diff --git a/frappy_psi/network_analysers/ZVL/ZVLDriver.py b/frappy_psi/network_analysers/ZVL/ZVLDriver.py
index 8290ec99..580eaf20 100644
--- a/frappy_psi/network_analysers/ZVL/ZVLDriver.py
+++ b/frappy_psi/network_analysers/ZVL/ZVLDriver.py
@@ -30,32 +30,50 @@ class ZVLNetAnalyzer():
         self.base_data = np.array([])
         self.base_data = self.get_data()[1]
         
+        self.min_freq = 0
+        self.max_freq = 0
+        
     def reset(self):
-        #self.instrument.write('*RST')
-        #self.instrument.write('SYST:PRES') # reloads current setup.
-        self.instrument.write('*CLS')
+        self.instrument.write('*RST')
         self.instrument.write('INST:NSEL 2')
         self.instrument.write('DISPlay:WINDow1:STATe ON')
         self.instrument.write(":CALC:PAR:MEAS 'Trc1', 'S11'")
         self.instrument.write('CALC:FORM MLOG')
         self.instrument.write('INIT:CONT OFF')
         self.instrument.write("SYST:USER:DISP:TITL 'Frappy connection'")
-        #self.instrument.write('INIT:SCOP OFF')
-        #self.instrument.write('DISPlay:WINDow2:STATe ON')
+        self.instrument.write('*ESE')
+        
+        self.min_freq, self.max_freq = self.get_freq_range() # default is largest.
     
-    def load_calibration(self, f):
-        self.instrument.write(f":MMEMORY:STORE:CORR 1, 'OSM1 {f}'") # put calibration in pool
-        self.instrument.write(f":MMEMORY:LOAD:CORR 1, 'OSM1 {f}'") # load from pool
+    def reload_calibration(self):
+        self.reset()
+        #self.instrument.write("DISP:MENU:KEY:SEL 'Correction Off'")
+        #self.instrument.write("DISP:MENU:KEY:EXEC 'Correction Off'")
+        self.instrument.write("DISP:MENU:KEY:EXEC 'Recall Last Cal Set'")
+        time.sleep(1)
+        self.min_freq, self.max_freq = self.get_freq_range() # default is largest.
+        
+    def get_freq_range(self):
+        start = float(self.instrument.ask('SENS1:FREQ:STAR?'))
+        stop = float(self.instrument.ask('SENS1:FREQ:STOP?'))
+    
+        return start, stop
     
     def set_freq_range(self, start, stop):
         '''In Hz'''
-        self.instrument.write(f'SENS1:FREQ:STAR {start}')
-        self.instrument.write(f'SENS1:FREQ:STOP {stop}')
+        if(start >= self.min_freq) and (stop <= self.max_freq):
+            
+            self.instrument.write(f'SENS1:FREQ:STAR {start}')
+            self.instrument.write(f'SENS1:FREQ:STOP {stop}')
+            self.start_freq = start
+            self.stop_freq = stop
         
     def set_freq_span(self, center, span):
         '''In Hz'''
-        self.instrument.write(f'SENS1:FREQ:CENT {center}')
-        self.instrument.write(f'SENS1:FREQ:SPAN {span}')
+        start = center - span/2
+        stop = center + span/2
+        
+        self.set_freq_range(start, stop)
         
     def set_averaging_passes(self,avgs):
         '''
@@ -101,6 +119,7 @@ class ZVLNetAnalyzer():
         assert(averaging_passes<=999)
         assert(units in ['dB', 'unitless'])
             
+        self.instrument.write('INIT:CONT OFF')
         self.instrument.write(f'SWE:POIN {N}')
         self.instrument.write(f'SWE:COUN {averaging_passes}')
         
diff --git a/frappy_psi/network_analysers/ZVL/test.py b/frappy_psi/network_analysers/ZVL/test.py
new file mode 100644
index 00000000..922affb5
--- /dev/null
+++ b/frappy_psi/network_analysers/ZVL/test.py
@@ -0,0 +1,50 @@
+from ZVLDriver import *
+import matplotlib.pyplot as plt
+
+# example code. profiles the per-point delay for reading data and   
+ip = '129.129.156.201'
+ip = '169.254.83.53'
+import matplotlib.pyplot as plt
+print('start')
+z = ZVLNetAnalyzer()
+z.reset()
+
+
+#mm, mmi, fr, frq = z.find_peak(50_000_000, 350_000_000, 20_000_000)
+#plt.plot(frq, fr)
+#plt.axvline(frq[mmi])
+#plt.axhline(mm)
+#plt.show()
+
+#z.reset()
+##z.set_freq_range(1_000_000, 2_000_000.5)
+##z.set_freq_span(1_000_000, 10_000)
+z.set_freq_range(25_750_000, 75_250_000)
+plt.scatter(*(z.get_data()))
+
+z.reload_calibration()
+#z.set_freq_span(220_000_000, 50_000_000)
+plt.scatter(*(z.get_data()))
+plt.show()
+
+#Ns = np.linspace(3, 1000, 100).astype(int)
+#ts = []
+#for N in Ns:
+#    st = time.time()
+#    freqs, data = z.get_data(N)
+#    et = time.time()
+#    dt = (et-st)
+#    print(f'got data, {dt/N} ({dt})')
+#    ts += [dt]
+#
+#plt.scatter(Ns, ts)
+#plt.show()
+#plt.scatter(Ns, np.array(ts)/np.array(Ns))
+#plt.show()
+    
+#input()
+#plt.plot(*z.get_data(averaging_passes=1), alpha=0.3)
+#plt.plot(*z.get_data(averaging_passes=64), alpha=0.3)
+#plt.show()
+
+input()
\ No newline at end of file