The basic arrangement of the radio receiver used an antenna feeding an amplifier and down-converter (see Frequency mixer) feeding an automatic gain control, which fed an analog-to-digital converter that was on a computer VMEbus with a lot of digital signal processors (Texas Instruments C40s). The transmitter had digital to analog converters on the PCI bus feeding an up converter (mixer) that led to a power amplifier and antenna. The very wide frequency range was divided into a few sub-bands with different analog radio technologies feeding the same analog to digital converters. This has since become a standard design scheme for wideband software radios.