diff --git a/lib/fluxsource/catweasel.cc b/lib/fluxsource/catweasel.cc
new file mode 100644
index 00000000..2598c8cf
--- /dev/null
+++ b/lib/fluxsource/catweasel.cc
@@ -0,0 +1,36 @@
+#include "lib/globals.h"
+#include "lib/fluxmap.h"
+#include "lib/bytes.h"
+#include "lib/fluxsource/catweasel.h"
+
+std::unique_ptr<Fluxmap> decodeCatweaselData(
+    const Bytes& bytes, nanoseconds_t clock)
+{
+    std::unique_ptr<Fluxmap> fluxmap(new Fluxmap);
+    uint32_t pending = 0;
+    bool oldindex = true;
+    const uint8_t* ptr = bytes.begin();
+    while (ptr != bytes.end())
+    {
+        uint32_t b = *ptr++;
+        bool index = !!(b & 0x80);
+        b &= 0x7f;
+        if (b == 0x7f)
+        {
+            pending += 0x7f;
+            continue;
+        }
+        b += pending;
+        pending = 0;
+
+        double interval_ns = b * clock;
+        fluxmap->appendInterval(interval_ns / NS_PER_TICK);
+        fluxmap->appendPulse();
+
+        if (index && !oldindex)
+            fluxmap->appendIndex();
+        oldindex = index;
+    }
+
+    return fluxmap;
+}
diff --git a/lib/fluxsource/catweasel.h b/lib/fluxsource/catweasel.h
new file mode 100644
index 00000000..07c1464f
--- /dev/null
+++ b/lib/fluxsource/catweasel.h
@@ -0,0 +1,10 @@
+#ifndef CATWEASEL_H
+#define CATWEASEL_H
+
+class Fluxmap;
+class Bytes;
+
+extern std::unique_ptr<Fluxmap> decodeCatweaselData(
+    const Bytes& bytes, nanoseconds_t clock);
+
+#endif
diff --git a/lib/fluxsource/dmkfluxsource.cc b/lib/fluxsource/dmkfluxsource.cc
new file mode 100644
index 00000000..5d526335
--- /dev/null
+++ b/lib/fluxsource/dmkfluxsource.cc
@@ -0,0 +1,77 @@
+#include "lib/globals.h"
+#include "lib/fluxmap.h"
+#include "lib/fluxsource/fluxsource.pb.h"
+#include "lib/fluxsource/fluxsource.h"
+#include "lib/fluxsource/catweasel.h"
+#include "lib/proto.h"
+#include "lib/logger.h"
+#include <fstream>
+#include <filesystem>
+
+class DmkFluxSourceIterator : public FluxSourceIterator
+{
+public:
+    DmkFluxSourceIterator(const std::string& path, int track, int side):
+        _path(path),
+        _track(track),
+        _side(side)
+    {
+    }
+
+    bool hasNext() const override
+    {
+        std::string p = getPath();
+        return std::filesystem::exists(getPath());
+    }
+
+    std::unique_ptr<const Fluxmap> next() override
+    {
+        std::string path = getPath();
+        log("DMK: reading {}", path);
+        std::ifstream ifstream(getPath(), std::ios::binary);
+        if (!ifstream)
+            return std::make_unique<Fluxmap>();
+        _count++;
+
+        Bytes bytes(ifstream);
+        return decodeCatweaselData(bytes, 1e9 / 7080500.0);
+    }
+
+private:
+    const std::string getPath() const
+    {
+        return fmt::format(
+            "{}/C_S{:01}T{:02}.{:03}", _path, _side, _track, _count);
+    }
+
+private:
+    const std::string _path;
+    const int _track;
+    const int _side;
+    int _count = 0;
+};
+
+class DmkFluxSource : public FluxSource
+{
+public:
+    DmkFluxSource(const DmkFluxSourceProto& config): _path(config.directory())
+    {
+    }
+
+public:
+    std::unique_ptr<FluxSourceIterator> readFlux(int track, int side) override
+    {
+        return std::make_unique<DmkFluxSourceIterator>(_path, track, side);
+    }
+
+    void recalibrate() override {}
+
+private:
+    const std::string _path;
+};
+
+std::unique_ptr<FluxSource> FluxSource::createDmkFluxSource(
+    const DmkFluxSourceProto& config)
+{
+    return std::unique_ptr<FluxSource>(new DmkFluxSource(config));
+}