public static void ChangeReceiverChannel(int receiverId, int channel)
        {
            var receiver = Receivers.FirstOrDefault(r => r.Id == receiverId);

            if (receiver == null)
            {
                return;
            }

            var emittersOnChannel =
                Emitters.Where(e => e.EmitChannel == channel).ToList();

            var signal = emittersOnChannel.Any() ? emittersOnChannel.First().Signal : 0;

            NotifyReceivers(channel, signal);

            receiver.Channel = channel;
        }
        public static void ChangeEmitterChannel(int emitterId, int channel)
        {
            var emitter = Emitters.FirstOrDefault(e => e.Id == emitterId);

            if (emitter == null)
            {
                return;
            }

            var othersOnChannel =
                Emitters.Where(e => e.Id != emitterId && e.EmitChannel == emitter.EmitChannel).ToList();

            var leaveSignal = othersOnChannel.Any() ? othersOnChannel.First().Signal : 0;

            NotifyReceivers(emitter.EmitChannel, leaveSignal);

            emitter.EmitChannel = channel;
            NotifyReceivers(emitter.EmitChannel, emitter.Signal);
        }