Soft66LC4 frequency control

The easiest way is to use soft66-control from CLI.

% soft66-control -t 7020000
Tuned to 7020.000kHz

It seems I need another thread to avoid overrun with Alsa Sound System.

void f() {
	system("/usr/local/bin/soft66-control -t 7025400");
}

void g() {
	system("/usr/local/bin/soft66-control -t 7025100");
}

bool MyDrawingArea2::on_draw(const Cairo::RefPtr<Cairo::Context> &cr) {

	static int count = 0;

	if( (count++)%100 == 0) {
		if( (count/100) % 2 == 0) {
			thread t1(f);
			t1.detach();
		} else {
			thread t1(g);
			t1.detach();
		}
	}
}

Since IC-7410 is tuned to 7026.000kHz, a 600Hz tone and a 900Hz are observed alternatively.