SB NEWS @ AMSAT $SPC0612 * SpaceNews 12-Jun-00 * BID: $SPC0612 ========= SpaceNews ========= 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. T#000,099,139,059,028,042,11110000 T#001,099,133,110,032,088,11111110 T#002,099,138,140,032,092,11110000 T#003,099,132,132,032,096,11111100 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: N1WED W8JSA * FEEDBACK/INPUT WELCOMED * =========================== Comments and input for SpaceNews should be directed to the editor (John, KD2BD) via any of the paths listed below: WWW: http://www.njin.net/~magliaco/ MAIL: John A. Magliacane, KD2BD Department of Engineering and Technology Brookdale Community College 765 Newman Springs Road Lincroft, New Jersey 07738 U.S.A. PACKET: KD2BD @ N2TDU.NJ.USA.NA INTERNET: kd2bd@amsat.org, magliaco@email.njin.net SATELLITE: AMSAT-OSCAR-16, KITSAT-OSCAR-25 <<=- SpaceNews: The first amateur newsletter read in space! -=>> <<=- Serving the planet (and beyond) since 1987 -=>> /EX