Some Voyager LECP Documentation
(Last updated 2024-06-12)

Important Dates (also see the events page)
Event V1 Date V2 Date
Launch 8/20/1977 (d232) 9/5/1977 (d248)
Jupiter closest approach 3/5/1979 (d64) 7/9/1979 (d190)
Saturn closest approach 11/20/1980 (d325) 8/25/1981 (d237)
V2 detector 0 failed, very few Rate 32 (o241), 33 (o240),
34 (o220), or 35 (o221) PHAs afterwards
N/A8/26/1981 (d238)
Uranus closest approach N/A 1/24/1986 (d24)
Neptune closest approach N/A 8/25/1989 (d237)
Cruise-5a (CR5a) telemetry mode 8/8/1990 (d220) 6/4/1990 (d155)
FDS MODE UV-5A to CR-5T N/A 9/7/1994 (d250)
V1 detector D3 OFF 1997-10-15 13:28 (d288) -
1997-11-05 08:55 (d309)
V2 discriminator issues started N/A 4/6/2005 (d097)
Termination Shock Crossing 12/1/2004 (d336) 8/30/2007 (d242)
V2 FDS issue, no science data N/A 4/22/2010 (d112)
V2 FDS issue resolved, science data resumes N/A 5/23/2010 (d143)
V2 discriminator issues seemingly self-corrected N/A 8/14/2017 (d226)
Heliopause Crossing 8/25/2012 (d238) 11/5/2018 (d309)
V2 power cycled N/A 1/26/2020 (d026)
V2 LECP recovered N/A 2/5/2020 (d036)
Heater Off 5/16/2021 (d136) 2/23/2021 (d054)
V1 D2 commanded OFF 11/12/2021 (d316)
(data gap) 11:43
V1 D2 commanded ON 12/3/2021 (d337)
for unknown reason
12/9/2021 (d343)
V1 D2 commanded OFF 12/27/2021 (d362)
V1 SUB_COM D1 Fast
commanded ON
1/27/2022 (d027)
CRS Heater Off 5/18/2022 (d138) 06/09/2019 Replacement
06/27/2019 Supplemental
V2 in EL-40 Mode instead
of CR-5T Mode
N/A 8/6/2022T05:25 - 8/11/2022T18:15
(d218 - 223)
No V2 data due to DSN
hardware problem
N/A 8/16/2022 (d228)
V2 enters voltage management N/A 3/31 - 4/1/2023 (d090-091)
V2 CCS Error N/A 7/1/2023 20:36 (d182)
A series of planned commands sent to NASA’s Voyager 2
spacecraft July 21 inadvertently caused the antenna
to point 2 degrees away from Earth.
N/A 7/21/2023 (d202)
NASA has reestablished full communications with Voyager 2. N/A 8/4/2023 (d216)
Voyager 1 FDS issue, no science or engineering data 11/14/2023 (d318) N/A
NASA’s Voyager 1 Resumes Sending Engineering Updates to Earth 04/20/2024 (d111) N/A
LECP INIT commands executed 2024-05-25 12:28:30 SCET (d146) N/A
Voyager 1 enters voltage management 2024-06-07 11:02:03.796 SCET (d159) N/A


UMD Voyager Processing Information

Krigimis LECP Science Paper

Steve Gary LECP Engineering Paper

Peletier LECP Engineering Paper

Art Hogrefe Voyager LECP Pulse Height Analyzer (1977)

Matt's 1998 scholarly paper / MS thesis - Methods of Analysis for Voyager Lecp Data

Handout from Doug with Rate Channel Logic and Detector Thresholds

IVF File Information

Drawings of the LECP detector layout and notes on the anticoincidence detectors

Web pages from the Data Analysis Handbook from Fundamental Technologies (old version of the site)

MRT Layout from Matt's thesis
Words Bytes Name Data Type
1 - 38 1 - 76 MRT Record Header 1 & 2 Byte Integer Words
39 - 282 77 - 564 Rate Data 4 Byte Real Words (in 1 and 3 word groups)
283 - 404 565 - 808 Rate Data Quality Words 2 Byte Real Words (in 1 and 3 word groups)
405 - 484 809 - 968 PHA Data 1 Byte Logical Words, 32 (5-Word) Data Points

Fig. 1-2 CR5a MRT Record layout. Rate data are stored each TAI for each rate- channel. Only 32 PHA data points are stored, selected by the priority scheme.

PHA info from Matt's thesis

The PHA data are a list of 32 PHA data points. Each data point contains one identification byte (PHA-ID) and four PHA energy-channel values, corresponding to four of the five detectors. For particles identified as being low energy (i.e., LEPT particles) the five-dimensional PHA data point is represented by: (PHA-ID,D1,D2,D3,D4). For the high energy (HEPT) particles: (PHA-ID,D5,D2,D3,D4). The second byte of each five-byte data point is thus alternately D1 or D5 and is sometimes written D1D5 or D1/D5 to indicate this fact. It should be emphasized that while there is always a rate value assigned for a given rate-channel, the list of PHA data points depends on the identification and frequency of the incoming ions. For example, one record might have 32 PHA data points all identified with CH31, say, while another record could have 16 CH31 PHA data points, 8 CH17 PHA's and 8 CH01 PHA's.

PHA info from the Gary paper

Because the PHA output consists of five eight-bit words per event, only a very limited sampling of events is actually analyzed and transmitted... The output for each event consists of one identifier word and four 8-bit words representing the amplitudes of the signals in each of four detectors. The ID word denotes the rate channel corresponding to the analyzed event. This word is defined in Table 2-3. Depending on the rate channel into which the event falls, either the D1 or D5 signal is analyzed, as are the D2, D3 and D4 signals. The analyzed events are read out in the LECP telemetry stream during cruise and far encounter modes of operation.

Rate Channel Logic from the Gary paper

Plots of Channels With Tracks

E1/5 vs E2

E2 vs E3

E5 vs E4

index.html last modified on 4/25/24 at 4:21 AM by sel