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Re: [Discuss-gnuradio] How to use IQ Bal Optimize/Fix?

From: Jeff Long
Subject: Re: [Discuss-gnuradio] How to use IQ Bal Optimize/Fix?
Date: Wed, 31 Jan 2018 10:11:15 -0500
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2

1. Add a throttle after the source.

2. You are feeding the optimizer and the balancer from the original signal. They need to be connected to the output of the imbalance generator.

3. Whatever the scale of magnitude is in the imbalance generator, 1.0 is too small to see on the time plot.

4. The time plots will look different if the phase is rotated, so different is not necessarily wrong.

5. Add a slider to control magnitude, and you can see the optimizer adjust.

On 01/31/2018 09:21 AM, kokosz wrote:
This is exactly what I am doing, but restored signal looks very weird (its real part is close to zero). I have attached example *grc file showing the problem.

Dnia 31 stycznia 2018 12:34 Jeff Long <address@hidden> napisał(a):

    If you put 0 in the manual fields and wire




    it seems to work fine. Do you have a GRC file?

    "period" is some sort of time constant, in samples. If you set it to
    samp_rate, optimization will happen within a second. Smaller values for
    faster response up to a point.

    On 01/31/2018 05:54 AM, kokosz wrote:

        Dear all,

        It looks like IQ imbalance is causing problems in my
        application, as I
        was able to simulate real-world-like problems after adding "IQ
        Generator" to my GRC flowgraph. So, after simulating this
        imbalance, I
        wanted to get rid of it with the help of "IQ Bal Optimize" and
        "IQ Bal
        Fix" combo. Unfortunately, I can't get it work.

        As far as I understand, "IQ Bal Optimize" is automatically
        settings (i.e. magnitude and phase correction values) for "IQ
        Bal Fix"
        and pass it to the latter block via message connection called
        "iqbal_corr". Is this is true, I don't understand why I have to
        set "Magnitude" and "Phase" in "IQ Bal Fix" (otherwise I cannot
        run the
        flowgraph because of empty fields). I think that these fields
        were meant
        for making manual fix possible, but when using "IQ Bal
        Optimize"/"IQ Bal
        Fix" combo, message connection should be all what is necessary,
        Also, because of lack of detailed documentation, I am not sure
        how to
        interpret "Period" field in IQ Bal Optimize - what units are
        expected here?

        I am using GRC v3.7.11, compiled from source files few days ago.

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