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.
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.
