The Design Of DS/SS Signal Generator Based On PCI Bus

Spread spectrum communication is born in the last century50’s, compared with theconventional communication manner, the excellence is that the signal has a very widespectrum. It introduces the spread spectrum and despread process, that is using the spreadspectrum sequence to extend the spectrum of the signal to a very wide frequency band beforethe signal transmission, and despread it to restore the signal bandwidth using the samespreading sequence after receiving the signal. Now spread spectrum communication has beenwidely used in military and civil fields, moreover, direct sequence spread spectrum iscurrently the most widely used means of spread spectrum.Based on the problem of lacking of DS/SS signal generator in the DS/SS communicationsystem, this paper designs a spread spectrum communication signal generator which cansimulate the characteristics of the channel, and initially constructs the hardware platform ofsimulated DS/SS communication signal, providing for the signal generator for the future tocarry out the DS/SS system.The modulation mode of spread spectrum communication signal generator is BPSK; thecarrier frequency is5MHz; PN code is M sequence, m sequence, GOLD sequence and othercommon sequence with PN code rate of0.2MHz; the SNR is adjustable in10to-10dB; thenoise generating means is computer simulation; interface is based on PCI bus.The paper uses the designing of virtual instrument,and it has two parts,the upper andlower machine. The upper machine achieves control interface through the Visual C++6.0programming, including the information symbol input, spread spectrum sequence selection,spread spectrum, modulation, plus noise, PCI bus control. And the lower machine achievesPCI bus protocol using PCI9054, realizes PCI9054timing control, data cache and DACcontrol using FPGA.The paper firstly introduced the background, current situation and relevant theoreticalknowledge of the spread spectrum communication and computer bus, then expounded the thehardware and software design and debugging method of the system, finally gave theexperimental results also verified the correctness of the design.