https://github.com/kismetwireless/kismet/pull/593
https://github.com/kismetwireless/kismet/pull/594

Index: capture_sdr_rtl433_v2/capture_sdr_rtl433_v2.c
--- capture_sdr_rtl433_v2/capture_sdr_rtl433_v2.c.orig
+++ capture_sdr_rtl433_v2/capture_sdr_rtl433_v2.c
@@ -342,8 +342,8 @@ int open_callback(kis_capture_handler_t *caph, uint32_
 
     char buf[STATUS_MAX];
 
-    // rtl_433 -F json -M level -d X -f Y [additional]
-    unsigned int num_args = 9;
+    // rtl_433 -F json -M level -s 1024k -d X -f Y [additional]
+    unsigned int num_args = 11;
 
     // Channel, if any
     char *channel = NULL;
@@ -452,6 +452,8 @@ int open_callback(kis_capture_handler_t *caph, uint32_
     local433->rtl_argv[n++] = strdup("json");
     local433->rtl_argv[n++] = strdup("-M");
     local433->rtl_argv[n++] = strdup("level");
+    local433->rtl_argv[n++] = strdup("-s");
+    local433->rtl_argv[n++] = strdup("1024k");
     local433->rtl_argv[n++] = strdup("-f");
     snprintf(buf, STATUS_MAX, "%lu", local433->freq);
     local433->rtl_argv[n++] = strdup(buf);
@@ -488,8 +490,6 @@ void capture_thread(kis_capture_handler_t *caph) {
 
     wrap_cond_wait(&local433->rtl433_valid_cond,
             &local433->rtl433_valid_cond_mutex);
-    pthread_mutex_unlock(&local433->rtl433_valid_cond_mutex);
-
 }
 
 int main(int argc, char *argv[]) {
