TimesToCome Mobile

iOS apps and tips, tricks and tools for smart phones

Using the FFT to decipher a signal

I recently began to learn about signal processing. There’s a lot of theory out there but little on the basics and much of what should be obvious isn’t. I ended up writing a test program I could play with and decipher. By adjusting the signal, frequency of samples, window size &c you’ll see how it all fits together.


Download the full project

Signal Processing Resources:
Texts (free, online)
Intro to Digital Filters
Mathematics of the Discrete Fourier Transform
Spectral Signal Processing
The Scientists and Engineer’s Guild to Digital Signal Processing
Signal Processing for Communications
Complex to Real, Tutorials on Digital Communications Engineering

The Nyquist Sampling Theorem
An Interactive Guide to the Fourier Transform

Mike Ash: Obtaining and Interpreting Audio Data
Invasive Code: A Quasi Real Time Video Processing on iOS

Arxiv: DSP

Online Classes
Coursera DSP
Coursera Fundamentals EE

The best of the iOS7 tips and tricks

1) In messages, in a conversation swipe right to left and hold to see the time the message was sent.

2) In Safari, tap bookmarks, see the ‘@’ at the top right? Tap that to see links in your Twitter feed

3) Settings->Privacy->Advertising – Limit Ad Tracking

4) Settings->Phone->Blocked ( I set up one contact and put all the spam numbers in there, then blocked the spam contact )

5) Set up a silent ringtone for contacts you don’t want to hear from

6) Push alerts up to make them vanish – no more waiting for the 5 second time out

7) Calendar list view is still here, tap the search button at the top of calendar to view your list

8) Tap the temperature in the weather application to get humidity, wind speed, chance of rain information.

Apple just started an iPhone 5S Tips and Tricks page

Silent ringtone for iPhone

Someone must’ve given out my number the telemarketers have been calling. A silent ringtone keeps you from being interrupted or even noticing someone called.

I downloaded a silent ringtone
10 Seconds Silence.m4r

Add it to iTunes, sync your phone and set your default ringtone one of the silent ones.
Close friends and family are assigned a ringtone that makes noise.

See also:
Make iPhone Ringtone free for OSX and painless to use.

iPhone 5 iOS 6 tips and tricks

1) To quickly lock your device click the power off button

2) To quickly open the camera when the device is locked -> click the power off button -> swipe up on the camera icon next to the unlock slider at the bottom

3) To change the volume while locked double click the home button

4) To add keyboard shortcuts ( type a few letters and it will autofill in the rest of the text for you ) go to Settings->General->Keyboard->Shortcuts

5) To dictate Siri must be on ( Settings->General->Siri ) and you must be connected to the internet. A microphone will appear on your keyboard – tap it to begin dictating

6) To turn off notifications from appearing in the notification center go to Settings->Notifications->(chose the app to remove) ->Select none for the Alert style, then turn notification center off

7) Press the on/off button to silence a ringing phone, press twice quickly to send the call straight to voice mail

8) Block calls but not the internet ->Settings-> (turn airplane mode on) Go to WiFi and turn it on

9) To use a different signature on different email accounts go to Settings->Mail,Contacts,Calendars->Signature and check Per Account

10) To get written map directions instead of spoken, tap the icon that looks like a list next to the 3D icon on the bottom left of the maps view

11) Go to Settings->Maps and change the label size ( scroll to bottom) to small to get more detail on your maps

For a whole lot more information see:
iPhone User Guide