Trigger 58 Description
Sequence: C19, C20, C21
Trigger 58 (High Rate Cyclic Mode)
This mode is designed to step through various RPWS high resolution
observations over periods of order 1 hour or longer. Eight different high
resolution modes are sampled for periods of 3 to 9 minutes with one complete
cycle taking 1 hour. The cyclic repeats until it is stopped by the issuance
of a new trigger command, typically Trigger 80. The targeted average data
rate (averaged over 1 hour) is 40 kbps, but the true, compressed data rate
realized is closer to 30.5 kbps although this is somewhat data dependent.
Figure 1 provides an overview of the Trigger 58 cyclic. As can be seen,
WBR modes are alternated with WFR modes. This is primarily to ensure that
high rate modes (WBR) are separated by periods of significantly lower data
rate periods (WFR) to minimize non-linear effects in SSR managment. The peak
data rates for the WBR modes are of order 115 kbps while those of the WFR
modes are of order 6 kbps. Specifically, this cyclic collects WBR data in
25-kHz bands centered on 8.025 MHz, 1.025 MHz, and 125 kHz, in the 75-kHz and
10.5-kHz baseband modes interspersed with periods of 2.5-kHz and 26-Hz WFR
modes. The user is referred to individual descriptions of these underlying
triggers (as listed in Figure 1) for details on each of these.
Trigger 58 Overview
__ ________ _____ ________ ___________ __ _____ ___________
| | | | | | | | | | |
|32| 3E | 38 | 40 |34| 3E |36| 3C | 3A | 3E |
|__|________|_____|________|__|________|__|_____|_____|_____|
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
0 1 2 3 4 5 6
0 0 0 0 0 0 0
Step Receiver Frequency Duration
---------- -------- ------------------ ---------
Trigger 32 HF-WBR 8.025 MHz 3 minutes
Trigger 34 HF-WBR 1.025 MHz 3 minutes
Trigger 36 HF-WBR 0.125 MHz 3 minutes
Trigger 38 WBR 0 - 75 KHz 6 minutes
Trigger 3A WBR 0 - 10.5 KHz 6 minutes
Trigger 3C HFR Max. Spectral Res. 6 minutes
Trigger 3E WFR 0 - 2.5 KHz 6 or 9 minutes
Trigger 40 WFR 0 - 25 Hz 9 minutes
Low Rate Measurements During the Trigger 58 Cyclic
Underlying Trigger 58, the RPWS continues to collect spectral survey data
over the entire RPWS frequency range (1 Hz - 16.1 MHz) as continuously as
possible, provided the limitations of the RPWS hardware and software limits.
The survey data are collected as follows:
1. Low Frequency Receiver: This covers the frequency range from 1 to 25 Hz
using a 2-channel mode of the WFR, specifically using Ex (dipole) and Bx
sensors. One waveform series of 512 samples are collected every 32 seconds
simultaneously for each of these two sensors. The waveform is spectrum
analyzed on board and a 28-channel(?) quasi-logarithmic spectrum is
constructed by binning adjacent Fourier components. The initial AGC gain is
set to 20 dB for Ex and 30 dB for Bx and is updated after every waveform
series. The AGC set point is 17, 85; this means there is 10 dB of headroom
and a 12 dB wide window for hysteresis. These data are collected during the
Trigger 3A, 3C, and 3E elements of the cyclic, (10.5-kHz WBR, high resolution
HFR, and 2.5-kHz WFR). The raw data required to construct these channels are
collected in Trigger 40, but are routed directly to the ground and can be
filled in for this mode in ground processing, if required. The data cannot
be collected in triggers 32, 34, 36, or 38 (the HF-WBR or 75-kHz WBR modes)
because of hardware limitations. Beginning in C26, a periodic LFR (every 32
seconds) was included in the trigger 38 setup; the downside of this decision
is that every 32 seconds, the WBR data is not acquired while the 5.12 seconds
of LFR data is captured.
2. Medium Frequency Receiver: The spectral data for the frequency range
from 25 Hz to 12 kHz are collected by the MFR continuously throughout Trigger
58 using the Ew and Bz sensors. A spectrum from the Ew sensor is collected
during one 32-second period and the Bz spectrum is collected during the
following 32-second period. Previous to C23, the MFR sensor was allowed to
remain as it was previous to Trigger 58; however, starting with C23 the MFR
sensor was set to use EW, in order to reduce interference between the WBR and
the MFR.
3. High Frequency Receiver: When the HFR is not required to do otherwise, it
is set to the so-called composite mode survey mode during Trigger 58. This
is the case for Triggers 38, 3A, 3E, and 40. 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 16 n 1000 1 3.6-319 kHz
H1 2E y 2 n 80 1 30 50 325k-1.8MHz
H2 1E 1 n 20 1 72 200 1.8M-16MHz
Bands ABC require 3.16 sec to complete, H1 requires 2.524 sec, and H2 requires
1.461 sec for a total of 7.25 sec per sweep.
For the HF-WBR modes the HFR is required to be in freeze mode at the frequency
being analyzed by the HF-WBR. During these times, the HFR is in millisecond
mode, collecting AGC values once per millisecond for use with the HF-WBR data.
The AGC values are collected in sets of 2048 samples taken over 2.12 seconds.
There is approximately a 0.4-second gap between each AGC value set. The
HF-WBR modes are interrupted once per minute to collect one HFR sweep in the
composite mode survey described above.
Finally, the HFR is run in its highest spectral resolution mode during
Trigger 3C:
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 8 n 160 1 79 50 125k-4MHz
H2 2E y y 8 n 80 1 243 50 4M-16.1MHz
Bands ABC require 3.12 sec to complete, H1 requires 13.9 sec, and H2 requires
21.75 sec for a total of 38.8 sec per sweep. Data collection and formatting
requires a little more time, and the time between analyses is 42.125 seconds.