USRP2/Gnuradio - satellite application

GNU Radio
#1

Good evening,

I will appreciate your help and guidance. since 3 weeks I’m trying to
implement an application
to derive the sky noise and attenuation from a beacon satellite signal.
Using gnuardio and USRP2 (Ettus N210) I’m able to receive the and see
the
beacon signal at a defined frequency (FFT plot). What I need is write an
application in python or C++ that allow to me to retrieve and plot the
skynoise and attenuation values.
The problem I have is when using the blocks in gnuradio how to retrieve
the
signal power so then I can use a math formulas to derive both
attenuation
and skynoise and then plot them again in new graph to show them?

I would appreciate any help from your side.

Thank you and best regards

Abdeslam B.

#2

Hi Abdeslam,

I assume you already have definite formulas that define the estimator
for these two numbers.
Unless you can directly “click together” that estimator in GRC, you will
most likely have to implement it.
In many cases, doing this in Python is rather easy (especially if you
come from a python or matlab background),
so I’d recommend reading at least the first 3 chapters of
https://gnuradio.org/redmine/projects/gnuradio/wiki/Guided_Tutorials

Best regards,
Marcus

#3

Hi,

The problem I have is when using the blocks in gnuradio how to retrieve the
signal power

You mean you want the signal power as a dBm value ?

Just won’t happen … Too many things in the chain, you’d have to
calibrate it for a specific freq / board / gain / temp / phase of the
moon / …

Cheers,

Sylvain

#4

Hi,

@Marcus : Yes I have already the formulas ad now trying to implement in
C++. The problem I have is I need the output from the “USRP source” as
number for instaance and then apply formuas and again show it in time
axis.
I will go back again to the s first chapter maybe I miss something.
@Sylvain : Yes that’s true from the “USRP source” I need the value as a
dBm
or dB. The calibration part will do it after getting the value from the
source then I will derive the attenuation from noise within formuals. I
already did the link budget need just now to values from the source.

Thank you and best regards
Abdeslam

Abdeslam B.

#5

Dear Abs,

you’ve asked this question on discuss-gnuradio and already got two
answers.
In case you’ve missed those, and to avoid that people tell you what you
already know:

Sylvain wrote that, due to a large number of factors contributing to
what you see as digital amplitude, you will need to calibrate yourself,
using exactly the system you want to use to measure power:

You mean you want the signal power as a dBm value ?

Just won’t happen … Too many things in the chain, you’d have to
calibrate it for a specific freq / board / gain / temp / phase of the
moon / …

And I explained that if you have a mathematical representation of how
your estimator works, you might be able to write a custom estimator
block for both of your values of interest:

I assume you already have definite formulas that define the estimator
for these two numbers.
Unless you can directly “click together” that estimator in GRC, you
will most likely have to implement it.
In many cases, doing this in Python is rather easy (especially if you
come from a python or matlab background),
so I’d recommend reading at least the first 3 chapters of
https://gnuradio.org/redmine/projects/gnuradio/wiki/Guided_Tutorials

If these answers didn’t help you out, I think it would be wise to
explain what these answers are lacking, instead of just re-posting the
same question.

Best regards,
Marcus

#6

Dear Marcus,

I thought too differents forums I posted the same question at the same
time.
OK let’s continue here this is my reply :

Hi,

@Marcus : Yes I have already the formulas ad now trying to implement in
C++. The problem I have is I need the output from the “USRP source” as
number for instaance and then apply formuas and again show it in time
axis.
I will go back again to the s first chapter maybe I miss something.
@Sylvain : Yes that’s true from the “USRP source” I need the value as a
dBm or dB. The calibration part will do it after getting the value from
the
source then I will derive the attenuation from noise within formuals. I
already did the link budget need just now to values from the source.

Thank you and best regardsAbdeslam

Abdeslam B.

#7

Hello,

I need to communicate with the USRP and receive data like these :

2015-06-02 02:32:29.246055 center_freq 1000775000.0 freq 1000718750.0
power_db 5.59449106566 noise_floor_db -121.702764103
2015-06-02 02:32:29.246138 center_freq 1000775000.0 freq 1000725000.0
power_db 5.80020853614 noise_floor_db -121.702764103
2015-06-02 02:32:29.246236 center_freq 1000775000.0 freq 1000731250.0
power_db 6.41043187666 noise_floor_db -121.702764103
2015-06-02 02:32:29.246343 center_freq 1000775000.0 freq 1000737500.0
power_db 5.72799835886 noise_floor_db -121.702764103
2015-06-02 02:32:29.246443 center_freq 1000775000.0 freq 1000743750.0
power_db 8.61943426588 noise_floor_db

Regards
Abdeslam

Abdeslam B.

On 1 June 2015 at 22:36, Abdeslam B. [email protected]