May 31 2015

LightSail Signal Heard

Artists impression of LightSail

On the Planetary Society’s website Jason Davis @JasonRDavis reports LightSail is again transmitting on 437.435 MHz, AX.25, 9600 bps FSK.

Jason writes: The Planetary Society’s LightSail test spacecraft reported for duty this afternoon [May 30], heralding the end of an uneasy silence caused by a suspected software glitch. At 5:21 p.m. EDT (21:21 UTC), an automated radio chirp was received and decoded at the spacecraft’s Cal Poly San Luis Obispo ground station. Another came in eight minutes later at 5:29 p.m. The real-time clock on board the spacecraft, which does not reset after a software reboot, read 908,125 seconds—approximately ten-and-a-half days since LightSail’s May 20 launch.

LightSail is not out of the woods yet. Its exact position remains fuzzy, complicating two-way communication. Today’s [May 30] contact marks the first time engineers can compare the spacecraft’s signal with orbital models called two-line element sets, or TLEs. There are ten TLEs associated with the ULTRASat fleet that joined LightSail for a free ride to orbit courtesy of a United Launch Alliance Altas V rocket. Which TLE represents LightSail is unknown, but each radio chirp’s Doppler shift helps narrow down the possibilities.

Read Jason’s full post at http://www.planetary.org/blogs/jason-davis/2015/20150530-lightsail-phones-home.html

LightSail Transmissions Stopped https://amsat-uk.org/2015/05/26/lightsail-1-stops-transmitting/

May 26 2015

Listen for LightSail-1 – Transmissions Stopped

LightSail-1 with sail deployed – Credit Justin Foley KI6EPH

JoAnne Maenpaa K9JKM, AMSAT Vice-President User Services, reports that LightSail-1 has stopped transmitting on 437.435 MHz.

She says: Just read on-line at http://planet.ly/0gVop (Planetary Society) that the LightSail satellite stopped transmitting. The team is attempting a reboot.The telemetry data is sent on a downlink of 437.435 MHz, AX.25, 9600 bps FSK.

Excerpt from their page …
As of late Friday afternoon, LightSail was continuing to operate normally. The spacecraft’s ground stations at Cal Poly San Luis Obispo and Georgia Tech were receiving data on each pass. Power and temperature readings were trending stably, and the spacecraft was in good health.

But inside the spacecraft’s Linux-based flight software, a problem was brewing. Every 15 seconds, LightSail transmits a telemetry beacon packet. The software controlling the main system board writes corresponding information to a file called beacon.csv. If you’re not familiar with CSV files, you can think of them as simplified spreadsheets-in fact, most can be opened with Microsoft Excel.

As more beacons are transmitted, the file grows in size. When it reaches 32 megabytes-roughly the size of ten compressed music files-it can crash the flight system. The manufacturer of the avionics board corrected this glitch in later software revisions. But alas, LightSail’s software version doesn’t include the update.

Late Friday, the LightSail team received a heads-up warning them of the vulnerability. A fix was quickly devised to prevent the spacecraft from crashing, and it was scheduled to be uploaded during the next ground station pass. But before that happened, LightSail’s automated chirps fell silent. The last data packet received from the spacecraft was May 22 at 21:31 UTC (5:31 p.m. EDT).

A LightSail map tracking application is at http://sail.planetary.org/missioncontrol/

73 de JoAnne K9JKM
AMSAT VP User Services

LightSail-1 and other CubeSats Launch with X-37B https://amsat-uk.org/2015/05/20/lightsail-1-launch/

Keps for the CubeSats but which object corresponds to which satellite ?
https://docs.google.com/document/d/1o48dswYcTHb-op9ygaKhrizrelMGV9pYcUm0SFmxfS8/pub

May 26 2015

UK radio amateurs use PSK31 satellite transponder

PSAT PSK31 Transponder received by Peter Goodhall 2E0SQL May 26, 2015

After building a 28 MHz 1/4 Wave Ground Plane antenna to replace his dipole Peter Goodhall 2E0SQL was able to receive his 10 watt signal through the PSAT CubeSat PSK31 transponder for the first time on Tuesday, May 26.

Peter Martinez G3PLX posted a report to the RSGB Tech Yahoo Group reproduced here with permission:

Finally got my own signal back via PSAT just now and proved that the uplink frequency control works. The PSAT uplink receiver is about 300 Hz low of 28120 kHz which means that when the satellite is heading straight towards me at +600 Hz Doppler, my transmitter needs to be 900 Hz low.

If I chose to place my own signal on a downlink frequency of 1000 Hz, the transmit audio tone would have to be down at 100 Hz which is too low for my SSB transmitter. So I have chosen 1500 Hz in the downlink.

I will try again on the next few passes. I am just sending “Test de G3PLX via PSAT” continuously at the moment and not listening for replies. Still not getting a strong downlink SNR so the power control loop isn’t kicking in.

Bob Bruninga WB4APR has made a request to developers of PSK31 software to open their PSK31 frequency tracking to accommodate more than 1 Hz per second Doppler shift. Current implementations can do 1 Hz/s but completely fail at 3 Hz/s.

PSK31 Transponder Frequencies:
PSAT: 145.825 MHz FM 1200 baud AX.25 telemetry – digipeater currently off
PSAT PSK31: 435.350 MHz FM downlink, 28.120 MHz SSB PSK31 uplink. W3ADO-5 PSK TLM beacon on 315 Hz

BRICsat: 437.975 MHz 9600 baud telemetry every 20s
BRICsat PSK31 435.350 MHz FM downlink, 28.120 MHz SSB PSK31 uplink. W3ADO-6 PSK TLM beacon on 375 Hz

Guide to using the PSK31 transponder https://amsat-uk.org/beginners/how-to-work-psk31-satellites/

ParkinsonSAT (PSAT) http://www.aprs.org/psat.html

Fldigi PSK31 software http://www.w1hkj.com/Fldigi.html

Keplerian Two Line Elements (TLEs) ‘Keps’ for satellites launched in last 30 days
http://celestrak.com/NORAD/elements/tle-new.txt

Adding new satellites to SatPC32 and Gpredict
https://amsat-uk.org/2013/11/23/adding-new-satellites-to-satpc32/

Listen to satellite signals in the 145 and 435-438 MHz bands from anywhere in the world using the online SUWS WebSDR located near London. Further details at https://amsat-uk.org/2014/08/15/suws-websdr-moves-to-new-site/

AMSAT-UK
Web https://amsat-uk.org/
Twitter https://twitter.com/AmsatUK
Facebook https://facebook.com/AmsatUK
Flickr https://flickr.com/groups/AmsatUK
YouTube https://youtube.com/AmsatUK
Yahoo Group http://groups.yahoo.com/group/FUNcube

May 25 2015

29 MHz – the forgotten frequency for amateur radio satellites

Jan King W3GEY/VK4GEY prepares OSCAR 7 for a vibration test – Credit AMSAT-NA

Hans van de Groenendaal ZS6AKV writes in the EngineerIT magazine about the potential for 29 MHz as a satellite uplink band.

Universities and other scientific research institutions are using portions of the amateur spectrum for their CubeSat’s which has caused the 145 and 435 MHz amateur-satellite band segments to be very crowded, leading to an increasing number of satellite builders to explore alternatives.

For many, such as those requiring single-channel bandwidth greater than approximately 12.5 kHz, the best answer will be found in the microwave bands. However, for those who can use it, the International Amateur Radio Union (IARU) satellite frequency coordination process has now opened another alternative: 29 MHz uplinks.

Read the EngineerIT article at http://www.ee.co.za/article/29-mhz-forgotten-frequency-amateur-radio-satellites.html

IARU Satellite Frequency Coordination http://www.iaru.org/satellite.html

May 24 2015

PSAT PSK31 CubeSat Update May 24

PSAT PSK31 FM Downlink received by Martin G8JNJ at 1429 UT May 22, 2015 using the online SUWS WebSDR

Bob Bruninga WB4APR released this update on the PSAT PSK31 CubeSat on Sunday, May 24

28 MHz PSK31 Receiver Board Flight Prototype – Brno University of Technology

The PSAT PSK31 435.350 MHz FM downlink is full quieting with 6 bars using a decent UHF Yagi. But we have not seen any users other than those using the 28.120 PSK channel on HF normally. We welcome people to experiment with it.

Everyone within the 28.120 to 28.123 MHz ten meter passband will be uplinked and heard on the 435.350 MHz downlink.

The Naval Academy’s PSAT seems healthy with plenty of power (we are keeping the APRS digipeater off to allow max power for PSK31).

PSAT’s radio and packet system are a simple $250 APRS tracker http://www.byonics.com/mtt4b sent to space. The PSK31 transponder is a single 3.4″ square circuit board made by Brno Universtiy in the Czech Republic. The CPU for controlling bulletins and timing is a simple Parallax Basic Stamp.

PSAT is actually only about a 1U cubesat but in a 1.5U package since the flight was available and it gave us more power for our NON-SPACE solar cells. We are using standard silicon that are only half as efficient as multi-junction cells, but only cost 1% as much.

PSAT has a single 21″ VHF and 72″ long HF whip. It has two UHF 6″ orthogonal monopoles, all of very thin Nitinol wire.

More details will eventually follow as the page will be updated over the coming weeks http://aprs.org/psat.html

* PSAT packet telemetry is OK, Digipeater will be off (secondary mission)
* PSAT PSK31 transponder is ON with 28.120 MHz uplink! (primary mission)
* WOD data fixed. Spin data now available. Right now it is at 3 RPM with
+Z pointing 45 deg off Sun
* Launch TLE elements (below) are still very good
* http://PCSAT.APRS.ORG web page is now capturing PSAT telelmetry that
users inject into the APRS-IS
* BRICSAT telemetry has been heard but is cycling OFF due to low power
* BRICSAT PSK31 downlink (also FM) has also been heard barely (when ON)
* USS Langley not heard

Frequencies:

PSAT: 145.825 – 1200 baud AX.25 telemetry – digi off
PSAT PSK31-5: 435.350 FM down, 28.120 SSB PK31 uplink – Brno University Transponder

BRICsat: 437.975 – 9600 baud telemetry evry 20s
BRICsat PSK31-6 – same as PSAT but PSK TLM on 375 Hz (PSAT on 315 Hz)

USS Langley – 437.475 9600 baud telemetry <== CORRECTION

ULTRASat3  
1 99993U          15140.67013889  .00040043  00000-0  10235-2 0 00009
2 99993 055.0004 339.9238 0251027 182.3314 074.3075 15.12517086000014

Bob, WB4APR

Guide to using the PSK31 transponder https://amsat-uk.org/beginners/how-to-work-psk31-satellites/

ParkinsonSAT (PSAT) http://www.aprs.org/psat.html

Fldigi PSK31 software http://www.w1hkj.com/Fldigi.html

May 24 2015

Nine CAS-3 amateur radio satellites to launch in July

CAMSAT CAS-3A

The CAMSAT orchestrated CAS-3 amateur satellite system is now nearing completion.

Nine satellites, CAS-3A – CAS3i, should be launched on July 20, 2015 from the Taiyuan Satellite Launch Center on the new CZ-6 launcher. It is understood the CZ-6 will be carrying a total of 20 satellites.

Six of the CAMSAT satellites, CAS-3A-CAS-3F, are equipped with substantially the same amateur radio payloads. A 20 kHz bandwidth 435/145 MHz (mode U/V) 100 mW linear transponder for SSB/CW communications, a CW telemetry beacon and an AX.25 19.2k/9.6k bps GMSK telemetry downlink.

Each set of amateur radio equipment has the same technical characteristics, but operates on different frequencies in the 435 MHz uplink band and 145 MHz downlink band. While the amateur payloads are similar the sizes of the satellites differ, one is 20 kg, three are 10 kg and two are 1 kg.

CAS-3A will be deployed into a 450 km sun-synchronous orbit while the other satellites will in a 530 km sun-synchronous orbit.

LilacSat-2, developed at the Harbin Institute of Technology, has been renamed as CAS-3H, and has had to change frequencies to avoid a clash with other CAMSAT satellites on the flight. CAS-3H carries 145 MHz APRS, a 145/435 FM transponder and a 437 MHz CW beacon.

Two others satellites on the launch also carry amateur satellite service payloads and have been named as CAS-3G which has 9k6 GMSK AX25 downlinks on 145 MHz and 437 MHz and CAS-3i which has a 9k6 FSK telemetry downlink on 437 MHz.

Further information on the CAS-3A to CAS-3F satellites can be seen at
https://amsat-uk.org/satellites/communications/camsat-cas-3-series/

CAMSAT with support from the Qian Youth Space Academy has been developing two satellites CAS-2A1 and CAS-2A2. These will not be on this launch, instead they may fly on a CZ-2 at a later date.
https://amsat-uk.org/2012/10/18/cas-2a1-and-cas-2a2-linear-transponder-amateur-radio-satellites/

CAS-2 Series IARU Satellite Frequency Coordination page
http://www.amsatuk.me.uk/iaru/formal_detail.php?serialnum=264

CAS-3 Series IARU Satellite Frequency Coordination page
http://www.amsatuk.me.uk/iaru/formal_detail.php?serialnum=458

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