diff --git a/AM.md b/AM.md
index d1fb58a..30538f8 100644
--- a/AM.md
+++ b/AM.md
@@ -2,5 +2,5 @@
 2. csdr convert_i16_f 
 3. csdr gain_ff 4.0
 4. csdr dsb_fc
-5. rpitx -i - -m IQFLOAT -f "$1" -s 48000
+5. rpitx -i - -m IQFLOAT -f <frequency> -s 48000