diff --git a/examples/data/dolfyn/test_data/BenchFile01.nc b/examples/data/dolfyn/test_data/BenchFile01.nc
index fc3f4bcdc..57a73e44d 100644
Binary files a/examples/data/dolfyn/test_data/BenchFile01.nc and b/examples/data/dolfyn/test_data/BenchFile01.nc differ
diff --git a/examples/data/dolfyn/test_data/BenchFile01.repr.txt b/examples/data/dolfyn/test_data/BenchFile01.repr.txt
index 557298fc2..5e5d563c7 100644
--- a/examples/data/dolfyn/test_data/BenchFile01.repr.txt
+++ b/examples/data/dolfyn/test_data/BenchFile01.repr.txt
@@ -4,6 +4,7 @@
   . (100 pings @ 2Hz)
   Variables:
   - time ('time',)
+  - time_altraw ('time_altraw',)
   - time_b5 ('time_b5',)
   - vel ('dir', 'range', 'time')
   - vel_b5 ('range_b5', 'time_b5')
@@ -14,6 +15,8 @@
   - roll ('time',)
   - temp ('time',)
   - pressure ('time',)
+  - pressure_alt ('time',)
+  - pressure_altraw ('time_altraw',)
   - amp ('beam', 'range', 'time')
   - amp_b5 ('range_b5', 'time_b5')
   - corr ('beam', 'range', 'time')
diff --git a/examples/data/dolfyn/test_data/BenchFile01_avg.nc b/examples/data/dolfyn/test_data/BenchFile01_avg.nc
index ddd0e0327..0fa4e236b 100644
Binary files a/examples/data/dolfyn/test_data/BenchFile01_avg.nc and b/examples/data/dolfyn/test_data/BenchFile01_avg.nc differ
diff --git a/examples/data/dolfyn/test_data/BenchFile01_crop.nc b/examples/data/dolfyn/test_data/BenchFile01_crop.nc
new file mode 100644
index 000000000..278a872bf
Binary files /dev/null and b/examples/data/dolfyn/test_data/BenchFile01_crop.nc differ
diff --git a/examples/data/dolfyn/test_data/BenchFile01_rotate_beam2inst.nc b/examples/data/dolfyn/test_data/BenchFile01_rotate_beam2inst.nc
index dc10c6ef6..d36b432d1 100644
Binary files a/examples/data/dolfyn/test_data/BenchFile01_rotate_beam2inst.nc and b/examples/data/dolfyn/test_data/BenchFile01_rotate_beam2inst.nc differ
diff --git a/examples/data/dolfyn/test_data/BenchFile01_rotate_earth2principal.nc b/examples/data/dolfyn/test_data/BenchFile01_rotate_earth2principal.nc
index 5acd192b1..2a1ff37df 100644
Binary files a/examples/data/dolfyn/test_data/BenchFile01_rotate_earth2principal.nc and b/examples/data/dolfyn/test_data/BenchFile01_rotate_earth2principal.nc differ
diff --git a/examples/data/dolfyn/test_data/BenchFile01_rotate_inst2earth.nc b/examples/data/dolfyn/test_data/BenchFile01_rotate_inst2earth.nc
index 2a8e4b67c..194dee8a2 100644
Binary files a/examples/data/dolfyn/test_data/BenchFile01_rotate_inst2earth.nc and b/examples/data/dolfyn/test_data/BenchFile01_rotate_inst2earth.nc differ
diff --git a/examples/data/dolfyn/test_data/Sig1000_BadTime01.nc b/examples/data/dolfyn/test_data/Sig1000_BadTime01.nc
index 790d1e578..de929e2e4 100644
Binary files a/examples/data/dolfyn/test_data/Sig1000_BadTime01.nc and b/examples/data/dolfyn/test_data/Sig1000_BadTime01.nc differ
diff --git a/examples/data/dolfyn/test_data/Sig1000_IMU.nc b/examples/data/dolfyn/test_data/Sig1000_IMU.nc
index bee45bdb1..397475f51 100644
Binary files a/examples/data/dolfyn/test_data/Sig1000_IMU.nc and b/examples/data/dolfyn/test_data/Sig1000_IMU.nc differ
diff --git a/examples/data/dolfyn/test_data/Sig1000_IMU_bin.nc b/examples/data/dolfyn/test_data/Sig1000_IMU_bin.nc
index 317293a7f..2b0dcbbdc 100644
Binary files a/examples/data/dolfyn/test_data/Sig1000_IMU_bin.nc and b/examples/data/dolfyn/test_data/Sig1000_IMU_bin.nc differ
diff --git a/examples/data/dolfyn/test_data/Sig1000_IMU_ofilt.nc b/examples/data/dolfyn/test_data/Sig1000_IMU_ofilt.nc
index 51c45f146..b46762be3 100644
Binary files a/examples/data/dolfyn/test_data/Sig1000_IMU_ofilt.nc and b/examples/data/dolfyn/test_data/Sig1000_IMU_ofilt.nc differ
diff --git a/examples/data/dolfyn/test_data/Sig1000_IMU_rotate_beam2inst.nc b/examples/data/dolfyn/test_data/Sig1000_IMU_rotate_beam2inst.nc
index 2edd41f60..6c3337157 100644
Binary files a/examples/data/dolfyn/test_data/Sig1000_IMU_rotate_beam2inst.nc and b/examples/data/dolfyn/test_data/Sig1000_IMU_rotate_beam2inst.nc differ
diff --git a/examples/data/dolfyn/test_data/Sig1000_IMU_rotate_inst2earth.nc b/examples/data/dolfyn/test_data/Sig1000_IMU_rotate_inst2earth.nc
index 9944aeb7a..f7364c5f0 100644
Binary files a/examples/data/dolfyn/test_data/Sig1000_IMU_rotate_inst2earth.nc and b/examples/data/dolfyn/test_data/Sig1000_IMU_rotate_inst2earth.nc differ
diff --git a/examples/data/dolfyn/test_data/Sig1000_IMU_ud.nc b/examples/data/dolfyn/test_data/Sig1000_IMU_ud.nc
index f0f847653..05663f604 100644
Binary files a/examples/data/dolfyn/test_data/Sig1000_IMU_ud.nc and b/examples/data/dolfyn/test_data/Sig1000_IMU_ud.nc differ
diff --git a/examples/data/dolfyn/test_data/Sig1000_tidal.nc b/examples/data/dolfyn/test_data/Sig1000_tidal.nc
index f5bf6ba34..759fe4775 100644
Binary files a/examples/data/dolfyn/test_data/Sig1000_tidal.nc and b/examples/data/dolfyn/test_data/Sig1000_tidal.nc differ
diff --git a/examples/data/dolfyn/test_data/Sig1000_tidal_clean.nc b/examples/data/dolfyn/test_data/Sig1000_tidal_clean.nc
index f5148a480..8cb9e6678 100644
Binary files a/examples/data/dolfyn/test_data/Sig1000_tidal_clean.nc and b/examples/data/dolfyn/test_data/Sig1000_tidal_clean.nc differ
diff --git a/examples/data/dolfyn/test_data/Sig500_Echo.nc b/examples/data/dolfyn/test_data/Sig500_Echo.nc
index e80a279a5..78dbdd06f 100644
Binary files a/examples/data/dolfyn/test_data/Sig500_Echo.nc and b/examples/data/dolfyn/test_data/Sig500_Echo.nc differ
diff --git a/examples/data/dolfyn/test_data/Sig500_Echo_clean.nc b/examples/data/dolfyn/test_data/Sig500_Echo_clean.nc
index bf913bfa0..099334d74 100644
Binary files a/examples/data/dolfyn/test_data/Sig500_Echo_clean.nc and b/examples/data/dolfyn/test_data/Sig500_Echo_clean.nc differ
diff --git a/examples/data/dolfyn/test_data/Sig500_Echo_crop.nc b/examples/data/dolfyn/test_data/Sig500_Echo_crop.nc
index ed7fbe512..80d4bca81 100644
Binary files a/examples/data/dolfyn/test_data/Sig500_Echo_crop.nc and b/examples/data/dolfyn/test_data/Sig500_Echo_crop.nc differ
diff --git a/examples/data/dolfyn/test_data/Sig500_Echo_earth2inst.nc b/examples/data/dolfyn/test_data/Sig500_Echo_earth2inst.nc
index a5e0f5d7d..b44b1d8ca 100644
Binary files a/examples/data/dolfyn/test_data/Sig500_Echo_earth2inst.nc and b/examples/data/dolfyn/test_data/Sig500_Echo_earth2inst.nc differ
diff --git a/examples/data/dolfyn/test_data/Sig500_Echo_inst2beam.nc b/examples/data/dolfyn/test_data/Sig500_Echo_inst2beam.nc
index 711cdeff1..8e12197df 100644
Binary files a/examples/data/dolfyn/test_data/Sig500_Echo_inst2beam.nc and b/examples/data/dolfyn/test_data/Sig500_Echo_inst2beam.nc differ
diff --git a/examples/data/dolfyn/test_data/Sig500_last_ensemble_is_whole.nc b/examples/data/dolfyn/test_data/Sig500_last_ensemble_is_whole.nc
index b9aa117df..f52d8df45 100644
Binary files a/examples/data/dolfyn/test_data/Sig500_last_ensemble_is_whole.nc and b/examples/data/dolfyn/test_data/Sig500_last_ensemble_is_whole.nc differ
diff --git a/examples/data/dolfyn/test_data/Sig_SkippedPings01.nc b/examples/data/dolfyn/test_data/Sig_SkippedPings01.nc
index 2b2f0857c..90b41d3c7 100644
Binary files a/examples/data/dolfyn/test_data/Sig_SkippedPings01.nc and b/examples/data/dolfyn/test_data/Sig_SkippedPings01.nc differ
diff --git a/examples/data/dolfyn/test_data/VelEchoBT01.nc b/examples/data/dolfyn/test_data/VelEchoBT01.nc
index d7ff5dbcb..f2fb6183e 100644
Binary files a/examples/data/dolfyn/test_data/VelEchoBT01.nc and b/examples/data/dolfyn/test_data/VelEchoBT01.nc differ
diff --git a/examples/data/dolfyn/test_data/VelEchoBT01_rotate_beam2inst.nc b/examples/data/dolfyn/test_data/VelEchoBT01_rotate_beam2inst.nc
index 2462311e5..6cefd020c 100644
Binary files a/examples/data/dolfyn/test_data/VelEchoBT01_rotate_beam2inst.nc and b/examples/data/dolfyn/test_data/VelEchoBT01_rotate_beam2inst.nc differ
diff --git a/mhkit/dolfyn/io/api.py b/mhkit/dolfyn/io/api.py
index e540d53d0..23a68a308 100644
--- a/mhkit/dolfyn/io/api.py
+++ b/mhkit/dolfyn/io/api.py
@@ -76,7 +76,7 @@ def read(fname, userdata=True, nens=None, **kwargs):
     userdata : True, False, or string of userdata.json filename (default ``True``)
       Whether to read the '<base-filename>.userdata.json' file.
     nens : None, int or 2-element tuple (start, stop)
-      Number of pings or ensembles to read from the file. 
+      Number of pings or ensembles to read from the file.
       Default is None, read entire file
     **kwargs : dict
       Passed to instrument-specific parser.
@@ -173,8 +173,8 @@ def save(ds, filename,
     ds.attrs['complex_vars'] = []
     for var in ds.data_vars:
         if np.iscomplexobj(ds[var]):
-            ds[var+'_real'] = ds[var].real
-            ds[var+'_imag'] = ds[var].imag
+            ds[var + '_real'] = ds[var].real
+            ds[var + '_imag'] = ds[var].imag
 
             ds = ds.drop_vars(var)
             ds.attrs['complex_vars'].append(var)
@@ -183,15 +183,25 @@ def save(ds, filename,
         elif ds[var].dtype == np.float64:
             ds[var] = ds[var].astype('float32')
 
-    if compression:
-        enc = dict()
-        for ky in ds.variables:
-            enc[ky] = dict(zlib=True, complevel=1)
-        if 'encoding' in kwargs:
-            # Overwrite ('update') values in enc with whatever is in kwargs['encoding']
-            enc.update(kwargs['encoding'])
-        else:
-            kwargs['encoding'] = enc
+    # Write variable encoding
+    enc = dict()
+    if 'encoding' in kwargs:
+        enc.update(kwargs['encoding'])
+    for ky in ds.variables:
+        # Save prior encoding
+        enc[ky] = ds[ky].encoding
+        # Remove unexpected netCDF4 encoding parameters
+        # https://github.com/pydata/xarray/discussions/5709
+        params = ['szip', 'zstd', 'bzip2', 'blosc', 'contiguous', 'chunksizes']
+        [enc[ky].pop(p) for p in params if p in enc[ky]]
+
+        if compression:
+            # New netcdf4-c cannot compress variable length strings
+            if isinstance(ds[ky].data[0], str):
+                continue
+            enc[ky].update(dict(zlib=True, complevel=1))
+
+    kwargs['encoding'] = enc
 
     # Fix encoding on datetime64 variables.
     ds = _decode_cf(ds)
@@ -220,19 +230,20 @@ def load(filename):
 
     # Convert numpy arrays and strings back to lists
     for nm in ds.attrs:
-        if type(ds.attrs[nm]) == np.ndarray and ds.attrs[nm].size > 1:
+        if isinstance(ds.attrs[nm], np.ndarray) and ds.attrs[nm].size > 1:
             ds.attrs[nm] = list(ds.attrs[nm])
-        elif type(ds.attrs[nm]) == str and nm in ['rotate_vars']:
+        elif isinstance(ds.attrs[nm], str) and nm in ['rotate_vars']:
             ds.attrs[nm] = [ds.attrs[nm]]
 
     # Rejoin complex numbers
-    if hasattr(ds, 'complex_vars') and len(ds.complex_vars):
-        if len(ds.complex_vars[0]) == 1:
-            ds.attrs['complex_vars'] = [ds.complex_vars]
-        for var in ds.complex_vars:
-            ds[var] = ds[var+'_real'] + ds[var+'_imag'] * 1j
-            ds = ds.drop_vars([var+'_real', var+'_imag'])
-    ds.attrs.pop('complex_vars')
+    if hasattr(ds, 'complex_vars'):
+        if len(ds.complex_vars):
+            if len(ds.complex_vars[0]) == 1:
+                ds.attrs['complex_vars'] = [ds.complex_vars]
+            for var in ds.complex_vars:
+                ds[var] = ds[var + '_real'] + ds[var + '_imag'] * 1j
+                ds = ds.drop_vars([var + '_real', var + '_imag'])
+        ds.attrs.pop('complex_vars')
 
     return ds
 
@@ -318,7 +329,7 @@ def load_mat(filename, datenum=True):
     filename : str
       Filename and/or path with the '.mat' extension
     datenum : bool
-      If true, converts time from datenum. If false, converts time from 
+      If true, converts time from datenum. If false, converts time from
       "epoch time".
 
     Returns
@@ -351,12 +362,12 @@ def load_mat(filename, datenum=True):
 
     # Convert numpy arrays and strings back to lists
     for nm in ds.attrs:
-        if type(ds.attrs[nm]) == np.ndarray and ds.attrs[nm].size > 1:
+        if isinstance(ds.attrs[nm], np.ndarray) and ds.attrs[nm].size > 1:
             try:
                 ds.attrs[nm] = [x.strip(' ') for x in list(ds.attrs[nm])]
             except:
                 ds.attrs[nm] = list(ds.attrs[nm])
-        elif type(ds.attrs[nm]) == str and nm in ['time_coords', 'time_data_vars', 'rotate_vars']:
+        elif isinstance(ds.attrs[nm], str) and nm in ['time_coords', 'time_data_vars', 'rotate_vars']:
             ds.attrs[nm] = [ds.attrs[nm]]
 
     if hasattr(ds, 'orientation_down'):
diff --git a/mhkit/dolfyn/io/base.py b/mhkit/dolfyn/io/base.py
index 8f3b4469a..897013700 100644
--- a/mhkit/dolfyn/io/base.py
+++ b/mhkit/dolfyn/io/base.py
@@ -118,7 +118,7 @@ def _create_dataset(data):
     Direction 'dir' coordinates are set in `set_coords`
     """
     ds = xr.Dataset()
-    tag = ['_avg', '_b5', '_echo', '_bt', '_gps', '_ast', '_sl']
+    tag = ['_avg', '_b5', '_echo', '_bt', '_gps', '_altraw', '_sl']
 
     FoR = {}
     try:
@@ -205,6 +205,11 @@ def _create_dataset(data):
                                               'dim_1': 'time_echo'})
                     ds[key] = ds[key].assign_coords({'range_echo': data['coords']['range_echo'],
                                                      'time_echo': data['coords']['time_echo']})
+                elif key == 'samp_altraw':  # raw altimeter samples
+                    ds[key] = ds[key].rename({'dim_0': 'n_altraw',
+                                              'dim_1': 'time_altraw'})
+                    ds[key] = ds[key].assign_coords({'time_altraw': data['coords']['time_altraw']})
+
                 # ADV/ADCP instrument vector data, bottom tracking
                 elif shp[0] == n_beams and not any(val in key for val in tag[:3]):
                     if 'bt' in key and 'time_bt' in data['coords']:
diff --git a/mhkit/dolfyn/io/nortek.py b/mhkit/dolfyn/io/nortek.py
index 4709df7aa..3a4c4e2f2 100644
--- a/mhkit/dolfyn/io/nortek.py
+++ b/mhkit/dolfyn/io/nortek.py
@@ -165,8 +165,11 @@ class _NortekReader():
                '0x10': 'read_vec_data',
                '0x11': 'read_vec_sysdata',
                '0x12': 'read_vec_hdr',
-               '0x71': 'read_microstrain',
                '0x20': 'read_awac_profile',
+               '0x30': 'read_awac_waves',
+               '0x31': 'read_awac_waves_hdr',
+               '0x36': 'read_awac_waves',  # "SUV"
+               '0x71': 'read_microstrain',
                }
 
     def __init__(self, fname, endian=None, debug=False,
@@ -1026,6 +1029,77 @@ def sci_awac_profile(self,):
         self.data['attrs']['cell_size'] = cs
         self.data['attrs']['blank_dist'] = bd
 
+    def read_awac_waves_hdr(self,):
+        # ID: '0x31'
+        c = self.c
+        if self.debug:
+            print('Reading vector header data (0x31) ping #{} @ {}...'
+                  .format(self.c, self.pos))
+        hdrnow = {}
+        dat = self.data
+        ds = dat['sys']
+        dv = dat['data_vars']
+        if 'time' not in dat['coords']:
+            self._init_data(nortek_defs.waves_hdrdata)
+        byts = self.read(56)
+        # The first two are size, the next 6 are time.
+        tmp = unpack(self.endian + '8x4H3h2HhH4B6H5h', byts)
+        dat['coords']['time'][c] = self.rd_time(byts[2:8])
+        hdrnow['n_records_alt'] = tmp[0]
+        hdrnow['blank_dist_alt'] = tmp[1]  # counts
+        ds['batt_alt'][c] = tmp[2]  # voltage (0.1 V)
+        dv['c_sound_alt'][c] = tmp[3]  # c (0.1 m/s)
+        dv['heading_alt'][c] = tmp[4]  # (0.1 deg)
+        dv['pitch_alt'][c] = tmp[5]  # (0.1 deg)
+        dv['roll_alt'][c] = tmp[6]  # (0.1 deg)
+        dv['pressure1_alt'][c] = tmp[7]  # min pressure previous profile (0.001 dbar)
+        dv['pressure2_alt'][c] = tmp[8]  # max pressure previous profile (0.001 dbar)
+        dv['temp_alt'][c] = tmp[9]  # (0.01 deg C)
+        hdrnow['cell_size_alt'][c] = tmp[10]  # (counts of T3)
+        hdrnow['noise_alt'][c] = tmp[11:15]  # noise amplitude beam 1-4 (counts)
+        hdrnow['proc_magn_alt'][c] = tmp[15:19]  # processing magnitude beam 1-4
+        hdrnow['n_past_window_alt'] = tmp[19]  # number of samples of AST window past boundary
+        hdrnow['n_window_alt'] = tmp[20]  # AST window size (# samples)
+        hdrnow['Spare1'] = tmp[21:]
+        self.checksum(byts)
+        if 'data_header' not in self.config:
+            self.config['data_header'] = hdrnow
+        else:
+            if not isinstance(self.config['data_header'], list):
+                self.config['data_header'] = [self.config['data_header']]
+            self.config['data_header'] += [hdrnow]
+
+    def read_awac_waves(self,):
+        """Read awac wave and suv data
+        """
+        # IDs: 0x30 & 0x36
+        c = self.c
+        dat = self.data
+        if self.debug:
+            print('Reading awac wave data (0x30) ping #{} @ {}...'
+                  .format(self.c, self.pos))
+        if 'dist1_alt' not in dat['data_vars']:
+            self._init_data(nortek_defs.wave_data)
+            self._dtypes += ['wave_data']
+        # The first two are size
+        byts = self.read(20)
+        ds = dat['sys']
+        dv = dat['data_vars']
+        (dv['pressure'][c],  # (0.001 dbar)
+         dv['dist1_alt'][c],  # distance 1 to surface, vertical beam (mm)
+         ds['AnaIn_alt'][c],  # analog input 1
+         dv['vel_alt'][0, c],  # velocity beam 1 (mm/s) East for SUV
+         dv['vel_alt'][1, c],  # North for SUV
+         dv['vel_alt'][2, c],  # Up for SUV
+         dv['dist2_alt'][c],  # distance 2 to surface, vertical beam (mm) or vel 4 for non-AST
+         dv['amp_alt'][0, c],  # amplitude beam 1 (counts)
+         dv['amp_alt'][1, c],  # amplitude beam 2 (counts)
+         dv['amp_alt'][2, c],  # amplitude beam 3 (counts)
+         # AST quality (counts) or amplitude beam 4 for non-AST
+         dv['quality_alt'][c]) = unpack(self.endian + '3H4h4B', byts)
+        self.checksum(byts)
+        self.c += 1
+
     def dat2sci(self,):
         for nm in self._dtypes:
             getattr(self, 'sci_' + nm)()
diff --git a/mhkit/dolfyn/io/nortek2.py b/mhkit/dolfyn/io/nortek2.py
index fe4e3c9e7..11dd80ee8 100644
--- a/mhkit/dolfyn/io/nortek2.py
+++ b/mhkit/dolfyn/io/nortek2.py
@@ -26,7 +26,7 @@ def read_signature(filename, userdata=True, nens=None, rebuild_index=False,
     userdata : bool
       To search for and use a .userdata.json or not
     nens : None, int or 2-element tuple (start, stop)
-      Number of pings or ensembles to read from the file. 
+      Number of pings or ensembles to read from the file.
       Default is None, read entire file
     rebuild_index : bool
       Force rebuild of dolfyn-written datafile index. Useful for code updates.
@@ -218,9 +218,14 @@ def _init_burst_readers(self, ):
     def init_data(self, ens_start, ens_stop):
         outdat = {}
         nens = int(ens_stop - ens_start)
+
+        # ID 26 usually only recorded in first ensemble
         n26 = ((self._index['ID'] == 26) &
                (self._index['ens'] >= ens_start) &
                (self._index['ens'] < ens_stop)).sum()
+        if not n26 and 26 in self._burst_readers:
+            self._burst_readers.pop(26)
+
         for ky in self._burst_readers:
             if ky == 26:
                 n = n26
@@ -234,6 +239,7 @@ def init_data(self, ens_start, ens_stop):
             outdat[ky]['units'] = self._burst_readers[ky].data_units()
             outdat[ky]['long_name'] = self._burst_readers[ky].data_longnames()
             outdat[ky]['standard_name'] = self._burst_readers[ky].data_stdnames()
+
         return outdat
 
     def _read_hdr(self, do_cs=False):
@@ -273,13 +279,16 @@ def readfile(self, ens_start=0, ens_stop=None):
             except IOError:
                 return outdat
             id = hdr['id']
-            if id in [21, 22, 23, 24, 28]:  # vel, bt, vel_b5, echo
+            if id in [21, 22, 23, 24, 28]:  # "burst data record" (vel + ast),
+                # "avg data record" (vel_avg + ast_avg), "bottom track data record" (bt),
+                # "interleaved burst data record" (vel_b5), "echosounder record" (echo)
                 self._read_burst(id, outdat[id], c)
-            elif id in [26]:  # alt_raw (altimeter burst)
+            elif id in [26]:
+                # "burst altimeter raw record" (alt_raw) - recorded on nens==0
                 rdr = self._burst_readers[26]
                 if not hasattr(rdr, '_nsamp_index'):
                     first_pass = True
-                    tmp_idx = rdr._nsamp_index = rdr._names.index('altraw_nsamp')  # noqa
+                    tmp_idx = rdr._nsamp_index = rdr._names.index('nsamp_alt')
                     shift = rdr._nsamp_shift = calcsize(
                         defs._format(rdr._format[:tmp_idx],
                                      rdr._N[:tmp_idx]))
@@ -301,9 +310,9 @@ def readfile(self, ens_start=0, ens_stop=None):
                     rdr._cs_struct = defs.Struct(
                         '<' + '{}H'.format(int(rdr.nbyte // 2)))
                     # Initialize the array
-                    outdat[26]['altraw_samp'] = defs._nans(
+                    outdat[26]['samp_alt'] = defs._nans(
                         [rdr._N[tmp_idx],
-                         len(outdat[26]['altraw_samp'])],
+                         len(outdat[26]['samp_alt'])],
                         dtype=np.uint16)
                 else:
                     if sz != rdr._N[tmp_idx]:
@@ -314,8 +323,9 @@ def readfile(self, ens_start=0, ens_stop=None):
                 outdat[id]['ensemble'][c26] = c
                 c26 += 1
 
-            elif id in [27, 29, 30, 31, 35, 36]:  # bt record, DVL,
-                # alt record, avg alt_raw record, raw echo, raw echo transmit
+            elif id in [27, 29, 30, 31, 35, 36]:  # unknown how to handle
+                # "bottom track record", DVL, "altimeter record", "avg altimeter raw record", 
+                # "raw echosounder data record", "raw echosounder transmit data record"
                 if self.debug:
                     logging.debug(
                         "Skipped ID: 0x{:02X} ({:02d})\n".format(id, id))
@@ -401,8 +411,8 @@ def _reorg(dat):
     cfg['inst_make'] = 'Nortek'
     cfg['inst_type'] = 'ADCP'
 
-    for id, tag in [(21, ''), (22, '_avg'), (23, '_bt'), 
-                    (24, '_b5'), (26, '_ast'), (28, '_echo')]:
+    for id, tag in [(21, ''), (22, '_avg'), (23, '_bt'),
+                    (24, '_b5'), (26, 'raw'), (28, '_echo')]:
         if id in [24, 26]:
             collapse_exclude = [0]
         else:
@@ -454,10 +464,10 @@ def _reorg(dat):
                 outdat['standard_name'][ky + tag] = 'number_of_observations'
 
         for ky in ['vel', 'amp', 'corr', 'prcnt_gd', 'echo', 'dist',
-                   'orientmat', 'angrt', 'quaternions', 'ast_pressure',
-                   'alt_dist', 'alt_quality', 'alt_status',
-                   'ast_dist', 'ast_quality', 'ast_offset_time',
-                   'altraw_nsamp', 'altraw_dsamp', 'altraw_samp',
+                   'orientmat', 'angrt', 'quaternions', 'pressure_alt',
+                   'le_dist_alt', 'le_quality_alt', 'status_alt',
+                   'ast_dist_alt', 'ast_quality_alt', 'ast_offset_time_alt',
+                   'nsamp_alt', 'dsamp_alt', 'samp_alt',
                    'status0', 'fom', 'temp_press', 'press_std',
                    'pitch_std', 'roll_std', 'heading_std', 'xmit_energy',
                    ]:
@@ -466,20 +476,19 @@ def _reorg(dat):
 
     # Move 'altimeter raw' data to its own down-sampled structure
     if 26 in dat:
-        ard = outdat['altraw']
         for ky in list(outdat['data_vars']):
-            if ky.endswith('_ast'):
-                grp = ky.split('.')[0]
-                if '.' in ky and grp not in ard:
-                    ard[grp] = {}
-                ard[ky.rstrip('_ast')] = outdat['data_vars'].pop(ky)
+            if ky.endswith('raw') and not ky.endswith('_altraw'):
+                outdat['data_vars'].pop(ky)
+        outdat['coords']['time_altraw'] = outdat['coords'].pop('timeraw')
+        outdat['data_vars']['samp_altraw'] = outdat['data_vars']['samp_altraw'].astype('float32') / 2**8  # convert "signed fractional" to float
 
         # Read altimeter status
-        alt_status = lib._alt_status2data(outdat['data_vars']['alt_status'])
-        for ky in alt_status:
+        outdat['data_vars'].pop('status_altraw')
+        status_alt = lib._alt_status2data(outdat['data_vars']['status_alt'])
+        for ky in status_alt:
             outdat['attrs'][ky] = lib._collapse(
-                alt_status[ky].astype('uint8'), name=ky)
-        outdat['data_vars'].pop('alt_status')
+                status_alt[ky].astype('uint8'), name=ky)
+        outdat['data_vars'].pop('status_alt')
 
         # Power level index
         power = {0: 'high', 1: 'med-high', 2: 'med-low', 3: 'low'}
@@ -555,7 +564,7 @@ def _reduce(data):
     --- from different data structures within the same ensemble --- by
     averaging.
     """
-    
+
     dv = data['data_vars']
     dc = data['coords']
     da = data['attrs']
@@ -571,14 +580,14 @@ def _reduce(data):
 
     if 'vel' in dv:
         dc['range'] = ((np.arange(dv['vel'].shape[1])+1) *
-                    da['cell_size'] +
-                    da['blank_dist'])
+                       da['cell_size'] +
+                       da['blank_dist'])
         da['fs'] = da['filehead_config']['BURST']['SR']
         tmat = da['filehead_config']['XFBURST']
     if 'vel_avg' in dv:
         dc['range_avg'] = ((np.arange(dv['vel_avg'].shape[1])+1) *
-                    da['cell_size_avg'] +
-                    da['blank_dist_avg'])
+                           da['cell_size_avg'] +
+                           da['blank_dist_avg'])
         dv['orientmat'] = dv.pop('orientmat_avg')
         tmat = da['filehead_config']['XFAVG']
         da['fs'] = da['filehead_config']['PLAN']['MIAVG']
@@ -605,7 +614,7 @@ def _reduce(data):
     theta = da['filehead_config']['BEAMCFGLIST'][0]
     if 'THETA=' in theta:
         da['beam_angle'] = int(theta[13:15])
-    
+
     tm = np.zeros((tmat['ROWS'], tmat['COLS']), dtype=np.float32)
     for irow in range(tmat['ROWS']):
         for icol in range(tmat['COLS']):
diff --git a/mhkit/dolfyn/io/nortek2_defs.py b/mhkit/dolfyn/io/nortek2_defs.py
index 6b9b1d8f2..8ec776b38 100644
--- a/mhkit/dolfyn/io/nortek2_defs.py
+++ b/mhkit/dolfyn/io/nortek2_defs.py
@@ -296,11 +296,11 @@ def _calc_echo_struct(config, nc):
     flags = lib._headconfig_int2dict(config)
     dd = copy(_burst_hdr)
     dd[19] = ('blank_dist', 'H', [], _LinFunc(0.001))  # m
-    if any([flags[nm] for nm in ['vel', 'amp', 'corr', 'alt', 'ast',
-                                 'alt_raw', 'p_gd', 'std']]):
+    if any([flags[nm] for nm in ['vel', 'amp', 'corr', 'le', 'ast',
+                                 'altraw', 'p_gd', 'std']]):
         raise Exception("Echosounder ping contains invalid data?")
     if flags['echo']:
-        dd += [('echo', 'H', [nc], _LinFunc(0.01, dtype=dt32), 'dB', 
+        dd += [('echo', 'H', [nc], _LinFunc(0.01, dtype=dt32), 'dB',
                 'Echo Sounder Acoustic Signal Backscatter', 'acoustic_target_strength_in_sea_water')]
     if flags['ahrs']:
         dd += _ahrs_def
@@ -320,29 +320,33 @@ def _calc_burst_struct(config, nb, nc):
     if flags['corr']:
         dd.append(('corr', 'B', [nb, nc], None, '%', 'Acoustic Signal Correlation',
                   'beam_consistency_indicator_from_multibeam_acoustic_doppler_velocity_profiler_in_sea_water'))
-    if flags['alt']:
+    if flags['le']:
         # There may be a problem here with reading 32bit floats if
         # nb and nc are odd
-        dd += [('alt_dist', 'f', [], _LinFunc(dtype=dt32), 'm', 'Altimeter Range', 'altimeter_range'),
-               ('alt_quality', 'H', [], _LinFunc(0.01, dtype=dt32), '1', 'Altimeter Quality Indicator'),
-               ('alt_status', 'H', [], None, '1', 'Altimeter Status')]
+        dd += [('le_dist_alt', 'f', [], _LinFunc(dtype=dt32), 'm', 'Altimeter Range Leading Edge Algorithm',
+                'altimeter_range'),
+               ('le_quality_alt', 'H', [], _LinFunc(0.01, dtype=dt32), 'dB',
+                'Altimeter Quality Indicator Leading Edge Algorithm'),
+               ('status_alt', 'H', [], None, '1', 'Altimeter Status')]
     if flags['ast']:
         dd += [
-            ('ast_dist', 'f', [], _LinFunc(dtype=dt32), 'm', 'Acoustic Surface Tracking Range'),
-            ('ast_quality', 'H', [], _LinFunc(0.01, dtype=dt32), '1',
-             'Acoustic Surface Tracking Quality Indicator'),
-            ('ast_offset_time', 'h', [], _LinFunc(0.0001, dtype=dt32),
+            ('ast_dist_alt', 'f', [], _LinFunc(dtype=dt32), 'm', 'Altimeter Range Acoustic Surface Tracking',
+             'altimeter_range'),
+            ('ast_quality_alt', 'H', [], _LinFunc(0.01, dtype=dt32), 'dB',
+             'Altimeter Quality Indicator Acoustic Surface Tracking'),
+            ('ast_offset_time_alt', 'h', [], _LinFunc(0.0001, dtype=dt32),
              's', 'Acoustic Surface Tracking Time Offset to Velocity Ping'),
-            ('ast_pressure', 'f', [], None, 'dbar', 'Pressure measured during AST ping',
+            ('pressure_alt', 'f', [], None, 'dbar', 'Pressure measured during AST ping',
              'sea_water_pressure'),
-            ('ast_spare', 'B7x', [], None),
+            # This use of 'x' here is a hack
+            ('spare', 'B7x', [], None),
         ]
-    if flags['alt_raw']:
+    if flags['altraw']:
         dd += [
-            ('altraw_nsamp', 'I', [], None, '1', 'Number of Altimeter Samples'),
-            ('altraw_dsamp', 'H', [], _LinFunc(0.0001, dtype=dt32), 'm',
+            ('nsamp_alt', 'I', [], None, '1', 'Number of Altimeter Samples'),
+            ('dsamp_alt', 'H', [], _LinFunc(0.0001, dtype=dt32), 'm',
              'Altimeter Distance between Samples'),
-            ('altraw_samp', 'h', [], None),
+            ('samp_alt', 'h', [], None, '1', 'Altimeter Samples'),
         ]
     if flags['ahrs']:
         dd += _ahrs_def
diff --git a/mhkit/dolfyn/io/nortek2_lib.py b/mhkit/dolfyn/io/nortek2_lib.py
index f3575b6e6..d5ee385f3 100644
--- a/mhkit/dolfyn/io/nortek2_lib.py
+++ b/mhkit/dolfyn/io/nortek2_lib.py
@@ -101,8 +101,8 @@ def _create_index(infile, outfile, N_ens, debug):
     fout = open(_abspath(outfile), 'wb')
     fout.write(b'Index Ver:')
     fout.write(struct.pack('<H', _index_version))
-    ids = [21, 22, 23, 24, 26, 28, 
-           27, 29, 30, 31, 35, 36]  
+    ids = [21, 22, 23, 24, 26, 28,
+           27, 29, 30, 31, 35, 36]
     # Saved: burst, avg, bt, vel_b5, alt_raw, echo
     # Not saved: bt record, DVL, alt record, avg alt_raw record, raw echo, raw echo transmit
     ens = dict.fromkeys(ids, 0)
@@ -117,7 +117,7 @@ def _create_index(infile, outfile, N_ens, debug):
             dat = _hdr.unpack(fin.read(_hdr.size))
         except:
             break
-        if dat[2] in ids:  
+        if dat[2] in ids:
             idk = dat[2]
             d_ver, d_off, config = struct.unpack('<BBH', fin.read(4))
             fin.seek(4, 1)
@@ -192,7 +192,7 @@ def _check_index(idx, infile, fix_hw_ens=False):
 
 def _boolarray_firstensemble_ping(index):
     """
-    Return a boolean of the index that indicates only the first ping in 
+    Return a boolean of the index that indicates only the first ping in
     each ensemble.
     """
     dens = np.ones(index['ens'].shape, dtype='bool')
@@ -340,8 +340,8 @@ def _headconfig_int2dict(val, mode='burst'):
             vel=_getbit(val, 5),
             amp=_getbit(val, 6),
             corr=_getbit(val, 7),
-            alt=_getbit(val, 8),
-            alt_raw=_getbit(val, 9),
+            le=_getbit(val, 8),
+            altraw=_getbit(val, 9),
             ast=_getbit(val, 10),
             echo=_getbit(val, 11),
             ahrs=_getbit(val, 12),
@@ -456,7 +456,7 @@ def _collapse(vec, name=None, exclude=[]):
                           "Values found: {} (counts: {}).\n"
                           "Using the most common value: {}".format(
                               name, list(uniq), list(counts), val))
-    
+
         return val
 
 
diff --git a/mhkit/dolfyn/io/nortek_defs.py b/mhkit/dolfyn/io/nortek_defs.py
index 180af05eb..c0ad2ac79 100644
--- a/mhkit/dolfyn/io/nortek_defs.py
+++ b/mhkit/dolfyn/io/nortek_defs.py
@@ -155,7 +155,7 @@ def sci_func(self, data):
                      dtype=np.float64,
                      group='coords',
                      default_val=nan,
-                     units='seconds since 1970-01-01 00:00:00',
+                     units='seconds since 1970-01-01 00:00:00 UTC',
                      long_name='Time',
                      standard_name='time',
                      ),
@@ -201,7 +201,7 @@ def sci_func(self, data):
                      factor=0.1,
                      units='degree',
                      long_name='Roll',
-                     standard_name='platform_roll'
+                     standard_name='platform_roll',
                      ),
     'temp': _VarAtts(dims=[],
                      dtype=np.float32,
@@ -241,7 +241,7 @@ def sci_func(self, data):
     'time': _VarAtts(dims=[],
                      dtype=np.float64,
                      group='coords',
-                     units='seconds since 1970-01-01 00:00:00',
+                     units='seconds since 1970-01-01 00:00:00 UTC',
                      long_name='Time',
                      standard_name='time',
                      ),
@@ -340,3 +340,144 @@ def sci_func(self, data):
                     standard_name='signal_intensity_from_multibeam_acoustic_doppler_velocity_sensor_in_sea_water',
                     ),
 }
+
+waves_hdrdata = {
+    'time_alt': _VarAtts(dims=[],
+                         dtype=np.float64,
+                         group='coords',
+                         default_val=nan,
+                         units='seconds since 1970-01-01 00:00:00 UTC',
+                         long_name='Time',
+                         standard_name='time',
+                         ),
+    'batt_alt': _VarAtts(dims=[],
+                         dtype=np.uint16,
+                         group='data_vars',
+                         default_val=nan,
+                         factor=0.1,
+                         units='V',
+                         long_name='Battery Voltage',
+                         ),
+    'c_sound_alt': _VarAtts(dims=[],
+                            dtype=np.float32,
+                            group='data_vars',
+                            default_val=nan,
+                            factor=0.1,
+                            units='m s-1',
+                            long_name='Speed of Sound',
+                            standard_name='speed_of_sound_in_sea_water',
+                            ),
+    'heading_alt': _VarAtts(dims=[],
+                            dtype=np.float32,
+                            group='data_vars',
+                            default_val=nan,
+                            factor=0.1,
+                            units='degree',
+                            long_name='Heading',
+                            standard_name='platform_orientation',
+                            ),
+    'pitch_alt': _VarAtts(dims=[],
+                          dtype=np.float32,
+                          group='data_vars',
+                          default_val=nan,
+                          factor=0.1,
+                          units='degree',
+                          long_name='Pitch',
+                          standard_name='platform_pitch',
+                          ),
+    'roll_alt': _VarAtts(dims=[],
+                         dtype=np.float32,
+                         group='data_vars',
+                         default_val=nan,
+                         factor=0.1,
+                         units='degree',
+                         long_name='Roll',
+                         standard_name='platform_roll',
+                         ),
+    'pressure1_alt': _VarAtts(dims=[],
+                              dtype=np.float32,
+                              group='data_vars',
+                              default_val=nan,
+                              factor=0.001,
+                              units='dbar',
+                              long_name='Pressure Min',
+                              standard_name='sea_water_pressure',
+                              ),
+    'pressure2_alt': _VarAtts(dims=[],
+                              dtype=np.float32,
+                              group='data_vars',
+                              default_val=nan,
+                              factor=0.001,
+                              units='dbar',
+                              long_name='Pressure Max',
+                              standard_name='sea_water_pressure',
+                              ),
+    'temp_alt': _VarAtts(dims=[],
+                         dtype=np.float32,
+                         group='data_vars',
+                         default_val=nan,
+                         factor=0.01,
+                         units='degree_C',
+                         long_name='Temperature',
+                         standard_name='sea_water_temperature',
+                         ),
+}
+
+waves_data = {
+    'pressure_alt': _VarAtts(dims=[],
+                             dtype=np.float32,
+                             group='data_vars',
+                             default_val=nan,
+                             factor=0.001,
+                             units='dbar',
+                             long_name='Pressure',
+                             standard_name='sea_water_pressure',
+                             ),
+    'dist1_alt': _VarAtts(dims=[],
+                          dtype=np.uint16,
+                          group='data_vars',
+                          default_val=nan,
+                          factor=0.001,
+                          units='m',
+                          long_name='AST distance1 on vertical beam',
+                          standard_name='altimeter_range',
+                          ),
+    'dist2_alt': _VarAtts(dims=[],
+                          dtype=np.uint16,
+                          group='data_vars',
+                          default_val=nan,
+                          factor=0.001,
+                          units='m',
+                          long_name='AST distance2 on vertical beam',
+                          standard_name='altimeter_range',
+                          ),
+    'AnaIn1_alt': _VarAtts(dims=[],
+                           dtype=np.float32,
+                           group='sys',
+                           default_val=nan,
+                           units='n/a',
+                           ),
+    'vel_alt': _VarAtts(dims=[4, 'n'],
+                        dtype=np.float32,
+                        group='data_vars',
+                        default_val=nan,
+                        factor=0.001,
+                        units='m s-1',
+                        long_name='Water Velocity',
+                        ),
+    'amp_alt': _VarAtts(dims=[4, 'n'],
+                        dtype=np.uint8,
+                        group='data_vars',
+                        default_val=nan,
+                        units='1',
+                        long_name='Acoustic Signal Amplitude',
+                        standard_name='signal_intensity_from_multibeam_acoustic_doppler_velocity_sensor_in_sea_water',
+                        ),
+    'quality_alt': _VarAtts(dims=[],
+                            dtype=np.float32,
+                            group='data_vars',
+                            default_val=nan,       
+                            units='1',
+                            long_name='Altimeter Quality Indicator',
+                            ),
+}
diff --git a/mhkit/dolfyn/tools/fft.py b/mhkit/dolfyn/tools/fft.py
index 8810c78b0..04d982e60 100644
--- a/mhkit/dolfyn/tools/fft.py
+++ b/mhkit/dolfyn/tools/fft.py
@@ -32,12 +32,14 @@ def fft_frequency(nfft, fs, full=False):
 
 
 def _getwindow(window, nfft):
-    if window == 'hann':
+    if 'hann' in window:
         window = np.hanning(nfft)
-    elif window == 'hamm':
+    elif 'hamm' in window:
         window = np.hamming(nfft)
-    elif window is None or window == 1:
+    elif window is None or np.sum(window == 1):
         window = np.ones(nfft)
+    if len(window) != nfft:
+        raise ValueError("Custom window length must be equal to nfft")
     return window
 
 
diff --git a/mhkit/dolfyn/velocity.py b/mhkit/dolfyn/velocity.py
index 4ab0194bc..8c2ba9322 100644
--- a/mhkit/dolfyn/velocity.py
+++ b/mhkit/dolfyn/velocity.py
@@ -559,6 +559,8 @@ def bin_average(self, raw_ds, out_ds=None, names=None):
         for ky in names:
             # set up dimensions and coordinates for Dataset
             dims_list = raw_ds[ky].dims
+            if any([ar for ar in dims_list if 'altraw' in ar]):
+                continue
             coords_dict = {}
             for nm in dims_list:
                 if 'time' in nm:
@@ -630,6 +632,8 @@ def bin_variance(self, raw_ds, out_ds=None, names=None, suffix='_var'):
         for ky in names:
             # set up dimensions and coordinates for dataarray
             dims_list = raw_ds[ky].dims
+            if any([ar for ar in dims_list if 'altraw' in ar]):
+                continue
             coords_dict = {}
             for nm in dims_list:
                 if 'time' in nm:
diff --git a/mhkit/tests/dolfyn/test_read_adp.py b/mhkit/tests/dolfyn/test_read_adp.py
index cfd7f306b..b4e4a833a 100644
--- a/mhkit/tests/dolfyn/test_read_adp.py
+++ b/mhkit/tests/dolfyn/test_read_adp.py
@@ -148,16 +148,28 @@ def test_nortek2_crop(self):
                        range=[50, 100])
         td_sig_ie_crop = read('Sig500_Echo_crop.ad2cp')
 
+        crop_ensembles(infile=tb.exdt('BenchFile01.ad2cp'),
+                       outfile=tb.exdt('BenchFile01_crop.ad2cp'),
+                       range=[50, 100])
+        td_sig_crop = read('BenchFile01_crop.ad2cp')
+
         if make_data:
             save(td_sig_ie_crop, 'Sig500_Echo_crop.nc')
+            save(td_sig_crop, 'BenchFile01_crop.nc')
             return
 
         os.remove(tb.exdt('Sig500_Echo.ad2cp.index'))
         os.remove(tb.exdt('Sig500_Echo_crop.ad2cp'))
         os.remove(tb.exdt('Sig500_Echo_crop.ad2cp.index'))
+        os.remove(tb.exdt('BenchFile01.ad2cp.index'))
+        os.remove(tb.exdt('BenchFile01_crop.ad2cp'))
+        os.remove(tb.exdt('BenchFile01_crop.ad2cp.index'))
 
         cd_sig_ie_crop = load('Sig500_Echo_crop.nc')
+        cd_sig_crop = load('BenchFile01_crop.nc')
+
         assert_allclose(td_sig_ie_crop, cd_sig_ie_crop, atol=1e-6)
+        assert_allclose(td_sig_crop, cd_sig_crop, atol=1e-6)
 
 
 if __name__ == '__main__':
diff --git a/mhkit/tests/dolfyn/test_read_io.py b/mhkit/tests/dolfyn/test_read_io.py
index 16f1b2c6a..fdc9cfa74 100644
--- a/mhkit/tests/dolfyn/test_read_io.py
+++ b/mhkit/tests/dolfyn/test_read_io.py
@@ -15,13 +15,19 @@
 class io_testcase(unittest.TestCase):
     def test_save(self):
         ds = tv.dat.copy(deep=True)
-
+        ds2 = tp.dat_sig.copy(deep=True)
         save_netcdf(ds, 'test_save')
+        save_netcdf(ds2, 'test_save_comp.nc', compression=True)
         save_matlab(ds, 'test_save')
 
         assert os.path.exists(rfnm('test_save.nc'))
+        assert os.path.exists(rfnm('test_save_comp.nc'))
         assert os.path.exists(rfnm('test_save.mat'))
 
+        os.remove(rfnm('test_save.nc'))
+        os.remove(rfnm('test_save_comp.nc'))
+        os.remove(rfnm('test_save.mat'))
+
     def test_matlab_io(self):
         nens = 100
         td_vec = read('vector_data_imu01.VEC', nens=nens)
diff --git a/mhkit/tests/dolfyn/test_rotate_adp.py b/mhkit/tests/dolfyn/test_rotate_adp.py
index 4ec21353d..b74e38e8c 100644
--- a/mhkit/tests/dolfyn/test_rotate_adp.py
+++ b/mhkit/tests/dolfyn/test_rotate_adp.py
@@ -151,8 +151,8 @@ def test_rotate_earth2principal(self):
             td_rdi.vel.mean('range'))
         td_sig.attrs['principal_heading'] = calc_principal_heading(
             td_sig.vel.mean('range'))
-        td_awac.attrs['principal_heading'] = calc_principal_heading(td_awac.vel.mean('range'),
-                                                                    tidal_mode=False)
+        td_awac.attrs['principal_heading'] = calc_principal_heading(
+            td_awac.vel.mean('range'), tidal_mode=False)
         rotate2(td_rdi, 'principal', inplace=True)
         rotate2(td_sig, 'principal', inplace=True)
         rotate2(td_awac, 'principal', inplace=True)