Trigger 10 Description

Sequence: C2 (Antenna Deployment)
Trigger 10 (Sounder and Langmuir Probe Checkout)
This mode is part of the antenna deployment checkout. It runs a series of checkouts internal to the instrument. It starts with one HFR Sounder pulse in default mode and then it does a Langmuir Probe checkout. This trigger lasts for about 5 minutes. After the Sounder test, the HFR is in its default mode. After the Langmuir Probe checkout ends, the instrument internally executes Trigger 30. LFR, MFR, WBR and WFR data are collected during this trigger, with the receivers connected to the Langmuir Probe and the individual cylinders when appropriate. The internal sequence of this trigger is:
Operation                               Duration
-------------------------               ----------
HFR Sounder                             12 seconds
Ex- Cylinder Bias -13 V                 32 seconds
Ex- Cylinder Bias 0 V                   32 seconds
Ex- Cylinder Bias +13 V                 32 seconds
Ex+ Cylinder Bias -13 V                 32 seconds
Ex+ Cylinder Bias 0 V                   32 seconds
Ex+ Cylinder Bias +13 V                 32 seconds
LP Sphere Checkout                      96 seconds
Enter Trigger 30 Mode

During the initial inflight use of Trigger 10, 20, and 30 (during the antenna deployment in C2), the HFR did NOT go into the expected mode due to a software feature between the HFR and the order that the HFR commands were issued from the onboard sequence and the IEB (see ISA Z44412 for a discussion of this issue and the solutions implemented to prevent this from occurring in future sequences.
This problem only occurred during the antenna deployment sequence, and not when the Triggers were sent individually. Comments have been added to the C2 timeline to note which periods had Triggers that did not operate as expected. The primary affect of this problem was that Trigger 30 did NOT put the HFR in the expected mode at the end of Trigger 10 and 20 (the HFR stayed, or entered its default mode). Furthermore, for the first two uses of Trigger 20 (1997-298T00:15 and 03:38), the HFR collected no data during the internal Antenna checkout part of the trigger, resulting in no HFR data for about five minutes.

Receiver Frequency Range Sensors Time between Snapshots
LFR 1 - 25 Hz EW, BX
16 seconds
MFR 25 - 12 kHz EX, EW
32 seconds
WFR .1 - 2.5 kHz EU, EV, LP, BY, BZ 16 seconds
0.1 - 10.5 kHz
LP 8 seconds
HFR 3.6 KHz - 16 MHz EX, EW
24 seconds
Langmuir Probe
16 seconds
SOUNDER 3.6 - 115 KHz EW N/A

The HFR is in the following 'default' mode after the initial Sounder checkout.
This mode is defined by:
          Correlations     Channels        Integ.                Size Frequency
Band Ant. Auto-  Cross-    per Band   df   Period    Rep   Steps kHz  Start - Stop
---- ---- -----  ------    --------   --   ------    ---   ----- ---- ------------
ABC  2E     y      y          32       n    1000      1                3.6-319 kHz
H1   2E     y      y           4       n     160      1     70     25  250k-1.975MHz
H2   2E     y      y           1       n      80      1     70    200  2.025M-15.825MHz

Bands ABC require 3.12 sec to complete, H1 requires 12.30 sec, and H2 requires 6.27 sec for a total of about 21.7 sec per sweep. However, the time between analyses is set to 24 seconds.

The Sounder operation has a duration of approximately 12 seconds. This Sounder analysis is defined by:

sounder mode:   EZ AAA
1st  sounder freq:      0
last sounder freq:     89
T1 delay:         5 msec
T2 delay:         5 msec
T3 delay:         5 msec
passive spectra:      0
active  spectra:      1
# of cycles:       1
sounder output A:      3 autos
sounder output B:      3  AGCs