Proof of Concept for EDGE Research Lab, it is not 100% repeatably deployable as this stands.

Intro

The EDGE Spectral Awareness Payload (SAP) is a small, lightweight, RF power spectrum recorder specifically designed for high-altitude balloon deployment. Focusing on COTS hardware, this effort is intended to demonstrate the feasibility of the sensing portion of the payload-able whitespace radio concept (a dynamic radio determining useable bandwidth).

Scope

The SAP is a record-only, analyze-on-recovery, high-power requirement (>5W) payload.

BOM

• 1xRaspberryPi (originally the model B)
• 1xRFExplorer WSUB3G/3G
• 1xNwazet Key Lime Pi interface module, incl. MCP3008 ADC
• 2xFTDI TTL232R Cable
• 1xSFE Venus GPS Module
• 1xSFE Embedded GPS Antenna
• 1xHoneywell ASDX 0-15psi absolute pressure guage
• 2xDimension Engineering 5V / 1A (5W) switching regulator
• 1xPower-injected USB A – MiniUSB cable
• 1xUSB A – MiniUSB cable
• 1xWideband dipole antenna
• 1x36WH (minimum) LiPo battery

Power Connections

Battery

• 5v Reg 1
  • USB Hub Port 0: RasPi, GPS FTDI, Key Line Intf., GPS Module
• 5v Reg2
  • Power Injected USB: RF Explorer

Data Connections

RasPi

• USB Hub Mux Port
  • Port1: RF Explorer (/dev/ttyUSB0)
  • Port2: GPS FTDI (/dev/ttyUSB1) -> GPS Module
• GPIO Header
  • Key Line Iintf: FTDI Terminal, ADC -> Pressure Sensor

Software

Requirements:

• pyserial

• spidev

• RFE.py

  • Main executable

• nmea.py

  • GPS Sentence definitions

• StartRFE.sh

  • Auto-Restart script, set up as a cron job @reboot and repeated every 30 seconds.

Common Issues

• The RFE is not consistent with responding to the API, some commands require additional tries (such as shutdown, if it works at all - this is an issue with the RFE).
  • You will not see the screen shut off on initialization (a simple sign)
• The ports enumerated incorrectly, you may need to adjust RFE.py to look for different /dev/tty* devices.