diff --git a/Cargo.toml b/Cargo.toml
index 86cd6f7..7f9c419 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -20,8 +20,8 @@ anyhow = "1.0.75"
 
 # Numerics
 # Optional future feature for ndarray: blas
-ndarray = { version = "0.15.3", features = ["rayon"] }
-num = "0.4.1"
+ndarray = { version = "0.15.6", features = ["rayon"] }
+num = "0.4.3"
 # blas-src = { version = "0.8", features = ["openblas"] }
 # openblas-src = { version = "0.10", features = ["cblas", "system"] }
 
@@ -51,11 +51,11 @@ cfg-if = "1.0.0"
 reinterpret = "0.2.1"
 
 # Faster channels for multithreaded communication
-crossbeam = "0.8.2"
+crossbeam = "0.8.4"
 
 # Serialization
 serde = { version = "1.0.193", features = ["derive"] }
-toml = "0.8.8"
+toml = "0.8.14"
 
 # Initialize array for non-copy type
 array-init = "2.1.0"
@@ -68,15 +68,15 @@ hdf5-sys = { version = "0.8.1", features = ["static"], optional = true }
 hdf5 = { version = "0.8.1", optional = true }
 
 # Useful iterator stuff
-itertools = "0.12.0"
+itertools = "0.13.0"
 
 # For getting timestamps. Only useful when recording.
-chrono = {version = "0.4.31", optional = true}
+chrono = {version = "0.4.38", optional = true}
 # For getting UUIDs in recording
-uuid = { version = "1.6.1", features = ["v4"] , optional = true}
+uuid = { version = "1.9.1", features = ["v4"] , optional = true}
 
 # Command line argument parser, for CLI apps
-clap = { version = "4.4.11", features = ["derive", "color", "help", "suggestions"] }
+clap = { version = "4.5.8", features = ["derive", "color", "help", "suggestions"] }
 
 # FFT's
 realfft = "3.3.0"
diff --git a/src/config.rs b/src/config.rs
index 13f7f94..c8d7efc 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -1,10 +1,12 @@
-//! Configuration of module. Here, we can choose to compile for 32-bits or 64-bit floating point values
-//! as basic data storage and computation size. Default is f64.
+//! Configuration of module. Here, we can choose to compile for 32-bits or
+//! 64-bit floating point values as basic data storage and computation size.
+//! Default is f64.
 //!
 
 cfg_if::cfg_if! {
     if #[cfg(feature="f64")] {
-        /// Floating-point value, compile time option to make it either f32, or f64
+        /// Floating-point value, compile time option to make it either f32, or
+        /// f64.
         pub type Flt = f64;
         /// Ratio between circumference and diameter of a circle
         pub const pi: Flt = std::f64::consts::PI;
@@ -67,6 +69,7 @@ pub type Ccol = Array1<Cflt>;
 
 /// 2D array of floats
 pub type Dmat = Array2<Flt>;
+
 /// 2D array of complex floats
 pub type Cmat = Array2<Cflt>;
 
@@ -75,11 +78,11 @@ if #[cfg(feature = "python-bindings")] {
 
     /// 1D array of T as returned from Rust to Numpy
     pub type PyArr1<'py, T> = Bound<'py, PyArray<T, ndarray::Dim<[usize; 1]>>>;
-    
+
     /// 1D array Floats returned from Rust to Numpy
     pub type PyArr1Flt<'py> = PyArr1<'py, Flt>;
 
     /// 1D array of Complex returned from Rust to Numpy
     pub type PyArr1Cflt<'py> = PyArr1<'py, Cflt>;
 
-}}
\ No newline at end of file
+}}
diff --git a/src/daq/deviceinfo.rs b/src/daq/deviceinfo.rs
index 883bda6..fc63222 100644
--- a/src/daq/deviceinfo.rs
+++ b/src/daq/deviceinfo.rs
@@ -1,4 +1,3 @@
-//! Data acquisition model. Provides abstract layers around DAQ devices.
 #![allow(non_snake_case)]
 
 use super::StreamApiDescr;
diff --git a/src/daq/mod.rs b/src/daq/mod.rs
index f4910a4..aea8d2f 100644
--- a/src/daq/mod.rs
+++ b/src/daq/mod.rs
@@ -1,4 +1,15 @@
-//! Data acquisition model. Provides abstract layers around DAQ devices.
+//! Data acquisition code. Provides abstract layers around DAQ devices, creating
+//! input and output streams and interact with them (record, create signal
+//! generators, filter data, show real time sound levels and so on).
+//! 
+//! - Record data in a `Recording`
+//! - Interact with DAQ devices:
+//!   - Set number of channels, channel names etc.
+//!   - Enable / disable IEPE
+//!   - Set datatypes etc.
+//! 
+//! Most of the things are done using a [StreamMgr], which is an object to I/O
+//! DAQ data, interact with devices etc.
 
 mod api;
 mod daqconfig;
diff --git a/src/daq/streammgr.rs b/src/daq/streammgr.rs
index 320debc..2d3652b 100644
--- a/src/daq/streammgr.rs
+++ b/src/daq/streammgr.rs
@@ -39,7 +39,8 @@ struct StreamInfo<T> {
 /// Keep track of whether the stream has been created. To ensure singleton behaviour.
 static smgr_created: AtomicBool = AtomicBool::new(false);
 
-/// Configure and manage input / output streams.
+/// Configure and manage input / output streams. This method is supposed to be a
+/// SINGLETON. Runtime checks are performed to see whether this is true.
 ///
 #[cfg_attr(feature = "python-bindings", pyclass(unsendable))]
 pub struct StreamMgr {
@@ -67,7 +68,7 @@ pub struct StreamMgr {
     siggen: Option<crate::siggen::Siggen>,
 }
 
-#[cfg(feature="python-bindings")]
+#[cfg(feature = "python-bindings")]
 #[cfg_attr(feature = "python-bindings", pymethods)]
 impl StreamMgr {
     #[new]
@@ -112,11 +113,14 @@ impl Default for StreamMgr {
 }
 
 impl StreamMgr {
-    /// Create new stream manager. A stream manager is supposed to be a singleton.
+    /// Create new stream manager. A stream manager is supposed to be a
+    /// singleton. Note that we let Rust's ownership model handle that there is
+    /// only a single [StreamMgr].
     ///
     /// # Panics
     ///
     /// When a StreamMgr object is already alive.
+    ///
     pub fn new() -> StreamMgr {
         if smgr_created.load(std::sync::atomic::Ordering::Relaxed) {
             panic!("BUG: Only one stream manager is supposed to be a singleton");
@@ -603,7 +607,7 @@ impl Drop for StreamMgr {
     }
 }
 
-// Send to all queues, remove queues that are disconnected when found out
+/// Send to all queues, remove queues that are disconnected when found out
 // on the way.
 fn sendMsgToAllQueuesRemoveUnused(iqueues: &mut InQueues, msg: InStreamMsg) {
     // Loop over queues. Remove queues that error when we try to send
@@ -613,11 +617,3 @@ fn sendMsgToAllQueuesRemoveUnused(iqueues: &mut InQueues, msg: InStreamMsg) {
         Err(_e) => false,
     });
 }
-/// Daq devices
-trait Daq {}
-
-#[cfg(test)]
-mod tests {
-
-    // #[test]
-}
diff --git a/src/filter/biquad.rs b/src/filter/biquad.rs
index ee550fe..c37415c 100644
--- a/src/filter/biquad.rs
+++ b/src/filter/biquad.rs
@@ -236,6 +236,7 @@ impl<'a, T: AsArray<'a, Flt>> TransferFunction<'a, T> for Biquad {
         res
     }
 }
+
 #[cfg(test)]
 mod test {
     use approx::assert_abs_diff_eq;
diff --git a/src/filter/mod.rs b/src/filter/mod.rs
index 2c87412..6ddd075 100644
--- a/src/filter/mod.rs
+++ b/src/filter/mod.rs
@@ -1,9 +1,10 @@
-//! # Filter implemententations for biquads, series of biquads and banks of series of biquads.
+//! Contains filter implemententations for [Biquad]s, series of
+//! biquads ([SeriesBiquad]) and banks of series of biquads ([BiquadBank]).
 //!
 //! Contains [Biquad], [SeriesBiquad], and [BiquadBank]. These are all constructs that work on
-//! blocks of input data, and apply filters on it. Todo: implement FIR filter.
+//! blocks of input data, and apply filters on it. TODO: implement FIR filter.
 #![allow(non_snake_case)]
-pub use super::config::*;
+use super::config::*;
 
 mod biquad;
 mod biquadbank;
@@ -12,11 +13,12 @@ mod seriesbiquad;
 
 pub use biquad::Biquad;
 pub use biquadbank::BiquadBank;
+pub use dummy::DummyFilter;
 pub use seriesbiquad::SeriesBiquad;
 
 /// Implementations of this trait are able to DSP-filter input data.
 pub trait Filter: Send {
-    //! The filter trait is implemented by Biquad, SeriesBiquad, and BiquadBank
+    //! The filter trait is implemented by, for example, [Biquad], [SeriesBiquad], and [BiquadBank].
 
     /// Filter input to generate output. A vector of output floats is generated with the same
     /// length as input.
@@ -38,7 +40,15 @@ where
 {
     /// Compute frequency response (i.e. transfer function from input to output)
     ///
-    /// Args
+    /// # Args
+    ///
+    /// * `freq` - The frequency in [Hz]
+    ///
+    /// # Returns
+    ///
+    /// The transfer function: A column vector with the frequency response for
+    /// each frequency in `freq`.
+    ///
     fn tf(&self, fs: Flt, freq: T) -> Ccol;
 }
 
diff --git a/src/filter/seriesbiquad.rs b/src/filter/seriesbiquad.rs
index 3228c2e..a8b1846 100644
--- a/src/filter/seriesbiquad.rs
+++ b/src/filter/seriesbiquad.rs
@@ -110,8 +110,8 @@ impl<'a, T: AsArray<'a, Flt>> TransferFunction<'a, T> for SeriesBiquad {
     fn tf(&self, fs: Flt, freq: T) -> Ccol {
         let freq = freq.into();
         let mut res = self.biqs.first().unwrap().tf(fs, freq);
-        for i in self.biqs.iter().skip(1) {
-            res = &res * i.tf(fs, freq);
+        for biq in self.biqs.iter().skip(1) {
+            res = &res * biq.tf(fs, freq);
         }
         res
     }
@@ -144,4 +144,20 @@ mod test {
         inp[1] = 0.5;
         assert_eq!(&inp, &filtered);
     }
+    #[test]
+    fn test_seriesbiquad_tf1() {
+        let filter_coefs = vec![1., 0., 0., 1., 0., 0.];
+        let ser = SeriesBiquad::new(&filter_coefs).unwrap();
+        let tf = ser.tf(1., &[0., 1.]);
+        assert_eq!(tf[0].re, 1.0);
+        assert_eq!(tf[1].im, 0.0);
+    }
+    #[test]
+    fn test_seriesbiquad_tf2() {
+        let filter_coefs = &[0.5, 0., 0., 1., 0., 0., 0.5, 0., 0., 1., 0., 0.];
+        let ser = SeriesBiquad::new(filter_coefs).unwrap();
+        let tf = ser.tf(1., &[0., 1.]);
+        assert_eq!(tf[0].re, 0.25);
+        assert_eq!(tf[1].im, 0.0);
+    }
 }
diff --git a/src/lib.rs b/src/lib.rs
index da2a130..7c5f41f 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -18,10 +18,7 @@ pub mod daq;
 pub mod ps;
 pub mod siggen;
 mod math;
-
 use filter::*;
-use daq::*;
-
 
 /// A Python module implemented in Rust.
 #[cfg(feature = "python-bindings")]
@@ -29,6 +26,7 @@ use daq::*;
 #[pyo3(name="_lasprs")]
 fn lasprs(m: &Bound<'_, PyModule>) -> PyResult<()> {
     
+    daq::add_py_classses(m)?;
 
     // Add filter submodule
     m.add_class::<filter::Biquad>()?;
@@ -36,7 +34,6 @@ fn lasprs(m: &Bound<'_, PyModule>) -> PyResult<()> {
     m.add_class::<filter::BiquadBank>()?;
     m.add_class::<siggen::Siggen>()?;
 
-    daq::add_py_classses(m)?;
 
     Ok(())
 }
diff --git a/src/ps/aps.rs b/src/ps/aps.rs
index 3e8fe76..3de982c 100644
--- a/src/ps/aps.rs
+++ b/src/ps/aps.rs
@@ -1,5 +1,85 @@
 //! Averaged power spectra module. Used to compute power spectra estimations on
 //! long datasets, where nfft << length of data. This way, the variance of a
 //! single periodogram is suppressed with increasing number of averages.
-//! 
-//! For more information,
\ No newline at end of file
+//!
+//! For more information, see the book on numerical recipes.
+//!
+use super::*;
+use crate::config::*;
+use anyhow::{bail, Result};
+
+///  Provide the overlap of blocks for computing averaged (cross) power spectra.
+///  Can be provided as a percentage of the block size, or as a number of
+///  samples.
+pub enum Overlap {
+    Percentage(Flt),
+    Number(usize),
+}
+impl Default for Overlap {
+    fn default() -> Self {
+        Overlap::Percentage(50.)
+    }
+}
+
+/// Averaged power spectra computing engine
+struct AvPowerSpectra {
+    ps: PowerSpectra,
+    overlap_skip: usize,
+    // Time constant for time-weighted power spectra. If None, it averages out
+    // over all data.
+    fs_tau: Option<Flt>,
+    /// The number of frames already used in the average
+    N: usize,
+
+    // Current estimation of the power spectra
+    cur_est: Cmat
+}
+impl AvPowerSpectra {
+    fn get_overlap_skip(nfft: usize, overlap: Option<Overlap>) -> Result<usize> {
+        let overlap = overlap.unwrap_or_default();
+
+        let overlap_skip = match overlap {
+            Overlap::Number(i) if i >= nfft => bail!("Invalid overlap number of samples"),
+            Overlap::Number(i) if i < nfft => nfft - i,
+            Overlap::Percentage(p) if p >= 100. => {
+                bail!("Invalid overlap percentage. Should be >= 0. And < 100.")
+            }
+            Overlap::Percentage(p) => nfft - ((p * nfft as Flt) / 100.) as usize,
+            _ => unreachable!(),
+        };
+        if overlap_skip == 0 || overlap_skip > nfft {
+            bail!("Computed overlap results in invalid number of overlap samples. Please make sure the FFT length is large enough, when high overlap percentages are required.");
+        }
+        Ok(overlap_skip)
+    }
+    pub fn new(
+        nfft: usize,
+        wt: Option<WindowType>,
+        overlap: Option<Overlap>,
+        fs_tau: Option<Flt>,
+    ) -> Result<AvPowerSpectra> {
+        if nfft % 2 != 0 {
+            bail!("NFFT should be even")
+        }
+        if nfft == 0 {
+            bail!("Invalid NFFT")
+        }
+
+        if let Some(x) = fs_tau {
+            if x <= 0.0 {
+                bail!("Invalid time weighting constant [s]. Should be > 0 if given.")
+            }
+        }
+
+        let window = Window::new(wt.unwrap_or_default(), nfft);
+        let ps = PowerSpectra::newFromWindow(window);
+        let overlap_skip = Self::get_overlap_skip(nfft, overlap)?;
+        Ok(AvPowerSpectra {
+            ps,
+            overlap_skip,
+            fs_tau,
+            N: 0,
+            cur_est: Cmat::default((0,0))
+        })
+    }
+}
diff --git a/src/ps/mod.rs b/src/ps/mod.rs
index f352071..e186ff2 100644
--- a/src/ps/mod.rs
+++ b/src/ps/mod.rs
@@ -1,4 +1,8 @@
 //! Power spectra, averaged power spectra, etc. This module contains several 
-mod window;
-mod ps;
-mod fft;
\ No newline at end of file
+pub mod window;
+pub mod ps;
+mod fft;
+mod aps;
+
+pub use ps::PowerSpectra;
+pub use window::{Window, WindowType};
\ No newline at end of file
diff --git a/src/timebuffer.rs b/src/ps/timebuffer.rs
similarity index 100%
rename from src/timebuffer.rs
rename to src/ps/timebuffer.rs
diff --git a/src/ps/window.rs b/src/ps/window.rs
index 7d19091..58e922f 100644
--- a/src/ps/window.rs
+++ b/src/ps/window.rs
@@ -82,6 +82,11 @@ pub enum WindowType {
     /// Blackman window
     Blackman = 4,
 }
+impl Default for WindowType {
+    fn default() -> Self {
+        WindowType::Hann
+    }
+}
 
 /// Window (taper) computed from specified window type.
 #[derive(Clone)]
@@ -119,7 +124,9 @@ impl Window {
         self.win.len()
     }
 }
-//
+
+
+
 #[cfg(test)]
 mod test {
     use approx::assert_abs_diff_eq;
diff --git a/tools/watchdoc.sh b/tools/watchdoc.sh
index 8224d0a..b69547a 100755
--- a/tools/watchdoc.sh
+++ b/tools/watchdoc.sh
@@ -6,6 +6,6 @@
 # $ cargo install cargo-watch cargo-docserver`
 # ```
 #
-cargo watch -s "cargo rustdoc --lib && cargo test ${testargs} && cargo docserver"
+cargo watch -s "cargo rustdoc --lib && cargo docserve"
 
 # Then open: ${browser} http://localhost:4000