[Discuss-gnuradio] about tune the daughterboard

[hanwen]

Hi, all:)

I've read through the code of GMSK2 and I found the difference of tune in transmit_path and receive_path.

In the transmit_path:

    self.u.tune(self.subdev._which, self.subdev, target_freq)

In the receive_path:

    self.u.tune(0, self.subdev, target_freq)

 

The self.subdev._which indicate the channel of TX/RX, 0 for A, 1 for B. (Am I right?)

 

So I am confused about why the first parameter of tune depends on channel selection in transmit_path while it's set to 0 in receive_path?

 

I am using 2 USRP with a FLEX2400 on B channel of both, so subdev._which is actually 1. I change the 0 in recieve_path to subdev._which, and I cannot recieve the signal anymore. So 0 must be set when using usrp as source.

 

BUT, why? Can you explain in detail about the first parameter of tune() to me?

 

Thanks!