Power system

Power system

The RMU (Rocket Mounted Unit) and the FFU (Free FLying Unit) are electrically connected through the umbilical connector meaning that the FFU does not have any external connectors. This also means that the only external electrical connectors are situated on the RMU. The next two subsections give a brief description of the electronics design of each part. RMU The RMU is off as long as the RXSM does not supply it with voltage. The NSSB, located in the RMU, forwards the signals from RXSM to the FFU.

The FFU have internal batteries and has three main power states, standby, active and vFire state. To indicate the states the LED board is used. If external power is connected through the umbilical, the SQUID systems (except the actuators and transmitters) are powered. If external power is removed, the experiment can either continue on internal batteries (in the active state) or be in the standby state. While in stand by state the only components which are powered are the CMOS logic circuits on the DCDC board. The constant current supplying the logics has been measured to less than 0.1 mA from internal batteries. When the FFU has been set to active state the power to the rest of the system (except parts connected to vFire) is activated. The vFire state is finally entered when the safety switch has been activated by the ejection of the experiment. When the FFU has entered the vFire state the cutter, motors and radio transmitters are armed. Power system The power system is divided in between the RMU FFU. At the RMU it consists of the NSSB which is fed by the 28V bus from the RXSM. The NSSB contains a converter for delivering 8V to the FFU as well as a converter to deliver 4 V to the camera. The FFU contains two SAFT LSH14 batteries connected in series which will take over after FFU ejection. Apart from the batteries the FFU also contains five different voltage converters to power different systems.