makanaky
Advanced Member level 4
Hi,
I know that MSK can be interpreted as OQPSK and vice versa, the only issue I have is to find and prove the bit mapping relation, so that the bits input to MSK modulator (VCO) can be provided to OQPSK modulator (I,Q modulator).
The relation I can reach for MSK is :
yMSK= cos(Xk)*Cos(πt/(2*T))Cos(Wct)-Uk*cos(Xk)*Sin(πt/(2*T))Sin(Wct)
where Uk is the current bit = ±1; Xk=Xk-1 +(Uk-1 - Uk)*πk/2
I need to convert cos(Xk) to a function in Uk, Uk-1
Does this sound familiar ? Can somebody help e with this please ?
Thanks
I know that MSK can be interpreted as OQPSK and vice versa, the only issue I have is to find and prove the bit mapping relation, so that the bits input to MSK modulator (VCO) can be provided to OQPSK modulator (I,Q modulator).
The relation I can reach for MSK is :
yMSK= cos(Xk)*Cos(πt/(2*T))Cos(Wct)-Uk*cos(Xk)*Sin(πt/(2*T))Sin(Wct)
where Uk is the current bit = ±1; Xk=Xk-1 +(Uk-1 - Uk)*πk/2
I need to convert cos(Xk) to a function in Uk, Uk-1
Does this sound familiar ? Can somebody help e with this please ?
Thanks