APPENDIX F
DC-8 DATA DISTRIBUTION SYSTEM (DADS) CHARACTERISTICS
DC-8 Data Acquisition and Distribution System
(DADS)
Characteristics and Output Products
DC-8 DADS Data Products
A. In-Flight Data Products
During each flight there are several DADS displays,
viewable on monitors throughout the cabin. The DADS Parameter Display
(see table F1) shows a subset of DADS data in table format. The
Track Plot Display shows the aircraft flight track superimposed
on a reference map. The Real-Time Plot shows several parameters
as a color graph, generally in a time-series strip chart format.
All of these are configurable as required and are continuously
updated. In addition, the Weather Satellite APT Receiver displays
real-time satellite images from the NOAA polar orbiters whenever
available. It is also be possible to graphically examine all DADS
parameters from any portion of the flight at the DADS station computer
if necessary.
The DC-8 DADS serial transfer of housekeeping
data is available in-flight to allow easy access to aircraft data
by experimenter computers. The data is in ASCII format, in engineering
units Data is sent at one second intervals with transmission rates
of 1200, 9600, and 19.2K baud. Format and hardware interface requirements
are described in another section below.
B. Post-Flight Data Products
After each flight several hardcopy DADS data products
will be available. The DC-8 Mission Director Log will contain time/data
stamped commentary on the flight. A set of Track Plots will show
the DC-8 flight track, including flight-level winds. A set of Time-Series
Plots will show a selection of DADS parameters. The Parameter Printout
will contain 10-second picks of representative parameters. Other
graphical products may be produced by request of the Mission Director.
All of these products will be given to the GTE Project Office after
each flight, in both hardcopy and electronic format. The DADS ASCII-formatted
data set will also be submitted.
TABLE F1. ICATS Parameter Video Display Screen
Day
|
ddd
|
time
|
Hh:mm:ss.sss
|
Latitude
|
Deg mm.m
|
O3
|
ppbv
|
Longitude
|
Deg mm.m
|
CO
|
ppbv
|
Press altitude
|
ft
|
NO
|
volts
|
Press altitude
|
m
|
CO2
|
ppmv
|
pressure
|
mb
|
CH4
|
ppmv
|
Cabin altitude
|
ft
|
Aerosol num density
|
Counts/cc
|
True air speed
|
kts
|
Cryo H2O
|
Deg C
|
Mach Number
|
|
D/F point 2
|
Deg C
|
Ground Speed
|
kts
|
D/F point 3
|
Deg C
|
Vertical speed
|
Ft/min
|
Specific humidity
|
GH2O/kg air
|
Wind Speed
|
kts
|
Relative humidity(ice)
|
%
|
Wind Direction
|
deg
|
Relative humiditywtr)
|
%
|
To waypoint Number
|
|
Static air temperature
|
Deg C
|
Time to go
|
min
|
SAT computed
|
Deg C
|
True Heading
|
deg
|
Total air temperature
|
Deg C
|
Drift angle
|
deg
|
Potential temperature
|
Deg K
|
Pitch angle
|
deg
|
IR surface temperature
|
Deg C
|
Roll angle
|
deg
|
Sun elevation angle/er
|
deg
|
GPS altitude msl
|
ft
|
Sun azimuth angle/er
|
deg
|
Radar Altitude
|
ft
|
Solar zenith angle
|
deg
|
DADS Serial Outputs to Experiments
The DADS ASCII-formatted data is available in real
time in-flight through a serial interface, and post-flight as a
computer file (9600/19.2K baud format only). This section describes
the formats and hardware interface requirements used to access
this data.
A. 1200 Baud Data Format
Data is transferred once per second at 1200 baud
in two 56-character blocks which each begin with a unique character
identifier and end with an ASCII carriage return and line feed.
The total number of characters every second is 112. Parameter fields
within each block are not separated by a space, but there may be
one or more blanks at the end of a block (before the carriage return
and line feed) to pad the length to 56 characters. Table F2 shows
the configuration, and Table F3 shows an example.
TABLE F2. DADS Serial Output
1200 Baud Block Configuration
Identifer |
Parameters |
Field Format |
Units |
A |
Day |
aaa
|
day of year |
|
Time (UT)
|
bb:bb:bb.bbb
|
hour:min:sec
|
|
Latitude
|
±cc cc.c |
degrees/minutes
|
|
Longitude |
±ddd dd.d
|
degrees/minutes
|
|
Pitch
|
eee.e
|
deg
|
|
Roll |
ffff.f
|
deg
|
|
Wind speed
|
ggg |
knots
|
|
Wind direction |
hhh |
deg |
|
True air speed |
iii
|
knots |
B |
Ground speed |
jjjj |
knots |
|
True heading |
kkk.k |
deg
|
|
Drift angle |
lll.l |
deg
|
|
Pressure altitude |
mmmmm |
feet |
|
Radar altitude |
nnnnn |
feet |
|
Dew/frost point temp (GE 1011 hygrometer) with state flagged |
ooooo.o |
deg C |
|
Dew/frost point temp (EG&G 300 hygrometer) with state
flagged |
ppppp.p |
deg C |
|
Static air temperature |
qqq.q |
deg C |
|
Total air temperature |
rrr.r |
deg C |
|
IR surface temperature |
sss.s |
deg C |
TABLE F3. DADS Serial Output 1200 Baud Block Example
Aaaabb:bb:bb.bbb±cc cc.c±ddd dd.deee.effff.fggghhhiii <cr><lf>
Bjjjjkkk.klll.lmmmmmnnnnnooooo.oppppp.pqqq.qrrr.rsss.s<cr><lf>
A32101:22:45.105+34 25.0-122 03.0-10.3 -45.6110270450 <cr><lf>
B 425212.3 5.12800024050-1012.4-3012.7-10.1 14.6-15.9 <cr><lf>
|
Key
<cr>
<lf>
|
ASCII carriage return
ASCII line feed
|
B. 9600/19.2K Baud Data Format
Data is transferred once per second at 9600 and 19.2K
baud in seven 56-character blocks which each begin with a unique
character identifier and end with an ASCII carriage return and
line feed. The total number of characters available every second
is 392. Parameter fields within each block (including the start-of-block
character) are separated by at least one space, and there may be
one or more blanks at the end of a block (before the carriage return
and line feed) to pad the length to 56 characters. The contents
of the first five blocks (identifiers C through G) are fixed. The
contents of the last two blocks (identifiers H and I) are at the
discretion of the Mission Manager and will be configured for TRACE-P.
Table F4 shows the configuration, and Table F5 shows an example.
TABLE F4. DADS Serial Output
9600/19.2K Baud Block Configuration
Identifier |
Parameters |
Field Format |
Units |
C |
Day |
aaa |
day of year |
|
Time (UT)
|
bb:bb:bb.bbb |
hour:min:sec |
|
Latitude |
±cc cc.c
|
degrees/minutes |
|
Longitude |
±ddd dd.d
|
degrees/minutes |
|
Pitch
|
eee.e
|
deg
|
|
Roll
|
ffff.f
|
deg
|
|
Wind speed |
ggg |
knots
|
D |
Wind direction |
hhh |
deg |
|
True air speed
|
iii |
knots
|
|
Ground speed |
jjjj
|
knots
|
|
True heading
|
kkk.k
|
deg
|
|
Drift angle
|
lll.l |
deg
|
|
Pressure altitude |
mmmmm |
feet
|
|
Radar altitude
|
nnnnn
|
feet
|
|
Dew/forst point temp
(GE 1011 hygrometer)
with state flagged
|
ooooo.o
|
deg C |
|
Dew/frost point temp
(EG&G 300 hygrometer)
with state flagged
|
ppppp.p |
deg C |
|
Static air teemperature |
qqq.q
|
deg C |
|
Total air temperature |
rrr.r
|
deg C |
E |
IR surface temperature |
sss.s |
deg C |
|
Static air temperature, calculated
|
ttt.t
|
deg C
|
|
Indicated air speed
|
uuu
|
knots
|
|
Vertical speed
|
vvvvv
|
ft/min
|
|
Distance to go |
wwwww.w
|
nm |
|
Time to go |
xxxx.x
|
min |
|
Align status |
yy |
|
F |
Cabin Altitude |
OOO.O |
feet |
|
Pressure
|
zzzzz
|
mb
|
|
Mach number
|
JJJJ.J
|
|
|
Cross track distance
|
K.KKK |
nm
|
|
Desired track |
LLLLL.L |
deg
|
|
Track angle error
|
MMMM.M |
deg
|
|
Track angle
|
NNNN.N |
deg
|
|
Specific humidity |
P.PPP |
g H2/kg air |
G |
Partial pressure H2O |
QQ.Q |
deg |
|
Relative humidity with respect to ice
|
RR.R |
mb |
|
Relative humidity with respect to water
|
SS.S
|
%
|
|
Saturation vapor pressure of water
|
TT.TT |
%
|
|
Saturation vapor pressure relative to ice
|
UU.UU
|
mb |
|
Sun elevation in ground reference frame,
refracted
|
VVV.V
|
mb |
|
Sun elevation in aircraft reference frame,
refracted
|
WWW.W |
deg
|
|
Sun azimuth in ground reference frame
|
XXX.X
|
deg
|
|
Sun azimuth in aircraft reference frame
relative to the aircraft nose
|
YYYY.Y
|
deg |
H |
Aerosol density
Cryo H2O
Ozone
CO
NO
CH4
CO2
Gps altitude msl
|
|
Counts/cc
Deg C
ppbv
ppbv
ppmv
ppmv
ppmv
ft
|
I |
CH4
CO2
Gps altitude msl Egi latitude
Egi longitude
Sun Elev Earth ref
Sun Elev A/C ref
Declination sun
Ra sun
Solar zenith angle
Specific humidity
|
|
ppmv
ppmv
ft
deg
deg
deg
deg
deg
deg
gmH2O/kg air |
TABLE F5. DADS Serial Data
9600/19.2K Baud Block Example
9600/19.2K Baud Block Example
|
C aaa bb:bb:bb.bbb ±cc cc.c ±ddd
dd.d eee.e ffff.f ggg<cr><lf>
D hhh iii jjjj kkk.k lll.l mmmmm nnnnn ooooo.o ppppp.p<cr><lf>
E qqq.q rrr.r sss.s ttt.t uuu vvvvvv wwwww.w xxxx.x yy<cr><lf>
F zzzzz JJJJ.J K.KKK LLLLL.L MMMM.M NNNN.N OOO.O P.PPP<cr><lf>
G QQ.Q RR.R SS.S TT.TT UU.UU VVV.V WWW.W XXX.X YYYY.Y <cr><lf>
H ****************************************************<cr><lf>
I ****************************************************<cr><lf>
C 321 01:22:45.105 +34 25.0 -122 03.0 -10.3
-45.6 110<cr><lf>
D 270 450 425 212.3 5.1 28000 24050 -1012.4 -3012.7<cr><lf>
E -10.1 14.6 -15.9 -9.4 410 -1250 -332.6 50.8 45<cr><lf>
F 5100 466.7 0.714 332.0 240.7 -11.8 202.0 0.269<cr><lf>
G 13.4 15.2 20.2 34.22 37.66 10.6 13.7 252.3 -160.2 <cr><lf>
H ****************************************************<cr><lf>
I ****************************************************<cr><lf>
|
Key
<cr> ASCII carriage return
<lf> ASCII line feed
****... block content subject to Mission Manager's discretion
|
C. General DADS Serial Output Format Information
All data parameters are in engineering units. For
integer formats, the number of digits in a field may vary from
one to the number shown above. For other formats, the placement
of the decimal point and number of digits to the right of it are
guaranteed to be as shown. However, the number of digits to the
left of the decimal point may vary from one to the number shown
in the field format. Unused leading digits are padded with blanks
or zeroes.
Individual parameter fields will be filled with
special characters for the following reasons:
Condition |
Special Character |
Data was too big for parameter field
Data was too small for parameter field
Data formatting error occurred |
>
<
? |
Additionally, invalid or unavailable data may be
replaced by question marks (?), however, the absence of question
marks in a parameter field does not guarantee the validity of the
data.
D. Hardware Interface Information
The DADS data distribution subsystem provides a well-defined
data transfer mechanism between the DADS and onboard experiments.
It broadcasts aircraft houskeeping data in ASCII-formatted engineering
units via RS-232-C serial connections to experiment stations at
one second intervals. Experimenters who want to receive DADS serial
data in-flight will have a DADS data box on or near their experimenter
station. Each box outputs the data via three RS-232-C female DB-25
connectors, corresponding to the three baud rates, which may be
used in any combination. Each DB-25 connector may be configured
as a modem (DCE) or a computer (DTE) with a switch, which exchanges
pins 2 and 3. There is no handshaking capability between the DADS
and the experiments. The outputs are opto-isolated, and the RS-232-C
drivers are current limited. The serial protocol is one start bit,
8 data bits, no parity, and one stop bit. Table F6 shows the pinout
of the DADS box DB-25 connectors.
TABLE F6. DADS Distribution Box RS-232-C DB-25
Connector Pinout
Pin |
|
RS-232 |
Function |
Connection |
1 |
|
AA |
Protective Ground |
|
2 |
TD |
BA |
Transmit Data |
DADS serial data on this pin (if
switch selects pin 2) |
3 |
RD |
BB |
Receive Data |
DADS serial data on this pin (if
switch selects pin 3) |
4 |
RTS |
CA |
Request to Send |
Jumpered to pin 5 |
5 |
CTS |
CB |
Clear to Send |
Jumpered to pin 4 |
6 |
DSR |
CC |
Data Set Ready |
Jumpered to pins 8 and 20 |
7 |
|
AB |
Signal Ground |
DADS signal ground |
8 |
DCD |
CF |
Carrier Detect |
Jumpered to pins 6 and 20 |
20 |
DTR |
CD |
Data Terminal Ready |
Jumpered to pins 6 and 8 |
Table F7. DC-8 Ancillary Data
Data Available on Video Monitors Throughout
DC-8 Aircraft
|
Forward Cloud Video
Nadir Cloud Video
DIAL Aerosol & Ozone Profiles
Track Plot
Weather Radar & Nadir & Nadir Cloud Video, Forward
Cloud Video, & Parameters tab
PI Parameter Tabular Displays
PI Parameter Graphics Displays
APT
Weather Radar
|
Project Supplied Ancillary Data Displayed
by ICATS
|
H2O Cryo
NO
CO
CN
O3
CO2
CH4
|