VOCS is a platform implementing a VDES Half Duplex RF front-End for CubeSats (nanosat, microsat) withe deidcated Tx and Rx Radio front-end, for Half-Duplex and potentially Full-Duplex operations.

VDE-SAT standard is a VHF data exchange- satellite system defined in recommendation ITU-R M.2092.1 (February 2022).

VOCS project has implemented an RF Front End and Downlink PHY layer multi-channel. The project is a collaboration with ESA.

DWave has designed the Hardware and the Firmware. There are three  main goals achieved during the project with respect to the previous generations of this  developments:

1. lower mass 50%
2. lower volume 50%
3. lower power consumption 50%

the achievement has been reached using new approaches and technologies.

Breadbord Features

The front end is splitted in two sub systems: the TX front end and RX front end:

RF-FE_TX 

♦ Voltage Supplies for HPA, LNA, RF Switch and control logic:
– +28V, max 611mA (internally limited)
– +5V, 500mA

♦ Output signal peak power: 5W

♦  VDES Signal O

♦ MCX RF Connectors

♦ Weight: 0.350Kg

♦ Interfaces:

– TX RF input: receive RF signal from SDR
– RX RF output: RF signal to be provided to the RX path
– ANTENNA RF input/output: RF bidirectional signal (half-duplex)
– 2x I/O CMOS 3.3V control signals: TX Enable, RF Switch SPDT control for forward/reverse power detector  measurement
– 2x analog outputs: Power Detector level and temperature level
– 1x digital output: PA ShutDown Alarm

RF-FE_RX 

♦  Voltage Supply: +5V

♦  Max Current: 250mA

♦  Signal Output Gain: ~45dB

♦  MCX RF Connectors.

♦  Weight: 0.2Kg

♦  Interfaces:

– RX IN: RF received signal input
– RX OUT: amplified RF output signal route to SDR
– I/O CMOS 3.3V for RX Enable

Next Steps: 1U Cubesat for  IOD/IOV

The system will improved to achieve the TRL6.

A set of CubeSat compliant commercial versions of the VOCS Boards was developed, compatible with COTS SDR dimensions on the market.

The first figure below, on the left, shows the 3D view of the two commercial VOCS Boards  assembled with a GOMSpace NanoDock SDR, a GOMSpace NanoCom TR-600 and Z7000 modules.

The second and third figures show the detail of the commercial boards designed by DWave that implement the RX board and the TX board RF front end.

♦ Total cubesat system Dimensions: 90x96x65mm

♦ Total cubesat system Weight: 0.750Kg