Trigger 94 Description

Sequence: C27
Trigger 94 ( Aurora/SKR Mode, outside source crossing & low latitudes )

This mode is designed to provide a survey mode with full direction-finding (DF-3) up to 1.8 MHz.

Both low and high frequency WFR measurements are made. In high-frequency mode, there are 512 samples taken for the EX, EW, and BX antennas. These channels are also analyzed onboard using the LFDR FFT software, and the LFDR data is provided in addition to the waveform data. In low-frequency mode, 5-channel 1024-sample WFR measurements are made every 64 seconds.

Langmuir Probe sweeps are performed every 32 seconds; density measurements are made at a 100-Hz sampling rate to match the Low-Frequency WFR measurements. A simple up-going ramp sweep is performed; with a future software update, this will become a down-going voltage ramp.

A Sounder measurement replaces the HFR data every 320 seconds.

Receiver Frequency Range Sensors Time between Snapshots
LFR 0.1 - 2.5 KHz EX, EW, BX 32 seconds
MFR 25 - 12 KHz EZ, BZ 32 seconds
WFR(LF) 1 - 25 Hz EX,EW,BX,BY,BZ 64 seconds
WFR(HF) 0.1 - 2.5 KHz EX,EW,BX 32 seconds
HFR 3.6 KHz - 16 MHz EU, EV, EW, EX 32 seconds
LP N/A Langmuir Probe 32 seconds
Sounder 3.6 - 115 KHz EX, EW 320 seconds

The HFR is in direction-finding mode for bands A, B, C, and H1. 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         8       y    1000      1                3.6-319 kHz
H1   2E   y         y         1       y    80        1     60    25   325kHz-1.8MHz
H2   1E   n         n         1       n    20        1     72    50   1.8kHz-16MHz
Bands ABC require 6.42 sec to complete, H1 requires 10.31 sec, and H2 requires 1.46 sec for a total of 18.19 sec per sweep. However, the time between analyses is set to 32 seconds, in order to reduce interference due to antenna-switching done during the direction-finding measurements. Every 320 seconds the HFR normal analyses are replaced by a Sounder analysis. The Sounder operation has a duration of approximately 40 seconds. This Sounder analysis is defined by:
  sounder mode:   EZ AAA
  1st  sounder freq:      0
  last sounder freq:     89
  T1 delay:        10 msec
  T2 delay:        25 msec
  T3 delay:        25 msec
  passive spectra:      2
  active  spectra:      2
  # of cycles:       1
  sounder output A:      3 autos
  sounder output B:      3  AGCs