times throughout the year, but let’s stick to January 1.

It is also worth noticing  that the Feigenbaum constant approximation day could be celebrated today instead of pi.

  • Btw – what else than celebrating the imaginary number i on February 30.
Euro US Value Constant
22/07 03/01 3.14159265359 The pi day
19/07 11/04 2.71828182846 Eulers day
17/12 07/05 1.41421356237 Pythagoras day
19/11 12/07 1.73205080757 Theodorus day
20/09 09/04 2.2360679775 sqrt5-day
04/07 11/19 0.577215664902 Euler-Mascheroni constant
13/08 08/05 1.61803398875 Golden ratio
03/11 06/23 0.261497212848 Meissel-Mertens constant
02/07 07/25 0.280169499024 Bernsteins constant
03/10 07/23 0.303663002899 Gauss-Kuzmin-Wirsing constant
04/11 06/17 0.353236371855 Hafner-Sarnak-McCurley constant
01/02 01/02 0.5 Landaus constant
04/07 04/07 0.56714329041 Omega constant
05/08 05/08 0.624329988544 Golomb-Dickman constant
07/11 09/14 0.6434105462 Cahens constant
02/03 02/03 0.660161815847 Twin prime constant
02/03 02/03 0.662743419349 Laplace limit
07/10 07/10 0.70258 Embree-Trefethen constant
07/09 10/13 0.764223653589 Landau-Ramanujan constant
09/11 09/11 0.8093940205 Alladi-Grinstead constant
07/08 07/08 0.87058838 Bruns constant for prime quadruplets
11/12 11/12 0.915965594177 Catalans constant
01/01 01/01 1 Legendres constant
11/10 11/10 1.0986858055 Lengyels constant
09/08 09/08 1.13198824 Viswanaths constant
06/05 06/05 1.20205690316 Aperys constant
13/10 09/07 1.30357726903 Conways constant
13/10 09/07 1.30637788386 Mills constant
04/03 04/03 1.32471795724 Plastic constant
16/11 10/07 1.45136923488 Ramanujan-Soldner constant
16/11 10/07 1.45607494858 Backhouses constant
16/11 03/02 1.4670780794 Porters constant
17/11 11/07 1.5396007178 Liebs squareice constant
08/05 08/05 1.60669515242 Erdos-Borwein constant
17/10 12/07 1.70521114011 Nivens constant
19/10 11/06 1.9021605831 Bruns constant for twin primes
23/10 07/03 2.29558714939 Universal parabolic constant
05/02 05/02 2.5029078751 Feigenbaum constant
31/12 08/03 2.58498175958 Sierpinskis constant
27/10 08/03 2.68545200107 Khinchins constant
14/05 11/04 2.80777024203 Fransen-Robinson constant
23/07 10/03 3.27582291872 Levys constant
27/08 10/03 3.35988566624 Reciprocal Fibonacci constant
14/03 09/02 4.6692016091 Feigenbaum constant
30/2 2/30 i, sqrt(-1) The imaginary day (30/2!)

When will we bump into a transistor everywhere?

A while ago I made a comparison between Ostrogothia (Östergötland) and a silicon wafer. I wanted to put things into a graspable scale. If a transistor compares to an everyday object – how present will they be?

Maple-Martin, while digesting some Guinness at an Irish conference, suggested to take a look at the total number of available transistors on earth. According to Intel there were some 1.2e21 transistors worldwide last year(-ish).

 Let’s take some other dimensions into the picture:

  • On earth, there are 7 000 000 000 human beings (give or take some 100 millions), 7e9 
  • The earth’s equator is 40 000 km (4e7 m)
  • The earth’s total area is 510 million square kilometres, ie. 5.1e14 sqm
  • The channel length of an average transistor is assumed to be 100 nm
  • The channel width of an average transistor is assumed to be 100 nm
  • Each human consists of some 37e12 cells  [according to ]

Now, with these numbers at hand: Let us assume that we have too much time and we have somehow magically collect all the chips on earth and scrape off all transistors (that’s a big bag of chips). Then we decide to take a walk around the globe and put down some transistors here and there (perhaps to find our way back by picking them up on the way back?)

So if we neatly put them next to each other (think a long cascoded current source) in a long a row, we would have to walk

  • 1 200 000 000 000 000 000 000 pcs * 0.000 000 1 m/pcs = 120 000 000 000 000 m = 3 000 000 laps (!!!) around the globe.

Let’s assume we find that boring to just walk along the equator. If the transistors are 0.1 * 0.1 sq um big. They would then occupy 1e-14 = 1.2e21 * 1e-14 = 12e6 sq metres ~ 4000 * 3000 sq metres, or in non-American English: 4×3 sq km. Not that much (?)

If the transistors would be 600×600 sq um we would be able to cover the earth. 2010 – anyone?

We have 1.2e21 / 7e9 ~ 2e11 transistors per human being. That’s quite a potent processor! In an “ordinary” desktop computer there are some 5 billion transistors, i.e, 5e9 transistors. Which means that each human being is equipped, or has access to some 40 processors. (A phone, a computer, …)

Let’s bring the comparison further: Each human consists of some 37e12 cells which multiplies into a biomass of 37e12 * 7e9 = 270e21 human cells. Compare with 1.2e21 transistors – we are soon there! Soon we can assign one transistor to each human cell. 1984 – anyone?


PPT/ODP/PDF vs White/Blackboard

Following up on a facebook post and adding some more references and links as well as a poll for the fun of it . Also  noticing that there are 10 months since I posted here … other types of media have been used.

So, the question was about what we prefer to listen to. What type of performance do we prefer in the lecture hall – powerpoint or whiteboard? Personally, I do not feel very comfortable using powerpoint [PDF/ODP/beamer/whatever] to present nor listen to. The lectures I mostly enjoy are either the ones with just a few “simple” slides, or simpler annotations. For example

or why not the great lectures by

where you can find lectures by Prof. Adams or why not the great lectures by

(Yes, I admit that this is a “meta-discussion” in the sense that we watch someone lecture on a youtube channel thus making it more or less a powerpoint presentation – but I think you know what I mean).

I would also like to highlight the

that display a method that is somewhat in-between. A static “slide” (landscape?) but a detailed walk-through of the stuff on the board. Some of his “wild” [pun intended] ideas aside, it is comfortable to listen to him.

Back to powerpoint (or PDF or ODP) [copy from the facebook pages]: What especially annoys me are those presenters who read out loud the text displayed on the screen. The audience has already read the whole page twice before the presenter reaches the end of first sentence. And mostly, they have already understood the contents before presenter starts to mumble and desperately tries to remember what they’ve written three years earlier.

Too many times I have had lectures where the students have fallen asleep – more or less. It does not really matter if I distribute material in advance.  Yes, I know it is also my fault – I should probably prepare better slides and present them better. Perhaps I make the errors mentioned above.

But taking the pen and massaging the text and moving across the whiteboard is more satisfying. Making some errors now and then and erasing and rewriting after interaction from and with the audicence makes the presentation more live.

The downside is of course efficiency – which is important! – there is limited time slot in the teacher’s schedule and in the students’ schedules. Watching a professor slowly writing the formulae on the board could sometimes be as interesting as watching paint dry.

The combination of slides and board? Well, there is a risk of interupting the flow. There is no natural way of conetext-switching. Displaying some complex graphs? Equations? Well, yes, perhaps – but reproducing them line-by-line on the board is also part of the explanation procedure.

I am thinking of this graph, where yellow displays the “match” between entertainment and learning level. Doing the repetitive stuff, over and over again, is perhaps not that fun, but learning is better IMO. Think of it as a movie with Schwarzenegger vs a documentary with Attenborough vs peeling 200 kg of potatoe. (Well…) There are differences between being entertained, interacting and just performing repetitive patterns.  Can we fill the white boxes with yellow knowledge?





MM-48-130-10, case file 38139-8

[Nerd alert!] Comments to memorandum MM-48-130-10, case file 38139-8, från BTL

Quite a while now I’ve been fascinated by Bell Labs (Bell Telephone Laboratories, BTL). The famous lab that had its best days around and between the world wars. Nowadays Bell Labs is “owned” by Nokia, and hopefully the good traditions are carried further.

What intrigues me is the amount of brilliant people that seemed to work there. Imagine walking down the corridor and meeting all these oddities. Large amount of patents, inventions, great ideas, etc. Who were they?

Annually, Bell Labs also produced a rather big book (the “Bell Laboratories Record”)  with stories about their employees, their latest findings, etc. I have previously presented the fascinating story about the Swede and his wife.

Anyways. Going back to the naming of the transistor, which I also touched upon a while ago. Within Bell Labs they circulated a memo and had a vote about the name. The memo was MM-48-130-10, case file 38139-8 and can for example be found at

The list contains a set of people (here in alphabetic order). And what to do in late evenings than researching a bit on these guys (yes, all of them are male but the secretary Ms. XXX). Some of them are already so famous that they have gotten a wikipedia page. Therefore, I will only give a link and possibly some additional information for them. Some of the others were a bit more tricky to find information about. Some of them are also left in the darkness (i.e., not being on the internet). Some birthdates I had to find in civic registration records.

So, let’s go nerd!

1    J.A. Bardeen (1908/5/23 – 1991/1/30)

Well, one of the three… and might not need much more of introduction. Bardeen was a theorist.

2    H.L. Barney (1906/8/7 – 1960/12/30)

Harold L Barney worked with speech coding and a negative resistance device. He produced a paper with G. Peterson: “Control methods used in a study of vowels”. In the early days when bandwidth was sparse and increasing middle class with phone access, speech coding was a very important field of research.

3    J.A. Becker (1897/1/24-1961/7/13)

Joseph Adam Becker was born in Saar in Germany, came to America and studied at Cornell. He had some 20 patents (one of them on how to connect a resistor…)

4    H.S. Black (1898/4/14-1983/12/11)

Harold Stephen Black – the inventor of the negative-feedback amplifier and contributor to pulse-coding modulation techniques (PCM) for speech coding. Once again to be able to squeeze as many phone lines as possible into the same wire (and enable automated switch boards).

5    R. Bown (1891-1971/7)

Ralph Bown led the press conference that announced the invention of the transistor. He received the IEEE medal of honor and specialized in Radar and Radio.

6    W.H. Brattain (1902/2/10-1987/10/13)

Walter Houser Brattain, one of the three, was born in China. Needs no more introduction than that. Brattain is the older, more uncle-looking guy, in the lab-picture where Shockley has hi-jacked Bardeen’s microscope. Brattain was the experimentalist.

7    D.M. Chapin (1906/7/21-1995/1/19)

Daryl Muscott Chapin had a great idea. What if we could extract energy from the Sun into our semiconducting devices? He invented the silicon solar cell in 1954, the “solar battery”. Together with Fuller and Pearson he authored a rather famous article: “A New Silicon p-n Junction Photocell for Converting Solar Radiation into Electrical Power”.

8    E. Dickten (1904-)

Emil Dickten, Jr., also born in Germany. Together with Wallace and Schimpf (interesting name…) he authored a paper on “A Junction Transistor Tetrode for High-Frequency Use”. By adding a fourth terminal to bias the transistor higher gain at higher frequencies could be obtained.

9    J.O. Edson (1905-1970)

James Oliver Edson was a contributor to the so popular research on pulse-code modulation (PCM). He filed a few patents together with Black.

10    C.B. Feldman (1900-)

Carl Braft Henry Feldman studied at the University of Minnesota and then worked on steerable antennas at Bell. He worked on bandwidth-vs-transmission performance and was Shannon’s aid to formulate the channel capacity. He filed some 20 patents within the fields of antennas, PCM and transmission lines and authored papers with the famous H.T. Friis.

11    G.W. Gilman

George W. Gilman happens to share same with an inventor of pencils. “Our” Gilman, an MIT graduate, however, filed some 15 patents and worked typically on system’s engineering. He studied antennas and radio transmission.

12    F. Gray (1887/9/13-1969/5/23)

Frank Gray, the inventor of the Gray code, once again used for PCM. Gray also worked with television and filed quite a few patents.

13    H.C. Hart

Harry C Hart began working at Bell in 1939 and co-authored an interesting paper with Irven Travis on  analog computers.

  • H. C. Hart & I. Travis, “Mechanical solution of algebraic equations,” J. Franklin Inst., v. 215, 1938, p. 63-72.

The analog computers were designed to solve polynomial equations (root solver). He also designed an electronic harmonic synthesizer.

14    W.E. Kock (1909-1982)

Winston E. Kock later became the director of the NASA electronics research center (NASA ERC) and developed some of the first electronic musical organs!

15    J.G. Kreer (?-?)

John G. Kreer, Jr., is quite an unknown guy in the 31-man strong team. He has left some of his legacy in a paper

  • E. Peterson, J. G. Kreer, and L. A. Ware, “Regeneration Theory and Experiment,” Bell System Technical Journal 13 (October 1934): 680–700,

and he filed a handful of patents on various electronic circuitry.

16    C.O. Mallinckrodt (1907-1985)

Charles Olcoh Mallinckrodt probably had the coolest name among the crew. He also seemed to be an allround-type-of-guy and produced patents on both radio/wave transmission as well as companders and transistor circuits.

17    R.C. Mathes (1888-?)

Robert C Mathes was of Austrian descent and produced more than 50 patents! He typically worked with tubes, speech synthesis (PCM – anyone?) and frequency analysis. Mathes produced quite a few articles in the Boys’ Life magazine (scouts) on various topics. For example:

  • “Fun with a Pocket Compass – An Electrical Stunt that is Interesting and Helpful” (February 1914)


  • “Adventures in Electricity – Exciting Experiments With Your Static Machine”.

He also contributed to some of the refined first color television solutions. He was the most senior of the researchers and also jointed the BTL early.

18    J.W. McRae (1910-?)

James W McRae worked with transoceanic transmitter and is a recipient of the United States Legion of Merit.

19    L.A. Meacham (1908/9/3-?)

Larned Ames Meacham (also a cool name) invented the wobble organ in 1951 while not being busy with his work on PCM at BTL. Unfortunately, I could not find any clips with music played by this type of organ. More information you find at

20    S.E. Michaels  (?-?)

Another unknown in the team… S.E. Michaels authored a paper

  • L. A. Meacham and S. E. Michaels, “Observations of the Rapid Withdrawal of Stored Holes from Germanium Transistors and Varistors”, Phys. Rev. 78, 175 – Published 15 April 1950,

indicating that he worked in the measurement lab.

21    M.E. Mohr (1915/4/9-2000/7/17)

Milton E. Mohr, one of the youngsters in the team, filed a load of patents in various field of research. Given that I have worked quite extensively with data converters, I am quite happy to see Mohr’s name in the list. He constructed one of the first-ever quantizers. His Alma Mater was University of Wisconsin.

22    A.C. Norwine (?-?)

Andrew C. Norwine filed four patents with BTL and worked on pulse-code modulation. His patents related to coders and encoders. He found a clever way of doing an adaptive signal-to-noise ratio control, i.e., when there was less noise on the channel, the signal could be transmitted at less amplitude.

23    W.G. Pfann (1917/10/27-1982/10/22)

William Gardner Pfann was one of the outstanders – a chemist! He however played a very important role since he invented the zone melting process. This method enabled Bell to purify crystals, i.e., starting to produce high-quality semiconductors. For his deeds he also received the first Gordon E. Moore medal.

24    J.R. Pierce (1910/3/27-2002/4/2)

John Robinson Pierce is actually the key guy in this whole story, since he was the one coining the term “transistor”. He worked with Claude Shannon on channel capacity, traveling wave tubes and later relaying communication satellites.

25    R.K. Potter (?-?)

Ralph K Potter worked on frequency analysis of speech and how to be able to code speech more efficiently. He contributed to the theory of speech coding, worked for the NSA (since his techniques could also be used for cryptology). Perhaps most importantly, he is the mastermind behind:

  • “Frog Calls – the musical patterns produced by various species on a Summer night are made visible in traces”, published May 1, 1950.

26    A.J. Rack (1908-1988)

Aloïs J Rack produced a handful of patents on PCM decoders and radar implementations.

27    J.H. Scaff (1908-1980)

Jack Hall Scaff, a University of Michigan graduate, was a metallurgist and thus was contributing to the knowledge on how to dope the different materials used in the experiments and research.

28    J.N. Shive (1913/2/22-1984/6/1)

John N Shive refined the photo transistor and perhaps most importantly invented the Shive wave machine that could illustrate traveling waves. If not useful in theoretical work, it is an excellent way of illustrating standing waves, reflections, etc.

29    W. Shockley (1910-1989)

Shockley was the versatile guy, with the ideas to test and try, albeit a poor entrepreneur. Shockley does not need much more of introduction.

30    R.L. Wallace (1916/2/21-?)

Robert L Wallace, Jr., suggested that a point-contact transistor is not a practical component after all. This in turn led to the development of the junction transistor (also invented by Shockley). Wallace was a materials’ guy. Towards the end of this list, a quote from Wallace finds a good place:

“The advantage of the transistor is that it is inherently a small-size and low-power device,” noted Bell Labs circuit engineer Robert Wallace early in the 1950s. “This means you can pack a large number of them in a small space without excessive heat generation and achieve low propagation delays. And that’s what you need for logic applications. The significance of the transistor is not that it can replace the tube but that it can do things the vacuum tube could never do!”

31    J.R. Wilson (? – ?)

Also quite unknown after my research. He is not the main investor of Xerox, though (same name)… J.R. Wilson worked with Radar at Bell Labs and if nothing else, so far, we can get a glimpse of him at

Looks like a nice man overviewing the youngster’s experiments in the lab.



Top ten sensors to further develop or add to the smart phone

I have touched upon this subject before: sensors in smart phones. In my opinion, the development towards implementing the all-round tricorder has somewhat halted. Phone manufacturers are focusing on improving speed, power consumption, standby-time, etc., which of course is good, but the driver is not that clear to me. Surf faster on your favorite news web portal? Watch youtube videos? Play in-app purchase games? Take photos with crap cameras? Ubiquitous computing?

So, where is all that useful stuff? The things that would make your phone a real companion in your back pocket. To be used in the kitchen, during the walk in the forest, when DIY-ing or mcgyvering, etc.

In this post, I list the Top Ten sensors (well, …) I would like to see implemented in a phone quite soon. As far as I can see, a lot of technology and hardware is already there, so why not start expanding and combining it?

With that said, some of the listed sensors already today exist as 2nd- and/or 3rd-party products that can be attached to, or wirelessly connect to your phone. But still, integration would be desired. Further on, some of the applications for the different listed sensors do overlap, I am aware of that, but they could also be complemeting each other and further strengthen the combination.

image01With the risk of missing some, but to the best of my understanding, the following sensors are available on the Samsung Galaxy S5:

  • Vision (Camera)
  • Sound (Microphone)
  • Location (GPS)
  • Accelerometer
  • Gyroscope
  • Gravity
  • Light (Diode)
  • Orientation (Compass)
  • Magnetic field
  • Atmospheric pressure
  • Proximity (diode)
  • (Notably missing: Thermometer and Humidity – available in Samsung S4, though)

which are perhaps more than one would first think is actually found in your phone. On Google Play some of these sensors are utilized for first-order versions of the sensors listed below. However, the accuracy is quite low and it calls for improvements. See the snapshot from one of the apps in the play store.

I have deliberately not put focus on health sensors, such as heartbeat, etc. There a lot of things are happening and would probably fill this list by themselves: spirometer, oxymeter, and so on. I have not listed mind-reading devices and polygraphs either, for that matter, and notably omitting the age detector.

(Doppler) Radar

image02Some week ago I had a visit by Prof. Dag T Wisland from Oslo University and Novelda AS in Norway. Novelda manufacturers a low-power ultra-wideband radar module, the Xethru. See their web page at The device consumes 120mW and is comparatively compact. (This is the transceiver, additional computing is of course required by SoC and software in apps).

Novelda suggests more practical applications by utilizing the phase shift due to the doppler effect: presence detection, respiration detection, etc. Place your phone on the kitchen table and use it as an alarm. Wake-up detector for your sleeping children.

Or, why not become an expert in finding the beams and wiring and pipes behind the wall? That would impress your spouse (well, …) if you can assemble that IKEA wardrobes and fit to the wall without any mishaps. Bosch offers these kind of devices:

I want that integrated with my smart phone – and imagine what a cool app you could have.

Ultrasonic transceiver

Using an ultrasonic transceiver is quite a similar idea to the one above, I guess: a way to look inside objects. I admit, if it is used to see inside your body, the phone might become a bit gooey when you put that conductive gel on. But in fact, ultrasound can be used for other things: ranging, non-destructive inspection to look for cracks, and even communication.

Could the plummer use it to inspect the pipes after welding? Could the home-cook use it to check the bread – has it proved enough?

With ultrasonic microphones and speakers in e.g. a room, the phone can be used to quite accurately find out its own position and also the positions of other objects. The optimum sheng fui garage could finally become true:


I would like a more accurate thermometer (and in S5 I do not have one anyway). Now and then we need to take the  temperature and check for a fever or so (hard to push the phone into your ear though, but nevertheless). Also the ambience temperature is of interest. It could be a matter of logging the temperature in my  house to adjust the indoor temperature or opt for closing a window. This could be used to lower the energy consumption in my house (assuming that your already-installed heating system is not optimized). But also more practical things: what is the temperature of my christmas caramel? Or bakery in general.

Some apps are already available on Google Play and small ambient thermometers are for example sold by in Denmark. Similar devices are available for ear thermometers. Powered and read out through the audio interface.

The thermometer does not necessarily need to be a thermistor, but could also be supported by IR camera – if it would be portable enough. Products for smart phones are already sold by eg.

Photo- and laser diodes measuring longer distances and angles

Now and then I need to align some paintings or shelves to be mounted on a wall. Or find the center point on a wall, beneath a painting, or similar. This would be a way to complement the plane leveling-alignment laser, like for example Bosch sells too. There are apps measuring angles and distances given a couple of photos, gyro settings, etc.


With more intelligent software (and hardware) to control the laser pointer we could have the device “paint” the target on the wall directly. Let the phone auto-orient by identifying points through the camera or ultrasonic localization. Angles, distances, etc., could be measured and stored. Cleverly combining the diode and the camera could offer you to measure distances of complex objects.

A square box could indicate the boundaries for the placement of your latest diploma. The laser could be used to paint the actual time in the roof above your bed. It could be used for games and entertainment of many kinds. (But that is on the other hand not the path we want to go down in this post).


Already today, vibrations can be picked up by the accelerometer of the phone, and there is academic work out there describing how the accelerometer can be used for the purpose. For example, measuring the vibrations of machinery can be used to monitor the structural health of the device.

For more domestic applications the vibration in the washing machine could be logged to determine when the machine is ready. Earthquakes or traffic vibration, or for the handyman to check vibrations in pipes and ventilation could be used.

Perhaps it could be used in the car to detect and report quality of the road and in general give feedback on your car’s health and guide you towards service of the car.


The Samsung S4, for example, sports a humidity sensor. Use a phone to check the humidity health of your house or crowd-sense data and upload to the weather services. While sleeping at night or idling – let the phone collect information while still charging and doing nothing useful.

Those with sensitive skin are dependent on a healthy humidity level. With your phone you could more actively control a humidifier and let it adjust the level as per your presence in the house. Active humidification!

Metal detector

The phone does already today offer a magnetic sensor that can detect the field and disturbances in the force. The magnetic sensor in the phone will vary with presence of objects that alter the magnetic field. With the metal detector we can look for nails behind the wall, electrical wiring, pipes, “lost” wedding rings in the sand, etc.

Imagine you could finally get that superman power and see straight through objects. (Unless it is cryptonite, of course)! An xray could do the job for you, but I admit it would be hard to implement since you need to have a detector on the other side of the object or perhaps rely on microwaves and ultrasonic inspection. Then we’re back on list items 1 and 2 above.

Still though it would be practical to have right in the palm of your hand.

2016-02-29 11.10.24Scale

Weighing things has been integral for quite some time now. And wouldn’t it be good to be able to measure the correct amount of sugar for your cake? Pour up the sugar in a bowl and put it on the phone. Remove the bowl and the weight is displayed in the window.

In fact, a few phones (like my Samsung S5) does have a (air) pressure sensor and indirectly it could be used to measure the weight. In fact, there are (of course) apps out there that implement this – to a limited degree of success, perhaps. But who’s to blame, the handles are not really in place yet.

One would argue: why put an expensive phone in the kitchen and expose it to to water, fat, and grease? Good question, but consider this: the Sony Experia E4G, now cost approximately $70 dollars in Sweden. It is not water proof, but that’s semantics. The price is low and almost expendable.


Gas could be dangerous. Anyone who lives with (or works in the same cubicle as) someone that enjoys baked beans, onion, and lentils know that by now. Jokes aside. Mould, fungus, and moist could also be dangerous to your health (and to your house). A gas sensor in your phone would be able to sniff around the house and report any levels of strange gases.

To no surprise (?) there are third-party devices that can be connected to your smart phone to do the job. For example sensorcon,, does this. In fact, they have a sensor package that can do quite a few analysis in parallel.

At home, the gas sensor can also be used to detect smoke, checking if the cinnamon rolls are done or not, or indicating if you used too much perfume (or too little deodorant).


With a spectrometer you can measure the contents of a “foreign” object. See for example what Analog Devices currently is developing together with an Israeli startup :  a set of “market hand-held scanners that can be pointed at food or medicine to detect what’s inside.”

This is close to what the tricorder could do in the star trek movies. Just let the device scan the object and see what it is made of.  Other devices are suggested by commercial entities out there, such as the near infra-red spectrometer.