diff --git a/gnss/aidl/default/Gnss.cpp b/gnss/aidl/default/Gnss.cpp
index 7855b51..cf2c90d 100644
--- a/gnss/aidl/default/Gnss.cpp
+++ b/gnss/aidl/default/Gnss.cpp
@@ -19,6 +19,7 @@
 #include "Gnss.h"
 #include <inttypes.h>
 #include <log/log.h>
+#include <utils/Timers.h>
 #include "AGnss.h"
 #include "AGnssRil.h"
 #include "DeviceFileReader.h"
@@ -28,7 +29,6 @@
 #include "GnssConfiguration.h"
 #include "GnssDebug.h"
 #include "GnssGeofence.h"
-#include "GnssMeasurementInterface.h"
 #include "GnssNavigationMessageInterface.h"
 #include "GnssPsds.h"
 #include "GnssVisibilityControl.h"
@@ -95,6 +95,9 @@
     }
 
     mIsActive = true;
+    mThreadBlocker.reset();
+    // notify measurement engine to update measurement interval
+    mGnssMeasurementInterface->setLocationEnabled(true);
     this->reportGnssStatusValue(IGnssCallback::GnssStatusValue::SESSION_BEGIN);
     mThread = std::thread([this]() {
         this->reportSvStatus();
@@ -102,8 +105,12 @@
             std::this_thread::sleep_for(std::chrono::milliseconds(TTFF_MILLIS));
             mFirstFixReceived = true;
         }
-        while (mIsActive == true) {
+        do {
+            if (!mIsActive) {
+                break;
+            }
             this->reportSvStatus();
+            this->reportNmea();
 
             auto currentLocation = getLocationFromHW();
             mGnssPowerIndication->notePowerConsumption();
@@ -113,12 +120,29 @@
                 const auto location = Utils::getMockLocation();
                 this->reportLocation(location);
             }
-            std::this_thread::sleep_for(std::chrono::milliseconds(mMinIntervalMs));
-        }
+        } while (mIsActive && mThreadBlocker.wait_for(std::chrono::milliseconds(mMinIntervalMs)));
     });
     return ScopedAStatus::ok();
 }
 
+ScopedAStatus Gnss::stop() {
+    ALOGD("stop");
+    mIsActive = false;
+    mGnssMeasurementInterface->setLocationEnabled(false);
+    this->reportGnssStatusValue(IGnssCallback::GnssStatusValue::SESSION_END);
+    mThreadBlocker.notify();
+    if (mThread.joinable()) {
+        mThread.join();
+    }
+    return ScopedAStatus::ok();
+}
+
+ScopedAStatus Gnss::close() {
+    ALOGD("close");
+    sGnssCallback = nullptr;
+    return ScopedAStatus::ok();
+}
+
 void Gnss::reportLocation(const GnssLocation& location) const {
     std::unique_lock<std::mutex> lock(mMutex);
     if (sGnssCallback == nullptr) {
@@ -153,7 +177,6 @@
 
 std::vector<GnssSvInfo> Gnss::filterBlocklistedSatellites(
         std::vector<GnssSvInfo> gnssSvInfoList) const {
-    ALOGD("filterBlocklistedSatellites");
     for (uint32_t i = 0; i < gnssSvInfoList.size(); i++) {
         if (mGnssConfiguration->isBlocklisted(gnssSvInfoList[i])) {
             gnssSvInfoList[i].svFlag &= ~(uint32_t)IGnssCallback::GnssSvFlags::USED_IN_FIX;
@@ -174,14 +197,19 @@
     }
 }
 
-ScopedAStatus Gnss::stop() {
-    ALOGD("stop");
-    mIsActive = false;
-    this->reportGnssStatusValue(IGnssCallback::GnssStatusValue::SESSION_END);
-    if (mThread.joinable()) {
-        mThread.join();
+void Gnss::reportNmea() const {
+    if (mIsNmeaActive) {
+        std::unique_lock<std::mutex> lock(mMutex);
+        if (sGnssCallback == nullptr) {
+            ALOGE("%s: sGnssCallback is null.", __func__);
+            return;
+        }
+        nsecs_t now = systemTime(SYSTEM_TIME_MONOTONIC);
+        auto status = sGnssCallback->gnssNmeaCb(now, "$TEST,0,1,2,3,4,5");
+        if (!status.isOk()) {
+            ALOGE("%s: Unable to invoke callback", __func__);
+        }
     }
-    return ScopedAStatus::ok();
 }
 
 ScopedAStatus Gnss::startSvStatus() {
@@ -197,16 +225,12 @@
 }
 ScopedAStatus Gnss::startNmea() {
     ALOGD("startNmea");
+    mIsNmeaActive = true;
     return ScopedAStatus::ok();
 }
 ScopedAStatus Gnss::stopNmea() {
     ALOGD("stopNmea");
-    return ScopedAStatus::ok();
-}
-
-ScopedAStatus Gnss::close() {
-    ALOGD("close");
-    sGnssCallback = nullptr;
+    mIsNmeaActive = false;
     return ScopedAStatus::ok();
 }
 
@@ -249,7 +273,8 @@
 ScopedAStatus Gnss::setPositionMode(const PositionModeOptions& options) {
     ALOGD("setPositionMode. minIntervalMs:%d, lowPowerMode:%d", options.minIntervalMs,
           (int)options.lowPowerMode);
-    mMinIntervalMs = options.minIntervalMs;
+    mMinIntervalMs = std::max(1000, options.minIntervalMs);
+    mGnssMeasurementInterface->setLocationInterval(mMinIntervalMs);
     return ScopedAStatus::ok();
 }
 
@@ -283,8 +308,10 @@
 ScopedAStatus Gnss::getExtensionGnssMeasurement(
         std::shared_ptr<IGnssMeasurementInterface>* iGnssMeasurement) {
     ALOGD("getExtensionGnssMeasurement");
-
-    *iGnssMeasurement = SharedRefBase::make<GnssMeasurementInterface>();
+    if (mGnssMeasurementInterface == nullptr) {
+        mGnssMeasurementInterface = SharedRefBase::make<GnssMeasurementInterface>();
+    }
+    *iGnssMeasurement = mGnssMeasurementInterface;
     return ScopedAStatus::ok();
 }
 
diff --git a/gnss/aidl/default/Gnss.h b/gnss/aidl/default/Gnss.h
index 1489b4b..df10fc8 100644
--- a/gnss/aidl/default/Gnss.h
+++ b/gnss/aidl/default/Gnss.h
@@ -32,7 +32,9 @@
 #include <mutex>
 #include <thread>
 #include "GnssConfiguration.h"
+#include "GnssMeasurementInterface.h"
 #include "GnssPowerIndication.h"
+#include "Utils.h"
 
 namespace aidl::android::hardware::gnss {
 
@@ -84,6 +86,7 @@
 
     std::shared_ptr<GnssConfiguration> mGnssConfiguration;
     std::shared_ptr<GnssPowerIndication> mGnssPowerIndication;
+    std::shared_ptr<GnssMeasurementInterface> mGnssMeasurementInterface;
 
   private:
     void reportLocation(const GnssLocation&) const;
@@ -93,14 +96,17 @@
             std::vector<IGnssCallback::GnssSvInfo> gnssSvInfoList) const;
     void reportGnssStatusValue(const IGnssCallback::GnssStatusValue gnssStatusValue) const;
     std::unique_ptr<GnssLocation> getLocationFromHW();
+    void reportNmea() const;
 
     static std::shared_ptr<IGnssCallback> sGnssCallback;
 
     std::atomic<long> mMinIntervalMs;
     std::atomic<bool> mIsActive;
     std::atomic<bool> mIsSvStatusActive;
+    std::atomic<bool> mIsNmeaActive;
     std::atomic<bool> mFirstFixReceived;
     std::thread mThread;
+    ::android::hardware::gnss::common::ThreadBlocker mThreadBlocker;
 
     mutable std::mutex mMutex;
 };
diff --git a/gnss/aidl/default/GnssMeasurementInterface.cpp b/gnss/aidl/default/GnssMeasurementInterface.cpp
index 2c7241b..606de07 100644
--- a/gnss/aidl/default/GnssMeasurementInterface.cpp
+++ b/gnss/aidl/default/GnssMeasurementInterface.cpp
@@ -33,10 +33,11 @@
 
 std::shared_ptr<IGnssMeasurementCallback> GnssMeasurementInterface::sCallback = nullptr;
 
-GnssMeasurementInterface::GnssMeasurementInterface() : mMinIntervalMillis(1000) {}
+GnssMeasurementInterface::GnssMeasurementInterface()
+    : mIntervalMs(1000), mLocationIntervalMs(1000), mFutures(std::vector<std::future<void>>()) {}
 
 GnssMeasurementInterface::~GnssMeasurementInterface() {
-    stop();
+    waitForStoppingThreads();
 }
 
 ndk::ScopedAStatus GnssMeasurementInterface::setCallback(
@@ -44,8 +45,10 @@
         const bool enableCorrVecOutputs) {
     ALOGD("setCallback: enableFullTracking: %d enableCorrVecOutputs: %d", (int)enableFullTracking,
           (int)enableCorrVecOutputs);
-    std::unique_lock<std::mutex> lock(mMutex);
-    sCallback = callback;
+    {
+        std::unique_lock<std::mutex> lock(mMutex);
+        sCallback = callback;
+    }
 
     if (mIsActive) {
         ALOGW("GnssMeasurement callback already set. Resetting the callback...");
@@ -60,14 +63,16 @@
         const std::shared_ptr<IGnssMeasurementCallback>& callback, const Options& options) {
     ALOGD("setCallbackWithOptions: fullTracking:%d, corrVec:%d, intervalMs:%d",
           (int)options.enableFullTracking, (int)options.enableCorrVecOutputs, options.intervalMs);
-    std::unique_lock<std::mutex> lock(mMutex);
-    sCallback = callback;
+    {
+        std::unique_lock<std::mutex> lock(mMutex);
+        sCallback = callback;
+    }
 
     if (mIsActive) {
         ALOGW("GnssMeasurement callback already set. Resetting the callback...");
         stop();
     }
-    mMinIntervalMillis = options.intervalMs;
+    mIntervalMs = std::max(options.intervalMs, 1000);
     start(options.enableCorrVecOutputs);
 
     return ndk::ScopedAStatus::ok();
@@ -75,18 +80,35 @@
 
 ndk::ScopedAStatus GnssMeasurementInterface::close() {
     ALOGD("close");
-    stop();
-    std::unique_lock<std::mutex> lock(mMutex);
-    sCallback = nullptr;
-    mMinIntervalMillis = 1000;
+    if (mIsActive) {
+        stop();
+    }
+    {
+        std::unique_lock<std::mutex> lock(mMutex);
+        sCallback = nullptr;
+    }
+    mIntervalMs = 1000;
     return ndk::ScopedAStatus::ok();
 }
 
 void GnssMeasurementInterface::start(const bool enableCorrVecOutputs) {
     ALOGD("start");
+
+    if (mIsActive) {
+        ALOGD("restarting since measurement has started");
+        stop();
+    }
+    // Wait for stopping previous thread.
+    waitForStoppingThreads();
+
     mIsActive = true;
+    mThreadBlocker.reset();
     mThread = std::thread([this, enableCorrVecOutputs]() {
-        while (mIsActive == true) {
+        int intervalMs;
+        do {
+            if (!mIsActive) {
+                break;
+            }
             std::string rawMeasurementStr = "";
             if (ReplayUtils::hasGnssDeviceFile() &&
                 ReplayUtils::isGnssRawMeasurement(
@@ -103,15 +125,19 @@
                 auto measurement = Utils::getMockMeasurement(enableCorrVecOutputs);
                 this->reportMeasurement(measurement);
             }
-            std::this_thread::sleep_for(std::chrono::milliseconds(mMinIntervalMillis));
-        }
+            intervalMs =
+                    (mLocationEnabled) ? std::min(mLocationIntervalMs, mIntervalMs) : mIntervalMs;
+        } while (mIsActive && mThreadBlocker.wait_for(std::chrono::milliseconds(intervalMs)));
     });
-    mThread.detach();
 }
 
 void GnssMeasurementInterface::stop() {
     ALOGD("stop");
     mIsActive = false;
+    mThreadBlocker.notify();
+    if (mThread.joinable()) {
+        mFutures.push_back(std::async(std::launch::async, [this] { mThread.join(); }));
+    }
 }
 
 void GnssMeasurementInterface::reportMeasurement(const GnssData& data) {
@@ -128,4 +154,21 @@
     callbackCopy->gnssMeasurementCb(data);
 }
 
+void GnssMeasurementInterface::setLocationInterval(const int intervalMs) {
+    mLocationIntervalMs = intervalMs;
+}
+
+void GnssMeasurementInterface::setLocationEnabled(const bool enabled) {
+    mLocationEnabled = enabled;
+}
+
+void GnssMeasurementInterface::waitForStoppingThreads() {
+    for (auto& future : mFutures) {
+        ALOGD("Stopping previous thread.");
+        future.wait();
+        ALOGD("Done stopping thread.");
+    }
+    mFutures.clear();
+}
+
 }  // namespace aidl::android::hardware::gnss
diff --git a/gnss/aidl/default/GnssMeasurementInterface.h b/gnss/aidl/default/GnssMeasurementInterface.h
index bf77806..bb08027 100644
--- a/gnss/aidl/default/GnssMeasurementInterface.h
+++ b/gnss/aidl/default/GnssMeasurementInterface.h
@@ -19,8 +19,10 @@
 #include <aidl/android/hardware/gnss/BnGnssMeasurementCallback.h>
 #include <aidl/android/hardware/gnss/BnGnssMeasurementInterface.h>
 #include <atomic>
+#include <future>
 #include <mutex>
 #include <thread>
+#include "Utils.h"
 
 namespace aidl::android::hardware::gnss {
 
@@ -35,15 +37,22 @@
     ndk::ScopedAStatus setCallbackWithOptions(
             const std::shared_ptr<IGnssMeasurementCallback>& callback,
             const Options& options) override;
+    void setLocationInterval(const int intervalMs);
+    void setLocationEnabled(const bool enabled);
 
   private:
     void start(const bool enableCorrVecOutputs);
     void stop();
     void reportMeasurement(const GnssData&);
+    void waitForStoppingThreads();
 
-    std::atomic<long> mMinIntervalMillis;
+    std::atomic<long> mIntervalMs;
+    std::atomic<long> mLocationIntervalMs;
     std::atomic<bool> mIsActive;
+    std::atomic<bool> mLocationEnabled;
     std::thread mThread;
+    std::vector<std::future<void>> mFutures;
+    ::android::hardware::gnss::common::ThreadBlocker mThreadBlocker;
 
     // Guarded by mMutex
     static std::shared_ptr<IGnssMeasurementCallback> sCallback;
diff --git a/gnss/aidl/default/GnssNavigationMessageInterface.cpp b/gnss/aidl/default/GnssNavigationMessageInterface.cpp
index 4bc859d..75b9624 100644
--- a/gnss/aidl/default/GnssNavigationMessageInterface.cpp
+++ b/gnss/aidl/default/GnssNavigationMessageInterface.cpp
@@ -32,7 +32,7 @@
 GnssNavigationMessageInterface::GnssNavigationMessageInterface() : mMinIntervalMillis(1000) {}
 
 GnssNavigationMessageInterface::~GnssNavigationMessageInterface() {
-    stop();
+    waitForStoppingThreads();
 }
 
 ndk::ScopedAStatus GnssNavigationMessageInterface::setCallback(
@@ -46,7 +46,9 @@
 
 ndk::ScopedAStatus GnssNavigationMessageInterface::close() {
     ALOGD("close");
-    stop();
+    if (mIsActive) {
+        stop();
+    }
     std::unique_lock<std::mutex> lock(mMutex);
     sCallback = nullptr;
     return ndk::ScopedAStatus::ok();
@@ -54,9 +56,20 @@
 
 void GnssNavigationMessageInterface::start() {
     ALOGD("start");
+
+    if (mIsActive) {
+        ALOGD("restarting since nav msg has started");
+        stop();
+    }
+    // Wait for stopping previous thread.
+    waitForStoppingThreads();
+
     mIsActive = true;
     mThread = std::thread([this]() {
-        while (mIsActive == true) {
+        do {
+            if (!mIsActive) {
+                break;
+            }
             GnssNavigationMessage message = {
                     .svid = 19,
                     .type = GnssNavigationMessageType::GPS_L1CA,
@@ -66,15 +79,18 @@
                     .data = std::vector<uint8_t>(40, 0xF9),
             };
             this->reportMessage(message);
-            std::this_thread::sleep_for(std::chrono::milliseconds(mMinIntervalMillis));
-        }
+        } while (mIsActive &&
+                 mThreadBlocker.wait_for(std::chrono::milliseconds(mMinIntervalMillis)));
     });
-    mThread.detach();
 }
 
 void GnssNavigationMessageInterface::stop() {
     ALOGD("stop");
     mIsActive = false;
+    mThreadBlocker.notify();
+    if (mThread.joinable()) {
+        mFutures.push_back(std::async(std::launch::async, [this] { mThread.join(); }));
+    }
 }
 
 void GnssNavigationMessageInterface::reportMessage(const GnssNavigationMessage& message) {
@@ -91,4 +107,13 @@
     callbackCopy->gnssNavigationMessageCb(message);
 }
 
+void GnssNavigationMessageInterface::waitForStoppingThreads() {
+    for (auto& future : mFutures) {
+        ALOGD("Stopping previous thread.");
+        future.wait();
+        ALOGD("Done stopping thread.");
+    }
+    mFutures.clear();
+}
+
 }  // namespace aidl::android::hardware::gnss
diff --git a/gnss/aidl/default/GnssNavigationMessageInterface.h b/gnss/aidl/default/GnssNavigationMessageInterface.h
index 600b23a..b335348 100644
--- a/gnss/aidl/default/GnssNavigationMessageInterface.h
+++ b/gnss/aidl/default/GnssNavigationMessageInterface.h
@@ -18,7 +18,9 @@
 
 #include <aidl/android/hardware/gnss/BnGnssNavigationMessageInterface.h>
 #include <atomic>
+#include <future>
 #include <thread>
+#include "Utils.h"
 
 namespace aidl::android::hardware::gnss {
 
@@ -34,10 +36,13 @@
     void start();
     void stop();
     void reportMessage(const IGnssNavigationMessageCallback::GnssNavigationMessage& message);
+    void waitForStoppingThreads();
 
     std::atomic<long> mMinIntervalMillis;
     std::atomic<bool> mIsActive;
     std::thread mThread;
+    std::vector<std::future<void>> mFutures;
+    ::android::hardware::gnss::common::ThreadBlocker mThreadBlocker;
 
     // Guarded by mMutex
     static std::shared_ptr<IGnssNavigationMessageCallback> sCallback;