Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>Well I am currently working on a similar system of transmitting data using these high frequencies and this is what I found out. Al-thou keep in mind that I am doing this with Android phones, mostly Galaxy S line. First of all spectrum of 20khz to 22khz seems quite promising because it can be detected by all phones we tested and even reproduced by some of them. These frequencies are inaudible to humans of any age and even the dogs and cats seem to not notice them. If you are targeting (actually avoiding) detection by humans you could even go to as low as 18khz since most people wouldn't hear that. This gives you a bandwidth of 4000hz which you can Frequency modulate a data into. Of course don't expect to transmit 8mp images but some small data can be transmitted. You are right in the part that you could than use FFT to transit into frequency domain and analyse those frequencies, this can be done even on older phones in Java (I think doing it in objective c would be even faster).</p> <p>Also if you have few iPhones on your disposal you could install any frequency analyser and play the frequencies you want on another iPhone or some speaker to test what they can detect. Just keep in mind that standard desktop speakers would probably be able to play the given frequencies but will introduce noise of lower frequency. Piezo tweeters are probably best for these type of sounds al-thou I must say I am using iPhone 4 to play these frequencies for testing quete efficiently.</p> <p>I read somewhere that Shopkick now even plays there sound codes over stores PA-s and since those speakers are not really optimised for above 20khz response I too am starting to suspect they are using frequencies below that. Take a look at this website for different store codes that some people are using to cheat the system <a href="http://www.ceploitips.com/2011/03/shopkick-walk-in-files.html" rel="nofollow">http://www.ceploitips.com/2011/03/shopkick-walk-in-files.html</a> Keep in mind that using these might ban your account since they improved there misuse detection algorithms.</p> <p>Also I too would like to read more about the Shopkick implementation so if anyone viewing this has some link please share.</p>
    singulars
    1. This table or related slice is empty.
    1. POUltrasound iphone (Shopkick signal technology)
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USPSIXO
    1. USPSIXO
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. POUltrasound iphone (Shopkick signal technology)
      singulars
      1. PTQuestion
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. This table or related slice is empty.
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload