diff --git a/OpticalChannelTester/App.cpp b/OpticalChannelTester/App.cpp
index a7a9be1..62b0854 100644
--- a/OpticalChannelTester/App.cpp
+++ b/OpticalChannelTester/App.cpp
@@ -93,7 +93,13 @@ void App::update() {
   if (state_ == AppState::SOLO_MEASURE) {
     const MeasureState ms = measurement_.update();
     if (ms == MeasureState::FAIL) { printStageStats(measurement_.stats(), requestedHz_); finish(false, measurement_.reason()); }
-    else if (ms == MeasureState::PASS) { printStageStats(measurement_.stats(), requestedHz_); stagePassed(); }
+    else if (ms == MeasureState::PASS) {
+      printStageStats(measurement_.stats(), requestedHz_);
+      if (measurement_.reason() == FailReason::DATA_LOST) {
+        sweepHadDataLoss_ = true; if (!firstDataLossHz_) firstDataLossHz_ = requestedHz_;
+      }
+      stagePassed();
+    }
   } else if (state_ == AppState::MASTER_DISCOVER || state_ == AppState::MASTER_WAIT_READY ||
              state_ == AppState::MASTER_WAIT_RESULT) {
     handleRadio(); updateMaster();
@@ -150,7 +156,7 @@ void App::showMenu() {
 
 void App::startTest() {
   params_ = store_.params(settings_); stageCount_ = frequencyPointCount(params_.startHz, params_.endHz, params_.stepHz);
-  stageIndex_ = 0; pendingReason_ = FailReason::NONE;
+  stageIndex_ = 0; pendingReason_ = FailReason::NONE; sweepHadDataLoss_ = false; firstDataLossHz_ = 0;
   if (!stageCount_) { finish(false, FailReason::UNSUPPORTED); return; }
   Log::printf("TEST", "starting role=%s stages=%lu", roleName(static_cast<Role>(settings_.role)), stageCount_);
   if (SERIAL_MINIMAL_LOG)
@@ -208,7 +214,11 @@ bool App::startLocalMeasurement(float hz, float duty) {
 void App::stagePassed() {
   Log::printf("TEST", "stage %lu/%lu PASS; PWM stopping", stageIndex_ + 1, stageCount_);
   pwm_.stop();
-  if (++stageIndex_ >= stageCount_) { finish(true, FailReason::NONE); return; }
+  if (++stageIndex_ >= stageCount_) {
+    if (sweepHadDataLoss_) { requestedHz_ = firstDataLossHz_; finish(false, FailReason::DATA_LOST); }
+    else finish(true, FailReason::NONE);
+    return;
+  }
   if (static_cast<Role>(settings_.role) == Role::SOLO) { if (prepareStage()) state_ = AppState::SOLO_MEASURE; }
   else if (static_cast<Role>(settings_.role) == Role::MASTER) {
     requestedHz_ = frequencyAt(params_.startHz, params_.endHz, params_.stepHz, stageIndex_);
@@ -320,7 +330,8 @@ void App::updateSlave() {
     const MeasureState ms = measurement_.update();
     if (ms != MeasureState::PASS && ms != MeasureState::FAIL) return;
     printStageStats(measurement_.stats(), requestedHz_);
-    pendingPacket_ = makePacket(MessageType::RESULT); pendingPacket_.passed = ms == MeasureState::PASS;
+    pendingPacket_ = makePacket(MessageType::RESULT);
+    pendingPacket_.passed = ms == MeasureState::PASS && measurement_.reason() == FailReason::NONE;
     pendingPacket_.reason = static_cast<uint8_t>(measurement_.reason()); pendingPacket_.periods = measurement_.stats().periods;
     pendingPacket_.minPeriodTicks = measurement_.stats().minPeriod; pendingPacket_.maxPeriodTicks = measurement_.stats().maxPeriod;
     pendingPacket_.sequence = ++sequence_; radio_.sendTo(peer_, pendingPacket_);
@@ -377,7 +388,9 @@ void App::printStageStats(const StageStats &s, uint32_t hz) {
   if (!s.periods) return;
   const float measuredHz = static_cast<float>(receiver_.tickHz()) * s.periods / s.periodSum;
   const float measuredDuty = 100.0f * s.activeSum / s.periodSum;
-  Log::printf("RESULT", "%luHz %s periods=%lu measured=%.2fHz duty=%.2f%%%s%s",
-    hz, s.reason == FailReason::NONE ? "PASS" : "FAIL", s.periods, measuredHz, measuredDuty,
+  const char *status = s.reason == FailReason::NONE ? "PASS" :
+    (s.reason == FailReason::DATA_LOST ? "DATA_LOST" : "FAIL");
+  Log::printf("RESULT", "%luHz %s periods=%lu measured=%.2fHz duty=%.2f%% lost=%lu%s%s",
+    hz, status, s.periods, measuredHz, measuredDuty, s.lostItems,
     s.reason == FailReason::NONE ? "" : " reason=", s.reason == FailReason::NONE ? "" : failName(s.reason));
 }
diff --git a/OpticalChannelTester/App.h b/OpticalChannelTester/App.h
index 52c3035..922365c 100644
--- a/OpticalChannelTester/App.h
+++ b/OpticalChannelTester/App.h
@@ -64,5 +64,7 @@ class App {
   uint8_t retries_ = 0;
   ProtocolPacket pendingPacket_ = {};
   bool initialized_ = false, bootResetCandidate_ = false;
+  bool sweepHadDataLoss_ = false;
+  uint32_t firstDataLossHz_ = 0;
   uint32_t bootCheckStartedMs_ = 0;
 };
diff --git a/OpticalChannelTester/Config.h b/OpticalChannelTester/Config.h
index 8a465e0..c402650 100644
--- a/OpticalChannelTester/Config.h
+++ b/OpticalChannelTester/Config.h
@@ -49,6 +49,8 @@ constexpr uint8_t NO_SIGNAL_TIMEOUT_PERIODS = 8;
 constexpr uint16_t RMT_MIN_RECEIVE_SYMBOLS = 48;
 constexpr uint16_t RMT_MAX_RECEIVE_SYMBOLS = 512;
 constexpr uint32_t RMT_TARGET_CHUNK_US = 5000;
+constexpr uint8_t RMT_QUEUE_BLOCKS = 8;
+constexpr uint16_t PERIOD_BATCH_SIZE = 128;
 
 constexpr uint32_t C3_STRICT_MAX_HZ = 1000000;
 constexpr uint32_t S3_STRICT_MAX_HZ = 1000000;
diff --git a/OpticalChannelTester/Core.cpp b/OpticalChannelTester/Core.cpp
index 893039a..5bb5d4e 100644
--- a/OpticalChannelTester/Core.cpp
+++ b/OpticalChannelTester/Core.cpp
@@ -11,7 +11,7 @@ const char *roleName(Role r) {
 const char *failName(FailReason r) {
   static const char *names[] = {"NONE", "NO SIGNAL", "PERIOD OUT", "DUTY OUT",
     "EXTRA EDGE", "GLITCH", "LOST EDGE", "TOO FEW PERIODS", "LINK LOST",
-    "UNSUPPORTED", "RESOLUTION", "ABORTED"};
+    "UNSUPPORTED", "RESOLUTION", "ABORTED", "DATA LOST"};
   const uint8_t i = static_cast<uint8_t>(r);
   return i < (sizeof(names) / sizeof(names[0])) ? names[i] : "UNKNOWN";
 }
@@ -81,8 +81,10 @@ FailReason validateResolution(uint32_t frequencyHz, float dutyPct, float accurac
   if (periodTicks < 4.0f || activeTicks < 2.0f || inactiveTicks < 2.0f) return FailReason::RESOLUTION;
   const float timerPeriodError = 100.0f / periodTicks;
   const float timerDutyError = 100.0f / periodTicks;
-  const float pwmDutyStep = 100.0f / static_cast<float>((1UL << pwmBits) - 1UL);
-  return (timerPeriodError > accuracyPct || timerDutyError > accuracyPct || pwmDutyStep > accuracyPct)
+  // Measurement uses the duty actually programmed into LEDC. A coarse PWM
+  // step is not itself an error when the requested value (e.g. 50%) is exactly
+  // representable; only the selected value's actual quantization matters.
+  return (timerPeriodError > accuracyPct || timerDutyError > accuracyPct)
     ? FailReason::RESOLUTION : FailReason::NONE;
 }
 
@@ -107,3 +109,56 @@ FailReason evaluatePeriod(const PulsePeriod &p, uint32_t tickHz, float expectedH
   }
   return reason;
 }
+
+bool makePeriodLimits(uint32_t expectedHz, float expectedDuty, float tolerance,
+                      uint32_t tickHz, PeriodLimits &limits) {
+  if (!expectedHz || !tickHz || tolerance < 0.0f || tolerance >= 100.0f ||
+      expectedDuty <= 0.0f || expectedDuty >= 100.0f) return false;
+  const uint32_t toleranceX100 = static_cast<uint32_t>(lroundf(tolerance * 100.0f));
+  const uint32_t dutyX100 = static_cast<uint32_t>(lroundf(expectedDuty * 100.0f));
+  const uint64_t numerator = static_cast<uint64_t>(tickHz) * 10000ULL;
+  const uint64_t highDenominator = static_cast<uint64_t>(expectedHz) * (10000U + toleranceX100);
+  const uint64_t lowDenominator = static_cast<uint64_t>(expectedHz) * (10000U - toleranceX100);
+  limits.minPeriodTicks = static_cast<uint32_t>((numerator + highDenominator - 1U) / highDenominator);
+  limits.maxPeriodTicks = static_cast<uint32_t>(numerator / lowDenominator);
+  limits.minDutyX100 = dutyX100 > toleranceX100 ? dutyX100 - toleranceX100 : 0;
+  limits.maxDutyX100 = dutyX100 + toleranceX100;
+  return limits.minPeriodTicks && limits.maxPeriodTicks >= limits.minPeriodTicks;
+}
+
+FailReason evaluatePeriodFast(const PulsePeriod &p, uint32_t tickHz,
+                              const PeriodLimits &limits, uint8_t repeat,
+                              StageStats &s) {
+  if (!p.periodTicks || p.activeTicks >= p.periodTicks) return FailReason::EXTRA_EDGE;
+  ++s.periods;
+  s.periodSum += p.periodTicks; s.activeSum += p.activeTicks;
+  if (p.periodTicks < s.minPeriod) s.minPeriod = p.periodTicks;
+  if (p.periodTicks > s.maxPeriod) s.maxPeriod = p.periodTicks;
+  if (p.activeTicks < s.minActive) s.minActive = p.activeTicks;
+  if (p.activeTicks > s.maxActive) s.maxActive = p.activeTicks;
+
+  FailReason reason = FailReason::NONE;
+  if (p.periodTicks < limits.minPeriodTicks || p.periodTicks > limits.maxPeriodTicks) {
+    reason = FailReason::PERIOD_OUT;
+  } else {
+    // The configured range (>= 1 kHz at 80 MHz capture) fits these products
+    // into 32 bits. Keep a 64-bit fallback for unusually slow external input.
+    if (p.periodTicks <= UINT32_MAX / 10000U && limits.maxDutyX100 <= 10000U) {
+      const uint32_t scaledActive = p.activeTicks * 10000U;
+      const uint32_t minActive = p.periodTicks * limits.minDutyX100;
+      const uint32_t maxActive = p.periodTicks * limits.maxDutyX100;
+      if (scaledActive < minActive || scaledActive > maxActive) reason = FailReason::DUTY_OUT;
+    } else {
+      const uint64_t scaledActive = static_cast<uint64_t>(p.activeTicks) * 10000ULL;
+      const uint64_t minActive = static_cast<uint64_t>(p.periodTicks) * limits.minDutyX100;
+      const uint64_t maxActive = static_cast<uint64_t>(p.periodTicks) * limits.maxDutyX100;
+      if (scaledActive < minActive || scaledActive > maxActive) reason = FailReason::DUTY_OUT;
+    }
+  }
+  if (reason != FailReason::NONE && s.reason == FailReason::NONE) {
+    s.reason = reason; s.firstBadPeriod = s.periods; s.firstBadRepeat = repeat;
+    s.badFrequency = static_cast<float>(tickHz) / p.periodTicks;
+    s.badDuty = 100.0f * p.activeTicks / p.periodTicks;
+  }
+  return reason;
+}
diff --git a/OpticalChannelTester/Core.h b/OpticalChannelTester/Core.h
index 64041cc..4646638 100644
--- a/OpticalChannelTester/Core.h
+++ b/OpticalChannelTester/Core.h
@@ -6,7 +6,7 @@
 enum class Role : uint8_t { SOLO, MASTER, SLAVE };
 enum class FailReason : uint8_t {
   NONE, NO_SIGNAL, PERIOD_OUT, DUTY_OUT, EXTRA_EDGE, GLITCH, LOST_EDGE,
-  TOO_FEW_PERIODS, LINK_LOST, UNSUPPORTED, RESOLUTION, ABORTED
+  TOO_FEW_PERIODS, LINK_LOST, UNSUPPORTED, RESOLUTION, ABORTED, DATA_LOST
 };
 
 const char *roleName(Role role);
@@ -53,10 +53,18 @@ struct StageStats {
   uint8_t firstBadRepeat;
   float badFrequency;
   float badDuty;
+  uint32_t lostItems;
   FailReason reason;
   void reset();
 };
 
+struct PeriodLimits {
+  uint32_t minPeriodTicks;
+  uint32_t maxPeriodTicks;
+  uint32_t minDutyX100;
+  uint32_t maxDutyX100;
+};
+
 uint32_t settingsChecksum(const Settings &s);
 uint32_t frequencyPointCount(uint32_t startHz, uint32_t endHz, uint32_t stepHz);
 uint32_t frequencyAt(uint32_t startHz, uint32_t endHz, uint32_t stepHz, uint32_t index);
@@ -70,3 +78,8 @@ FailReason validateResolution(uint32_t frequencyHz, float dutyPct, float accurac
 FailReason evaluatePeriod(const PulsePeriod &period, uint32_t tickHz, float expectedHz,
                           float expectedDuty, float tolerancePct, uint8_t repeat,
                           StageStats &stats);
+bool makePeriodLimits(uint32_t expectedHz, float expectedDuty, float tolerancePct,
+                      uint32_t tickHz, PeriodLimits &limits);
+FailReason evaluatePeriodFast(const PulsePeriod &period, uint32_t tickHz,
+                              const PeriodLimits &limits, uint8_t repeat,
+                              StageStats &stats);
diff --git a/OpticalChannelTester/Measurement.cpp b/OpticalChannelTester/Measurement.cpp
index f220aaa..2682c35 100644
--- a/OpticalChannelTester/Measurement.cpp
+++ b/OpticalChannelTester/Measurement.cpp
@@ -4,12 +4,17 @@
 
 bool Measurement::start(float hz, float duty, float tolerance, uint32_t timeMs,
                         uint8_t repeats, uint8_t settleCycles) {
-  if (!hz || !timeMs || !repeats || repeats > 10 || !receiver_.start(static_cast<uint32_t>(hz))) return false;
-  expectedHz_ = hz; expectedDuty_ = duty; tolerance_ = tolerance;
+  expectedHz_ = static_cast<uint32_t>(hz + 0.5f);
+  if (!expectedHz_ || !timeMs || !repeats || repeats > 10 ||
+      !makePeriodLimits(expectedHz_, duty, tolerance, receiver_.tickHz(), limits_) ||
+      !receiver_.start(expectedHz_)) return false;
   timeMs_ = timeMs; repeats_ = repeats; settleLeft_ = settleCycles;
   stats_.reset(); memset(repeatPeriods_, 0, sizeof(repeatPeriods_));
   measurementStartTick_ = deadlineTick_ = 0; startedMs_ = millis();
   measurementStartMs_ = lastPeriodMs_ = 0;
+  currentRepeat_ = 0;
+  expectedPeriodMs_ = static_cast<uint32_t>((1000ULL + expectedHz_ - 1U) / expectedHz_);
+  if (!expectedPeriodMs_) expectedPeriodMs_ = 1;
   state_ = MeasureState::SETTLING; return true;
 }
 
@@ -18,53 +23,65 @@ void Measurement::fail(FailReason reason) {
   receiver_.stop(); state_ = MeasureState::FAIL;
 }
 
+void Measurement::completeWindow() {
+  receiver_.stop();
+  stats_.lostItems += receiver_.takeDroppedItems();
+  if (receiver_.overflowed()) { fail(FailReason::GLITCH); return; }
+  for (uint8_t i = 0; i < repeats_; ++i) if (!repeatPeriods_[i]) {
+    fail(FailReason::TOO_FEW_PERIODS); return;
+  }
+  if (stats_.lostItems && stats_.reason == FailReason::NONE) stats_.reason = FailReason::DATA_LOST;
+  state_ = MeasureState::PASS;
+}
+
 MeasureState Measurement::update() {
   if (state_ != MeasureState::SETTLING && state_ != MeasureState::RUNNING) return state_;
   if (receiver_.overflowed()) { fail(FailReason::GLITCH); return state_; }
-  PulsePeriod period;
-  while (receiver_.poll(period)) {
-    if (state_ == MeasureState::SETTLING) {
-      if (settleLeft_) --settleLeft_;
-      if (!settleLeft_) {
-        measurementStartTick_ = period.startTick + period.periodTicks;
-        repeatTicks_ = static_cast<uint64_t>(receiver_.tickHz()) * timeMs_ / 1000ULL;
-        deadlineTick_ = measurementStartTick_ + repeatTicks_ * repeats_;
-        stats_.reset(); measurementStartMs_ = lastPeriodMs_ = millis(); state_ = MeasureState::RUNNING;
+  bool receivedPeriod = false;
+  for (;;) {
+    const size_t periodCount = receiver_.readPeriods(periodBatch_, PERIOD_BATCH_SIZE);
+    stats_.lostItems += receiver_.takeDroppedItems();
+    if (!periodCount) break;
+    receivedPeriod = true;
+    for (size_t periodIndex = 0; periodIndex < periodCount; ++periodIndex) {
+      const PulsePeriod &period = periodBatch_[periodIndex];
+      if (state_ == MeasureState::SETTLING) {
+        if (settleLeft_) --settleLeft_;
+        if (!settleLeft_) {
+          measurementStartTick_ = period.startTick + period.periodTicks;
+          repeatTicks_ = static_cast<uint64_t>(receiver_.tickHz()) * timeMs_ / 1000ULL;
+          deadlineTick_ = measurementStartTick_ + repeatTicks_ * repeats_;
+          nextRepeatTick_ = measurementStartTick_ + repeatTicks_;
+          stats_.reset(); measurementStartMs_ = lastPeriodMs_ = millis(); state_ = MeasureState::RUNNING;
+        }
+        continue;
       }
-      continue;
+      const uint64_t endTick = period.startTick + period.periodTicks;
+      if (period.startTick < measurementStartTick_) continue; // leading incomplete period
+      if (endTick > deadlineTick_) { completeWindow(); return state_; } // trailing incomplete period
+      while (currentRepeat_ + 1U < repeats_ && period.startTick >= nextRepeatTick_) {
+        ++currentRepeat_; nextRepeatTick_ += repeatTicks_;
+      }
+      ++repeatPeriods_[currentRepeat_];
+      const FailReason r = evaluatePeriodFast(period, receiver_.tickHz(), limits_, currentRepeat_ + 1, stats_);
+      if (r != FailReason::NONE) { fail(r); return state_; }
     }
-    const uint64_t endTick = period.startTick + period.periodTicks;
-    if (period.startTick < measurementStartTick_) continue; // leading incomplete period
-    if (endTick > deadlineTick_) break;                     // trailing incomplete period
-    uint8_t repeat = static_cast<uint8_t>((period.startTick - measurementStartTick_) / repeatTicks_);
-    if (repeat >= repeats_) repeat = repeats_ - 1;
-    ++repeatPeriods_[repeat];
-    lastPeriodMs_ = millis();
-    const FailReason r = evaluatePeriod(period, receiver_.tickHz(), expectedHz_, expectedDuty_,
-                                        tolerance_, repeat + 1, stats_);
-    if (r != FailReason::NONE) { fail(r); return state_; }
   }
-  uint64_t expectedPeriodMs = static_cast<uint64_t>(ceilf(1000.0f / expectedHz_));
-  if (!expectedPeriodMs) expectedPeriodMs = 1;
+  if (receivedPeriod && state_ == MeasureState::RUNNING) lastPeriodMs_ = millis();
   const uint64_t edgeBasedTimeout =
-    static_cast<uint64_t>(PWM_SETTLE_CYCLES + NO_SIGNAL_TIMEOUT_PERIODS) * expectedPeriodMs + 20;
+    static_cast<uint64_t>(PWM_SETTLE_CYCLES + NO_SIGNAL_TIMEOUT_PERIODS) * expectedPeriodMs_ + 20;
   const uint64_t rmtBatchTimeout =
-    static_cast<uint64_t>(RMT_MIN_RECEIVE_SYMBOLS + NO_SIGNAL_TIMEOUT_PERIODS) * expectedPeriodMs + 20;
+    static_cast<uint64_t>(RMT_MIN_RECEIVE_SYMBOLS + NO_SIGNAL_TIMEOUT_PERIODS) * expectedPeriodMs_ + 20;
   const uint64_t settleTimeout = edgeBasedTimeout > rmtBatchTimeout ? edgeBasedTimeout : rmtBatchTimeout;
   if (state_ == MeasureState::SETTLING && millis() - startedMs_ > settleTimeout) fail(FailReason::NO_SIGNAL);
   if (state_ == MeasureState::RUNNING && measurementStartTick_) {
     const uint32_t now = millis();
     const uint32_t totalMs = timeMs_ * repeats_;
-    const uint32_t edgeTimeoutMs = static_cast<uint32_t>(expectedPeriodMs * NO_SIGNAL_TIMEOUT_PERIODS + 2);
+    const uint32_t edgeTimeoutMs = expectedPeriodMs_ * NO_SIGNAL_TIMEOUT_PERIODS + 2;
     if (now - measurementStartMs_ < totalMs && now - lastPeriodMs_ > edgeTimeoutMs) {
       fail(FailReason::LOST_EDGE); return state_;
     }
-    if (now - measurementStartMs_ > totalMs + expectedPeriodMs + 2) {
-      for (uint8_t i = 0; i < repeats_; ++i) if (!repeatPeriods_[i]) {
-        fail(FailReason::TOO_FEW_PERIODS); return state_;
-      }
-      receiver_.stop(); state_ = MeasureState::PASS;
-    }
+    if (now - measurementStartMs_ > totalMs + expectedPeriodMs_ + 2) completeWindow();
   }
   return state_;
 }
diff --git a/OpticalChannelTester/Measurement.h b/OpticalChannelTester/Measurement.h
index 68a18f7..944d688 100644
--- a/OpticalChannelTester/Measurement.h
+++ b/OpticalChannelTester/Measurement.h
@@ -15,13 +15,17 @@ class Measurement {
   const StageStats &stats() const { return stats_; }
  private:
   void fail(FailReason reason);
+  void completeWindow();
   PulseReceiver &receiver_;
   MeasureState state_ = MeasureState::IDLE;
   StageStats stats_ = {};
-  float expectedHz_ = 0, expectedDuty_ = 0, tolerance_ = 0;
+  PeriodLimits limits_ = {};
+  uint32_t expectedHz_ = 0;
   uint32_t timeMs_ = 0;
-  uint8_t repeats_ = 0, settleLeft_ = 0;
-  uint64_t measurementStartTick_ = 0, deadlineTick_ = 0, repeatTicks_ = 0;
+  uint8_t repeats_ = 0, settleLeft_ = 0, currentRepeat_ = 0;
+  uint64_t measurementStartTick_ = 0, deadlineTick_ = 0, repeatTicks_ = 0, nextRepeatTick_ = 0;
   uint32_t startedMs_ = 0, measurementStartMs_ = 0, lastPeriodMs_ = 0;
+  uint32_t expectedPeriodMs_ = 1;
   uint32_t repeatPeriods_[10] = {};
+  PulsePeriod periodBatch_[PERIOD_BATCH_SIZE] = {};
 };
diff --git a/OpticalChannelTester/Pwm.cpp b/OpticalChannelTester/Pwm.cpp
index c776f09..b9fa72c 100644
--- a/OpticalChannelTester/Pwm.cpp
+++ b/OpticalChannelTester/Pwm.cpp
@@ -14,12 +14,12 @@ bool PwmGenerator::start(uint32_t hz, uint8_t dutyPct, ActualPwm &a) {
   const uint8_t bits = choosePwmResolution(hz, LEDC_SOURCE_CLOCK_HZ, LEDC_MAX_BITS);
   if (!bits) return false;
   if (!ledcAttachChannel(GPIO_PWM, hz, bits, LEDC_CHANNEL)) return false;
-  const uint32_t top = (1UL << bits) - 1UL;
-  const uint32_t duty = (static_cast<uint64_t>(top) * dutyPct + 50U) / 100U;
+  const uint32_t levels = 1UL << bits;
+  const uint32_t duty = (static_cast<uint64_t>(levels) * dutyPct + 50U) / 100U;
   if (!ledcWriteChannel(LEDC_CHANNEL, duty)) { ledcDetach(GPIO_PWM); return false; }
   const uint32_t actualHz = ledcReadFreq(GPIO_PWM);
   if (!actualHz) { ledcDetach(GPIO_PWM); return false; }
-  a = {hz, actualHz, 100.0f * duty / top, bits};
+  a = {hz, actualHz, 100.0f * duty / levels, bits};
   running_ = true;
   return true;
 }
diff --git a/OpticalChannelTester/Receiver.cpp b/OpticalChannelTester/Receiver.cpp
index afe4a83..282864e 100644
--- a/OpticalChannelTester/Receiver.cpp
+++ b/OpticalChannelTester/Receiver.cpp
@@ -16,7 +16,7 @@ uint32_t PulseReceiver::tickHz() const {
 
 bool PulseReceiver::begin() {
 #if OPTICAL_USE_RMT_DMA
-  queue_ = xQueueCreate(16, sizeof(SymbolBlock));
+  queue_ = xQueueCreate(RMT_QUEUE_BLOCKS, sizeof(SymbolBlock));
   rmt_rx_channel_config_t cfg = {};
   cfg.clk_src = RMT_CLK_SRC_DEFAULT; cfg.resolution_hz = CAPTURE_RESOLUTION_HZ;
   cfg.gpio_num = static_cast<gpio_num_t>(GPIO_RX);
@@ -77,7 +77,7 @@ void PulseReceiver::stop() {
 
 void PulseReceiver::resetStream() {
   if (queue_) xQueueReset(queue_);
-  overflow_ = false; haveRise_ = haveFall_ = haveRawTick_ = false;
+  overflow_ = false; droppedItems_ = 0; haveRise_ = haveFall_ = haveRawTick_ = false;
   lastRawTick_ = 0; tickEpoch_ = rise_ = fall_ = 0;
 #if OPTICAL_USE_RMT_DMA
   block_ = {}; blockIndex_ = 0; phase_ = 0; haveLevel_ = false; level_ = false; rmtTick_ = 0;
@@ -109,17 +109,22 @@ bool PulseReceiver::overflowed() {
   const bool value = overflow_; overflow_ = false; return value;
 }
 
+uint32_t PulseReceiver::takeDroppedItems() {
+  return __atomic_exchange_n(&droppedItems_, 0, __ATOMIC_RELAXED);
+}
+
 #if OPTICAL_USE_RMT_DMA
 bool IRAM_ATTR PulseReceiver::onRmt(rmt_channel_handle_t, const rmt_rx_done_event_data_t *data, void *ctx) {
   PulseReceiver *self = static_cast<PulseReceiver *>(ctx);
   BaseType_t wake = pdFALSE;
   size_t offset = 0;
   while (offset < data->num_symbols) {
-    SymbolBlock b = {};
+    SymbolBlock &b = self->isrBlock_;
     b.count = static_cast<uint16_t>((data->num_symbols - offset) > BLOCK_SYMBOLS ?
       BLOCK_SYMBOLS : (data->num_symbols - offset));
     memcpy(b.symbols, data->received_symbols + offset, b.count * sizeof(rmt_symbol_word_t));
-    if (xQueueSendFromISR(self->queue_, &b, &wake) != pdTRUE) self->overflow_ = true;
+    if (xQueueSendFromISR(self->queue_, &b, &wake) != pdTRUE)
+      __atomic_fetch_add(&self->droppedItems_, b.count, __ATOMIC_RELAXED);
     offset += b.count;
   }
   return wake == pdTRUE;
@@ -146,10 +151,12 @@ bool PulseReceiver::nextRmtEdge(Edge &edge) {
   }
 }
 
-bool PulseReceiver::poll(PulsePeriod &period) {
+size_t PulseReceiver::readPeriods(PulsePeriod *periods, size_t capacity) {
+  size_t count = 0;
   Edge e;
-  while (nextRmtEdge(e)) if (consumeEdge(e, period)) return true;
-  return false;
+  while (count < capacity && nextRmtEdge(e))
+    if (consumeEdge(e, periods[count])) ++count;
+  return count;
 }
 #else
 void IRAM_ATTR PulseReceiver::onGpio(void *ctx) {
@@ -158,13 +165,16 @@ void IRAM_ATTR PulseReceiver::onGpio(void *ctx) {
   if (RX_SIGNAL_INVERTED) level = !level;
   Edge e = {esp_cpu_get_cycle_count(), static_cast<uint8_t>(level)};
   BaseType_t wake = pdFALSE;
-  if (xQueueSendFromISR(self->queue_, &e, &wake) != pdTRUE) self->overflow_ = true;
+  if (xQueueSendFromISR(self->queue_, &e, &wake) != pdTRUE)
+    __atomic_fetch_add(&self->droppedItems_, 1U, __ATOMIC_RELAXED);
   if (wake) portYIELD_FROM_ISR();
 }
 
-bool PulseReceiver::poll(PulsePeriod &period) {
+size_t PulseReceiver::readPeriods(PulsePeriod *periods, size_t capacity) {
+  size_t count = 0;
   Edge e;
-  while (xQueueReceive(queue_, &e, 0) == pdTRUE) if (consumeEdge(e, period)) return true;
-  return false;
+  while (count < capacity && xQueueReceive(queue_, &e, 0) == pdTRUE)
+    if (consumeEdge(e, periods[count])) ++count;
+  return count;
 }
 #endif
diff --git a/OpticalChannelTester/Receiver.h b/OpticalChannelTester/Receiver.h
index 90f3d83..4629cc4 100644
--- a/OpticalChannelTester/Receiver.h
+++ b/OpticalChannelTester/Receiver.h
@@ -18,8 +18,9 @@ class PulseReceiver {
   bool start(uint32_t expectedHz);
   void stop();
   void resetStream();
-  bool poll(PulsePeriod &period);
+  size_t readPeriods(PulsePeriod *periods, size_t capacity);
   bool overflowed();
+  uint32_t takeDroppedItems();
   uint32_t tickHz() const;
   uint16_t receiveChunkSymbols() const { return receiveChunkSymbols_; }
   bool highRateBackend() const {
@@ -34,13 +35,14 @@ class PulseReceiver {
   bool consumeEdge(const Edge &edge, PulsePeriod &period);
 
 #if OPTICAL_USE_RMT_DMA
-  static constexpr size_t BLOCK_SYMBOLS = 64;
+  static constexpr size_t BLOCK_SYMBOLS = RMT_MAX_RECEIVE_SYMBOLS;
   struct SymbolBlock { uint16_t count; rmt_symbol_word_t symbols[BLOCK_SYMBOLS]; };
   static bool IRAM_ATTR onRmt(rmt_channel_handle_t, const rmt_rx_done_event_data_t *, void *);
   bool nextRmtEdge(Edge &edge);
   rmt_channel_handle_t channel_ = nullptr;
   rmt_symbol_word_t receiveBuffer_[RMT_MAX_RECEIVE_SYMBOLS];
   uint16_t receiveChunkSymbols_ = 0;
+  SymbolBlock isrBlock_ = {};
   SymbolBlock block_ = {};
   uint16_t blockIndex_ = 0;
   uint8_t phase_ = 0;
@@ -53,6 +55,7 @@ class PulseReceiver {
 #endif
   QueueHandle_t queue_ = nullptr;
   volatile bool overflow_ = false;
+  volatile uint32_t droppedItems_ = 0;
   bool running_ = false;
   bool haveRise_ = false, haveFall_ = false, haveRawTick_ = false;
   uint32_t lastRawTick_ = 0;
diff --git a/README.md b/README.md
index 52e9484..2a72e64 100644
--- a/README.md
+++ b/README.md
@@ -202,7 +202,7 @@ PWM_SETTLE_CYCLES / actualFrequency + TEST_TIME * REPEATS
 
 | Target | Arduino-ESP32 | Flash | RAM | Результат |
 |---|---:|---:|---:|---|
-| ESP32-C3 | 3.3.10 | 1,024,299 B (78%) | 39,460 B (12%) | PASS |
+| ESP32-C3 | 3.3.10 | 1,025,021 B (78%) | 45,380 B (13%) | PASS |
 | ESP32-S3 | 3.3.10 | 950,608 B (72%) | 48,620 B (14%) | PASS |
 
 Локальные unit-тесты: `core tests: PASS`, `button tests: PASS`. Они покрывают неделимый диапазон, END без дубля, ALL, границы допусков, немедленный FAIL, resolution, checksum настроек, CRC протокола и отсутствие short после long.