diff --git a/src/audio_receiver/foreign_signal.rs b/src/audio_receiver/foreign_signal.rs
new file mode 100644
index 0000000..0f52049
--- /dev/null
+++ b/src/audio_receiver/foreign_signal.rs
@@ -0,0 +1,6 @@
+pub struct ForeignTwoStateCarrier {
+    pub acquired: bool,
+    pub clock_hz: f64,
+    pub freq_low: Option<f64>,
+    pub freq_high: Option<f64>,
+}
diff --git a/src/audio_receiver/input_dsp.rs b/src/audio_receiver/input_dsp.rs
index e6e6c18..f0a7232 100644
--- a/src/audio_receiver/input_dsp.rs
+++ b/src/audio_receiver/input_dsp.rs
@@ -1,40 +1,59 @@
-use std::io::Write;
 use std::collections::VecDeque;
+use std::io::Write;
 
 use cpal::{FromSample, Sample, SampleRate};
 
-use rustfft::{FftPlanner, num_complex::Complex};
+use ringbuf::{traits::*, LocalRb};
+
+use rustfft::{num_complex::Complex, FftPlanner};
+
+use super::ForeignTwoStateCarrier;
 
 pub fn take_input_pcm<T>(
     pcm: &[T],
     sample_rate: SampleRate,
     channel: &tokio::sync::mpsc::Sender<Vec<f64>>,
     pcm_buffer: &mut VecDeque<Complex<f64>>,
-) where 
+    carrier: &mut ForeignTwoStateCarrier,
+) where
     T: ToString + Sample + FromSample<f64> + std::fmt::Debug,
-    f64: FromSample<T>
+    f64: FromSample<T>,
 {
-    // TODO: Obtain this information during the handshake
-    let fft_size = 320
+    let fft_size = (sample_rate / carrier.symbol_rate).round() as u32;
 
-    pcm_buffer.extend(
-        pcm
-            .iter()
-            .map(|s| Complex { re: s.to_sample::<f64>(), im: 0.0f64 })
-    );
+    pcm_buffer.extend(pcm.iter().map(|s| Complex {
+        re: s.to_sample::<f64>(),
+        im: 0.0f64,
+    }));
 
     let mut fft_planner = FftPlanner::<f64>::new();
-    let fft_machine = fft_planner.plan_fft_forward(FFT_SIZE); // TODO: cfgable
+    let fft_machine = fft_planner.plan_fft_forward(fft_size); // TODO: cfgable
+    let mut fft_frame = pcm_buffer[..fft_size];
 
-    while pcm_buffer.len() >= FFT_SIZE {
-        let mut fft_frame =
-            pcm_buffer.drain(..FFT_SIZE).collect::<Vec<Complex<f64>>>();
+    // Zero-pad for a better freq resolution. 8192 fft should be fast enough
+    if fft_size < 8192 {
+        fft_frame.extend([0.0_f64].repeat(8192 - fft_size));
+    }
+
+    let mut window_offset = 0;
+
+    while !carrier.acquired
+        && pcm_buffer.len() >= fft_size
+        && window_offset < fft_size
+    {
         fft_machine.process(&mut fft_frame);
 
-        
+        let frame_index = fft_size * carrier.clock_hz / sample_rate.0 as usize;
+        if let Some(bin) = fft_frame.get(frame_index) {
+            // yay
+        }
+    }
+
+    while carrier.acquired && pcm_buffer.len() >= fft_size {
+        fft_machine.process(&mut fft_frame);
 
         /*for (i, s) in fft_frame.iter().enumerate() {
-            let freq = sample_rate.0 as usize * i / FFT_SIZE;
+            let freq = sample_rate.0 as usize * i / fft_size;
             let ampl = s.norm();
             let confidence = ampl;
             if ampl > 50.0 {
@@ -45,3 +64,10 @@ pub fn take_input_pcm<T>(
         }*/
     }
 }
+
+fn ampl_between_bins_quadratic(
+    fft_res: VecDeque<Complex<f64>>,
+    freq: f64,
+) -> f64 {
+    todo!();
+}
diff --git a/src/audio_receiver/mod.rs b/src/audio_receiver/mod.rs
index 9d10fa0..1b18802 100644
--- a/src/audio_receiver/mod.rs
+++ b/src/audio_receiver/mod.rs
@@ -7,6 +7,9 @@ use tracing::{info, trace, warn};
 
 use std::collections::VecDeque;
 
+pub mod foreign_signal;
+use foreign_signal::ForeignTwoStateCarrier;
+
 mod input_dsp;
 use self::input_dsp::take_input_pcm;
 
@@ -50,12 +53,19 @@ pub fn audio_receiver_main(
 
     let mut pcm_buf: VecDeque<rustfft::num_complex::Complex<f64>> =
         vec![].into();
+    // TODO: determine freqs from handshake
+    let mut foreign_carrier = ForeignTwoStateCarrier {
+        acquired: false,
+        symbol_rate: 1200.0,
+        freq_low: Some(2400.0),
+        freq_high: Some(3600.0),
+    };
 
     let input_stream = match cpal_input_config.sample_format() {
         cpal::SampleFormat::U8 => cpal_input.build_input_stream(
             &cpal_input_config.into(),
             move |pcm, _: &_| {
-                take_input_pcm::<u8>(pcm, sample_rate, &tx_for_demod, &mut pcm_buf)
+                take_input_pcm::<u8>(pcm, sample_rate, &tx_for_demod, &mut pcm_buf, &mut foreign_carrier)
             },
             failed_pcm_take,
             None,
@@ -63,7 +73,7 @@ pub fn audio_receiver_main(
         cpal::SampleFormat::I8 => cpal_input.build_input_stream(
             &cpal_input_config.into(),
             move |pcm, _: &_| {
-                take_input_pcm::<i8>(pcm, sample_rate, &tx_for_demod, &mut pcm_buf)
+                take_input_pcm::<i8>(pcm, sample_rate, &tx_for_demod, &mut pcm_buf, &mut foreign_carrier)
             },
             failed_pcm_take,
             None,
@@ -71,7 +81,7 @@ pub fn audio_receiver_main(
         cpal::SampleFormat::I16 => cpal_input.build_input_stream(
             &cpal_input_config.into(),
             move |pcm, _: &_| {
-                take_input_pcm::<i16>(pcm, sample_rate, &tx_for_demod, &mut pcm_buf)
+                take_input_pcm::<i16>(pcm, sample_rate, &tx_for_demod, &mut pcm_buf, &mut foreign_carrier)
             },
             failed_pcm_take,
             None,
@@ -79,7 +89,7 @@ pub fn audio_receiver_main(
         cpal::SampleFormat::I32 => cpal_input.build_input_stream(
             &cpal_input_config.into(),
             move |pcm, _: &_| {
-                take_input_pcm::<i32>(pcm, sample_rate, &tx_for_demod, &mut pcm_buf)
+                take_input_pcm::<i32>(pcm, sample_rate, &tx_for_demod, &mut pcm_buf, &mut foreign_carrier)
             },
             failed_pcm_take,
             None,
@@ -87,7 +97,7 @@ pub fn audio_receiver_main(
         cpal::SampleFormat::F32 => cpal_input.build_input_stream(
             &cpal_input_config.into(),
             move |pcm, _: &_| {
-                take_input_pcm::<f32>(pcm, sample_rate, &tx_for_demod, &mut pcm_buf)
+                take_input_pcm::<f32>(pcm, sample_rate, &tx_for_demod, &mut pcm_buf, &mut foreign_carrier)
             },
             failed_pcm_take,
             None,
@@ -95,7 +105,7 @@ pub fn audio_receiver_main(
         cpal::SampleFormat::F64 => cpal_input.build_input_stream(
             &cpal_input_config.into(),
             move |pcm, _: &_| {
-                take_input_pcm::<f64>(pcm, sample_rate, &tx_for_demod, &mut pcm_buf)
+                take_input_pcm::<f64>(pcm, sample_rate, &tx_for_demod, &mut pcm_buf, &mut foreign_carrier)
             },
             failed_pcm_take,
             None,
@@ -103,7 +113,7 @@ pub fn audio_receiver_main(
         cpal::SampleFormat::U64 => cpal_input.build_input_stream(
             &cpal_input_config.into(),
             move |pcm, _: &_| {
-                take_input_pcm::<u64>(pcm, sample_rate, &tx_for_demod, &mut pcm_buf)
+                take_input_pcm::<u64>(pcm, sample_rate, &tx_for_demod, &mut pcm_buf, &mut foreign_carrier)
             },
             failed_pcm_take,
             None,
@@ -111,7 +121,7 @@ pub fn audio_receiver_main(
         cpal::SampleFormat::I64 => cpal_input.build_input_stream(
             &cpal_input_config.into(),
             move |pcm, _: &_| {
-                take_input_pcm::<i64>(pcm, sample_rate, &tx_for_demod, &mut pcm_buf)
+                take_input_pcm::<i64>(pcm, sample_rate, &tx_for_demod, &mut pcm_buf, &mut foreign_carrier)
             },
             failed_pcm_take,
             None,