Re: [Discuss-gnuradio] Using Correlate Estimation with hardware

[Sebastian]

 

Hi Bob,

 

i am sorry for answering that late (was on holidays wiht very limited Internet access).

 

Changing frequency solved my problem. But I am not sure why. I use a wbx v3 daugtherboard (range 68,75 – 2200 MHz ).

uhd_usrp_probe-file is attached.

 

Thanks for  your help.

 

Sebastian

Von: Robert McGwier
Gesendet: Montag, 28. August 2017 17:11
An: Sebastian
Cc: address@hidden
Betreff: Re: [Discuss-gnuradio] Using Correlate Estimation with hardware

 

Sebastian

 

What center frequency did you use?

What RF cards are you using?

Are you using coaxial cable,to connect transmit to receive or are you transmitting and receiving through an antenna?

 

If you are using antennas please describe them. 

 

Cheers

Bob

 

 

Bob

 

 

On Aug 26, 2017 12:12 PM, "Sebastian" <address@hidden> wrote:

 

 

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.

 

 

 

 

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uhd_usrp_probe.txt
Description: Text document