Re: This flow graph is radiating negative Tx power

[AKINYELE ITAMAKINDE]

connected the antenna to the good channel Rx/TxThanks, I have been checking out your suggestions.

What i meant by "negative Tx power" is that the Tx power is giving negative value (-30dbm)

1. I have upgraded to GNURadio >=3.8 but it is giving this warning message after trying to import QT GUI sink

Block paths:
/home/elect/gnuradio/share/gnuradio/grc/blocks
Warning: restarting the docstring loader (crashed while loading 'qtgui_bercurve_sink')
Warning: restarting the docstring loader (crashed while loading 'qtgui_const_sink_x')
Warning: restarting the docstring loader (crashed while loading 'qtgui_edit_box_msg')
Warning: restarting the docstring loader (crashed while loading 'qtgui_freq_sink_x')
Warning: restarting the docstring loader (crashed while loading 'qtgui_histogram_sink_x')
Warning: docstring loader crashed too often

Pls, can you help to solve this problem?

2. For QT GUI Sink bandwidth, I will do that when the above problem is solved.

3.  Yes I measured the signal power using a spectrum analyzer.

4.  Did you check your signal amplitude at USRP bloc input? i don't know how to do this but check it when i solve the problem

5. yes, i connected the antenna to the good channel Rx/Tx.

On Fri, Mar 12, 2021 at 3:30 PM Christophe Seguinot <christophe.seguinot@orange.fr> wrote:

Hi

- What does "negative Tx power" means ?

A few suggestions:

• move to GNURadio >=3.8 (most of us uses GR 3.8 or 3.9 so it's difficult to help for outdated GR 3.7)
  
• QT GUI Sink : Bandwith should be equal to sample rate of the block incoming signal, i.e. samp_rate at the RRC Filter output (the FFT Sink does not work as a real spectrum analyzer)
  
• Did you measure the signal power using a spectrum analyzer ? When do so, the receiving antennna being close to the emitter antenna, you should get the -20 to -30 dB as compared to the emitted power (frequency close to 1GHz and 6dBi antennas (Indoor panel), this is depending on frequency and antenna gain). If your emitted power is +20 dBm, you should measure something in the range 0 dBm to -20 dBm. If not, there is something wrong in the transmission chain.
  
• Did you check your signal amplitude at USRP bloc input (The maximum value should be 1 Volt to get maximum RF  power which also depend on USRP settings
• Did you connected the antenna to the good channel Rx/Tx ?

Sincerely, Christophe

On 12/03/2021 15:08, AKINYELE ITAMAKINDE wrote:

Good day to  all community members.

Please, I need you to help correct this flow graph configuration. The Tx power radiating is too minimal. I have adjusted and also added some other blocks to boost the signal but all to no avail. The flow graph is been used for propagation channel measurement. I will like someone to take me through or send video and other link on how to solve this problem. The flow graph is attached.

 Thank you.

Akinyele.