diff --git a/sw/src/userspace/remotectl.cpp b/sw/src/userspace/remotectl.cpp
index 091d919..a5978ea 100644
--- a/sw/src/userspace/remotectl.cpp
+++ b/sw/src/userspace/remotectl.cpp
@@ -12,6 +12,7 @@
 #include <math.h>
 #include <stdarg.h>
 #include <stdio.h>
+#include <time.h>
 #include <algorithm>
 #include <chrono>
 #include <fstream>
@@ -776,6 +777,38 @@ private:
         return std::to_string(timestamp);
     }
 
+    /** Handle command REALTIME? */
+    std::string qry_realtime(CommandEnvironment env)
+    {
+        struct timespec tp1, tp2, tp3;
+        uint64_t ts1, ts2, ts3, ts4;
+
+        // Read approximately simultaneous real time and timestamp.
+        ts1 = m_device.get_timestamp();
+        clock_gettime(CLOCK_REALTIME, &tp1);
+        ts2 = m_device.get_timestamp();
+        clock_gettime(CLOCK_REALTIME, &tp2);
+        ts3 = m_device.get_timestamp();
+        clock_gettime(CLOCK_REALTIME, &tp3);
+        ts4 = m_device.get_timestamp();
+
+        // Choose shortest interval out of three.
+        const uint64_t timestamp_mask = 0xffffffffffff;
+        uint64_t d1 = (ts2 - ts1) & timestamp_mask;
+        uint64_t d2 = (ts3 - ts2) & timestamp_mask;
+        uint64_t d3 = (ts4 - ts3) & timestamp_mask;
+        if (d3 < d1 && d3 < d2) {
+            ts1 = ts3;
+            tp1 = tp3;
+        } else if (d2 < d1) {
+            ts1 = ts2;
+            tp1 = tp2;
+        }
+
+        return str_format("%lld.%09ld %llu",
+            (long long)tp1.tv_sec, (long)tp1.tv_nsec, ts1);
+    }
+
     /** Handle command AIN:CHANNELS:COUNT? */
     std::string qry_channels_count(CommandEnvironment env)
     {
@@ -1424,6 +1457,7 @@ private:
             command_table_no_args = {
         { "*idn?",                  &CommandHandler::qry_idn },
         { "timestamp?",             &CommandHandler::qry_timestamp },
+        { "realtime?",              &CommandHandler::qry_realtime },
         { "ain:channels:count?",    &CommandHandler::qry_channels_count },
         { "ain:channels:active?",   &CommandHandler::qry_channels_active },
         { "ain:chN:range?",         &CommandHandler::qry_channel_range },