[Discuss-gnuradio] Using Correlate Estimation with hardware

[Sebastian]

 

 

Hi all,

 

i run into trouble using the correlate estimation block.

 

As far as i understand this blocks is used to search for a praeamble which is modulated and filtered with match filter.

To achieve this i used modulate vector. I used this block like it`s done in the corr_est exapmles provided in  /gnuradio/gr-digital/examples/.

 

Using no UHD but a channel modell everything works fine having clear correlation peak.

Using it with hardware device it doesn`t work anymore, having more peaks avaiable.

 

My flowgraph is very simple:

 

Vector_source (using prae+data as vector tagged with tx_sob and tx_eob) -> constellation Modulator(default-QPSK-object) -> stream mux with null_source for break -> uhd sink(sync = PC_clock)

 

Uhd source (sync = PC_clock) -> low_pass -> corr_est(modulated_vector, 0.9) -> Pll-clock-sync -> Costas Loop -> constellation-demodulator -> float_to_char -> qt time sink

 

 

Modulate vector is called with default-qpsk-object as constellation object and [1] as filter taps which i think is right.

The praeamble i am using is the one provided in the examples, so it should be ok too.

 

I dont have that much experience in this topic so I hope somebody is able to help me.

I am looking forward to hearing from you and thank you in advance.

 

 

Sebastian

 

PS : I am not sure where and how to provide the flowgraph itself but i´ll try to do it asap.