diff --git a/src/wspr.c b/src/wspr.c
--- a/src/wspr.c
+++ b/src/wspr.c
@@ -61,8 +61,13 @@ void wspr_wakeup(void)
 
 
 // Bring up TCXO and oscillator IC
-void wspr_transmit(void)
+void wspr_transmit(uint8_t* grid_locator)
 {
+	// Copy 4 digit grid locator to local buffer; null terminate
+	for(uint8_t i=0; i<4; i++)
+		loc[i] = grid_locator[i];
+	loc[4] = '\0';
+
     HAL_GPIO_WritePin(OSC_NOTEN, 0);
     HAL_GPIO_WritePin(TCXO_EN, 1);
     HAL_Delay(100);