$50SAT / MO-76 six months in space and counting

Yaesu handheld and $50SAT 1.5U PocketQube

Yaesu handheld and $50SAT 1.5U PocketQube

Wednesday, May 21, 2014, marked the six month anniversary of the launch of the tiny $50SAT / MO-76 PocketQube satellite which is just 5x5x7.5 cm and 210 grams.

Michael Kirkhart KD8QBA has released an update on this remarkable satellite:

We have finally completed the first pass cleanup of the telemetry data provided by all of you.  We cannot thank you enough for this data, as it will help us understand how $50SAT/MO-76 has been operating.  Keep it coming!

On the Dropbox, you will find a new directory (Telemetry-analysis/Battery-voltage-2014-06-04) containing our first set of processed data, which serves as an initial investigation into the performance of the on-board Li-ion battery.  Included in this directory is a spreadsheet with all the battery voltage data we have up to now, in both tabular and graphical form; it consists of 1097 individual telemetry observations.  For convenience sake, there is also a copy of the graph in PDF form.  Over the past 6 months, the daily average battery voltage has been dropping.  A best fit line through all the data has a slope of -0.670 mV per day.  The drop, however, has not always been gradual.  For instance, there is a large step change of about -60 mV sometime near February 20, 2014.  We are not sure what happened here.  Anybody out there know what might be going on?

Ignoring the two outliers on the graph, the current low battery voltage is 3521 mV.  This has been observed at least 5 times, including twice by yours truly.  This, of course, occurs when $50SAT/MO-76 happens to be at its lowest temperature, which has been -28 degrees C until yesterday evening, where I observed a temperature of -29 degrees C.  While our depth of discharge on the battery is relatively low (our initial calculations were about 22 mA-hr), it is going through about a -28 degree C to 26 degree C (or possibly higher – this is our highest recorded temperature) and back down to -28 degrees C 14.5 times per day.  Does this violate the conditions of the warranty?

As to whether or not the orbit is decaying, a comparison of the current TLEs with a set from early December 2013 show it is, although by a small amount.

Here are the TLEs from December 4, 2013 (element set 7):
2013-066W
1 39436U 13066W   13337.88841924  .00010097  00000-0  12132-2 0    70
2 39436  97.8019  50.2525 0031655 170.6351 189.5525 14.83797851  1855

Here are the TLEs from June 2, 2014 (element set 223):
EAGLE 2
1 39436U 13066W   14152.25170112  .00007510  00000-0  78254-3 0  2235
2 39436  97.7787 226.1156 0024706 303.1274  56.7439 14.89857855 28503

$50SAT Boards

$50SAT Boards

The second to last element on line 2 is the mean motion, in units of orbits per day.  From this number, the semi-major axis of the orbit can be computed.  On December 4, 2013, it was 6,995.50 km, and on June 2, 2014, it was 6,976.51 km.  This means the orbit has decayed by about 19 km during this time period.  The orbit has also become slightly less elliptical.  The forth element on line 2 is the eccentricity, which has an implied decimal point in front of it.  On December 4, 2013, it was 0.0031655, and on June 2, 2014, it was 0.0024706.  From this and the computed semi-major axis, the apogee and perigee altitudes are as follows:
December 4, 2013:  apogee = 639.64 km, perigee = 595.36 km
June 2, 2014: apogee = 615.75 km, perigee = 581.27 km

The technical challenge we posed to the amateur community to successfully uplink to $50SAT/MO-76 has yet to be met.  We have since realized some of the documentation, specifically the Silicon Labs Si4432 data sheet, was not clear on at least one of the needed details.  To encourage the amateur radio community to answer our challenge, we will post some information that should be helpful in uplinking to $50SAT/MO-76; look for this sometime in the next few days.

$50SAT/MO-76 has made it onto YouTube!  See a video of the excellent talk on $50SAT/MO-76 given by Howie DeFelice, AB2S, and a video of yours truly operating the AMSAT demo station during a $50SAT/MO-76 pass at the Dayton Hamvention.

73

Michael Kirkhart
KD8QBA
$50SAT/MO-76 team

Talk by Howie DeFelice AB2S at the May 14, 2014, PocketQube workshop
(thanks to Gustavo, LW2DTZ, for taking and posting this video)

$50SAT was a collaborative education project between Professor Bob Twiggs, KE6QMD, Morehead State University and three other radio amateurs, Howie DeFelice, AB2S, Michael Kirkhart, KD8QBA, and Stuart Robinson, GW7HPW. The transmitter power is just 100 mW on 437.505 MHz (+/-9 kHz Doppler shift) FM CW/RTTY. $50SAT uses the low cost Hope RFM22B single chip radio and PICAXE 40X2 processor.

Michael Kirkhart KD8QBA operates AMSAT demo station during $50SAT/MO-76 pass Friday, May 16
(thanks to Patrick Stoddard, WD9EWK, AMSAT-NA Vice President for Field Operations, for this video)

$50SAT PocketQube Amateur Radio Challenge
https://amsat-uk.org/2014/02/21/50sat-amateur-radio-challenge/

Further information in the $50SAT Dropbox https://www.dropbox.com/sh/l3919wtfiywk2gf/-HxyXNsIr8

$50SAT – Eagle2 – Communications – Release Version V1_2.pdf
http://tinyurl.com/50DollarSatCommunicationsV1-2

Hope RFM22B single chip radio http://www.hoperf.com/rf/fsk_module/RFM22B.htm

There is a discussion group for $50SAT http://groups.yahoo.com/groups/50dollarsat/

50DollarSat http://www.50dollarsat.info/

$50SAT celebrates five months in space

Yaesu handheld and $50SAT 1.5U PocketQube

Yaesu handheld and $50SAT 1.5U PocketQube

Michael Kirkhart KD8QBA provides an update on the $50SAT (MO-76) PocketQube. The tiny satellite which is just 5x5x7.5 cm and 210 grams has completed five months in space.

As of Monday, April 21, 2014, $50SAT/MO-76 has been operating continuously for 5 months!  Moreover, the weather here in EN82 land has improved considerably, allowing me to gather telemetry more often.  I recently purchased a TEAC VR-20 digital recorder, which has eliminated the need for me to use my netbook computer for recording audio from my radios.  In fact, I can basically “wear” all my gear – my FT-817ND is strapped around my neck, my headphones are over my ears, my AMSAT preamp is in my left pocket, my VR-20 is in my right pocket, and my Arrow antenna (or homebrew 6 element WA5VJB Yagi) is in my left hand, leaving my right hand available for tuning.

About 2 to 3 weeks ago, the downlink frequency shifted down to where it should be, centered at 437.505 MHz.  This caught me (and probably some of you) by surprise, as I had trouble finding the downlink signal when running LSB.  As soon as I got used to tuning down, the frequency shifted back up to where it was originally – about 3 kHz high.  Anybody else notice this?

The daily average battery voltage continues to slowly drop.  It does get to about 3700 mV when solar power is available, but will drop as low as 3541 mV just as $50SAT comes out of eclipse.  When it drops below 3600 mV, the sleep time (the time between operational cycles) extends from about 50 seconds (4 * 6 * 2.1 seconds) to about 126 seconds (10 * 6 * 2.1 seconds).  This was done to help stabilize the battery voltage in case of insufficient solar charging, but does have a downside: there are fewer operational cycles per pass.  A rough estimate of operational cycles per pass can be computed using the following information:

1. Typical pass duration is 10 minutes, or 600 seconds
2. The typical operational cycle time for Fast Morse telemetry messages is about 32 seconds
3. The typical operational cycle time for RTTY telemetry messages is about 51 seconds
4. A full cycle of operational cycles consists of 3 RTTY telemetry cycles and 2 Fast Morse telemetry cycles

The average operation cycle time is thus (3 * 51 + 2 * 32) / 5 = 43 seconds

If the battery voltage is less than 3700 mV but greater than or equal to 3600 mV, the number of operational cycles per pass about 600 / (43 + 50) = 6.45, giving somewhere between 6 and 7 cycles per pass.

If the battery voltage is less than 3600 mV but greater than or equal to 3500 mV, the number of operational cycles per pass about 600 / (43 + 126) = 3.55, giving somewhere between 3 and 4 cycles per pass.

$50SAT Boards

$50SAT Boards

Up on the Dropbox, I have uploaded a new TLE set (element set 174) as well as an updated RTTY reports file.  Thanks to all of you, this file has grown significantly.  As of Tuesday, April 22, we have 950 unique telemetry packet captures.  We are working on “scrubbing” through the telemetry data and importing it either to a spreadsheet or a database so we can start analyzing the data.  We appreciate all of you folks who have been gathering telemetry for us, and encourage you to keep doing it.

I have also uploaded a spreadsheet showing the “valid” values for both solar and battery voltage.  Even though $50SAT reports both of these voltages in units of mV, its resolution is only about 20.2 mV.  As a result, there is a finite set of valid voltage values which can be reported.  The spreadsheet uses the actual calibration values from the MK4 CPU board used in the flight model, and computes the mV values the same way the PICAXE CPU in $50SAT does.  This information is quite helpful in recovering partially corrupted RTTY packets.

73

Michael Kirkhart
KD8QBA
$50SAT/MO-76 team

$50SAT was a collaborative education project between Professor Bob Twiggs, KE6QMD, Morehead State University and three other radio amateurs, Howie DeFelice, AB2S, Michael Kirkhart, KD8QBA, and Stuart Robinson, GW7HPW.  The transmitter power is just 100 mW on 437.505 MHz (+/-9 kHz Doppler shift) FM CW/RTTY. $50SAT uses the low cost Hope RFM22B single chip radio and PICAXE 40X2 processor.

$50SAT PocketQube Amateur Radio Challenge
https://amsat-uk.org/2014/02/21/50sat-amateur-radio-challenge/

Further information in the $50SAT Dropbox https://www.dropbox.com/sh/l3919wtfiywk2gf/-HxyXNsIr8

$50SAT – Eagle2 – Communications – Release Version V1_2.pdf
http://tinyurl.com/50DollarSatCommunicationsV1-2

Hope RFM22B single chip radio http://www.hoperf.com/rf/fsk_module/RFM22B.htm

There is a discussion group for $50SAT http://groups.yahoo.com/groups/50dollarsat/

50DollarSat http://www.50dollarsat.info/

MO-76 $50sat is Rev-Ed project of the month

Yaesu handheld and $50SAT 1.5U PocketQube

Yaesu handheld and $50SAT 1.5U PocketQube

The MO-76 $50sat amateur radio satellite team is pleased to announce that the PICAXE based $50sat was chosen as Project of the Month by Bath based Revolution Education who supply PICAXE microcontroller development systems.

$50SAT is one of the smallest amateur radio satellites ever launched at 5x5x7.5 cm and weighs only 210 grams. Transmitter power is just 100 mW on 437.505 MHz (+/-9 kHz Doppler shift) FM CW/RTTY. It uses the low cost Hope RFM22B single chip radio and PICAXE 40X2 processor.

$50SAT was a collaborative education project between Professor Bob Twiggs, KE6QMD, Morehead State University and three other radio amateurs, Howie DeFelice, AB2S, Michael Kirkhart, KD8QBA, and Stuart Robinson, GW7HPW.

PICAXE $50sat http://www.picaxe.com/Project-Gallery/50SAT/

Bath based Revolution Education http://www.rev-ed.co.uk/

$50SAT PocketQube Amateur Radio Challenge
https://amsat-uk.org/2014/02/21/50sat-amateur-radio-challenge/

Further information in the $50SAT Dropbox https://www.dropbox.com/sh/l3919wtfiywk2gf/-HxyXNsIr8

$50SAT – Eagle2 – Communications – Release Version V1_1.pdf
http://tinyurl.com/50DollarSatCommunicationsV1-1

Hope RFM22B single chip radio http://www.hoperf.com/rf/fsk_module/RFM22B.htm

There is a discussion group for $50SAT http://groups.yahoo.com/groups/50dollarsat/

50DollarSat http://www.50dollarsat.info/

$50SAT designated Morehead-OSCAR-76

Yaesu handheld and $50SAT 1.5U PocketQube

Yaesu handheld and $50SAT 1.5U PocketQube

The $50SAT team have applied for and been designated an OSCAR number for their PocketQube satellite – Morehead-OSCAR-76, or MO-76.

$50SAT is one of the smallest amateur radio satellites ever launched at 5x5x7.5 cm and weighs only 210 grams. Transmitter power is just 100 mW on 437.505 MHz (+/-9 kHz Doppler shift) FM CW/RTTY. It uses the low cost Hope RFM22B single chip radio and PICaxe 40X2 processor.

$50SAT has been a collaborative education project between Professor Bob Twiggs, KE6QMD, Morehead State University and three other radio amateurs, Howie DeFelice, AB2S, Michael Kirkhart, KD8QBA, and Stuart Robinson, GW7HPW.

$50SAT PocketQube Amateur Radio Challenge
https://amsat-uk.org/2014/02/21/50sat-amateur-radio-challenge/

Further information in the $50SAT Dropbox https://www.dropbox.com/sh/l3919wtfiywk2gf/-HxyXNsIr8

$50SAT – Eagle2 – Communications – Release Version V1_1.pdf
http://tinyurl.com/50DollarSatCommunicationsV1-1

Hope RFM22B single chip radio http://www.hoperf.com/rf/fsk_module/RFM22B.htm

There is a discussion group for $50SAT http://groups.yahoo.com/groups/50dollarsat/

50DollarSat http://www.50dollarsat.info/

Information on obtaining an OSCAR number for your satellite can be found on the OSCAR Numbers Policy page at http://www.amsat.org/?page_id=2478

$50SAT PocketQube Amateur Radio Challenge

Yaesu handheld and $50SAT 1.5U PocketQube

Yaesu handheld and $50SAT 1.5U PocketQube

The $50sat PocketQube satellite team, AB2S, KD8QBA and GW7HPW, are celebrating 90 days in orbit by proposing a technical challenge to all interested radio amateurs.

$50sat is capable of responding to uplink command packets. There are three open packets:

• Test packet – $50SAT responds by sending the RSSI of the received packet in slow FM Morse.

• Request data packet – the normal data packet is sent.

• Request RTTY – The RTTY is sent.

In addition all received packets result in two copies of the ack packet being sent, that contains the RSSI of the received packet.

All the required information to accomplish this is available on the Dropbox location available through the $50sat web page. See the document $50SAT – Eagle2 – Communications – Release Version V1_1.pdf

Anyone that can demonstrate a successful command uplink by submitting a recording of the response packet along with the date, time and location of of the contact will receive a Certificate of Technical Accomplishment signed by all three builders of $50sat.  Submissions can be made to the $50sat email address; 50dollarsat at yahoo.com

This is a significant challenge because there is no magic black box that you can buy to do this.

$50SAT Boards

$50SAT Boards

After 90 days of operation, the Kodak KLIC-7002 camera battery that powers the satellite has fallen off about 100mV, but operations still seem normal.

We have also programmed a special 5th Morse beacon to thank our launch sponsor and mentor Prof. Bob Twiggs. Please give a listen for  the message TNX KE6QMD on the FM Morse beacon.

QSL cards are still available to anyone that posts telemetry, either hand copied CW or RTTY captures, to the 50dollarsat yahoo group.

73 and good luck to all from the $50sat team

$50SAT is one of the smallest amateur radio satellites ever launched at 5x5x7.5 cm and weighs only 210 grams. Transmitter power is just 100 mW on 437.505 MHz (+/-9 kHz Doppler shift) FM CW/RTTY. It uses the low cost Hope RFM22B single chip radio and PICaxe 40X2 processor.

$50SAT has been a collaborative education project between Professor Bob Twiggs, KE6QMD, Morehead State University and three other radio amateurs, Howie DeFelice, AB2S, Michael Kirkhart, KD8QBA, and Stuart Robinson, GW7HPW.

Further information in the $50SAT Dropbox https://www.dropbox.com/sh/l3919wtfiywk2gf/-HxyXNsIr8

$50SAT – Eagle2 – Communications – Release Version V1_1.pdf
http://tinyurl.com/50DollarSatCommunicationsV1-1

Hope RFM22B single chip radio http://www.hoperf.com/rf/fsk_module/RFM22B.htm

There is a discussion group for $50SAT http://groups.yahoo.com/groups/50dollarsat/

50DollarSat http://www.50dollarsat.info/

$50SAT PocketQube Update

Yaesu handheld and $50SAT 1.5U PocketQube

Yaesu handheld and $50SAT 1.5U PocketQube

Michael Kirkhart KD8QBA provides this update on the $50SAT PocketQube which transmits on 437.505 MHz (+/-9 kHz Doppler shift).

The TLEs on the Dropbox have been updated to reflect the latest element set available from Celestrak. This probably is not necessary, as many (if not all) of you are probably pulling them down into your satellite prediction programs straight from Celestrak’s WWW site.

Construction of the replacement engineering model (engineering model 1 was promoted to flight model 1 and is what is in orbit) has been completed, and preliminary tests show it to be operating correctly. I posted a few photos of the build up on the Dropbox in the Pictures/Engineering-Model-2 folder. Final mass is 202.1 g, which is about 4 to 5 grams lighter than the flight model. This is in line with expectations, as it only has 1 fully populated solar panel, and the missing solar cells (18 of the 24 used on the flight model) would add about 4 to 5 g.

The RTTY reports file has been updated to include all telemetry posted/collected as of 2014-02-11. This file has nearly doubled in size from the last update, which was only 16 days ago. Thanks to everyone who has been feeding the data beast by posting their telemetry; please keep doing so. QSL cards for those who have been posting telemetry should start appear in your mailbox in the next few weeks (or sooner).

$50SAT Boards

$50SAT Boards

While it is still quite cold (and snowy) here in EN82, I have been going out with my FT-60 to listen for at least one pass per day. As the terminator continues to move north (not fast enough for some of us who would like to get past winter), I have noticed the point where the FM Morse beacon transitions to slow code speed (indicating it is now warm enough to turn on the solar power) has been occurring earlier in the pass. As soon as it warms up a bit, I will gather some telemetry just to see how much solar power is being generated.

I have a bit more analysis to do, but thanks to some telemetry captured by Kristaps, we believe the low temperature of $50SAT to be about -24 degrees C.

73
Michael Kirkhart KD8QBA
$50SAT team

$50SAT is one of the smallest amateur radio satellites ever launched at 5x5x7.5 cm and weighs only 210 grams. Transmitter power is just 100 mW on 437.505 MHz (+/-9 kHz Doppler shift) FM CW/RTTY. It uses the low cost Hope RFM22B single chip radio and PICaxe 40X2 processor.

$50SAT has been a collaborative education project between Professor Bob Twiggs, KE6QMD, Morehead State University and three other radio amateurs, Howie DeFelice, AB2S, Michael Kirkhart, KD8QBA, and Stuart Robinson, GW7HPW.

Further information in the $50SAT Dropbox https://www.dropbox.com/sh/l3919wtfiywk2gf/-HxyXNsIr8

There is a discussion group for $50SAT http://groups.yahoo.com/groups/50dollarsat/

50DollarSat http://www.50dollarsat.info/