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bug fix: altiude and TAS
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@junzis
junzis committed Jan 23, 2021
1 parent 89e67fa commit 3bb8c36
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Showing 2 changed files with 45 additions and 38 deletions.
31 changes: 15 additions & 16 deletions pyModeS/decoder/bds/bds05.py
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Original file line number Diff line number Diff line change
Expand Up @@ -34,13 +34,13 @@ def airborne_position(msg0, msg1, t0, t1):
raise RuntimeError("Both even and odd CPR frames are required.")

# 131072 is 2^17, since CPR lat and lon are 17 bits each.
cprlat_even = common.bin2int(mb0[22:39]) / 131072.0
cprlon_even = common.bin2int(mb0[39:56]) / 131072.0
cprlat_odd = common.bin2int(mb1[22:39]) / 131072.0
cprlon_odd = common.bin2int(mb1[39:56]) / 131072.0
cprlat_even = common.bin2int(mb0[22:39]) / 131072
cprlon_even = common.bin2int(mb0[39:56]) / 131072
cprlat_odd = common.bin2int(mb1[22:39]) / 131072
cprlon_odd = common.bin2int(mb1[39:56]) / 131072

air_d_lat_even = 360.0 / 60
air_d_lat_odd = 360.0 / 59
air_d_lat_even = 360 / 60
air_d_lat_odd = 360 / 59

# compute latitude index 'j'
j = common.floor(59 * cprlat_even - 60 * cprlat_odd + 0.5)
Expand All @@ -64,13 +64,13 @@ def airborne_position(msg0, msg1, t0, t1):
nl = common.cprNL(lat)
ni = max(common.cprNL(lat) - 0, 1)
m = common.floor(cprlon_even * (nl - 1) - cprlon_odd * nl + 0.5)
lon = (360.0 / ni) * (m % ni + cprlon_even)
lon = (360 / ni) * (m % ni + cprlon_even)
else:
lat = lat_odd
nl = common.cprNL(lat)
ni = max(common.cprNL(lat) - 1, 1)
m = common.floor(cprlon_even * (nl - 1) - cprlon_odd * nl + 0.5)
lon = (360.0 / ni) * (m % ni + cprlon_odd)
lon = (360 / ni) * (m % ni + cprlon_odd)

if lon > 180:
lon = lon - 360
Expand All @@ -95,11 +95,11 @@ def airborne_position_with_ref(msg, lat_ref, lon_ref):

mb = common.hex2bin(msg)[32:]

cprlat = common.bin2int(mb[22:39]) / 131072.0
cprlon = common.bin2int(mb[39:56]) / 131072.0
cprlat = common.bin2int(mb[22:39]) / 131072
cprlon = common.bin2int(mb[39:56]) / 131072

i = int(mb[21])
d_lat = 360.0 / 59 if i else 360.0 / 60
d_lat = 360 / 59 if i else 360 / 60

j = common.floor(lat_ref / d_lat) + common.floor(
0.5 + ((lat_ref % d_lat) / d_lat) - cprlat
Expand All @@ -110,9 +110,9 @@ def airborne_position_with_ref(msg, lat_ref, lon_ref):
ni = common.cprNL(lat) - i

if ni > 0:
d_lon = 360.0 / ni
d_lon = 360 / ni
else:
d_lon = 360.0
d_lon = 360

m = common.floor(lon_ref / d_lon) + common.floor(
0.5 + ((lon_ref % d_lon) / d_lon) - cprlon
Expand Down Expand Up @@ -143,9 +143,8 @@ def altitude(msg):

if tc < 19:
altcode = altbin[0:6] + "0" + altbin[6:]
alt = common.altitude(altcode)
else:
altcode = altbin[0:6] + "0" + altbin[6:]

alt = common.altitude(altcode)
alt = common.bin2int(altbin) * 3.28084

return alt
52 changes: 30 additions & 22 deletions pyModeS/decoder/bds/bds09.py
View file
Original file line number Diff line number Diff line change
Expand Up @@ -24,7 +24,7 @@ def airborne_velocity(msg, source=False):
- Angle (degree), either ground track or heading
- Vertical rate (ft/min)
- Speed type ('GS' for ground speed, 'AS' for airspeed)
- [Optional] Direction source ('TRUE_NORTH' or 'MAGENTIC_NORTH')
- [Optional] Direction source ('TRUE_NORTH' or 'MAGNETIC_NORTH')
- [Optional] Vertical rate source ('BARO' or 'GNSS')
"""
Expand All @@ -35,29 +35,35 @@ def airborne_velocity(msg, source=False):

subtype = common.bin2int(mb[5:8])

if common.bin2int(mb[14:24]) == 0 or common.bin2int(mb[25:35]) == 0:
return None

if subtype in (1, 2):
v_ew_sign = -1 if mb[13] == "1" else 1
v_ew = common.bin2int(mb[14:24]) - 1 # east-west velocity
if subtype == 2: # Supersonic
v_ew *= 4

v_ns_sign = -1 if mb[24] == "1" else 1
v_ns = common.bin2int(mb[25:35]) - 1 # north-south velocity
if subtype == 2: # Supersonic
v_ns *= 4
v_ew = common.bin2int(mb[14:24])
v_ns = common.bin2int(mb[25:35])

if v_ew == 0 or v_ns == 0:
spd = None
trk_or_hdg = None
vs = None
else:
v_ew_sign = -1 if mb[13] == "1" else 1
v_ew = v_ew - 1 # east-west velocity
if subtype == 2: # Supersonic
v_ew *= 4

v_we = v_ew_sign * v_ew
v_sn = v_ns_sign * v_ns
v_ns_sign = -1 if mb[24] == "1" else 1
v_ns = v_ns - 1 # north-south velocity
if subtype == 2: # Supersonic
v_ns *= 4

spd = math.sqrt(v_sn * v_sn + v_we * v_we) # unit in kts
spd = int(spd)
v_we = v_ew_sign * v_ew
v_sn = v_ns_sign * v_ns

trk = math.atan2(v_we, v_sn)
trk = math.degrees(trk) # convert to degrees
trk = trk if trk >= 0 else trk + 360 # no negative val
spd = math.sqrt(v_sn * v_sn + v_we * v_we) # unit in kts
spd = int(spd)

trk = math.atan2(v_we, v_sn)
trk = math.degrees(trk) # convert to degrees
trk = trk if trk >= 0 else trk + 360 # no negative val

spd_type = "GS"
trk_or_hdg = round(trk, 2)
Expand All @@ -67,13 +73,15 @@ def airborne_velocity(msg, source=False):
if mb[13] == "0":
hdg = None
else:
hdg = common.bin2int(mb[14:24]) / 1024.0 * 360.0
hdg = common.bin2int(mb[14:24]) / 1024 * 360.0
hdg = round(hdg, 2)

trk_or_hdg = hdg

spd = common.bin2int(mb[25:35])

spd = None if spd == 0 else spd - 1

if subtype == 4: # Supersonic
spd *= 4

Expand All @@ -82,7 +90,7 @@ def airborne_velocity(msg, source=False):
else:
spd_type = "TAS"

dir_type = "MAGENTIC_NORTH"
dir_type = "MAGNETIC_NORTH"

vr_source = "GNSS" if mb[35] == "0" else "BARO"
vr_sign = -1 if mb[36] == "1" else 1
Expand All @@ -96,7 +104,7 @@ def airborne_velocity(msg, source=False):


def altitude_diff(msg):
"""Decode the differece between GNSS and barometric altitude.
"""Decode the difference between GNSS and barometric altitude.
Args:
msg (str): 28 hexdigits string, TC=19
Expand Down

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