The current concept incorporates a wireless transmitter and receiver and is thought to be used for remote controlled airplanes or appliances with two seperate parts. In other words, we have one dedicated transmitter (acquisition, filtering) and one dedicated receiver part (user-interface, look-up table, calibration, storage), capable of being connected together with any physical layer, e.g. wired, wireless, infrared. If you want to build a standalone altimeter/variometer just for hiking or mountaineering, this setup can obviously be simplified by omitting the wireless components.The following components have been used: Analog to digital converter NSC ADC12130, a Microchip PIC16F84 controller, a quad op-amp NSC LMC660, a Maxim MAX232 RS232 level shifter, and the Motorola MPXS4100A absolute pressure sensor.[read]