DFT Trait

src/bfsk.rs

@@ -0,0 +1,60 @@
+// 2-FSK Modulator
+
+use crate::complex::Complex;
+use crate::fft::FFT;
+use crate::nco::Nco;
+
+pub struct BFSKMod<'a, T: Iterator<Item = bool>> {
+    samples_per_bit: u32,
+    bandwidth: f32,
+    bit_stream: &'a mut T,
+
+    // State
+    oscillator: Nco,
+    sample_index: u32,
+}
+
+impl<'a, T> BFSKMod<'a, T>
+where
+    T: Iterator<Item = bool>,
+{
+    pub fn new(samples_per_bit: u32, bandwidth: f32, bit_stream: &'a mut T) -> Self {
+        BFSKMod {
+            samples_per_bit,
+            bandwidth,
+            oscillator: Nco::new(0.0),
+            bit_stream,
+            sample_index: samples_per_bit,
+        }
+    }
+
+    pub fn step_modulate(&mut self) -> Option<Complex<f32>> {
+        if self.sample_index == self.samples_per_bit {
+            self.sample_index = 0;
+            let bit = self.bit_stream.next()?;
+
+            let frequency = if bit {
+                self.bandwidth / 2.0
+            } else {
+                -self.bandwidth / 2.0
+            };
+            self.oscillator.set_frequency(frequency);
+        }
+
+        self.sample_index += 1;
+        self.oscillator.step();
+        Some(self.oscillator.cexp())
+    }
+}
+
+// FSK Demodulator (dumb non coherent + no symbol timing recovery)
+pub struct BFSKDem {
+    samples_per_bit: u32,
+    deviation: f32,
+
+    // State
+    sample_index: u32,
+    fft: FFT,
+}
+
+impl BFSKDem {}