diff --git a/Libraries/LogHelpers.js b/Libraries/LogHelpers.js
index e55af0f6..c4d5847f 100644
--- a/Libraries/LogHelpers.js
+++ b/Libraries/LogHelpers.js
@@ -63,18 +63,22 @@ function get_version_and_board(log) {
                 // Check we have bracketed the messages we need
                 continue
             }
+            let types = []
+            for (const type of Object.keys(build_types)) {
+                types.push("(?:" + type + ")")
+            }
+            const regex = new RegExp("(" + types.join("|") + ").+\\((.+)\\)", 'g')
+            const found = regex.exec(MSG.Message[i])
+            if (found == null) {
+                continue
+            }
             if (fw_string == null) {
-                let types = []
-                for (const type of Object.keys(build_types)) {
-                    types.push("(?:" + type + ")")
-                }
-                const regex = new RegExp("(" + types.join("|") + ").+\\((.+)\\)", 'g')
-                const found = regex.exec(MSG.Message[i])
-                if (found == null) {
-                    continue
-                }
                 fw_string = found[0]
+            }
+            if (build_type == null) {
                 build_type = build_types[found[1]]
+            }
+            if (fw_hash == null) {
                 fw_hash = found[2]
             }
             os_string = MSG.Message[i+1]
diff --git a/PIDReview/ArduCopter_angle_rate_control_loop.drawio.png b/PIDReview/ArduCopter_angle_rate_control_loop.drawio.png
new file mode 100644
index 00000000..0d95a194
Binary files /dev/null and b/PIDReview/ArduCopter_angle_rate_control_loop.drawio.png differ
diff --git a/PIDReview/PIDReview.js b/PIDReview/PIDReview.js
index 175a1ab2..4da4498f 100644
--- a/PIDReview/PIDReview.js
+++ b/PIDReview/PIDReview.js
@@ -4,7 +4,7 @@ var DataflashParser
 const import_done = import('../modules/JsDataflashParser/parser.js').then((mod) => { DataflashParser = mod.default });
 
 // Keys in data object to run FFT of
-const fft_keys = ["Tar", "Act", "Err", "P", "I", "D", "FF", "Out"]
+const fft_keys = ["Tar", "Act", "Err", "P", "I", "D", "FF", "DFF", "Out"]
 
 function run_batch_fft(data_set) {
 
@@ -64,7 +64,8 @@ function run_batch_fft(data_set) {
                 // Log section is too short, skip
                 continue
             }
-            var ret = run_fft(data_set[j][i], fft_keys, window_size, window_spacing, windowing_function, fft)
+            const valid_keys = fft_keys.filter(key => data_set[j][i][key] != null)
+            var ret = run_fft(data_set[j][i], valid_keys, window_size, window_spacing, windowing_function, fft)
 
             // Initialize arrays
             if (!have_data) {
@@ -76,7 +77,7 @@ function run_batch_fft(data_set) {
             }
 
             data_set[j].FFT.time.push(...array_offset(array_scale(ret.center, sample_time), data_set[j][i].time[0]))
-            for (const key of fft_keys) {
+            for (const key of valid_keys) {
                 data_set[j].FFT[key].push(...ret[key])
             }
         }
@@ -272,7 +273,7 @@ function setup_plots() {
     Plotly.newPlot(plot, TimeInputs.data, TimeInputs.layout, {displaylogo: false})
 
 
-    const pid_outputs = ["P","I","D","FF","Output"]
+    const pid_outputs = ["P","I","D","FF","D FF","Output"]
     TimeOutputs.data = []
     for (const item of pid_outputs) {
         TimeOutputs.data.push({ mode: "lines",
@@ -388,7 +389,7 @@ function link_plots() {
 }
 
 // Add data sets to FFT plot
-const plot_types = ["Target", "Actual", "Error", "P", "I", "D", "FF", "Output"]
+const plot_types = ["Target", "Actual", "Error", "P", "I", "D", "FF", "D FF", "Output"]
 function get_FFT_data_index(set_num, plot_type) {
     return set_num*plot_types.length + plot_type
 }
@@ -618,13 +619,13 @@ function add_param_sets() {
     set_cell_style(item)
 
     const names = get_PID_param_names(PID.params.prefix)
-    for (const [name, param_string] of Object.entries(names)) {
+    for (const [name, param] of Object.entries(names)) {
         let item = document.createElement("th")
         header.appendChild(item)
         set_cell_style(item)
 
-        item.appendChild(document.createTextNode(name.replace("_", " ")))
-        item.setAttribute('title', param_string)
+        item.appendChild(document.createTextNode(param.title))
+        item.setAttribute('title', param.name)
     }
 
     // Add line for each param set
@@ -667,21 +668,21 @@ function add_param_sets() {
         checkbox.disabled = (valid_sets == 1) || !valid
         item.appendChild(checkbox)
 
-        for (const name of Object.keys(names)) {
+        for (const [key, param] of Object.entries(names)) {
             let item = document.createElement("td")
             row.appendChild(item)
             set_cell_style(item, color)
 
-            const value = set[name]
+            const value = set[key]
             if (value == null) {
                 continue
             }
 
-            const text = document.createTextNode(value.toFixed(4))
+            const text = document.createTextNode(value.toFixed(param.decimalPlaces))
 
             let changed = false
             if (i > 0) {
-                const last_value = PID.params.sets[i-1][name]
+                const last_value = PID.params.sets[i-1][key]
                 if (value != last_value) {
                     changed = true
                 }
@@ -724,6 +725,11 @@ function add_param_sets() {
     document.getElementById("Spec_D").disabled = !have_all
     document.getElementById("Spec_FF").disabled = !have_all
 
+    // DFF is only available in newer firmware logs
+    const have_DFF = have_all && PID.sets.some(set => set != null && set.some(batch => batch.DFF != null))
+    document.getElementById("PIDX_DFF").disabled = !have_DFF
+    document.getElementById("Spec_DFF").disabled = !have_DFF
+
     // Uncheck any that are disabled
     if (!have_all) {
         document.getElementById("PIDX_Err").checked = false
@@ -731,17 +737,20 @@ function add_param_sets() {
         document.getElementById("PIDX_I").checked = false
         document.getElementById("PIDX_D").checked = false
         document.getElementById("PIDX_FF").checked = false
+    }
+    if (!have_DFF) {
+        document.getElementById("PIDX_DFF").checked = false
+    }
 
-        // Change to Out on spectrogram if disabled option is set
-        const disabled_checked = document.getElementById("Spec_Err").checked ||
-                                 document.getElementById("Spec_P").checked ||
-                                 document.getElementById("Spec_I").checked ||
-                                 document.getElementById("Spec_D").checked ||
-                                 document.getElementById("Spec_FF").checked
-        if (disabled_checked) {
-            document.getElementById("Spec_Out").checked = true
-        }
-    
+    // Change to Out on spectrogram if disabled option is set
+    const disabled_checked = document.getElementById("Spec_Err").checked ||
+                             document.getElementById("Spec_P").checked ||
+                             document.getElementById("Spec_I").checked ||
+                             document.getElementById("Spec_D").checked ||
+                             document.getElementById("Spec_FF").checked ||
+                             document.getElementById("Spec_DFF").checked
+    if ((!have_all || !have_DFF) && disabled_checked) {
+        document.getElementById("Spec_Out").checked = true
     }
 
 
@@ -806,7 +815,10 @@ function redraw() {
             if ("FF" in set[i]) {
                 TimeOutputs.data[3].y = TimeOutputs.data[3].y.concat(set[i].FF)
             }
-            TimeOutputs.data[4].y = TimeOutputs.data[4].y.concat(set[i].Out)
+            if (set[i].DFF != null) {
+                TimeOutputs.data[4].y = TimeOutputs.data[4].y.concat(set[i].DFF)
+            }
+            TimeOutputs.data[5].y = TimeOutputs.data[5].y.concat(set[i].Out)
         }
     }
 
@@ -1204,7 +1216,7 @@ function update_hidden(source) {
         var index
         for (let j = 0; j < fft_keys.length; j++) {
             const key = fft_keys[j]
-            if (id.endsWith(key)) {
+            if (id.endsWith("_" + key)) {
                 index = j
                 break
             }
@@ -1296,15 +1308,68 @@ function time_range_changed() {
 }
 
 function get_PID_param_names(prefix) {
-    return { KP:            prefix + "P",
-             KI:            prefix + "I",
-             KD:            prefix + "D",
-             FF:            prefix + "FF",
-             I_max:         prefix + "IMAX",
-             Target_filter: prefix + "FLTT",
-             Error_filter:  prefix + "FLTE",
-             D_filter:      prefix + "FLTD",
-             Slew_max:      prefix + "SMAX"}
+    return { 
+        KP: {
+            title: "KP",
+            name: prefix + "P",
+            decimalPlaces: 4,
+        },
+        KI: {
+            title: "KI",
+            name: prefix + "I",
+            decimalPlaces: 4,
+        },
+        KD: {
+            title: "KD",
+            name: prefix + "D",
+            decimalPlaces: 4,
+        },
+        FF: {
+            title: "KFF",
+            name: prefix + "FF",
+            decimalPlaces: 4,
+        },
+        D_FF: {
+            title: "KDFF",
+            name: prefix + "D_FF",
+            decimalPlaces: 4,
+        },
+        I_max: {
+            title: "I Max",
+            name: prefix + "IMAX",
+            decimalPlaces: 4,
+        },
+        Target_filter: {
+            title: "Target Filter (Hz)",
+            name: prefix + "FLTT",
+            decimalPlaces: 4,
+        },
+        Notch_target: {
+            title: "Target Notch Index",
+            name: prefix + "NTF",
+            decimalPlaces: 0,
+        },
+        Error_filter: {
+            title: "Error Filter (Hz)",
+            name: prefix + "FLTE",
+            decimalPlaces: 4,
+        },
+        Notch_error: {
+            title: "Error Notch Index",
+            name: prefix + "NEF",
+            decimalPlaces: 0,
+        },
+        D_filter: {
+            title: "D Filter (Hz)",
+            name: prefix + "FLTD",
+            decimalPlaces: 4,
+        },
+        Slew_max: {
+            title: "Slew Max",
+            name: prefix + "SMAX",
+            decimalPlaces: 4,
+        }
+    }
 }
 
 // Split use the given time array to return split points in log data
@@ -1459,14 +1524,14 @@ async function load(log_file) {
             let last_set_end
             for (let j = 0; j < PARM.Name.length; j++) {
                 const param_name = PARM.Name[j]
-                for (const [name, param_string] of Object.entries(names)) {
-                    if (param_name !== param_string) {
+                for (const [key, param] of Object.entries(names)) {
+                    if (param_name !== param.name) {
                         continue
                     }
                     const time = PARM.TimeUS[j] * US2S
                     const value = PARM.Value[j]
                     found_param = true
-                    if (param_values[name] != null  && (param_values[name] != value)) {
+                    if (param_values[key] != null  && (param_values[key] != value)) {
                         if ((last_set_end == null) || (time - last_set_end > 1.0)) {
                             // First param change for a second
                             last_set_end = time
@@ -1479,12 +1544,12 @@ async function load(log_file) {
 
                         } else {
                             // Very recent param change, combine with latest set, this leaves gap between sets
-                            param_values[name] = value
+                            param_values[key] = value
                             param_values.start_time = time
 
                         }
                     }
-                    param_values[name] = value
+                    param_values[key] = value
                     break
                 }
             }
@@ -1545,7 +1610,9 @@ async function load(log_file) {
                                                                      P:   Array.from(log_msg.P.slice(batch.batch_start, batch.batch_end)),
                                                                      I:   Array.from(log_msg.I.slice(batch.batch_start, batch.batch_end)),
                                                                      D:   Array.from(log_msg.D.slice(batch.batch_start, batch.batch_end)),
-                                                                     FF:  Array.from(log_msg.FF.slice(batch.batch_start, batch.batch_end))})
+                                                                     FF:  Array.from(log_msg.FF.slice(batch.batch_start, batch.batch_end)),
+                                                                     DFF: ("DFF" in log_msg) ? Array.from(log_msg.DFF.slice(batch.batch_start, batch.batch_end)) : null,
+                    })
                 }
             }
 
@@ -1610,7 +1677,7 @@ async function load(log_file) {
                 const len = batch.P.length
                 batch.Out = new Array(len)
                 for (let i = 0; i<len; i++) {
-                    batch.Out[i] = batch.P[i] + batch.I[i] + batch.D[i] + batch.FF[i]
+                    batch.Out[i] = batch.P[i] + batch.I[i] + batch.D[i] + batch.FF[i] + (batch.DFF != null ? batch.DFF[i] : 0)
                 }
             }
         }
diff --git a/PIDReview/Readme.md b/PIDReview/Readme.md
index 06f7a0c3..3c0cdf92 100644
--- a/PIDReview/Readme.md
+++ b/PIDReview/Readme.md
@@ -1,3 +1,65 @@
-## PID review
+# PID Review
 
-A FFT tool for reviewing flight logs and PID settings. A windowed FFT is applied to the logged PID data, the step response is extracted by estimating the transfer function between the target and actual. Log is split in to sections based on parameter changes.
+A browser-based tool for analysing ArduPilot flight logs and evaluating PID tuning quality.
+
+## Requirements
+
+The **PID** bit of the `LOG_BITMASK` parameter should be set before flying so that `PIDx` log messages (`PIDR`, `PIDP`, `PIDY`, `PIQR`, `PIQP`, `PIQY`, `PIDS`, `PIDA`) are recorded.
+Without this the tool will fallback to using the less detailed `RATE` messages and will disable some features.
+
+## Supported vehicles
+
+| Vehicle | Axes / controllers |
+|---------|--------------------|
+| Copter | Roll, Pitch, Yaw rate PIDs (`PIDR/P/Y`) and raw RATE (`RATE R/P/Y`) |
+| Plane | Roll, Pitch, Yaw rate PIDs (`PIDR/P/Y`), VTOL rate PIDs (`PIQR/P/Y`) and VTOL RATE |
+| Rover | Steering rate (`PIDS`) and speed (`PIDA`) controllers |
+
+### ArduCopter angle rate control loop
+
+For this vehicle type, here is the annotated signal diagram:
+
+![ArduCopter angle rate control loop](ArduCopter_angle_rate_control_loop.drawio.png)
+
+## How to use
+
+1. Open the tool in a browser and load a `.bin` log file using the file picker.
+2. Select the axis / controller to analyse using the radio buttons in the **Axis** panel.
+3. Optionally narrow the analysis window using the **Start / End** time inputs or by zooming into the **Flight Data** plot and dragging the range slider.
+4. Click **Calculate** to run the FFT. The button is re-enabled automatically whenever the time range or window size is changed.
+
+## Plots
+
+### Flight Data
+
+Overview of roll, pitch, throttle and altitude for the whole flight.
+Use the range slider to set the analysis time window.
+
+### Time Domain
+
+- **Inputs** – target, actual and error signals in the time domain, in deg/s.
+- **Outputs** – individual PID components (P, I, D, FF) and total output in the time domain.
+
+Multiple test sections (caused by in-flight parameter changes) are shown with coloured background rectangles and can be toggled on/off individually in the **Tests** table.
+
+### Frequency Domain (FFT)
+
+Averaged windowed FFT of the selected PID signals over the chosen time range.
+Each signal (Target, Actual, Error, P, I, D, FF, DFF, Output) can be shown or hidden independently.
+
+- **Amplitude scale** – Linear, dB, or Power Spectral Density (PSD).
+- **Frequency scale** – Linear or logarithmic, in Hz or RPM.
+- **Window size** – Controls FFT frequency resolution; must be a power of two. Changing it re-enables the Calculate button.
+
+The **Logging rate** and **Frequency resolution** fields below the checkboxes reflect the actual sample rate and bin width of the computed FFT.
+
+### Step Response *(Roll / Pitch / Yaw axes only)*
+
+Estimates the closed-loop step response from the flight data using a Wiener-filter / transfer-function approach between the target and actual signals.
+Individual window estimates are shown in grey; the mean response is shown as a coloured line.
+Useful for evaluating rise time, overshoot, and overall damping without requiring a dedicated step-input manoeuvre.
+
+### PID Spectrogram
+
+Time–frequency heatmap of the selected PID component.
+Shows how the spectral content of the control signal evolves throughout the flight, making it easy to spot resonances that appear only at certain throttle levels or flight phases.
diff --git a/PIDReview/index.html b/PIDReview/index.html
index 9dab9e2b..c6b5cae8 100644
--- a/PIDReview/index.html
+++ b/PIDReview/index.html
@@ -32,6 +32,11 @@ <h1 style="text-align:center"><a href="" style="color: #000000; text-decoration:
 
 <body>
 
+<p style="width:1150px; text-align:justify; padding-left:30px; margin-block-start: 0; margin-block-end: 0.5em;">
+This tool takes a .bin log with RATE or PID messages and shows the time and frequency content of the rate controller target, response and output. To record the full set of PID components the <b>PID</b> bit of the <code>LOG_BITMASK</code> parameter must be set before flying. The <code>RATE</code> log message is enabled by default and can also be used by this tool. Here are <a href="https://github.com/ArduPilot/WebTools/blob/main/PIDReview/Readme.md">more details about this tool and how to use it</a>.
+</p>
+
+
 <style>
     div.plotly-notifier {
         visibility: hidden;
@@ -157,14 +162,11 @@ <h2 style="text-align:center">
 
 </td></tr></table>
 
-<table>
-    <tr>
-        <td style="width: 50px;"></td>
-        <td>
-            <fieldset style="width:300px">
+<div style="width:1145px; display: flex; flex-direction:row; margin-left:30px">
+            <fieldset>
                 <legend>PID</legend>
                 <p>
-                    <fieldset style="width:300px">
+                    <fieldset style="width:215px">
                         <legend ondblclick="update_hidden(this)">Inputs</legend>
                         <input type="checkbox" id="PIDX_Tar" onchange="update_hidden(this)">
                         <label for="PIDX_Tar">Target</label>
@@ -177,7 +179,7 @@ <h2 style="text-align:center">
                     </fieldset>
                 </p>
                 <p>
-                    <fieldset style="width:300px">
+                    <fieldset style="width:215px">
                         <legend ondblclick="update_hidden(this)">Components</legend>
                         <input type="checkbox" id="PIDX_P" onchange="update_hidden(this)">
                         <label for="PIDX_P">P</label>
@@ -190,26 +192,25 @@ <h2 style="text-align:center">
 
                         <input type="checkbox" id="PIDX_FF" onchange="update_hidden(this)">
                         <label for="PIDX_FF">FF</label>
+
+                        <input type="checkbox" id="PIDX_DFF" onchange="update_hidden(this)">
+                        <label for="PIDX_DFF">D FF</label>
                     </fieldset>
                 </p>
                 <p>
-                    <fieldset style="width:300px">
+                    <fieldset style="width:215px">
                         <legend ondblclick="update_hidden(this)">Output</legend>
                         <input type="checkbox" id="PIDX_Out" onchange="update_hidden(this)">
-                        <label for="PIDX_Out">PID + FF</label>
+                        <label for="PIDX_Out">PID + FF + D FF</label>
                     </fieldset>
                 </p>
                 Logging rate: <label id="FFT_infoA"></label> Hz<br><br>
                 Frequency resolution: <label id="FFT_infoB"></label> Hz
              </fieldset>
-        </td>
-        <td>
-            <fieldset style="width:600px; min-height:300px" id="test_sets">
+            <fieldset style="min-height:300px; flex: 1;" id="test_sets">
                 <legend>Tests</legend>
             </fieldset>
-        </td>
-    </tr>
-</table>
+        </div>
 
 <div id="FFTPlot" style="width:1200px;height:450px"></div>
 
@@ -275,7 +276,7 @@ <h2 style="text-align:center">
 <table>
     <td style="width: 375px;"></td>
     <td>
-        <fieldset style="width:450px;height:40px">
+        <fieldset style="width:500px;height:40px">
             <legend>PID component</legend>
             <input type="radio" id="Spec_Tar" name="Spec" onchange="redraw_Spectrogram()">
             <label for="Spec_Tar">Target</label>
@@ -298,6 +299,9 @@ <h2 style="text-align:center">
             <input type="radio" id="Spec_FF" name="Spec" onchange="redraw_Spectrogram()">
             <label for="Spec_FF">FF</label>
 
+            <input type="radio" id="Spec_DFF" name="Spec" onchange="redraw_Spectrogram()">
+            <label for="Spec_DFF">D FF</label>
+
             <input type="radio" id="Spec_Out" name="Spec" onchange="redraw_Spectrogram()">
             <label for="Spec_Out">Output</label>
         </fieldset>
diff --git a/Readme.md b/Readme.md
index 7601c76e..68e887bc 100644
--- a/Readme.md
+++ b/Readme.md
@@ -1,6 +1,8 @@
 ## ArduPilot Web Tools
 
-This repository contains a number of web based tools for targeted ArduPilot log review and insight. These tools are live on [ardupilot.org](https://firmware.ardupilot.org/Tools/WebTools). For general review see [UAVLogViewer](https://github.com/ArduPilot/UAVLogViewer).
+This repository contains a number of web based tools for targeted ArduPilot log review and insight.
+These tools are live on [ardupilot.org](https://firmware.ardupilot.org/Tools/WebTools).
+For general review see [UAVLogViewer](https://github.com/ArduPilot/UAVLogViewer).
 
 ## Development setup
 
@@ -14,20 +16,24 @@ git clone --recurse-submodules https://github.com/ArduPilot/WebTools.git
 
 Host locally using python by running the following command in the root of the repo:
 
-```
+```console
 python3 -m http.server --bind 127.0.0.1
 ```
 
-The landing page can then be found at http://127.0.0.1:8000/
+The landing page can then be found at `http://127.0.0.1:8000/`
+
+You need to keep your submodules updated.
+When you rebase, or switch branches, update them like so:
 
-You need to keep your submodules update. When you rebase, or switch branches, update them like so:
 ```console
 git submodule update --init --recursive
 ```
 
 ## VSCode
 
-This repository contains VSCode launch configurations for debugging with Chrome and Edge. WebTools are either hosted with python as above or using the [LiveServer extension](https://marketplace.visualstudio.com/items?itemName=ritwickdey.LiveServer) which enables auto-reload. More information on debugging with VSCode [here](https://code.visualstudio.com/docs/editor/debugging).
+This repository contains VSCode launch configurations for debugging with Chrome and Edge.
+WebTools are either hosted with python as above or using the [LiveServer extension](https://marketplace.visualstudio.com/items?itemName=ritwickdey.LiveServer) which enables auto-reload.
+Here is [more information on debugging with VSCode](https://code.visualstudio.com/docs/editor/debugging).
 
 <p align="center">
 <img src="images/VSCode%20debug.png" width="80%">