--- a/src/lib/signal.rs	Fri Jun 05 21:43:11 2020 -0400
+++ b/src/lib/signal.rs	Fri Jun 05 21:34:25 2020 -0400
@@ -23,6 +23,7 @@
 mod filesink;
 mod filesource;
 mod gain;
+mod mixer;
 
 use super::IQSample;
 
@@ -30,6 +31,7 @@
 pub use filesink::FileSinkSignal;
 pub use filesource::FileSourceSignal;
 pub use gain::Gain;
+pub use mixer::Mixer;
 
 pub trait SignalFormatter {
     const SAMPLE_SIZE: usize;

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/lib/signal/mixer.rs	Fri Jun 05 21:34:25 2020 -0400
@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 2020 Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+use crate::IQSample;
+use super::Signal;
+
+pub struct Mixer<T: Signal, U: Signal> {
+    rate: u64,
+    /* TODO: freq */
+    lhs: T,
+    rhs: U,
+}
+
+impl<T: Signal, U: Signal> Mixer<T, U> {
+    pub fn new(lhs: T, rhs: U) -> Mixer<T, U> {
+        if lhs.sample_rate() != rhs.sample_rate() {
+            panic!("sample rate mismatch: {} {}", lhs.sample_rate(), rhs.sample_rate());
+        }
+
+        Mixer {
+            rate: lhs.sample_rate(),
+            lhs: lhs,
+            rhs: rhs,
+        }
+    }
+}
+
+impl<T: Signal, U: Signal> Signal for Mixer<T, U> {
+    fn sample_rate(&self) -> u64 {
+        self.rate
+    }
+
+    fn sample_size(&self) -> usize {
+        std::mem::size_of::<IQSample>()
+    }
+
+    fn freq(&self) -> u64 {
+        panic!("TODO");
+    }
+}
+
+impl<T: Signal, U: Signal> Iterator for Mixer<T, U> {
+    type Item = IQSample;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        match (self.lhs.next(), self.rhs.next()) {
+            (Some(a), Some(b)) => Some(a * b),
+            _ => None
+        }
+    }
+}