The RockBLOCK data cycle

Do you know how your RockBLOCK works? Here's the lowdown.

Collect Data

Chances are, you will be attaching your RockBLOCK to some kind of controller, like an Arduino or Raspberry Pi equipped with a GPS module, temperature sensor or other data collection device.

In this chapter, the data processing cycle will be outlined to give users a basic understanding of how the RockBLOCK modem handles data from your devices.

Assemble ASCII/Binary Packet

The RockBLOCK uses an Iridium 9602/9603 SBD modem which is capable of transmitting ASCII or Binary messages in packets of up to 340 bytes and receiving packets of up to 270 bytes.

ASCII messages take up more space and thus use up more credits. A binary message is able to squeeze in more information per transmission but may require conversion to return your data to its original form.

Sending/Receiving Data

Messages transmitted from the RockBLOCK are defined as MO (Mobile Originated) - that is, they originate from your mobile device. Messages transmitted to the RockBLOCK are defined as MT (Mobile Terminated) as they terminate on your mobile device.

Data transmission with the RockBLOCK is a two-step process. Before a send/receive command is executed (called an SBD transmission), data must be transferred from your controller to the MO buffer of the RockBLOCK modem.

Next, the SBD transmission sends your MO message and receives the MT message that's next in line. Information is also given on the status of the sent MO message, as well as on any further MT messages waiting to be downloaded.

This process is outlined in the Transmit ASCII data, Transmit binary data and Receive data chapters.

Transfer data from the MT buffer

Following an SBD transmission, data in the MT buffer needs to be transferred from the RockBLOCK modem to your controller.

Signal Strength

It would seem intuitive to check the signal strength before sending/receiving data. In practice, we consider the process as impractical for reasons we outline in a dedicated chapter.

Ring Alerts

Some users, though not sending MO messages, are more interested to know if there is another MT message waiting to be downloaded. This is done in two ways - either through a (free) ring alert, or through a mailbox check.