diff --git a/CHANGELOG.md b/CHANGELOG.md
index ea9d3b1dd..63b990f23 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@ All notable changes to this project will be documented in this file.
 This project uses the changelog in accordance with [keepchangelog](http://keepachangelog.com/). Please use this to write notable changes, which is not the same as git commit log...
 
 ## [unreleased][unreleased]
+- Fixed `data modulation` - the 160 sample antenna settle trim was never undone, so the graph buffer stayed short for everything after it (@mfcarroll)
 - Changed `tests/lf_t55xx_writetest.lua` - reads each block three times and names how a bad read differs (`rol1`, `ror5`, `inverted`, `shr1`) instead of only pass/fail (@mfcarroll)
 - Fixed `lf t55xx detect` - PSK1 now detects at every bit rate and subcarrier. (@iceman1001)
 - Fixed `lf t55xx detect` - FSK was skipped entirely when the field-clock pair measured as neither legal pair, losing FSK1 at RF/32 and RF/40 and every variant at RF/16 (@iceman1001)
diff --git a/client/src/cmddata.c b/client/src/cmddata.c
index 411515da9..979ecc31b 100644
--- a/client/src/cmddata.c
+++ b/client/src/cmddata.c
@@ -2778,8 +2778,7 @@ static int try_detect_modulation(void) {
         clk = GetPskClock("", false);
         if (clk > 0) {
             // allow undo
-            buffer_savestate_t saveState = save_bufferS32(g_GraphBuffer, g_GraphTraceLen);
-            saveState.offset = g_GridOffset;
+            buffer_savestate_t saveState = save_graphbuffer();
             // skip first 160 samples to allow antenna to settle in (psk gets inverted occasionally otherwise)
             CmdLtrim("-i 160");
             if ((PSKDemod(0, 0, 6, false) == PM3_SUCCESS)) {
@@ -2791,8 +2790,7 @@ static int try_detect_modulation(void) {
                 tests[hits].carrier = GetPskCarrier(false);
             }
             //undo trim samples
-            restore_bufferS32(saveState, g_GraphBuffer);
-            g_GridOffset = saveState.offset;
+            restore_graphbuffer(saveState);
         }
     }
 
diff --git a/client/src/cmdlf.c b/client/src/cmdlf.c
index bf8186d73..26fb3d83f 100644
--- a/client/src/cmdlf.c
+++ b/client/src/cmdlf.c
@@ -1609,8 +1609,7 @@ static bool check_chiptype(bool getDeviceData) {
     }
 
     //Save the state of the Graph and Demod Buffers
-    buffer_savestate_t saveState_gb = save_bufferS32(g_GraphBuffer, g_GraphTraceLen);
-    saveState_gb.offset = g_GridOffset;
+    buffer_savestate_t saveState_gb = save_graphbuffer();
     buffer_savestate_t saveState_db = save_buffer8(g_DemodBuffer, g_DemodBufferLen);
     saveState_db.clock = g_DemodClock;
     saveState_db.offset = g_DemodStartIdx;
@@ -1683,12 +1682,12 @@ static bool check_chiptype(bool getDeviceData) {
 
     PrintAndLogEx(INFO, "Couldn't identify a chipset");
 out:
-    restore_buffer8(saveState_db, g_DemodBuffer);
+    // the detections above demodulate, so the length comes back with the contents
+    g_DemodBufferLen = restore_buffer8(saveState_db, g_DemodBuffer);
     g_DemodClock = saveState_db.clock;
     g_DemodStartIdx = saveState_db.offset;
 
-    restore_bufferS32(saveState_gb, g_GraphBuffer);
-    g_GridOffset = saveState_gb.offset;
+    restore_graphbuffer(saveState_gb);
 
     return retval;
 }
diff --git a/client/src/cmdlfti.c b/client/src/cmdlfti.c
index 17d843a7c..57965d8d2 100644
--- a/client/src/cmdlfti.c
+++ b/client/src/cmdlfti.c
@@ -89,8 +89,7 @@ int demodTI(bool verbose) {
         1, 1, 1, 1, 1, 1, 1, 1
     };
 
-    buffer_savestate_t saveState = save_bufferS32(g_GraphBuffer, g_GraphTraceLen);
-    saveState.offset = g_GridOffset;
+    buffer_savestate_t saveState = save_graphbuffer();
 
     int lowLen = ARRAYLEN(LowTone);
     int highLen = ARRAYLEN(HighTone);
@@ -278,8 +277,7 @@ int demodTI(bool verbose) {
 
 out:
     if (retval != PM3_SUCCESS) {
-        restore_bufferS32(saveState, g_GraphBuffer);
-        g_GridOffset = saveState.offset;
+        restore_graphbuffer(saveState);
     }
 
     return retval;
diff --git a/client/src/cmdlfvisa2000.c b/client/src/cmdlfvisa2000.c
index 092f38e30..93e8ff466 100644
--- a/client/src/cmdlfvisa2000.c
+++ b/client/src/cmdlfvisa2000.c
@@ -84,8 +84,7 @@ static uint8_t visa_parity(uint32_t id) {
 //see ASKDemod for what args are accepted
 int demodVisa2k(bool verbose) {
     (void) verbose; // unused so far
-    buffer_savestate_t saveState = save_bufferS32(g_GraphBuffer, g_GraphTraceLen);
-    saveState.offset = g_GridOffset;
+    buffer_savestate_t saveState = save_graphbuffer();
 
     //CmdAskEdgeDetect("");
 
@@ -93,8 +92,7 @@ int demodVisa2k(bool verbose) {
     bool st = true;
     if (ASKDemod_ext(64, 0, 0, 0, false, false, false, 1, &st) != PM3_SUCCESS) {
         PrintAndLogEx(DEBUG, "DEBUG: Error - Visa2k: ASK/Manchester Demod failed");
-        restore_bufferS32(saveState, g_GraphBuffer);
-        g_GridOffset = saveState.offset;
+        restore_graphbuffer(saveState);
         return PM3_ESOFT;
     }
     size_t size = g_DemodBufferLen;
@@ -109,8 +107,7 @@ int demodVisa2k(bool verbose) {
         else
             PrintAndLogEx(DEBUG, "DEBUG: Error - Visa2k: ans: %d", ans);
 
-        restore_bufferS32(saveState, g_GraphBuffer);
-        g_GridOffset = saveState.offset;
+        restore_graphbuffer(saveState);
         return PM3_ESOFT;
     }
     setDemodBuff(g_DemodBuffer, 96, ans);
@@ -128,8 +125,7 @@ int demodVisa2k(bool verbose) {
     // test checksums
     if (chk != calc) {
         PrintAndLogEx(DEBUG, "DEBUG: error: Visa2000 checksum (%s) %x - %x\n", _RED_("fail"), chk, calc);
-        restore_bufferS32(saveState, g_GraphBuffer);
-        g_GridOffset = saveState.offset;
+        restore_graphbuffer(saveState);
         return PM3_ESOFT;
     }
     // parity
@@ -137,8 +133,7 @@ int demodVisa2k(bool verbose) {
     uint8_t chk_par = (raw3 & 0xFF0) >> 4;
     if (calc_par != chk_par) {
         PrintAndLogEx(DEBUG, "DEBUG: error: Visa2000 parity (%s) %x - %x\n", _RED_("fail"), chk_par, calc_par);
-        restore_bufferS32(saveState, g_GraphBuffer);
-        g_GridOffset = saveState.offset;
+        restore_graphbuffer(saveState);
         return PM3_ESOFT;
     }
     PrintAndLogEx(SUCCESS, "Visa2000 - Card " _GREEN_("%u") ", Raw: %08X%08X%08X", raw2,  raw1, raw2, raw3);
diff --git a/client/src/cmdlfzx8211.c b/client/src/cmdlfzx8211.c
index 793cc3d54..00e19d152 100644
--- a/client/src/cmdlfzx8211.c
+++ b/client/src/cmdlfzx8211.c
@@ -41,8 +41,7 @@ static int CmdHelp(const char *Cmd);
 // see ASKDemod for what args are accepted
 int demodzx(bool verbose) {
     (void) verbose; // unused so far
-    buffer_savestate_t saveState = save_bufferS32(g_GraphBuffer, g_GraphTraceLen);
-    saveState.offset = g_GridOffset;
+    buffer_savestate_t saveState = save_graphbuffer();
 
     // CmdAskEdgeDetect("");
 
@@ -50,8 +49,7 @@ int demodzx(bool verbose) {
     bool st = true;
     if (ASKDemod_ext(64, 0, 0, 0, false, false, false, 1, &st) != PM3_SUCCESS) {
         PrintAndLogEx(DEBUG, "DEBUG: Error - ZX: ASK/Manchester Demod failed");
-        restore_bufferS32(saveState, g_GraphBuffer);
-        g_GridOffset = saveState.offset;
+        restore_graphbuffer(saveState);
         return PM3_ESOFT;
     }
     size_t size = g_DemodBufferLen;
@@ -66,8 +64,7 @@ int demodzx(bool verbose) {
         else
             PrintAndLogEx(DEBUG, "DEBUG: Error - ZX: ans: %d", ans);
 
-        restore_bufferS32(saveState, g_GraphBuffer);
-        g_GridOffset = saveState.offset;
+        restore_graphbuffer(saveState);
         return PM3_ESOFT;
     }
     setDemodBuff(g_DemodBuffer, 96, ans);
diff --git a/client/src/graph.c b/client/src/graph.c
index 80c1e4dc0..8df84d829 100644
--- a/client/src/graph.c
+++ b/client/src/graph.c
@@ -648,3 +648,21 @@ size_t restore_buffer8(buffer_savestate_t saveState, uint8_t *dest) {
 
     return index;
 }
+
+// Save/restore the graph buffer as a unit: contents, length and grid offset.
+// A caller that drops restore_bufferS32()'s return leaves g_GraphTraceLen short.
+buffer_savestate_t save_graphbuffer(void) {
+    buffer_savestate_t saveState = save_bufferS32(g_GraphBuffer, g_GraphTraceLen);
+    saveState.offset = g_GridOffset;
+    return saveState;
+}
+
+void restore_graphbuffer(buffer_savestate_t saveState) {
+    size_t len = restore_bufferS32(saveState, g_GraphBuffer);
+    if (len == 0) {
+        // nothing was restored, so leave the buffer and its length alone
+        return;
+    }
+    g_GraphTraceLen = len;
+    g_GridOffset = saveState.offset;
+}
diff --git a/client/src/graph.h b/client/src/graph.h
index 6f0822f96..1a46d6362 100644
--- a/client/src/graph.h
+++ b/client/src/graph.h
@@ -67,6 +67,9 @@ size_t restore_buffer32(buffer_savestate_t saveState, uint32_t *dest);
 size_t restore_bufferS32(buffer_savestate_t saveState, int32_t *dest);
 size_t restore_buffer8(buffer_savestate_t saveState, uint8_t *dest);
 
+buffer_savestate_t save_graphbuffer(void);
+void restore_graphbuffer(buffer_savestate_t saveState);
+
 #define MAX_GRAPH_TRACE_LEN (40000 * 32)
 #define GRAPH_SAVE 1
 #define GRAPH_RESTORE 0
diff --git a/tools/pm3_tests.sh b/tools/pm3_tests.sh
index a63279319..b0f257ab6 100755
--- a/tools/pm3_tests.sh
+++ b/tools/pm3_tests.sh
@@ -468,6 +468,7 @@ while true; do
       if ! CheckExecute "data qrcode invalid hex" "$CLIENTBIN -c 'data qrcode -d zz' 2>&1" "QR data must contain only hex characters"; then break; fi
       if ! CheckExecute "data qrcode odd hex"     "$CLIENTBIN -c 'data qrcode -d a' 2>&1" "QR data must contain an even number of hex digits"; then break; fi
       if ! CheckExecute "data qrcode spaced hex"  "$CLIENTBIN -c 'data qrcode -d \"aa bb\"' 2>&1" "Spaces are not supported; encode a space byte as 20"; then break; fi
+      if ! CheckExecute "data modulation keeps trace" "$CLIENTBIN -c 'data load -f traces/lf_Q5_mod-psk1-32-4.pm3; data modulation; data autocorr -w 99999'" "smaller than trace \\( 20000 samples \\)"; then break; fi
       if ! CheckExecute "mfu pwdgen test"         "$CLIENTBIN -c 'hf mfu pwdgen --test'" "Selftest ok"; then break; fi
       if ! CheckExecute "mfu keygen test"         "$CLIENTBIN -c 'hf mfu keygen --uid 11223344556677'" "80 B1 C2 71 D8 A0"; then break; fi
       if ! CheckExecute "jooki encode test"       "$CLIENTBIN -c 'hf jooki encode --test'" "04 28 F4 DA F0 4A 81  \( ok \)"; then break; fi