AMSAT - Satellite Detail - Gurwin OSCAR-32

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fahnen/2.jpg Satellite Detail - Gurwin OSCAR-32

Launch Pad

Navigator

Gurwin OSCAR-32
(TechSat1b)

Spacecraft Summary

OSCAR Designation:	Gurwin OSCAR-32	Oscar Number:	GO-32
International Designator:	1998-043D	Norad Number:	25397
Common Name:	TechSat1b	Alternate Name:	Gurwin II
Satellite Type:	Microsatellite	Launch Date:	10 July, 1998
Launch Location:	Baikonur Cosmodrome	Launch Vehicle:	Zenith
Apogee:	816.00	Perigee:	814.00
Inclination:	98.48	Period:	101.19
Dimensions:	44.5 x 44.5 x 44.5 cm cube	Weight:	60.000 Kg
Organization:	Technion Institute of Technology

Frequency Information


Mode V/U (J) APRS (Set Path to be via 4XTECH): Non-Operational
Uplink:	145.9300 MHz FM 9600 BPS
Downlink	435.2250 MHz FM 9600 BPS

Mode V/U (J) PacSat BBS: Non-Operational
Uplink:	145.8500 MHz FSK 9600 BPS

Mode V/U (J) PacSat BBS (PBBS has been off, in bootloader mode): Semi-Operational
Uplink:	145.8900 MHz FSK 9600 BPS
Downlink	435.2250 MHz FSK 9600 BPS

Mode V/U (J) PacSat BBS: Non-Operational
Uplink:	145.9300 MHz FSK 9600 BPS

Mode U TLM Beacon (Alternate Downlink): Semi-Operational
Downlink	435.3250 MHz FM 9600 BPS

Mode L/U PacSat BBS: Non-Operational
Uplink:	1269.7000 MHz FSK 9600 BPS
Uplink:	1269.8000 MHz FSK 9600 BPS
Uplink:	1269.9000 MHz FSK 9600 BPS
Downlink	435.2250 MHz FSK 9600 BPS

Callsign(s)

BBS:	4XTECH-12
Beacon:	4XTECH-11

Current Keplerian Elements

GO-32
1 25397U 98043D   10250.49870466 -.00000125  00000-0 -37481-4 0  2778
2 25397  98.3172 253.4263 0001854  57.0196 303.1178 14.23183514631756

Weekly Satellite Report

GO-32 is in MBL mode, but is expected to return to service (de KO4MA 12/29/2008)

The GO32 uplinks and downlinks are for the PACSAT store and forward system and users. APRS is on a secondary basis and should not be operated unattended. If you see that the BBS PBLIST is full of other users, do not enable your APRS since the uplink will be busy. RIght now, the PBLIST is not in APRS format so you cannot see it unless you are running normal packet mode. But we will work on that...

On the D700 you can press PMON on the front panel and see these packets... but they FLY by...

ACCESS TIMES: GO-32 is sun synchronous and so it comes over everywhere three times between about 8 AM to Noon and again between 8 PM to midnight local sun time. During these two windows at least one pass each will be an overhead pass which might also work for an HT. The other passes will be lower to the East or West and will work fine for a 50W mobile.

WHAT YOU HEAR: 9600 baud sounds almost exactly like open squelch, though the tuned ear can soon distinguish the difference. Before the pass, set your squelch normally to quiet the speaker. When you hear the satellite, the squelch will open and you may see up to 3 bars on your S meter. Tune to the "best sounding" noise.

DOPPLER: Depending on how low to the horizon you can see, the satelite approaches 10 KHz high at 435.235 MHz... But it is maybe 3000 km away. As it gets higher, and 6 dB closer, it will be on 435.230 MHz, passing through 435.225 published center frequency at the middle point, and then drop down through 435.220 and ending at 435.215.

But since it is 6 to 10 dB closer (and stronger) towards the center of the pass (800 km overhead), the mobile antenna is probably only going to hear the middle 435.230, .225, .220 portion easily. So I would start my receiption at 435.230...

UPLINK CHANNELS: GO-32 allows two APRS uplinks. One is exclusive to D7/D700 tactical position reporting and the other exclusive to messaging. This is in hardware, not policy...

1) All APRS messaging (or fixed station non-Mic-E positions) must use the 145.85 uplink where GO32 only digipeats APRS packets with TOCALLs that begin with the usual "APxxxx". (Even the D7 and D700 use "APKxxx" for messages.)

2) All APRS Mic-E position uplinks (D7, D700 and D710s) must be on 145.93 MHz and they must have the position comment set to "Committed, Special or PRIORITY"... With those comment settings then the TOCALL first LATITUDE digit will be 1,2,3,4,5,6,7 and only these will be accepted by GO32 for
digipeating from 145.93.

DATA CARRIER DETECT: The D700 and non(g) model D7's will NOT TX if they are hearing the downlink at the same time due to CARRIER DETECT. The D7(g) model has DCD IGNORE that *will* let it TX anyway. So use separate rigs for TX and for RX if you want to see yourself.

Otherwise stick to the receommended TX rates and know that you are getting in if you stick to the protocol. Sticking to the recommended rates also keeps channel loading low, so that everyone gets in with less congestion.

PERMANENT SATGATES: Here is a great place to use your D7 HT when you are not using it otherwise. Simply connect it to a 19" whip over a ground plane and to your APRS IGate system. The antenna does not even need to be high, since it cannot hear, nor will it be on frequency for low packets near the horizon 3000 km away. Set it to 9600 baud RX and tune to 435.230 (which is 5 KHz high). This Doppler setting will match the stronger signals.

This 19.5" whip (3/4 wave on 435) does not need to see below 25 degrees, since its max gain (almost 7 dB) is between 30 to 70 degrees anwyay. This also protects your HT from lightning, since it can be low, below all of your other antnenas. Yes, your station will only see about 30% of all possible packets and only on the best two passes per day, but combined with dozens of other such unattended SATgates, all packets should be heard somewhere by someone and injected into the APRS Internet system.

-----

Mineo, JE9PEL, reports February 02, 2006:
4XTECH-12>STATUS [02/02/06 20:39:52] :
UTC: Thu Feb 02 11:39:35 2006 | Gurwin Techsat1B (V9.86)
BBS(9.86) is active ,AsherSpaceResearchInst greets you.
2 Users/8 Broadcasts, Uplink freq:145.890,145.850,145.930, 1269.800,
1269.900

TechRam2V9.87 beta

Detailed Description

The TechSat/Gurwin-II satellite is of cubic shape with a size of 445 mm x 445 mm x 445 mm. The platform is three-axis stabilized, using a momentum wheel and three magnetorquers as actuators, and a three-axis magnetometer as attitude sensor. All attitude instruments have a total power consumption of about 3 W. The power consumption for all housekeeping functions is less than 10 W (including transmitters, receivers, on-board computer, and power conditioning. The satellite attitude history, based on the magnetometer telemetry processed both by the onboard and ground station Kalman filters, was statistically analyzed, to summarize the long-term performance of the attitude control system. The analysis made it evident, that throughout the most part of the flight, the magnetic control provided the 3-axis stabilization of the satellite with nadir-pointing accuracy of about 2º-2.5º.

The solar cells employ thin-film photovoltaic cell technology (developed in Russia); they are mounted on four sides of the six outer aluminum panels. A NiCd battery is provided for eclipse operations. The fifth panel, pointing toward Earth, includes antennas, the retroreflector, the UV spectro radiometer (OM-2) and an imaging camera. When 3-axis stabilized, the satellite would have its sixth panel unlit; it is not exposed to the sun and therefore does not include any solar cells. The structure plays a major role in the thermal design. The heat flows from the solar illuminated panels to all parts of the structure that are used as radiators. The S/C mass is 48 kg, the total payload mass is 6.6 kg, power = 20 W. The S/C design life is one year.

The Earth-pointing satellite was launched as a secondary payload on July 10, 1998. A Russian Zenit-2 vehicle carried the Resurs-O1-4 satellite and five piggyback payloads (TMSAT, TechSat/Gurwin-II, FASat-Bravo, and SAFIR-2) from the Baikonur Cosmodrome into orbit.

RF communications: Communication is realized via receive and transmit antennas. Three uplinks in the 145 MHz VHF band (2 m), three uplinks in the 1270 MHz L-band (23 cm), and one downlink in the 435 MHz UHF-band (70cm). Data is transmitted at two available rates: 1200 bit/s and 9600 bit/s. At 1200 bit/s the carrier modulation is BPSK (downlink) and FM (uplink). At 9600 bit/s the carrier modulation is FM (downlink & uplink).

Satellite operations are conducted from a ground station at Technion. The S/C features a digital store and forward multi-user system, compatible with existing store and forward facilities already in use on microsatellites (use by the international amateur radio electronic community).

One of the TechSat mission goals was to carry out long-term experiments, and to compare the actual in-flight parameters of the onboard equipment with those at the design stage. power, attitude control, communication, computer, and thermal subsystems performed stably and provided the satellite's normal functioning in any of its possible operational modes. No substantial failures or malfunctions were noticed either in the housekeeping of the whole bus, or in its separate modules.

All subsystems of TechSat were tested under various operational conditions. Flight experiments with ERIP were carried out only periodically for short durations. The XDEX instrument was stopped because of no correct calibration of the detector. For SUPEX, the tests were finished after 2 years because of cooler degradation. OM-2 failed after 10 months of operations.

By 2004, the digital store&forward multi-user system on TechSat was able to provide its services to the global amateur radio community. In the initial phase of the mission, there were some difficulties with the amateur BBS (Bulletin Board System) program. Considerable effort was invested to bring about the necessary changes in the satellite software to enable operation of the satellite by the radio amateur community.

Reference Documents: