(12/12/01)

Dust Dart Orion Interface

UNH will provide an interface electronics box to convert the Dart science body signals for use on the Orion. This box will contain DC-DC converters to provide USU +12, -12 and +5V from a 28V input buss. It will also contain 16-bit ADC circuitry to convert 5 high resolution analog channels to WFF93 serial data. This interface box should be mounted near the base of the mast. Connection to the Dart science body is via a 20-pin high density ribbon cable connector (dart pinout). Interface to the Orion payload is via a 37pin D-sub.

Power Requirements

Nominal +28V. Current draw of less than 100mA.

TM Channels

 sig     type      rate                 description
 SERN   serial   4000 samp/sec   UNH 16-bit data (LF,DUST 2K each)
 SERU   serial  30000 samp/sec   USU 16-bit data (DC2,EFIELD,DC1 10K each)
 SMON   analog    250 samp/sec   ion sweep monitor
 DTEMP  analog    250 samp/sec   temperature sensor
 TS13   analog    250 samp/sec   temperature sensor
 TS14   analog    250 samp/sec   temperature sensor
 NE     analog    250 samp/sec   electron density

The serial data is multiplexed internally as shown. The combined serial channel can have unevenly spaced samples as long as the individual signals are evenly sampled in time.

Timing Signals

GCKN -- Gated clock output for the SERN serial channel. RS-422 differential.

GCKU -- Gated clock output for the SERU serial channel. RS-422 differential.

MAJF -- A logic pulse at the PCM frame rate. RS-422 differential.

DLEG -- A 28V logic level that is 0V on the upleg and +28V on the downleg. This is used to switch the detector from dust mode to ion RPA mode. Presumably this comes from a flight timer.

Interface Connector

All interface to telemetry and power is through a 37 pin D connector. A 37P connector will be mounted on the UNH electronics box. Wallops will supply a mating 37S connector on the cable.

Signals are wired as twisted pairs. The pinout lists give the signal pin and show its pair pin in parenthesis. For PCM digital signals the + and - differential lines are twisted together. The - pin is NOT ground.

Independent pairs should be carried through to the final destination. All power returns should be wired independently to power ground. Analog signal returns may be tied together at a ground buss near their destination.

The single wire "chassis" pin is intended as a redundant means of insuring a good electrical connection between the experiment chassis and the TM section chassis. This pin may be tied to chassis in the TM section wherever it is convenient. 

Orion Interface   37 pin D connector
    SIG RET     
     1  (20)    +28V    power
     2  (21)    +28V    power
     3  (22)            unused
     4  (23)    DLEG    timer signal
     
     +   -
     5  (24)    MAJF    PCM major frame sync
     6  (25)    GCKN    Gated shift clock for SERN
     7  (26)    GCKU    Gated shift clock for SERU
     8  (27)    SERN    UNH serial data
     9  (28)    SERU    USU serial data
     
    SIG  RET
    10  (29)    SMON    ion sweep monitor
    11  (30)    DTMP    temperature sensor
    12  (31)    TS13    temperature sensor
    13  (32)    TS14    temperature sensor
    14  (33)    NE      electron density
    
    15  (34)            unused
    16  (35)            unused
    17  (36)            unused
    18                  unused
    19                  unused  
         37             chassis ground

Mechanical

Electronics box approximately 1 X 3.4 X 4.4in. 0.5 lb.