diff --git a/htdocs/css/admin.css b/htdocs/css/admin.css
index c9df225c..1079c548 100644
--- a/htdocs/css/admin.css
+++ b/htdocs/css/admin.css
@@ -82,7 +82,8 @@ h1 {
 
 /* col-1 */
 .bookmarks table [data-editor="name"] {
-    width: 35%;
+    white-space: nowrap;
+    width: 29%;
 }
 
 /* col-2 */
@@ -101,15 +102,28 @@ h1 {
 }
 
 /* col-4 */
-.bookmarks table [data-editor="description"] {
-    width: 35%;
+.bookmarks table [data-editor="underlying"] {
+    white-space: nowrap;
+    min-width: 160px;
+    width: 10%;
 }
 
 /* col-5 */
+.bookmarks table [data-editor="description"] {
+    width: 29%;
+}
+
+/* col-6 */
+.bookmarks table [data-editor="scannable"] {
+    width: 2%;
+    text-align: center;
+}
+
+/* col-7 */
 .bookmarks table tr td:last-child, .bookmarks table tr th:last-child {
     text-align: right;
     width: 10%;
- }
+}
 
 .bookmarks table input, .bookmarks table select {
     text-align: inherit;
diff --git a/htdocs/css/openwebrx.css b/htdocs/css/openwebrx.css
index 76e46fff..a38f0bb6 100644
--- a/htdocs/css/openwebrx.css
+++ b/htdocs/css/openwebrx.css
@@ -1512,17 +1512,16 @@ img.openwebrx-mirror-img
 }
 
 .openwebrx-dialog {
-	background-color: #575757;
-	padding: 10px;
-	color: white;
-	position: fixed;
-	font-size: 10pt;
-	border-radius: 15px;
-	-moz-border-radius: 15px;
+    background-color: #575757;
+    padding: 10px;
+    color: white;
+    font-size: 10pt;
+    border-radius: 15px;
+    -moz-border-radius: 15px;
     position: fixed;
     left: 50%;
     top: 50%;
-    transform: translate(-50%, 0);
+    transform: translate(-50%, -50%);
 }
 
 .openwebrx-dialog .form-field {
diff --git a/htdocs/index.html b/htdocs/index.html
index b75b02ba..16873c1b 100644
--- a/htdocs/index.html
+++ b/htdocs/index.html
@@ -378,12 +378,16 @@
             </div>
             <div class="form-field">
                 <label for="frequency">Frequency:</label>
-                <input type="number" id="frequency" name="frequency">
+                <input type="number" id="frequency" name="frequency" min="1">
             </div>
             <div class="form-field">
                 <label for="modulation">Modulation:</label>
                 <select name="modulation" id="modulation"></select>
             </div>
+            <div class="form-field">
+                <label for="underlying">Underlying:</label>
+                <select name="underlying" id="underlying"></select>
+            </div>
             <div class="form-field">
                 <label for="name">Description:</label>
                 <input type="text" id="description" name="description">
diff --git a/htdocs/lib/BookmarkBar.js b/htdocs/lib/BookmarkBar.js
index 65ca2040..77048e04 100644
--- a/htdocs/lib/BookmarkBar.js
+++ b/htdocs/lib/BookmarkBar.js
@@ -2,7 +2,7 @@ function BookmarkBar() {
     var me = this;
     me.modesToScan = ['lsb', 'usb', 'cw', 'am', 'sam', 'nfm'];
     me.localBookmarks = new BookmarkLocalStorage();
-    me.$container = $("#openwebrx-bookmarks-container");
+    me.$container = $('#openwebrx-bookmarks-container');
     me.bookmarks = {};
 
     me.$container.on('click', '.bookmark', function(e){
@@ -11,9 +11,7 @@ function BookmarkBar() {
         var b = $bookmark.data();
         if (!b || !b.frequency || !b.modulation) return;
         me.getDemodulator().set_offset_frequency(b.frequency - center_freq);
-        if (b.modulation) {
-            me.getDemodulatorPanel().setMode(b.modulation, b.underlying);
-        }
+        me.getDemodulatorPanel().setMode(b.modulation, b.underlying);
         $bookmark.addClass('selected');
         stopScanner();
     });
@@ -41,7 +39,7 @@ function BookmarkBar() {
         me.showEditDialog();
     });
 
-    me.$dialog = $("#openwebrx-dialog-bookmark");
+    me.$dialog = $('#openwebrx-dialog-bookmark');
     me.$dialog.find('.openwebrx-button[data-action=cancel]').click(function(){
         me.$dialog.hide();
     });
@@ -108,25 +106,60 @@ BookmarkBar.prototype.render = function(){
 
 BookmarkBar.prototype.showEditDialog = function(bookmark) {
     if (!bookmark) {
-        var mode = this.getDemodulator().get_secondary_demod() || this.getDemodulator().get_modulation();
+        var mode1 = this.getDemodulator().get_secondary_demod()
+        var mode2 = this.getDemodulator().get_modulation();
+        // if no secondary demod, use the primary one
+        if (!mode1) { mode1 = mode2; mode2 = ''; }
         bookmark = {
-            name: "",
+            name: '',
             frequency: center_freq + this.getDemodulator().get_offset_frequency(),
-            modulation: mode,
-            description: "",
-            scannable : this.modesToScan.indexOf(mode) >= 0
+            modulation: mode1,
+            underlying: mode2,
+            description: '',
+            scannable : this.modesToScan.indexOf(mode1) >= 0
         }
+        this.sanitizeBookmark(bookmark);
     }
     this.$dialog.bookmarkDialog().setValues(bookmark);
     this.$dialog.show();
     this.$dialog.find('#name').focus();
 };
 
+BookmarkBar.prototype.sanitizeBookmark = function(b) {
+    // must have name, frequency, and modulation
+    if (!b.name || !b.frequency || !b.modulation)
+        return "Must have name, frequency, and modulation.";
+
+    // must have non-empty name
+    b.name = b.name.trim();
+    if (b.name.length <= 0) return "Must have a non-empty name.";
+
+    // must have positive frequency
+    b.frequency = Number(b.frequency);
+    if (b.frequency <= 0) return "Frequency must be positive.";
+
+    // must have valid modulation
+    var mode = Modes.findByModulation(b.modulation);
+    if (!mode) return "Must have valid modulation."
+
+    // check that underlying demodulator is valid
+    if (!b.underlying)
+        b.underlying = '';
+    else if (!mode.underlying)
+        return "Must not have underlying modulation.";
+    else if (mode.underlying.indexOf(b.underlying) < 0)
+        return "Must have valid underlying modulation.";
+
+    return null;
+};
+
 BookmarkBar.prototype.storeBookmark = function() {
     var me = this;
     var bookmark = this.$dialog.bookmarkDialog().getValues();
     if (!bookmark) return;
-    bookmark.frequency = Number(bookmark.frequency);
+
+    var error = this.sanitizeBookmark(bookmark);
+    if (error) { alert(error); return; }
 
     var bookmarks = me.localBookmarks.getBookmarks();
 
diff --git a/htdocs/lib/BookmarkDialog.js b/htdocs/lib/BookmarkDialog.js
index ee7c2fd4..d6b2a71d 100644
--- a/htdocs/lib/BookmarkDialog.js
+++ b/htdocs/lib/BookmarkDialog.js
@@ -2,16 +2,25 @@ $.fn.bookmarkDialog = function() {
     var $el = this;
     return {
         setModes: function(modes) {
-            $el.find('#modulation').html(modes.filter(function(m){
+            $el.find('#modulation').html(modes.filter(function(m) {
                 return m.isAvailable();
             }).map(function(m) {
                 return '<option value="' + m.modulation + '">' + m.name + '</option>';
             }).join(''));
             return this;
         },
+        setUnderlying: function(modes) {
+            $el.find('#underlying').html('<option value="">None</option>' +
+            modes.filter(function(m) {
+                return m.isAvailable() && !m.underlying && m.type === 'analog';
+            }).map(function(m) {
+                return '<option value="' + m.modulation + '">' + m.name + '</option>';
+            }).join(''));
+            return this;
+        },
         setValues: function(bookmark) {
             var $form = $el.find('form');
-            ['name', 'frequency', 'modulation', 'description', 'scannable'].forEach(function(key){
+            ['name', 'frequency', 'modulation', 'underlying', 'description', 'scannable'].forEach(function(key) {
                 var $input = $form.find('#' + key);
                 if ($input.is(':checkbox')) {
                     $input.prop('checked', bookmark[key]);
@@ -25,7 +34,7 @@ $.fn.bookmarkDialog = function() {
         getValues: function() {
             var bookmark = {};
             var valid = true;
-            ['name', 'frequency', 'modulation', 'description', 'scannable'].forEach(function(key){
+            ['name', 'frequency', 'modulation', 'underlying', 'description', 'scannable'].forEach(function(key) {
                 var $input = $el.find('#' + key);
                 valid = valid && $input[0].checkValidity();
                 bookmark[key] = $input.is(':checkbox')? $input.is(':checked') : $input.val();
@@ -38,4 +47,4 @@ $.fn.bookmarkDialog = function() {
             return bookmark;
         }
     }
-}
+};
diff --git a/htdocs/lib/Modes.js b/htdocs/lib/Modes.js
index 0bdac90b..1ec050d1 100644
--- a/htdocs/lib/Modes.js
+++ b/htdocs/lib/Modes.js
@@ -5,7 +5,9 @@ var Modes = {
     setModes:function(json){
         this.modes = json.map(function(m){ return new Mode(m); });
         this.updatePanels();
-        $('#openwebrx-dialog-bookmark').bookmarkDialog().setModes(this.modes);
+        var bookmarkDialog = $('#openwebrx-dialog-bookmark').bookmarkDialog();
+        bookmarkDialog.setUnderlying(this.modes);
+        bookmarkDialog.setModes(this.modes);
     },
     getModes:function(){
         return this.modes;
diff --git a/htdocs/lib/settings/BookmarkTable.js b/htdocs/lib/settings/BookmarkTable.js
index f251c9a6..f9e73cf6 100644
--- a/htdocs/lib/settings/BookmarkTable.js
+++ b/htdocs/lib/settings/BookmarkTable.js
@@ -177,8 +177,8 @@ ModulationEditor.prototype = new Editor();
 
 ModulationEditor.prototype.getInputHtml = function() {
     return '<select class="form-control form-control-sm">' +
-        $.map(this.modes, function(name, modulation) {
-            return '<option value="' + modulation + '">' + name + '</option>';
+        $.map(this.modes, function(mode, name) {
+            return '<option value="' + name + '">' + mode.name + '</option>';
         }).join('') +
         '</select>';
 };
@@ -188,6 +188,30 @@ ModulationEditor.prototype.getHtml = function() {
     return $option.html();
 };
 
+function UnderlyingEditor(table) {
+    Editor.call(this, table);
+    this.modes = table.data('modes');
+}
+
+UnderlyingEditor.prototype = new Editor();
+
+UnderlyingEditor.prototype.getInputHtml = function() {
+    return '<select class="form-control form-control-sm">' +
+        '<option value="">None</option>' +
+        $.map(this.modes, function(mode, name) {
+            if (mode.analog && !mode.underlying.length)
+                return '<option value="' + name + '">' + mode.name + '</option>';
+            else
+                return '';
+        }).join('') +
+        '</select>';
+};
+
+UnderlyingEditor.prototype.getHtml = function() {
+    var $option = this.input.find('option:selected')
+    return $option? $option.html() : '';
+};
+
 function DescriptionEditor(table) {
     Editor.call(this, table);
 }
@@ -220,16 +244,21 @@ ScannableEditor.prototype.getHtml = function() {
     return this.getValue()? '&check;' : '';
 };
 
+var renderModulation = function(m, modes) {
+    return !m? 'None' : m in modes? modes[m].name : m;
+}
+
 $.fn.bookmarktable = function() {
     var editors = {
         name: NameEditor,
         frequency: FrequencyEditor,
         modulation: ModulationEditor,
+        underlying: UnderlyingEditor,
         description: DescriptionEditor,
         scannable: ScannableEditor
     };
 
-    $.each(this, function(){
+    $.each(this, function() {
         var $table = $(this).find('table');
 
         $table.on('dblclick', 'td', function(e) {
@@ -252,9 +281,11 @@ $.fn.bookmarktable = function() {
                     data: JSON.stringify(Object.fromEntries([[name, editor.getValue()]])),
                     contentType: 'application/json',
                     method: 'POST'
-                }).done(function(){
+                }).done(function() {
                     $cell.data('value', editor.getValue());
                     $cell.html(editor.getHtml());
+                }).fail(function() {
+                    $cell.html(html);
                 });
             };
 
@@ -337,7 +368,10 @@ $.fn.bookmarktable = function() {
                     data: JSON.stringify([data]),
                     contentType: 'application/json',
                     method: 'POST'
-                }).done(function(data){
+                }).fail(function(data) {
+                    //  adding failed, reenable inputs
+                    $.map(inputs, function(input, name) { input.disable(false); });
+                }).done(function(data) {
                     if (data.length && data.length === 1 && 'bookmark_id' in data[0]) {
                         row.attr('data-id', data[0]['bookmark_id']);
                         var tds = row.find('td');
@@ -347,16 +381,16 @@ $.fn.bookmarktable = function() {
                             td.data('value', input.getValue());
                             td.html(input.getHtml());
                         });
+                    }
 
-                        var $cell = row.find('td').last();
-                        var $group = $cell.find('.btn-group');
-                        if ($group.length) {
-                            $group.remove;
-                            $cell.html('<div class="btn btn-sm btn-danger bookmark-delete">delete</div>');
-                        }
+                    // remove inputs
+                    var $cell = row.find('td').last();
+                    var $group = $cell.find('.btn-group');
+                    if ($group.length) {
+                        $group.remove;
+                        $cell.html('<div class="btn btn-sm btn-danger bookmark-delete">delete</div>');
                     }
                 });
-
             });
 
             $table.append(row);
@@ -372,16 +406,13 @@ $.fn.bookmarktable = function() {
                 var modes = $table.data('modes');
                 var $list = $('<table class="table table-sm">');
                 $list.append(bookmarks.map(function(b) {
-                    var modulation = b.modulation;
-                    if (modulation in modes) {
-                        modulation = modes[modulation];
-                    }
                     var row = $(
                         '<tr>' +
-                            '<td><input class="form-check-input select" type="checkbox"></td>' +
+                            '<td><input class="form-check-input select" type="checkbox">&nbsp;</td>' +
                             '<td>' + b.name + '</td>' +
                             '<td class="frequency">' + renderFrequency(b.frequency) + '</td>' +
-                            '<td>' + modulation + '</td>' +
+                            '<td>' + renderModulation(b.modulation, modes) + '</td>' +
+//                            '<td>' + renderModulation(b.underlying, modes) + '</td>' +
                         '</tr>'
                     );
                     row.data('bookmark', b);
@@ -407,31 +438,30 @@ $.fn.bookmarktable = function() {
                         data: JSON.stringify(selected),
                         contentType: 'application/json',
                         method: 'POST'
-                    }).done(function(data){
+                    }).fail(function(data) {
+                        // import failed
+                        $table.find('.emptytext').remove();
+                    }).done(function(data) {
                         $table.find('.emptytext').remove();
                         var modes = $table.data('modes');
                         if (data.length && data.length == selected.length) {
                             $table.append(data.map(function(obj, index) {
-                                var bookmark = selected[index];
-                                var modulation_name = bookmark.modulation;
-                                if (modulation_name in modes) {
-                                    modulation_name = modes[modulation_name];
-                                }
-                                // provide reasonable default for missing fields
-                                if (!('description' in bookmark)) {
-                                    bookmark.description = '';
-                                }
-                                if (!('scannable' in bookmark)) {
+                                var b = selected[index];
+                                // provide reasonable defaults for missing fields
+                                if (!('underlying' in b))  b.underlying = '';
+                                if (!('description' in b)) b.description = '';
+                                if (!('scannable' in b)) {
                                     var modesToScan = ['lsb', 'usb', 'cw', 'am', 'sam', 'nfm'];
-                                    bookmark.scannable = modesToScan.indexOf(bookmark.modulation) >= 0;
+                                    b.scannable = modesToScan.indexOf(b.modulation) >= 0;
                                 }
                                 return $(
                                     '<tr data-id="' + obj.bookmark_id + '">' +
-                                        '<td data-editor="name" data-value="' + bookmark.name + '">' + bookmark.name + '</td>' +
-                                        '<td data-editor="frequency" data-value="' + bookmark.frequency + '" class="frequency">' + renderFrequency(bookmark.frequency) +'</td>' +
-                                        '<td data-editor="modulation" data-value="' + bookmark.modulation + '">' + modulation_name + '</td>' +
-                                        '<td data-editor="description" data-value="' + bookmark.description + '">' + bookmark.description + '</td>' +
-                                        '<td data-editor="scannable" data-value="' + bookmark.scannable + '">' + (bookmark.scannable? '&check;':'') + '</td>' +
+                                        '<td data-editor="name" data-value="' + b.name + '">' + b.name + '</td>' +
+                                        '<td data-editor="frequency" data-value="' + b.frequency + '" class="frequency">' + renderFrequency(b.frequency) +'</td>' +
+                                        '<td data-editor="modulation" data-value="' + b.modulation + '">' + renderModulation(b.modulation, modes) + '</td>' +
+                                        '<td data-editor="underlying" data-value="' + b.underlying + '">' + renderModulation(b.underlying, modes) + '</td>' +
+                                        '<td data-editor="description" data-value="' + b.description + '">' + b.description + '</td>' +
+                                        '<td data-editor="scannable" data-value="' + b.scannable + '">' + (b.scannable? '&check;':'') + '</td>' +
                                         '<td>' +
                                             '<button type="button" class="btn btn-sm btn-danger bookmark-delete">delete</button>' +
                                         '</td>' +
diff --git a/owrx/bookmarks.py b/owrx/bookmarks.py
index b7b3aeea..81f7b93a 100644
--- a/owrx/bookmarks.py
+++ b/owrx/bookmarks.py
@@ -16,6 +16,7 @@ class Bookmark(object):
         self.name = j["name"]
         self.frequency = j["frequency"]
         self.modulation = j["modulation"]
+        self.underlying = j["underlying"] if "underlying" in j else ""
         self.description = j["description"] if "description" in j else ""
         self.srcFile = srcFile
         # By default, only scan modulations that make sense to scan
@@ -33,6 +34,9 @@ class Bookmark(object):
     def getModulation(self):
         return self.modulation
 
+    def getUnderlying(self):
+        return self.underlying
+
     def getDescription(self):
         return self.description
 
@@ -47,6 +51,7 @@ class Bookmark(object):
             "name": self.getName(),
             "frequency": self.getFrequency(),
             "modulation": self.getModulation(),
+            "underlying": self.getUnderlying(),
             "description": self.getDescription(),
             "scannable": self.isScannable(),
         }
diff --git a/owrx/controllers/settings/bookmarks.py b/owrx/controllers/settings/bookmarks.py
index 1c9c9a09..f2e6499c 100644
--- a/owrx/controllers/settings/bookmarks.py
+++ b/owrx/controllers/settings/bookmarks.py
@@ -2,7 +2,7 @@ from owrx.controllers.template import WebpageController
 from owrx.controllers.admin import AuthorizationMixin
 from owrx.controllers.settings import SettingsBreadcrumb
 from owrx.bookmarks import Bookmark, Bookmarks
-from owrx.modes import Modes
+from owrx.modes import Modes, AnalogMode
 from owrx.breadcrumb import Breadcrumb, BreadcrumbItem, BreadcrumbMixin
 import json
 import math
@@ -24,7 +24,7 @@ class BookmarksController(AuthorizationMixin, BreadcrumbMixin, WebpageController
     def render_table(self):
         bookmarks = Bookmarks.getSharedInstance().getEditableBookmarks()
         emptyText = """
-            <tr class="emptytext"><td colspan="4">
+            <tr class="emptytext"><td colspan="7">
                 No bookmarks in storage. You can add new bookmarks using the buttons below. 
             </td></tr>
         """
@@ -35,6 +35,7 @@ class BookmarksController(AuthorizationMixin, BreadcrumbMixin, WebpageController
                     <th>Name</th>
                     <th class="frequency">Frequency</th>
                     <th>Modulation</th>
+                    <th>Underlying</th>
                     <th>Description</th>
                     <th>Scan</th>
                     <th>Actions</th>
@@ -43,7 +44,11 @@ class BookmarksController(AuthorizationMixin, BreadcrumbMixin, WebpageController
             </table>
         """.format(
             bookmarks="".join(self.render_bookmark(b) for b in bookmarks) if bookmarks else emptyText,
-            modes=json.dumps({m.modulation: m.name for m in Modes.getAvailableModes()}),
+            modes=json.dumps({m.modulation: {
+                "name"       : m.name,
+                "analog"     : isinstance(m, AnalogMode),
+                "underlying" : m.underlying if hasattr(m, "underlying") else []
+            } for m in Modes.getAvailableModes()}),
         )
 
     def render_bookmark(self, bookmark: Bookmark):
@@ -65,13 +70,18 @@ class BookmarksController(AuthorizationMixin, BreadcrumbMixin, WebpageController
                 suffix = suffixes[exp]
             return "{num:g} {suffix}Hz".format(num=num, suffix=suffix)
 
-        mode = Modes.findByModulation(bookmark.getModulation())
-        scan = bookmark.isScannable()
+        scan  = bookmark.isScannable()
+        name1 = bookmark.getModulation()
+        name2 = bookmark.getUnderlying()
+        mode1 = Modes.findByModulation(name1)
+        mode2 = Modes.findByModulation(name2)
+
         return """
             <tr data-id="{id}">
                 <td data-editor="name" data-value="{name}">{name}</td>
                 <td data-editor="frequency" data-value="{frequency}" class="frequency">{rendered_frequency}</td>
                 <td data-editor="modulation" data-value="{modulation}">{modulation_name}</td>
+                <td data-editor="underlying" data-value="{underlying}">{underlying_name}</td>
                 <td data-editor="description" data-value="{description}">{description}</td>
                 <td data-editor="scannable" data-value="{scannable}">{scannable_check}</td>
                 <td>
@@ -84,8 +94,10 @@ class BookmarksController(AuthorizationMixin, BreadcrumbMixin, WebpageController
             # TODO render frequency in si units
             frequency=bookmark.getFrequency(),
             rendered_frequency=render_frequency(bookmark.getFrequency()),
-            modulation=bookmark.getModulation() if mode is None else mode.modulation,
-            modulation_name=bookmark.getModulation() if mode is None else mode.name,
+            modulation=name1 if mode1 is None else mode1.modulation,
+            underlying=name2 if mode2 is None else mode2.modulation,
+            modulation_name=name1 if mode1 is None else mode1.name,
+            underlying_name="None" if not name2 else name2 if mode2 is None else mode2.name,
             description=bookmark.getDescription(),
             scannable="true" if scan else "false",
             scannable_check="&check;" if scan else "",
@@ -98,6 +110,45 @@ class BookmarksController(AuthorizationMixin, BreadcrumbMixin, WebpageController
         except StopIteration:
             return None
 
+    def _sanitizeBookmark(self, data):
+        try:
+            # Must have name, frequency, modulation
+            if "name" not in data or "frequency" not in data or "modulation" not in data:
+                return "Bookmark missing required fields"
+            # Name must not be empty
+            data["name"] = data["name"].strip()
+            if len(data["name"]) == 0:
+                return "Empty bookmark name"
+            # Frequency must be integer
+            if not isinstance(data["frequency"], int):
+                data["frequency"] = int(data["frequency"])
+            # Frequency must be >0
+            if data["frequency"] <= 0:
+                return "Frequency must be positive"
+            # Get both modes
+            mode1 = Modes.findByModulation(data["modulation"]) if "modulation" in data else None
+            mode2 = Modes.findByModulation(data["underlying"]) if "underlying" in data else None
+            # Unknown main mode
+            if mode1 is None:
+                return "Invalid modulation"
+            # No underlying mode
+            if mode2 is None:
+                data["underlying"] = ""
+            else:
+                # Main mode has no underlying mode or underlying mode incorrect
+                if not hasattr(mode1, "underlying") or mode2.modulation not in mode1.underlying:
+                    return "Incorrect underlying modulation"
+                # Underlying mode is at the default value
+                #if mode2.modulation == mode1.underlying[0]:
+                #    data["underlying"] = ""
+
+        except Exception as e:
+            # Something else went horribly wrong
+            return str(e)
+
+        # Everything ok
+        return None
+
     def update(self):
         bookmark_id = int(self.request.matches.group(1))
         bookmark = self._findBookmark(bookmark_id)
@@ -105,18 +156,26 @@ class BookmarksController(AuthorizationMixin, BreadcrumbMixin, WebpageController
             self.send_response("{}", content_type="application/json", code=404)
             return
         try:
+            newd = {}
             data = json.loads(self.get_body().decode("utf-8"))
-            for key in ["name", "frequency", "modulation", "description", "scannable"]:
+            for key in ["name", "frequency", "modulation", "underlying", "description", "scannable"]:
                 if key in data:
-                    value = data[key]
-                    if key == "frequency":
-                        value = int(value)
-                    setattr(bookmark, key, value)
+                    newd[key] = data[key]
+                elif hasattr(bookmark, key):
+                    newd[key] = getattr(bookmark, key)
+            # Make sure everything is correct
+            error = self._sanitizeBookmark(newd)
+            if error is not None:
+                raise ValueError(error)
+            # Update and store bookmark
+            for key in newd:
+                setattr(bookmark, key, newd[key])
             Bookmarks.getSharedInstance().store()
             # TODO this should not be called explicitly... bookmarks don't have any event capability right now, though
             Bookmarks.getSharedInstance().notifySubscriptions(bookmark)
             self.send_response("{}", content_type="application/json", code=200)
-        except json.JSONDecodeError:
+        except (json.JSONDecodeError, ValueError) as e:
+            logger.warning("Failed updating bookmark: " + str(e))
             self.send_response("{}", content_type="application/json", code=400)
 
     def new(self):
@@ -125,12 +184,12 @@ class BookmarksController(AuthorizationMixin, BreadcrumbMixin, WebpageController
         def create(bookmark_data):
             # sanitize
             data = {}
-            for key in ["name", "frequency", "modulation", "description", "scannable"]:
+            for key in ["name", "frequency", "modulation", "underlying", "description", "scannable"]:
                 if key in bookmark_data:
-                    if key == "frequency":
-                        data[key] = int(bookmark_data[key])
-                    else:
-                        data[key] = bookmark_data[key]
+                    data[key] = bookmark_data[key]
+            error = self._sanitizeBookmark(data)
+            if error is not None:
+                raise ValueError(error)
             bookmark = Bookmark(data)
             bookmarks.addBookmark(bookmark)
             return {"bookmark_id": id(bookmark)}
@@ -140,7 +199,8 @@ class BookmarksController(AuthorizationMixin, BreadcrumbMixin, WebpageController
             result = [create(b) for b in data]
             bookmarks.store()
             self.send_response(json.dumps(result), content_type="application/json", code=200)
-        except json.JSONDecodeError:
+        except (json.JSONDecodeError, ValueError) as e:
+            logger.warning("Failed creating bookmark: " + str(e))
             self.send_response("{}", content_type="application/json", code=400)
 
     def delete(self):