Thursday, February 11, 2016

Sensor Plots App - How to Use it

Sensor Plots app is data acquisition apps to capture accelerometer, gyroscope and magnetometer sensors. The data acquisition method is similar for all the sensors. You can download the app from  Apple Appstore.

App Main Screen

The app is very simple and easy to use. Select the sensor whose data you want to acquire.  And then select the action you would to do.

You can select the sensor whose data you want to acquire from the bottom of the screen.


Once you select a particular sensor you can select different options for that specific sensor. The options available from left to right are shown below:

  1. Email: This options will create a attachment in .csv format and open your email app. So you can email the data to your email address.
  2. Trash: This options will delete the temporary .csv file and test data saved in persistent device storage. 
  3. Go/Stop: This toggle option starts and stops the data acquisition task.
  4. Setup: Configure the sample rate for the sensor. The value is from 1 to 100 Hz or samples per second. 

Walkthrough of the App

Here is walkthrough of the app.

I hope you enjoy the app. Please share your findings and contribute to the global knowledge. Thank you.

Tuesday, February 9, 2016

Sensor Plots - App for iPhone Sensor data acquisition


If you ever wondered how the iPhone or iOS device count your steps, knows device landscape or portrait orientation or provides directions -- then this app will help you dig deeper. Most of the iOS devices have multiple sensors such as -- accelerometer, gyroscope and magnetometer. These sensors are first line of intelligence that captures the data to make the inference. Sensor Plots is a iOS data acquisition app that will collect the digital data for further analysis and illustration.

Accelerometer Reference Frame

Accelerometer is a sensor that measures the g-force, also called Proper Acceleration, that acts on the device. Its helps iPhone determine how the iPhone is held by the user. The data reported by the accelerometer  are in a x,y,z co-ordinate system that is attached to the phone. It has a frame as shown in following picture. 

A Simple Accelerometer Experiment

The values providing on are a measure of g-force acting on the system. The earth's gravitational force is downwards but an object that is seating in an elevator it is getting a opposite force upwards. So a phone is kelt on a table facing upwards it will measure x = 0, y = 0, and z = -1. If you change the orientation of the phone to vertical landscape position with home button towards your left the values will be x = 1, y =position w 0 and z = 0. With phone in vertical portrait with hime button down the values reported by accelerometer will be x = 0, y = 1 and z = 1. The Sensor Plots app screenshot below shows this data as phone is moved in sequence in these positions. The rms-value (red line) represents the root-mean-square value which is magnitude of the net force and is equal to square root of (x*x+y*y+z*z).

Take a Few Steps

Take few steps after visualize your effect your walking style has on the accelerometer. The data is shown in following picture. The sample rate for this was 48Hz. if you increase the sample rate you can analyze the style of walking and pattern. 

The Gyroscope

Gyroscope measures rate of rotation, that is how fast something is rotating. It's measure is radians per second around a specific axis. It helps in determining how fast the phone is rotated by the user, it helps games to offer how fast phone is being rotated by the user. You can make the phone as steering wheel in some games.

Gyroscope Reference Frame

The gyroscope measure are also reported in three values - x, y and z. Each value is rate of rotation around the axis. The sign of the value is determined by Right Hand Rule: take you right hand and curl your fingers in semi-circle they will point in positive direction.  The figure below shows the positive direction.

A Simple Gyroscope Experiment

If you keep your phone on the table with face up, then perform the following steps:

  1. Use your right hand curl with thumb facing upwards. The rotate the phone by 90 degrees in direction of your finger curl. You can correlate the values measured by iPhone gyro in graph below. The z-value (behind red rms line) goes up positive and then goes to zero when phone stops at 90 degree. Then rotate the phone back to where you started (opposite to direction of your curl) and you see z-values going negative and then back to zero.
  2. Then face your right hand thumb towards your right and curl your fingers. Move the phone around x-axis i.e. upwards unto 90 degrees. You can see the x-value rising (behind red res-value) and goes to zero as phone comes to stop. Them move the phone in same direction back, you can see the x-values going negative and back to zero.
Figure below shows the data as shown by the app Sensor Plots app. 


It measures total magnetic field observed by the device, that is sum of earth's magnetic field, surrounding magnetic field and device bias. The values are measured in x,y,z similar to accelerometer axis but represent deviation from devices magnetic reference frame.

A Simple Magnetometer Experiment

Take your iPhone and calibrate it using your native  Compass app. Align the phone towards magnetic north (phone y-axis). Start the Sensor Plots app and do a magnetometer test. The following figure shows the raw magnetometer values as sensed by a iPhone 6 and iPhone 6+. The earth raw magnetic field is around 50 micro Tesla at the equator.  These readings include the total magnetic field at the iPhone sensor.

Wednesday, June 10, 2015

My experience with Moto 360

Moto 360 Experience.

My number one reason to buy the Moto 360 watch was to set my son's picture as my personalized watch face. I bought this watch from by only looking at pictures and specifications. Few other things that I liked were:
  1. Round shape
  2. Android compatibility
  3. And, a full day battery life
Following picture captures why I bought Moto 360.

My son on Moto 360 watch-face.


The watch comes beautifully packed in a nice package. Easy to open and get started. The battery had some charge in it. But before I started I charged it to fullest. 

Getting Started:

Before pairing the watch with phone (I am using Samsung Note 3) download install following two apps:
1. Android Wear: link on Play store
2. Motorola Connect App: link on play store

Then pair your Moto 360 to your phone. It took me somewhere about 40 minutes from updating the app software to pairing with Note 3. Here is a youtube video of how to do it.

The Rough Beginning

1. My goal was to set a custom watch face with picture in my phone. I tried using Motorola Connect app. Well thats when my problems started. I just could not get the phone to sync with the app to update my custom watch face with the picture. I probably tried to reset the device about 20 times. Yes I was committed to get it [watch face] on. I got it working at least once. That is the picture above.  And that was only time it worked.
2. After some searching I cam across "Watch faces for Android Wear" by Intellicom (Play store link). Although it takes some work to design the watch face it worked like a charm.

A Pleasant Surprise

One the biggest surprising discovery for me was fitness data. For the duration I wore my watch I had this urge to keep my fitness stats up. That included not to sit for long time, take daily walks and try and keep myself active.


What drove me nuts and wasted a lot of my time was fact that watch lost its bluetooth connection frequently [to my Note 3] as I would not keep phone with me all the time. It never re-paired itself with the phone when they were near. To re-pair I always had to reset the watch. It took time, more than 10 minutes. If there is one thing that Motorola should fix in next version it should be to make watch work seamlessly with phone. And nor more resets to pair please. It is a beautiful watch and I like to use it for more than two weeks.

Moving On

It is too tiring to keep up with this watch. The wearable is supposed to help save my time and energy. Instead I find myself serving this watch and seeing time to keep it connected and working. So it is sad to say that I have to keep this one in the gadget box. Even my 10 year old does not want it. Trying apple watch next. Apple products work well with each other so hopefully the watch stays connected at very least.

"Rihanna - Don't Stop The Music" video to cross 100M+ views on YouTube

As of Sat 26, 2009 there are only youtube videos with 100M+ views. The top spot is still held by Jusdon Laipply's evolution of dance with 126M views with Avril's Girlfriend music video close second with 125M+ views. Evolution of dance was posted on April 6, 2006. Aviril's video was posted on Feb 27, 2007. Aviril's video will most probably become #1 youtube video.

So far there are only 4 youtube videos that have crossed 100M+ views. The fifth being Rihanna's "Don't Stop The Music" with 99M+ views.

Top 10 Youtube videos:
  1. 126,795,745 views: Evolution of Dance.
  2. 125,974,726 views: Avril Lavigne - Girlfriend.
  3. 122,565,011 views: Charlie bit my finger - again !
  4. 101,387,693 views: Miley Cyrus - 7 Things - Official Music Video
  5. 99,050,417 views: Rihanna - Don't Stop The Music
  6. 98,204,836 views: Chris Brown - With You
  7. 97,955,354 views: Lo que tú Quieras Oír
  8. 95,540,762 views: Jeff Dunham - Achmed the Dead Terrorist
  9. 92,174,098 views: Hahaha
  10. 89,992,327 views: Leona Lewis - Bleeding Love

Sunday, September 12, 2010

AutoStitch Panorama iPhone App Review

Our family went for a weekend of camping at Lewis Campgrounds in French Meadows (+39° 8' 13.74", -120° 24' 37.49" Lat/Lon) in California. The weather was perfect: no rain, neither too hot nor too cold. We were having fun barbecuing, enjoying company of friends and nature. During the day hike this small reservoir captured my imagination. Beautiful blue water against backdrop of lush green mountain range and blue sky was a moment that needed to be captured and shared. I took out my iPhone 4 and took 3 pictures carefully from left to right. Hoping there must be an app for that: stitching the pictures together.

On the way back while my beautiful wife was driving while I searched "photo stitch" on AppStore. Then I downloaded most rated "AutoStitch Panorama" for $2.99. I was very impressed with the simplicity of the app. The app rocks for its simplicity, ease of configuration and operation.

Configuring Options:
From home screen tap on "Info" --> "Option" and configure for the resolution your data usage and storage requirements. Setup Blending to Best. Setting blending to None/Standard is faster but output is very poor quality. Here are few screen shots of configuration screens.

Stitching the pictures:

Once the configuration is done you are ready to stitch the pictures. On the home screen choose "Camera Roll" select images you want to stitch together. Once you have input the pictures tap on "Stitch" and you are all set. The app does all the magic and presents a beautifully stitched image. Take a look at the output if you like it "Crop" it and you are ready to share.

If you are satisfied with the output you can save it local images, send it via email or post it to your Facebook Wall. I use email most often to add pictures to my picasaweb album.

If you are wondering how did my three pictures on the top looked after stitched using 100% Resolution and Best Blending, here it is:

Pretty cool. I found this app to work best on still scenes. As, IMO, algorithm can easily identify commonality between two images and use that to stitch a panoramic view. However, I was able to take five pictures of our tired group after camping seating in a lunch table and stitch them together. It was not bad:

Enjoy panoramic pictures on your iPhone. And don't forget to share. If you need more info got to the AutoStitch Website.

Other good reviews of the app I found on web:
1. AutoStitch Panorama iPhone app Review
2. iPhone Apps I actually use: Part III – AutoStitch
3. AutoStitch Panorama vs. Pano – iPhone Panorama Apps Review

Enjoy your iPhone and AutoStitch app.

Tuesday, September 7, 2010

Gourmandia's Recipe TV Premium iPhone 1.2 App Features enhanced its Recipe TV Premium App specially designed for iPhone users. It brings secrets of Michelin Star restaurants Chef's into palm of your hand. The featured video Gourmet foods recipes are prepared by Chefs like Chef Alain Pic, at their Michelin rated restaurants. If you love cooking in the comfort of your home, are looking forward for unforgettable time with your loved ones then this app for you. Try cooking a Gourmet meal under the guidance of a World's Best Michelin rated Chef in your kitchen. The app also features some interesting how to napkin folding and travel videos.

The post looks at the features of this app.

Application Details:
The App allows you to view Featured Recipes, Category and Chef. You can save your favorite recipes and view them at your leisure.

What's new in this version:
This version of app provides following enhancements over version 1.1:
1. Checked to work in latest IOS release 4.1
2. Fixed App crashes.
3. Upgraded the video player. Can see videos in portrait mode.
4. Added NEW videos label.

App Images:

Following pictures show various app screen views. Its show how Features, Categories, Chefs and Favorite sections of the app look:

This section of the app lists recipes that are features by a Gourmet specialist. Take your time to visit this and see what is in surprise for you here.

This section features the ten different kinds of recipes types that are available. Be it Appetizers, Seafood, Healthy or Dessert. The app also features very famous Napkin folding and Travel videos. Each of these categories feature up-to five videos. The Gourmet Specialist also chooses five new videos every week. Each of these new videos are clearly marked NEW, take a look in screen-shot above. Take your time to explore and find these NEW videos to enjoy them.

You can also look the recipes by a Chef. Just go to Chef tab. Look for the Chef you are interested in by his name and tap on it. Then you can browse the recipes by that Chef.

Once you tap on a video you will be taken to a screen that looks something like below. Once you are on a Recipe Video screen. Tap on the "Play Video" to watch the recipe TV video presentation. Most of the videos are in English language overlayed on French speaking background. The app features new video player on iPhone that allows you to play videos in both portrait and landscape mode. The portrait mode is very helpful if want to listen in to your recipe while you actually cook it. Place the iPhone or iPod Toch on a dock such as iHome and enjoy recipe videos in portrait mode on good sound without having to worry about the battery drain.

If you missed certain steps. Do not worry, on the video screen tap on the Recipe Details and and you can see the ingredients and preparation steps in English. If you like a video, please rate it by clicking on the video. If you like to come back to a video again or save it future use mark it as your favorite.

The Gourmet specialist will choose five NEW recipes every week. Explore the app and see if you have something new you can try for weekends or holidays.

See this tab to see all videos you have marked favorite. It provides you a quick access so you get going on the recipe you would love.

Known Bugs:
Pictures of Chef does not match the actual Chef in some cases. We plan to fix this in the next release.

In conclusion, Gourmandia Recipe TV Premium 1.2 app is more stable and provide ability to enjoy your recipe videos while you are cooking by placing on docks such as iHime. Gourmest specialist will now offer NEW videos every week.

Saturday, August 29, 2009

Upgrading MacBook Air from Mac OS X 10.5.6 to Mac OS X 10.6 (Snow Leopard)

Devices that I used:

1. MacBook Air 2.13 GHz Intel Core Duo, Memory 2GB 1067 MHz DDR3
2. HP Pavillion dv600, AMD Turion 64 X2 Mobile Technology TL-56 1.8GHz, 2.00 GB, Windows Vista Home Premium Edition. Service Pack 1

A) Set up MacBook Air in same workgroup as your Windows laptop. Do it by "System Preference" --> "Internet and Wireless: Network" --> "Advanced" --> "WINS": Enter workgroup name of your network. Note: When you do this you would be able to see your shared network resources on the MacBook Air, eg - shared drives, NAS (on same workgroup) etc.

B) Setup Windows computer to share its DVD drive over network with MacBook Air:
  • Use the "Mac OS X Install DVD" that came with the Mac OS X that is installed in your MacBook Air. Note that do not use the "Mac OS X Snow Leopard CPU Drop-in DVD" at this time. This is to install a version of "DVD or CD Share" on Windows XP laptop that would work with MacBook Air.
  • Install "DVD or CD share" program in the Win laptop. You may have to reboot the Win laptop.
  • Go to "control panel" and click on "DVD or CD Sharing Options". Check both boxes that appear. You may need to reboot your computer at this time.
C) You are now ready to install the latest Snow Leopard on your MacBook Air.
  • On MacBook Air "Macintosh HD" --> "DEVICES" --> "Remote Disc" --> "remote-laptop name" --> "Ask to use"
  • On Win Laptop "click on Accept" pop-up that appears.
  • Insert your "Mac OS X Snow Leopard CPU Drop-in DVD" in win laptop
  • On MacBook Air "proceed with installation process". It may take anywhere from 45 min to 2 hours depending upon your WiFi & Win Laptop speed.
D) After installations is complete on MacBook Air, update your Win laptop with latest "DVD or CD share" software.
  • On win laptop un-install "DVD or CD share" software.
  • Put in the "Mac OS X Snow Leopard CPU Drop-in DVD" in win laptop
  • Re-install the "DVD or CD share" program
  • Go to "control panel" and click on "DVD or CD Sharing Options". Check both boxes that appear. You may need to reboot your computer at this time.
Now you can use the DVD drive on win laptop to install other software (MS Office) on MacBook Air.

Enjoy your MacBook Air with Snow Leopard.

Challenges that I faced:
  1. I used the "Mac OS X Snow Leopard CPU Drop-in DVD" in step B above to install the "DVD or CD share" on win laptop. The MacBook Air did not recognize the Snow Leopard DVD. Then I removed the program and re-installed with "Mac OS X Install DVD". Then MacBook Air could recognize the Snow Leopard DVD.
  2. I faced some challenges setting up my MacBook Air in same workgroup. Rebooting MacBook help fix that problem.