pulsed biphase modulator design

Discussion in 'The Projects Forum' started by sankaran, May 19, 2011.

  1. sankaran

    Thread Starter New Member

    May 19, 2011
    i want to make a radar waveform synthesizer which would generate a pulsed, biphase modulated sine wave at 430 MHz . The pulse width would be 64 microseconds and the pulse repetition frequency of 8 KHz.(typical values).During this 64 microseconds i want to bi phase modulate the sine wave with a NRZ waveform (or even a TTL signal) of 1 microsecond width.

    baud number = 64,
    baud width = 1 us
    pulse width = 64 us
    pulse repetition frequency = 8 kHz
    sine wave frequency = 430 MHz
    i've attached a picture showing the timing relationship

    my signal inputs to the synthesizer would be the bi phase coding signal and the pulse modulation signal.

    Can i achieve the above mentioned modulations inside a DDS chip by giving the Modulating signals? i do not want to generate only a sine wave from a dds and then use seperate blocks of pulse modulator, bpsk modulator etc. instead i want to do all these using a single DDS chip Analog Devices DDS chips have maximum fclk of 1 GHz. practically how much is the maximum output frequency that i can get? Isn't it only around of 300 Mhz? Even then i may be able to upconvert the DDS output using a mixer and another local oscillator.In that case pls suggest the kind of deterioration that might occur to my DDS generated signal. Please give suggestions on choosing the Analog devices DDS chip which can implement the above mentioned modulations.