File Transferring in Emergencies




About: Innovative Projects, Diy's, Life Hacks

Next time you go to a place in the world without an internet connection to save lives, make sure your laptop has some software installed. Also take a digital sound recorded, 3.5mm male to make cable and the headphones.

In my previous instructable, I was transferring files via radio by using morse code.

It was not practical, but it was fun.

There are other, much faster ways to transfer files via radio, but that's for a future instructable.

I decided

Let's have a look at how can you transfer small files to your computer from anywhere in the world.

I am not talking about using the internet, I am talking about file transfer via ordinary phone to your PC at home.

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Step 1:

Before going somewhere far, you need to set up your computers.

Computer that will stay at home and the laptop you will take with you.

Computer that stays at home/office/lab

Turn on your computer, connect the mobile phone to the laptop's Line-In/Mic-In port via 3.5mm audio cable. Install an app of your choice that can automatically answer a call. I used "Auto Answer Incoming Call" for Android. Make sure you turn off the sound and vibration mode. Run the "CallTTY" program and change the mode to "ASCII-7" or "ASCII-8". Make sure your computer is not going to turn off or go to sleep.

Install a "Base64 Encode/Decode Utility" on the computer.

Computer that goes with you

Install "CallTTY" and "Base64 Encode/Decode Utility"

Now you are ready to take the flight!

Step 2:

After collecting important data about "insert the subject", you might want to send it back home for your colleges to analyse.

If there is no internet connection, but there is a phone, it's your lucky day.

For this project, I used a small ".png" picture (1.17KB.)
Copy your file to the "Base64" program's folder. My file was "STF.png" Drag it on top of the "encb64.exe" file. Bas64 encoder will create a new file called "name.OriginalFileExtension.b64", so in my case "STF.png.b64" Newly created file, will contain a lot of symbols. Change the files extension to "txt", in my case "STF.png.txt".

Open that text file and Add a line at the top and a line at the bottom, containing text of your choice.

That text can help you to understand where code starts and where ends in case of any problems. It will also separate the information, in case you want to send more than one file.

I added "StartStartStartStartStartStartStartStart..." at the top and "EndEndEndEndEndEndEndEnd..." at the bottom.

Save it!

Step 3:

Run the "CallTTY" software and change the "Mode" to the same your computer at home is set to - "ASCII -7" or "ASCII -8"

At this point you have a choice to use the laptop to send the information home or first, transfer information to the digital sound recorder.

I used a public phone, so it made sense to record information to the sound recorder.

Connect the sound recorder to your PC and press record..

Open the "STF.png.txt" file and wait until it goes through all the text.

It will make an interesting sound.

Step 4:

When audio has been recorded, go to the nearest PayPhone and dial your mobile phone's number at home.

Once you hear that the call has been answered, start playing the sound until it finishes.

"CallTTY" program will record the sound via mobile phone and decode it.

I did some experiments and found out, that sometimes, it's better if you start playing the sound for a few seconds, then stop, start again, stop and on the 3rd time play all the file.

Not sure why, but my sound was decoded bad if I transferred it straight away. When I did this play a few seconds -stop, play a few seconds-stop, play it all technique, file was transfected perfectly.

It might be because my file was not 16bit mono as advised by "CallTTY". I also used unregistered version, registered version should unlock some features.

Now your colleagues can decode the file.

Step 5:

On the computer at home, copy the information from "CallTTY" to the "Notepad" and only keep the text between "StartStartStartStartStartStartStartStart..." and "EndEndEndEndEndEnd..." lines.

Save the file in "base64" folder as "name.originalExtension.b64", in my case "pic.png.b64".

Drag the file on top of the "decb64.exe"

A new file will be created - "name.originalExtension.b64.out", in my case "pic.png.b64.out".

Rename the file, leaving only the original extension - "pic.png".

If information was transferred correctly, you should see your file.

It took me around 6 minutes to transfer 1.17KB picture.

If you need to transfer only a plain text (txt), you don't need to use "base64" utility.

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    70 Discussions


    If anybody is interested, here is another video about file transferring via radio or from the audio cassette. I did not make another Instructable as it's pretty much the same thing, just a different program (by the same guy). Speed is very good. I was sending code @ 1200 baud. It took me around 13 minutes to transfer 68.5 KB video.

    This works great with radio transfer. All the amateur radio operators can send files all over the world, without the internet connection. This is not going to work over the phone, at least not at these speeds and this exact method.

    If code is larger than 10 KB, it's better to split it in more pieces before sending it. When I tried to send a large file, "TrueTTY" had problems playing the sound. You can split the text file with a software called "GSplit".


    4 years ago on Introduction

    I would like to see a USB acoustic coupler method. Would save on some parts and time, and enable live, albeit slow, connection to the home computer, which with internet sharing turned on, could even have the potential to give live internet to your laptop - over payphone.

    3 replies

    so im guessing with an FM transmitter and receiver you could basically have an FM dial-up kind of modem port.. this is really cool.


    4 years ago

    lol! That's funny! Goooood one! When was the last time you seen a pay phone! lol! :]


    4 years ago on Introduction

    OMG - this takes me back to the days of the TRS80! LOL

    Very creative! Might be a sneaky way to transmit security codes or passwords ... except I think the NSA probably runs everything through enough quantum computers to catch it.

    Now, what would be very interesting is to take that audio string and push it's frequency into the inaudible range - say 18KHz+, then play it at the same time as a conversation was occurring. Then take that recorded conversation, filter out the audible frequencies, re-range the audio back to the audible, and see if it could be decoded. I guess the question would be whether or not the microphones and speakers could effectively capture that.... ;)

    5 replies

    I had to google what is TRS80 - wow, that looks like a nice computer for that time.

    Yes, mic would probably fail at picking up the sound. I was playing around with another program (TrueTTY) made by the same person/company.

    It's a software for amateur radio communications.

    I was able to reach much faster transfer speeds, but it did not work via phone, only via radio.

    Turns our phone companies cut some HZ.

    I transfered 68.5Kb video via radio in around 13min (I will publish follow up instructable)


    It's amazing where, and how far the computer world has come in the past 50 or so years.. LOL! Everyone thinks the Internet started back in the 1980's, when it was actually older than 1970's, when the military started what they called the ARPANET (Advanced Research Projects Agency Network), which was actually conceived around 1963 (around the time the first Doctor Who Episode aired on the BBC, and I was born in late July.) The reason most telephones cut down on the frequency, is most calls are already being converted to different frequencies, and multiplexed across less wires, or even laser (welcome to the Fibre Optics).. Yes, I remember the original TRS-80 Model 1. I had one, a Color Computer-III, A Model-100, three Model II's (the BIG Business machines), and one Model-16 (a II, with a XENIX co-board.) Now, we've reduced phones down to pocket sized (so much for Dick Tracy's wrist Radio). Computers down to the size of out old Cell phones..

    Very interesting!

    What happened with all those computers you had? Did they end up in the bin? Technology is progressing so fast, that it's hard to keep up and really appreciated it. Fast progress has become a normal thing.


    Reply 4 years ago on Introduction

    "I guess the question would be whether or not the microphones and speakers could effectively capture that...."

    NO not the question

    Telephones: Bandwidth (THIS IS)

    In order to allow more long-distance calls to be transmitted, the frequencies transmitted are limited to a bandwidth
    of about 3,000 hertz. All of the frequencies in your voice below 400
    hertz and above 3,400 hertz are eliminated. That's why someone's voice
    on a phone has a distinctive sound.......

    And yes Don't forget the salt.


    Reply 4 years ago on Introduction

    Data URI encoding (base64) is certainly not an acceptable transmission of passwords or any other sensitive data. Easily decrypted and recognized. Perhaps if it were changed to use a password hash and a real encryption algorithm then sure this could be used for that.