diff --git a/bts/BTS_Tests.ttcn b/bts/BTS_Tests.ttcn
index a0d668d..fc714fe 100644
--- a/bts/BTS_Tests.ttcn
+++ b/bts/BTS_Tests.ttcn
@@ -1825,6 +1825,25 @@
 		}
 }
 
+/* handle incoming downlink SACCH, decode the L1 header into the given record */
+private altstep as_l1_sacch_l1h(inout SacchL1Header l1h,
+				boolean do_apply := true)
+runs on ConnHdlr
+{
+	var L1ctlDlMessage l1_dl;
+
+	[] L1CTL.receive(tr_L1CTL_DATA_IND(g_chan_nr, tr_RslLinkID_SACCH(?))) -> value l1_dl {
+		/* Parse the L1 SACCH header (MS Power Level & Timing Advance) */
+		l1h := dec_SacchL1Header(substr(l1_dl.payload.data_ind.payload, 0, 2));
+		log(%definitionId, "(): Rx SACCH L1 header: ", l1h);
+
+		if (do_apply) {
+			/* Update TA and MS power to follow what BTS requests */
+			f_L1CTL_PARAM(L1CTL, l1h.actual_ta, l1h.ms_power_lvl);
+		}
+	}
+}
+
 private altstep as_l1_dcch_loop() runs on ConnHdlr {
 	var L1ctlDlMessage l1_dl;
 	[] L1CTL.receive(tr_L1CTL_DATA_IND(g_chan_nr, tr_RslLinkID_DCCH(?))) -> value l1_dl {
@@ -2563,7 +2582,7 @@
 These power levels are valid for all bands and require no special handling */
 private function f_TC_rsl_ms_pwr_dyn_ass_updown(charstring id) runs on ConnHdlr {
 	var uint5_t pwr_var := 7;
-	var L1ctlDlMessage l1_dl;
+	var SacchL1Header l1h;
 
 	f_trxc_fake_rssi(rxlev2dbm(10));
 	f_l1_tune(L1CTL);
@@ -2586,10 +2605,8 @@
 	timer T2 := 6.0;
 	T2.start;
 	alt {
-	[] L1CTL.receive(tr_L1CTL_DATA_IND(g_chan_nr, tr_RslLinkID_SACCH(?))) -> value l1_dl {
-		/* Update sent MS power to follow what BTS requests */
-		f_L1CTL_PARAM(L1CTL, g_pars.l1_pars.ms_actual_ta, oct2int(l1_dl.payload.data_ind.payload[0]));
-		if (oct2int(l1_dl.payload.data_ind.payload[0]) < (pwr_var + 6)) {
+	[] as_l1_sacch_l1h(l1h) {
+		if (l1h.ms_power_lvl < (pwr_var + 6)) {
 			repeat;
 		}
 		T2.stop;
@@ -2607,10 +2624,8 @@
 	timer T4 := 6.0;
 	T4.start;
 	alt {
-	[] L1CTL.receive(tr_L1CTL_DATA_IND(g_chan_nr, tr_RslLinkID_SACCH(?))) -> value l1_dl {
-		/* Update sent MS power to follow what BTS requests */
-		f_L1CTL_PARAM(L1CTL, g_pars.l1_pars.ms_actual_ta, oct2int(l1_dl.payload.data_ind.payload[0]));
-		if (oct2int(l1_dl.payload.data_ind.payload[0]) > pwr_var) {
+	[] as_l1_sacch_l1h(l1h) {
+		if (l1h.ms_power_lvl > pwr_var) {
 			repeat;
 		}
 		T4.stop;
@@ -2631,7 +2646,7 @@
 /* check that we do not exceed the max power */
 private function f_TC_rsl_ms_pwr_dyn_max(charstring id) runs on ConnHdlr {
 	var uint5_t pwr_var := 7;
-	var L1ctlDlMessage l1_dl;
+	var SacchL1Header l1h;
 
 	/* set a low value to ensure power increases */
 	f_trxc_fake_rssi(rxlev2dbm(10));
@@ -2652,14 +2667,12 @@
 	timer T1 := 10.0;
 	T1.start;
 	alt {
-	[] L1CTL.receive(tr_L1CTL_DATA_IND(g_chan_nr, tr_RslLinkID_SACCH(?))) -> value l1_dl {
-		/* Update sent MS power to follow what BTS requests */
-		f_L1CTL_PARAM(L1CTL, g_pars.l1_pars.ms_actual_ta, oct2int(l1_dl.payload.data_ind.payload[0]));
-		repeat;
-		}
+	[] as_l1_sacch_l1h(l1h) { repeat; }
 	[] L1CTL.receive { repeat; }
 	[] T1.timeout {
-		if( oct2int(l1_dl.payload.data_ind.payload[0]) != pwr_var){
+		if (not isbound(l1h)) {
+			setverdict(fail, "No SACCH blocks were received");
+		} else if (l1h.ms_power_lvl != pwr_var) {
 			setverdict(fail, "Power level in L1 header should not have changed");
 		}
 		}
@@ -2672,7 +2685,7 @@
 
 /* see if we reach the band max power */
 private function f_TC_rsl_ms_pwr_dyn_up(charstring id) runs on ConnHdlr {
-	var L1ctlDlMessage l1_dl;
+	var SacchL1Header l1h;
 	var uint5_t pwr_var := 15;
 	var uint5_t pwr_max_var := f_get_max_power_from_band();
 
@@ -2698,19 +2711,16 @@
 	timer T1 := 10.0;
 	T1.start;
 	alt {
-	[] L1CTL.receive(tr_L1CTL_DATA_IND(g_chan_nr, tr_RslLinkID_SACCH(?))) -> value l1_dl {
-		/* Update sent MS power to follow what BTS requests */
-		f_L1CTL_PARAM(L1CTL, g_pars.l1_pars.ms_actual_ta, oct2int(l1_dl.payload.data_ind.payload[0]));
-		repeat;
-		}
+	[] as_l1_sacch_l1h(l1h) { repeat; }
 	[] L1CTL.receive { repeat; }
 	[] T1.timeout {
-		var int8_t rcv := oct2int(l1_dl.payload.data_ind.payload[0]);
-		if( f_power_level_is_highest_dbm(rcv) ){
+		if (not isbound(l1h)) {
+			setverdict(fail, "No SACCH blocks were received");
+		} else if (f_power_level_is_highest_dbm(l1h.ms_power_lvl)) {
 			setverdict(pass, "Power level in L1 header reduced as expected");
 		} else {
-			Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail,
-			log2str("Power Level in L1 header did not reach the expected value, e:",pwr_max_var," r:",rcv));
+			setverdict(fail, "Power level := ", l1h.ms_power_lvl, " did not ",
+				   "reach the expected value := ", pwr_max_var);
 		}
 		}
 	}
@@ -2722,7 +2732,7 @@
 
 /* see if we reach the band min power */
 private function f_TC_rsl_ms_pwr_dyn_down(charstring id) runs on ConnHdlr {
-	var L1ctlDlMessage l1_dl;
+	var SacchL1Header l1h;
 
 	/* set a high value to ensure power decreases */
 	f_trxc_fake_rssi(rxlev2dbm(50));
@@ -2749,18 +2759,15 @@
 	timer T1 := 10.0;
 	T1.start;
 	alt {
-	[] L1CTL.receive(tr_L1CTL_DATA_IND(g_chan_nr, tr_RslLinkID_SACCH(?))) -> value l1_dl {
-		/* Update sent MS power to follow what BTS requests */
-		f_L1CTL_PARAM(L1CTL, g_pars.l1_pars.ms_actual_ta, oct2int(l1_dl.payload.data_ind.payload[0]));
-		repeat;
-		}
+	[] as_l1_sacch_l1h(l1h) { repeat; }
 	[] L1CTL.receive { repeat; }
 	[] T1.timeout {
-		if( f_power_level_is_lowest_dbm(oct2int(l1_dl.payload.data_ind.payload[0])) ){
-			setverdict(pass, "Power level in L1 header increased to lowest power value");
+		if (not isbound(l1h)) {
+			setverdict(fail, "No SACCH blocks were received");
+		} else if (f_power_level_is_lowest_dbm(l1h.ms_power_lvl)) {
+			setverdict(pass, "Power level increased to lowest power value");
 		} else {
-			Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail,
-			"Power level in L1 header NOT increased to lowest power value");
+			setverdict(fail, "Power level NOT increased to lowest power value");
 		}
 		}
 	}
@@ -2773,7 +2780,7 @@
 /* see if we change the power level without receiving power parameters, which should not happen
 rsl chan act WITHOUT power parameters */
 private function f_TC_rsl_ms_pwr_dyn_active(charstring id) runs on ConnHdlr {
-	var L1ctlDlMessage l1_dl;
+	var SacchL1Header l1h;
 
 	/* set a high value to ensure power decreases */
 	f_trxc_fake_rssi(rxlev2dbm(50));
@@ -2795,8 +2802,8 @@
 	timer T1 := 10.0;
 	T1.start;
 	alt {
-	[] L1CTL.receive(tr_L1CTL_DATA_IND(g_chan_nr, tr_RslLinkID_SACCH(?))) -> value l1_dl {
-		if ( oct2int(l1_dl.payload.data_ind.payload[0]) != pwr_var) {
+	[] as_l1_sacch_l1h(l1h, do_apply := false) {
+		if (l1h.ms_power_lvl != pwr_var) {
 			Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail,
 			"BS power control should not be active unless we receive a power parameters IE!");
 		}
@@ -2814,7 +2821,7 @@
 /* see if we change the power level without receiving power parameters, which should not happen
 ms power control WITHOUT power parameters */
 private function f_TC_rsl_ms_pwr_dyn_active2(charstring id) runs on ConnHdlr {
-	var L1ctlDlMessage l1_dl;
+	var SacchL1Header l1h;
 
 	/* set a high value to ensure power decreases */
 	f_trxc_fake_rssi(rxlev2dbm(50));
@@ -2839,8 +2846,8 @@
 	timer T1 := 10.0;
 	T1.start;
 	alt {
-	[] L1CTL.receive(tr_L1CTL_DATA_IND(g_chan_nr, tr_RslLinkID_SACCH(?))) -> value l1_dl {
-		if ( oct2int(l1_dl.payload.data_ind.payload[0]) != pwr_var) {
+	[] as_l1_sacch_l1h(l1h, do_apply := false) {
+		if (l1h.ms_power_lvl != pwr_var) {
 			Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail,
 			"BS power control should not be active unless we receive a power parameters IE!");
 		}
@@ -2856,12 +2863,12 @@
 }
 
 private function f_wait_for_l1_power_level(integer level) runs on ConnHdlr {
-	var L1ctlDlMessage l1_dl;
+	var SacchL1Header l1h;
 	timer T0 := 10.0;
 	T0.start;
 	alt {
-	[] L1CTL.receive(tr_L1CTL_DATA_IND(g_chan_nr, tr_RslLinkID_SACCH(?))) -> value l1_dl {
-		if (not (l1_dl.payload.data_ind.payload[0] == int2oct(level, 1))) {
+	[] as_l1_sacch_l1h(l1h, do_apply := false) {
+		if (l1h.ms_power_lvl != level) {
 			Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail,
 			"Power level in L1 header != signaled (RSL) power level.");
 		}
@@ -3169,7 +3176,7 @@
 /* establish DChan, and send MS POWER CONTROL messages via RSL, verify that
  * the BTS is forwarding those values to the MS via the SACCH L1 header. */
 private function f_tc_rsl_ms_pwr_ctrl(charstring id) runs on ConnHdlr {
-	var L1ctlDlMessage l1_dl;
+	var SacchL1Header l1h;
 	var RSL_IE_MS_Power ms_power;
 	var RSL_Message rsl;
 	var uint5_t power_level := 0;
@@ -3191,15 +3198,11 @@
 	RSL.send(rsl);
 
 	alt {
-
-	/* Pick all SACCH blocks for checking */
-	[] L1CTL.receive(tr_L1CTL_DATA_IND(g_chan_nr, tr_RslLinkID_SACCH(?))) -> value l1_dl {
-
-		/* The first byte of the L1 header contains the power level.
-		 * The reserved bits and the fpc bit is set to 0, so we may
-		 * compare directly. */
-		if (not (l1_dl.payload.data_ind.payload[0] == int2oct(power_level, 1))) {
-			setverdict(fail, "Power level in L1 header does not match the signaled (RSL) power level.");
+	[] as_l1_sacch_l1h(l1h, do_apply := false) {
+		if (l1h.ms_power_lvl != power_level) {
+			setverdict(fail, "Power level := ", l1h.ms_power_lvl, "does not ",
+				   "match the signaled (RSL) power level := ", power_level);
+			Misc_Helpers.f_shutdown(__BFILE__, __LINE__);
 		}
 
 		/* Signal a new power level via RSL for the next turn. */
@@ -3240,9 +3243,8 @@
 /* establish DChan, verify that the BTS sets the TA in the first SACCH L1 header.
 TA for the IMM ASS messages is still controlled by g_pars.l1_pars.ms_actual_ta! */
 private function f_tc_rsl_chan_initial_ta(charstring id) runs on ConnHdlr {
-	var L1ctlDlMessage l1_dl;
 	var uint5_t ta_to_test := 16;
-
+	var SacchL1Header l1h;
 
 	f_l1_tune(L1CTL);
 	RSL.clear;
@@ -3254,12 +3256,8 @@
 
 
 	alt {
-
-	/* Pick all SACCH blocks for checking */
-	[] L1CTL.receive(tr_L1CTL_DATA_IND(g_chan_nr, tr_RslLinkID_SACCH(?))) -> value l1_dl {
-
-		/* The second byte of the L1 header contains the TA. */
-		if (not (l1_dl.payload.data_ind.payload[1] == int2oct(ta_to_test, 1))) {
+	[] as_l1_sacch_l1h(l1h, do_apply := false) {
+		if (l1h.actual_ta != ta_to_test) {
 			setverdict(fail, "TA in L1 header does not match the signaled (RSL) TA.");
 		}
 
@@ -3289,8 +3287,8 @@
 
 /* establish DChan, verify that the BTS sets MS power in the first SACCH L1 header. */
 private function f_tc_rsl_chan_initial_ms_pwr(charstring id) runs on ConnHdlr {
-	var L1ctlDlMessage l1_dl;
 	var uint5_t ms_power_level := 7;
+	var SacchL1Header l1h;
 
 	var RSL_IE_MS_Power ms_power;
 	ms_power.reserved := 0;
@@ -3306,10 +3304,10 @@
 	T.start;
 	alt {
 	/* Pick all SACCH blocks for checking */
-	[] L1CTL.receive(tr_L1CTL_DATA_IND(g_chan_nr, tr_RslLinkID_SACCH(?))) -> value l1_dl {
-		/* The first byte of the L1 header contains the power level.. */
-		if (not (l1_dl.payload.data_ind.payload[0] == int2oct(ms_power_level, 1))) {
-			setverdict(fail, "Power Level in L1 header does not match the signaled (RSL) MS Power Level.");
+	[] as_l1_sacch_l1h(l1h, do_apply := false) {
+		if (l1h.ms_power_lvl != ms_power_level) {
+			setverdict(fail, "Power level := ", l1h.ms_power_lvl, "does not ",
+				   "match the signaled (RSL) power level := ", ms_power_level);
 		}
 		}
 	/* Ignore all other blocks */