digital receiver problem

Discussion in 'General Electronics Chat' started by drake LEE, Sep 10, 2013.

  1. drake LEE

    Thread Starter New Member

    Mar 10, 2013
    I have had one question of the demodulator, AD8348 since the sensitivity of the TETRA terminal was tested.

    In ETSI standard, BER should be lower than 3% at -112dBm of input power. Our terminal has about -115dBm of the sensitivity.

    When the terminal input is connected to the Tetra test set and then modulated signal is injected to the terminal with about -115dBm input power, receiver may not recognize the signal from Tetra test set.

    But if higher level ( about -80dBm to -90dBm) is injected , the receiver can accept the random signal, and then up to -100, -110, and -115dBm the receiver is working well.

    I guess something in demodulator is wrong or may be dc offset problem. So I have searched troubleshooting about the demodulator and digital receiver.

    What do you think about this problem? Are you heard likewise problems? Help me know.