Talk:Guided Tutorial PSK Demodulation

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  • Implementation Hints
I greatly appreciate this guided tutorial.
I had some difficulties following along, so the following might help others using this tutorial.
* Hints for mpsk_rrc_rolloff.grc
 1. Constellation Modulator property Constellation = qpsk_const
    This setting uses the Constellation Rect. Object id qpsk_const (aka <con...(m=4))
* Hints for mpsk_stage1.grc
 1. Constellation Modulator property Constellation = qpsk_const
    This setting uses the Constellation Rect. Object id qpsk_const (aka <con...(m=4))
 2. Variable id rrc_taps value is firdes.root_raised_cosine(1.0,samp_rate,samp_rate/sps,excess_bw,11*sps).
    See GNU Radio Manual and C++ API Reference
    /*!
     * \brief design a Root Cosine FIR Filter (do we need a window?)
     *
     * \param gain            overall gain of filter (typically 1.0)
     * \param sampling_freq   sampling freq (Hz)
     * \param symbol_rate     symbol rate, must be a factor of sample rate
     * \param alpha           excess bandwidth factor
     * \param ntaps           number of taps
     */

RRC Filtering Information Link[edit]

This link helped me to understand match filtering using a Raised Cosine (& RRC) filter: https://www.analog.com/media/en/technical-documentation/application-notes/AN-922.pdf I think it would also be beneficial to spend a few sentences to describe why some of the filter coeficients were chosen and why they change for different flowgraphs throughout this tutorial.