Tuesday, 27 August 2013

Memoto updates: the world's smallest camera with GPS - and how to design a lifelogging camera

Last update 4th Oct 2013.


The Memoto camera is the world's smallest camera with GPS  and due to ship  November  for $348.75 in the UK.



 4th Oct 2013 Update covering, new investment, new company name, the  hardware design  and a new shipping date from Slashgear. The Memoto company now renamed Narrator.  It is still not clear if the GPS works from this article, but will be shipped without any GPS functionality such as location search. Here is the Sept progress report from Memoto on Kickstarter.


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This post covers some of the engineering issues of designing lifelogging cameras.
I was approached by the Memoto team in June 2012 with regards to help with sensing camera design and lifelogging. They were interested as I had designed the SenseCam for Microsoft, (Gordon Bell of Microsoft used this for the MyLifeBits project) and had been working in lifelogging designs since 1997, starting with The SmartQuill, the sensing technology which  is now used in Apple's iPhone as in this patent.  I am also a Consulting Expert for Apple on sensing and phone patents.  I had various chats with the Memoto team but I declined for various reasons including obligations to Northumbia University,  my employer, at the time.
I have no connection with Memoto apart from being an early Kickstarter  backer, but just for a small amount, $35.

Finance and resources

The Kickstater process start in Oct 2012 and it raised $550,000. This was the result of successful marketing including contacting 100 journalists by each of the 15 team members. More finance was planned to be found in Spring 2013 according to the WSJ Blog.
  Memoto has also raised 500,000 Euros  from the London based  Venture Capital company Passion Capital, giving a total of $1.2M. More here on  Secrets of a half-million-dollar Kickstarter campaign.
There have also been additional advance sales of 3000 cameras via the Memoto website, with income of approx $800,000.  Some early software designers staff have left  but there are new joiners  In Sept 2013 there were approximately 22 people working for Memoto.

How to design a lifelogging camera

The Memoto team asked how to design a life logging camera. 
  • Angle of view of lens.
 A wide angle lens greater than 104-120 degrees is much more useful than a narrow 70 degrees of view on a wearable camera with no viewfinder. The human eye has about 180 degrees of view so a sensing camera needs to replicate this.  As the camera can bounce around in different directions as the person moves, a wide angle is helpful as shown in this cycle ride, a  Sensecam video.  We also get about 4 times the image view with such a wide angle lens.  Here is a video comparing a 70 degrees camera to 140 degrees. Another advantage of a wide angle lens is the huge depth of field from about 6" to infinity, so no focusing needed. We get the image from our point of view showing our hands and also the landscape.

very early test image Microsoft Sensecam , approx 2004, view 104 degrees

  • Timing of capturing the image.
 Interesting life moments can be more easily captured using sensing, e.g. sudden movements, you met a friend, or light change as triggered by walking through a door into a new room or vista. If only  timelapse is used in a shotgun approach (e.g. approx every 30 seconds ) then a series of very dull, blurred, and random  pictures can  be recorded and all the great moments missed (e.g. your friend just walks into view but then walks out  - can easily be detected by heat sensor). If the camera used on timelapse  the camera might only be only sampling for about 1% of the time, rather than being driven by interrupts (sensing events).  Sensor triggering of images also allows very low power mode to be used and a whole day's battery life. Reading a sensor such as accelerometer allows a reduction in blurred images by waiting until camera has less movement, e.g. as caused by walking.  When there has been a quiet period for some minutes, only then were  pictures were captured every 30 seconds. The later Sensecams got around 22 hours battery life.
  • use of motion sensing. Using devices like accelerometers allows features like triggering images based on user's motion. It also allow landscape/portrait orientation of image. Knowing the position of the camera allows power down, e.g. place on a table to power down when in a rest room. There are a series of Apple and Microsoft patents, from 1997,  my designs, which cover these features. 
  • GPS design, power and antenna issues
It is not clear from the Memoto progress reports what the performance of the GPS is yet (I  asked on 31 Aug 2013, no reply by 17/9/2013 ) and the hardware and Printed Circuit Boards are still being revised.
There are so many low cost modules that do GPS well, it is easier to pay £29 on eBay for a dedicated unit, example here  but there are better ones. One advantage is the GPS has it's own power supply so not draining the camera battery. It is a challenge to design a GPS antenna in close proximity to other parts of the electronic circuit re noise issues. The human body can attenuate GPS signals.  These reasons are why a separate GPS unit was used with the Microsoft SenseCam. Later sensing cameras and mobile phones can minimise GPS on time by using a patented system, similar here,  that uses accelerometers or light level  to power down the GPS when no movement detected. You can also use the GPS on your phone to tag and find  camera images.
Note that location data is more accurate  in a mobile phone as the weak GPS signal can be assisted with wifi and cell phone tower triangulation. It is possible to get location information indoors in brick built buildings with cell phones. There is also more space in a mobile phone to isolate the GPS antenna from the rest of the circuit. Here is a good article from a Google engineer about battery issues with GPS. Also here is a useful article of GPS antenna design for small tracking devices. With animal tracking devices the antenna length can be extended along the animal's collar. If the [camera] case is long and thin this can help with antenna design.

If I was designing a tiny life logging camera now (2013), I would concentrate on the camera performance, and leave the GPS tracking  to my mobile phone which does a very good job of tracking, e.g. Google location history on Android phones and producing a track on a map.   No point in reinventing the wheel, if someone else has done a good job, e.g. Google. The camera images can be synced to the nearest second via timestamps. The GPS data is shared with Google but at least stored on your own pc and no need to pay to access it. Each circle on the image below have more data and a time stamp. It can tell me how long I sat drinking tea and chatting today!

Click to enlarge - Google location history 


  • Enclosure design. Although the aesthetics of a new electronic design are important, it is essential to design the miniaturised electronic circuit and test with the chosen battery, and antenna so that all fits inside the case. Design the case after the electronics are finalised. Tooling is expensive. 
This is one of the first wearable cameras from Philips: the beautiful  Key19. (around 2004)



  • Cloud storage. If a wearable camera is generating around 4Gbyte/day, which it could if capturing an image every 30 seconds rather than sensor driven, and is required to be uploaded to cloud storage, this could take some time. The fastest broadband UPLOAD speed in the UK today (August 2013)  is around 4.5Mbits/second.  It is preferable to do some image selection on the pc before uploading to the cloud. 
  • Image sorting, classifying  and processing.
 The 2004 Sensecam had an accelerometer, Passive Infra Red, (PIR) microphone (only for level detection), Red Green Blue (RGB) (16 Million steps) colour sensor, temperature sensor and external GPS.  The accelerometer was used for capturing images due to sudden movement and some simple image stabilisation. It also allowed for power down and power saving. The PIR was used to detect and tag people in photos  via the heat from their body.   The colour and light sensor was used to detect step light changes, e.g. walking through a doorway and capturing the vista of a new room. (I had tried acoustic echos to detect a "new room" but light steps were simpler).  The colour sensor was used to determine if using outdoors, indoors, darkness, flesh, pc screens,   in vegetation (green) etc and allowed simple classification of groups of images. Temperature sensing was not optimum as tended to heat up to 37C, i.e. the temperature of the user. These simple analog sensors allowed real time capturing of "flashbulb" moments at very low battery power. The images were all tagged with sensor data.
  The Memoto camera also uses colour to classify images.The images are clustered by their predominant colours and then then a diagram can be produced as to how the colours vary over the day. It seems that cloud processing is needed for this however and at a subscription cost of $108/year + tax,  with VAT this is $129.60 in the UK.

  • Gender issues
Design  the camera for men and women and consider the different clothes they wear. A clip is not ideal for a women's clothing, (remember the trouble they have with  name badges at conferences e.g. with a dress) so consider a pendant? The camera can also be attached through clothing via a rear magnet. Maybe women just feel uncomfortable with a wearable camera,  feel it is intrusive or ask why is it useful? When I was wearing and testing Sensecam, I would use it for sporting events, e.g. cycling but felt uncomfortable and rude in public and so rarely used it.   Out of a sample of 153 early investors for Memoto, only 4 were women, that is approx 3%. Why? It's probably not just Memoto, but also seems to apply to Google Glass etc.

  • Patents 
Interesting  quote from Memoto re patents and intellectual property:

And what about those patents? Källström reckons the idea of a wearable camera is now well-established enough that there are “no patents hindering new applications in that space”.
Hopefully he’s right. What we’re looking at here is a realization of Microsoft’s old SenseCam project, made realistic – if still a bit pricey – for consumers.

   I mentioned  some the above design aspects covered in my Microsoft SenseCam patent, but there is a work around to avoid infringing this patent.
  • Personal Privacy

 It is also crucial to have a flashing light to indicate image captured so people know the camera is "live" and intruding on their  privacy and so will modify their behaviour, as we do, in front of a live camera. There needs to be a method of not recording other people in public restrooms etc which Sensecam had. For privacy reasons also do not include audio recording, there are other devices to do this if people want. 

Hardware Teardown of Memoto


11 months pass (Oct 2012)   from the Kickstarter funds being placed and  customers want to know when the camera ship will ship. I know the challenges of converting a single working  hardware breadboard prototype into a production item, particularly with analogue design, noise issues, power supplies etc,
I am an electronic engineer so the hardware components interest me, a brief teardown as below:


  • Microcontroller Atmel ARM926   clocks up to 400Mhz, A191SAM9G25

  • 8GB FLASH  RAM Toshiba (is this Gbyte or Gbit?)
  • GPS unit, CellGuide's ACLYS Chip,  5mm x 5mm typical power 20mW, indoor and outdoor use, best resolution 3 metres  Here is the spec.
  • GPS antenna external to case 
  • 5M pixels Camera module, one of the Omnivision variants. These modules have auto focus and image stabilisation. The camera uses Backside Illumination for good low light performance.  In the Memoto the camera is used with fixed focus and an optical lens with 70 degrees of view.  As the  Memoto camera is 5 Mpixels it may be based on the OV5640 family.  Here is the Omnivision OV5640 confidential data sheet. 
  • Accelerometer  Analog Devices possibly ADXL346 This has 3 axis , 13 bit output and a range up to 16g. This accelerometer is  used for triggering images by motion detection and also  to orientate images. This technology  has been used in mobile phones, so much prior art. 
  • Compass AK8963 3 Axis Hall effect sensor
  • power regulator 
  • USB to serial  interface, possibly FT232
  • USB connector
  • custom USB charger cable, orange, unsure why custom cable is needed maybe for recharger or CE labelling? (a guess)
  • 4 LED indicators for battery life
  • power on/off there is no switch but possibly controlled by reading accelerometer orientation. 
  • Lithium Poly battery 3.7V 130mAhr
  • temperature sensing, none - only for the battery charging system. It is hard to measure ambient temperature on a body worn camera as after about 20 minutes it warms up  the temperature of the person.
  • other components not identified yet
  • All components fitted inside 36mm x 36mm x 9mm case.

All the above is powered by a tiny rechargable lithium 3.7V 130mAhr battery, similar to those used in model helicopters. This size of battery takes about 20-30 mins to charge.   Memoto claim the battery provides 24 hours of  life. This compares to the OMG Autographer camera (based on Microsoft's SenseCam) that is twice the size but has just 10 hours battery life.
A Li-poly battery similar to this has a maximum number of charges of 500 cycles and cost around $0.85 in quantity.

  Cell phones normally have a battery with around 5 times the capacity.

Image from Memoto showing 130mAHr battery 



Memoto hardware, picture from Memoto Facebook. Click to enlarge

Some of the power reduction is achieved by offloading the GPS calculation of latitude/longitude onto  a more powerful computer rather than the camera. This is actually done on Memoto's subscription cloud service, not the user's PC. Customers comment here re accessibility of their data  being only via the cloud.

Shipping date?

On 22nd  Nov 2012, Memoto  announced  here that "We are now finished with the last tweaks of the electronics and mechanics and are ready to go into trial manufacturing of both". 
There has been much discussion on the Memoto blog of why the ship date has slipped 8 months  from Feb 2013 to now end of Sept (as of 18/9/2013) There seem to have been engineering challenges since Jan 2013 with the performance of the GPS antenna  re sensitivity issues. The case is very small to fit the  antenna in such close proximity to the  rest of the noisy electronics.  The antenna is now wrapped around the inside of the case and tests ongoing.

 Update 30th August 2013, from Memoto,  there is no shipping date yet but there will be  another PCB revision to add improvements to GPS performance. There are 4000 cameras due to be shipped soon, around 2400 pre-ordered via Kickstarter.com.


  • UK price inc VAT


I will wait until  shipping and some hands on review before handing over my money. It will be interesting  to see the camera one day and I look forward to reviews from some customers. I want one for animal tracking, but autumn is here and the animals are starting to hibernate.


Here is a picture found on Google Street Maps (can revolve link  in 3D)  of the site of the  Memoto office.

This is the beautiful  Mjardevi Science Park  with fountains and  Memoto.




click to enlarge




Other GPS designs from Kickstarter


Memoto isn't the only well funded Kickstarter projects to run late with  hardware issues. The Bia sports watch, ($2.75M investment) also with wearable GPS, a tiny form factor and battery constraints. This  has some interesting mechanical but solvable engineering challenges e.g. waterproofing, to solve before shipping. Bia are open with their customers and explain in detail the technical problems and have good customer/investor  support. The image below shows how the Kickstarter funds are being spent.



Other cameras, some  with GPS

Another wearable lifelogging camera with GPS is  the OMG Autographer camera, based on Microsoft's Sensecam, with similar functions but images triggered by recognising  interesting events, but physically 3x  larger, and more expensive at £400, and now ships. I have no connection with Oxford Metrics (OMG).

Here is a  low cost data logging High Definition camera, GPS, wide angle. There seem to be numerous on eBay e.g. like this, £55, 5 Mpixels, 140 degree lens  with accelerometer data logger but I have not tested it out.



Wearable cat camera here.

photograph from Eyenimal 

Claimed to be  world's smallest 5.0 Megapixel camera,  11 UK pnds.


Lyndsay Williams Sensecam@gmail.com

2 comments:

  1. Nice write-up, thanks! I was just tempted to tear it down, but then I saw your blog post. Still, I might want to get access to the thing, because I don't have Microsoft or Apple. :-(

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