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[jamsat-news:1284] * SpaceNews 12-Jun-00 *
SB NEWS @ AMSAT $SPC0612
* SpaceNews 12-Jun-00 *
MONDAY JUNE 12, 2000
* SUNSAT-OSCAR-35 TELEMETRY INFO *
The SUNSAT-OSCAR-35 satellite has recently been transmitting telemetry
information in the form of AX.25-protocol packet radio frames on a
downlink frequency of 145.825 MHz. As Johann Lochner explains, the
spacecraft status and telemetry data formats follow the APRS standard.
A typical status message is shown below. After the identifying >
header, the onboard computer generating the message and its current
software version is shown. This is followed by the current uptime,
reset cause (pwrn: power on, tcmd: telecommand, wdog: watchdog) and
current onboard time.
>OBC1v6: up=3/03:20:54, rst=pwrn, Sat May 27 11:27:12 UTC 2000
The telemetry message contain ASCII data, which can be displayed in
human readable format by terminal software connected to a TNC. One
sample set (such as the four examples below) from a 25 entry circular
buffer (containing entries numbered 0 through 24) is transmitted at
approximately 9.59 second intervals (orbital period / 25^2). When
the buffer pointer wraps after 24, all entries are shifted towards
24, by moving a fresh sample set into 0 (and discarding 24). The
buffer thus contains a history of samples from the last orbit,
sampled at just under 4 minute intervals, with entry 0 being the
most recent addition.
Telemetry data is identified by a T# header. The message consists of
7 fields, numbered 0 through 6. The fields contain the following
data: buffer pointer (0 in the first example above), battery state of
charge (99 %), battery voltage (13.9 V), battery current (59 - 128 =
-69, indicating that the battery is a net source of 690 mA; this
field wraps at the extremes), battery temperature (28 C), top plate
sun sensor reading (42, an uncalibrated 8 bit value). The last field
indicates the state of the 8 solar panel strings (0: sourcing the
power bus, 1: shunted, dumping energy).
Data in fields 1 to 4 is supplied to OBC1 at 60 second intervals.
Fields 5 and 6 contain raw telemetry, sampled every 2.34 seconds.
Possible aliasing, as well as the unsynchronized nature of the two
data sources, should be considered when correlating fields.
[info via Johann Lochner, ZR1CBC]
* RS-15 NEWS *
Ken, N1WED reports copying RS-15 on June 6th during pass # 22430, a pass
North to South almost straight down the Mississippi River, that produced
a return signal of a solid 5-5. It was noted this occurred during the
approach phase and lasted for about four minutes at a range of 2100
statute miles. Ken called CQ and recorded the pass, but received zero
responses. After reaching perigee to his groundstation, SSB dropped
to zero, though a faint FM signal could still be received.
[Info via Ken, N1WED]
* PB/PG FOR LINUX UPDATED *
Bent Bagger, OZ6BL, has uploaded version 1.5 of PB and PG for Linux to
metalab.unc.edu. The file name is pbpg-1.5.tar.gz. Bent has placed
the file and the accompanying lsm-file in /incoming/Linux directory.
The target directory is /pub/linux/apps/ham. The file may also be
downloaded from ftp://ftp.amsat.org/amsat/software/Linux/pbpg-1.5.tar.gz.
The updated documentation is found in the file named README.
This is a patch release. Sometimes PB would send requests for directory
fills when it was not needed. This has been fixed. It was due to erroneous
handling of fragmented broadcast directory entries.
PB and PG for Linux are programs used for download from and upload to
digital satellites (Pacsats) supporting the FTL0 protocol. This software
allows groundstations to directly communicate with the Microsat series of
satellites. It provides a curses (ncurses) based user interface, and
features automatic directory fill requests, and simple rules-based file
download requests. This version of the programs will work with kernel
revisions 2.0.24 or higher.
[Info via Bent Bagger, OZ6BL]
* THANKS! *
Thanks to all who sent news items and/or messages of appreciation to
SpaceNews in recent weeks, especially:
* FEEDBACK/INPUT WELCOMED *
Comments and input for SpaceNews should be directed to the editor
(John, KD2BD) via any of the paths listed below:
MAIL: John A. Magliacane, KD2BD
Department of Engineering and Technology
Brookdale Community College
765 Newman Springs Road
Lincroft, New Jersey 07738
PACKET: KD2BD @ N2TDU.NJ.USA.NA
INTERNET: email@example.com, firstname.lastname@example.org
SATELLITE: AMSAT-OSCAR-16, KITSAT-OSCAR-25
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