sat.Send is a small device that allows you to send and receive messages and share your GPS location no matter where you are.

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sat.Send is an open source portable device that allows users to send messages and location anywhere on Earth with a clear view of the sky. It works far beyond the reach of WiFi and GSM networks. Designed to be used as stand alone or be connected to a device via Bluetooth Low-Energy (BTLE) or WiFi.

The project will consist of a microcontroller which will be the main "brains" of the system, a RockBlock Naked which will handle the satellite communications, a GPS unit to find position and ideally a display/input component to allow messages to be read/sent if there isn't a PC or phone available to connect to the unit via Wifi or Bluetooth. There will also be a web app written using the Meteor framework that records and displays messages and position, this will also forward messages to the SMS network using the Twilio API.

Below is the system design diagram:

Here's my video where I (try to) explain the basics.

  • 1 × RockBLOCK Naked Sends and receives Iridium SBD messages.
  • 1 × Arduino Yun Microcontroller board based on the ATmega32u4 and the Atheros AR9331.
  • 1 × Venus GPS Small, powerful and versatile GPS receiver.
  • 1 × Sparkfun Logic Level Converter Bi-Directional

  • Progress!

    John Grant05/27/2016 at 18:55 0 comments

    For anyone interested I'm collaborating with a great all round engineer/coder on a new project called MyComm at It's similar to the sat.Send concept but we decided to make it a standalone device with its own touchscreen interface and solar charging so that it can be a really reliable and accessible device. sat.Send never progressed as I wanted it to and working with someone else really helps to stimulate the brain cells and keeps driving things forward, we've already made good progress with a prototype so I hope you can check it out.

  • ESP8266

    John Grant06/29/2015 at 13:29 0 comments

    Over the last few months I've done a lot of experimenting with the RockBlock Naked at work and it's a pretty cool unit that is easy to use. I have a bunch of documentation and code I need to tidy up and upload but overall I'm happy it will work with no issues. I do still think it would be worth trying out a raw Iridium 9602 transceiver but this will have to wait.

    To make this unit viable and useful in real life it has to be portable so it has to be capable of running of it's own power source. I've had a nagging feeling for some time that my initial component selections are probably pretty power hungry so realistically will need to investigate lower power alternatives. For example the ESP8266 is a UART to WiFi SoC built around a Tensilica Xtensa LX3 processor. The standard breakout boards usually come with a firmware supporting a simple AT command set to configure and control the wireless module but the SoC is actually fully programmable and can be used as a micro-controller, with Wi-Fi and GPIO. Now the Arduino IDE has support for the ESP8266 and there is also a Lua based firmware available called NodeMcu. There are even tutorial detailing how to run a webserver and allow GPIO config via an interface. Could this be used to provide a user interface to the RockBlock?

  • Initial Yun Client Code

    John Grant08/18/2014 at 20:40 0 comments

    Using code from a previous project as the basis for the Yun client. This code is added to the GitHub satSendClient link. The code is a basic webserver for an Arduino Uno and includes basic network setup, page routing and HTML. A lot of this code will be easily altered to work on the Yun so forms a good starting point.

  • Power

    John Grant08/18/2014 at 20:23 0 comments

    Power is an issue that still needs further thought. Ideally I want the sat.Send to be portable so it could be used in remote or emergency situations so this would require some kind of battery. Possible to use solar to recharge? I need to finalise the system power requirements and then I will finalise the power supply. In the meantime during prototyping power will be supplied via a desktop supply.

  • Server Side

    John Grant08/17/2014 at 21:05 0 comments

    Meteor is an open-source platform for quickly building web apps. Both server and client code is written in Javascript and the framework is designed to be responsive and has a great community. I'm going to write a web app that logs the messages that have been sent to/from the device and it will also show a real time map of location points.

  • Basic Circuit

    John Grant08/17/2014 at 21:03 0 comments

    Basic circuit connection (without display and power). YUNs hardware serial is used to connect the MCU and CPU for the bridge communication library so software serials are used. A Sparkfun Bi-Directional Logic Level Converter is used to convert the GPS 3.3V to the YUN 5V.

  • GPS

    John Grant08/17/2014 at 21:02 0 comments

    I've had some experience of using the Venus GPS board in the past so I will use that and the TinyGPS++ Arduino library for parsing NMEA data streams.

  • Microcontroller

    John Grant08/17/2014 at 21:02 0 comments

    I've decided to use the Arduino Yun as the central hub of the project, from previous experience of Arduino development they are really easy to get started with, there's loads of information available and the community is great for support. The Yun is cool because as well as a Atmel ATmega32U4 processor it has an Atheros AR9331 processor that supports Linux which means it can be used as a webserver and can even run node.js which could be interesting and it has built in wifi. As well as all that I won one in a previous competition and I want to make use of it! A guide to the Yun can be found here and below is a brief overview of the specs taken from the product page:

    "The Arduino Yún is a microcontroller board based on the ATmega32u4 (datasheet) and the Atheros AR9331. The Atheros processor supports a Linux distribution based on OpenWrt named OpenWrt-Yun. The board has built-in Ethernet and WiFi support, a USB-A port, micro-SD card slot, 20 digital input/output pins (of which 7 can be used as PWM outputs and 12 as analog inputs), a 16 MHz crystal oscillator, a micro USB connection, an ICSP header, and a 3 reset buttons."

  • RockBLOCK Naked

    John Grant08/17/2014 at 21:00 0 comments

    The RockBLOCK Naked is used to handle the actual sending and receiving of the Iridium SBD messages. This unit has integrated transceiver, power and antenna and most importantly has been approved to transmit and operate on the Iridium network which allows a working project to be produced without the delay of waiting for FCC approval, etc. In the future I would like to produce my own open source Iridium communication board making use of the available Iridium 9602 transceiver

    Using the Rock 7 web interface a RockBlock can be configured to deliver message to a specific web application URL using HTTP POSTs as detailed in this guide. For the sat.Send the URL will be the sat.Send Meteor web application. The web app will process the POST parameters, store them for display and also forward the message to the relevant SMS number using the Twilio API. For return messages the process is similar, a HTTP POST can be made to the rock7 URL. This will be achieve by using the web app or by sending an SMS to a Twilio number that is associated with the sat.Send (see future post for details and code).

  • Last minute attempt!!

    John Grant08/11/2014 at 19:55 0 comments

    Only found out about the The Hackaday Prize and it's awesome!! There's hardly any time to get something done but the prize is so cool I'm going to try and get something for the initial entry date so please bear with me!

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HAmza wrote 03/31/2015 at 22:17 point

I got this message On video "This video is unavailable with Safety Mode enabled. To view this video, you will need to disable Safety Mode." ??!!

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John Grant wrote 04/01/2015 at 07:00 point

Hi, I think this is related to the settings on your local PC. Take a look here:

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HAmza wrote 04/01/2015 at 08:08 point

Thank you . i disable the safety mode in youtube 

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