ChangeSets: API and Code Changes between Versions¶

Version 3.5¶

Digital Modulation¶

Control Loops¶

All blocks that use a second-order control loop to track a phase and frequency are being replaced to inherit from the gri_control_loop parent class. This class takes care of setting the gains given a loop bandwidth and damping frequency. By default, it sets the damping frequency for a critically damped system so only the loop bandwidth is required. The constructor looks like:

gri_control_loop(float loop_bw, float max_freq, float min_freq);

All blocks that have this structure used to set the internal alpha and beta gains individually. Now, the constructors for their blocks have been replaced to accept the loop bandwidth instead of the two gains. All values, the loop bandwidth, damping factor, alpha, beta, current phase, and current frequency can all be retrieved (get_) and set (set_).

This affects the following blocks:

• gr_pll_carrier_tracking_cc
• gr_pll_freqdet_cf
• gr_pll_refout_cc
• digital_costas_loop_cc
• digital_constellation_receiver_cb
• digital_mpsk_receiver_cc (TBD)
• digital_clock_recover_mm_cc (TBD)
• digital_clock_recover_mm_ff (TBD)
• digital_fll_band_edge_cc (TBD)