AGC

using System;

namespace Radio
{
    public class AutomaticGainControl : IFilter
    {
        private const double MeanLevel = 0.02;
        private const double MaxFactor = 5000.0;
        private const double MinFactor = 1.0;
        private const double TimeConst = 0.001;

        private readonly Integrator _integrator = new Integrator(TimeConst);

        public double Process(double sample)
        {
            var dc = _integrator.Process(Math.Abs(sample));
            var factor = MeanLevel / dc;
            if (factor > MaxFactor)
            {
                factor = MaxFactor;
            }
            if (factor < MinFactor)
            {
                factor = MinFactor;
            }
            return sample * factor;
        }
    }
}