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DTUsat Chit-Chat

Informal news and or stories.

This page will be filled on a nonregular basis with small stories/news about the DTUsat project and related issues.

DTUsat Hardware on Display

In conjunction with LARM, the DTUsat project displayed some of it's HardWare in Rundetårn during "Day of Research", Thursday 19. April. The focus was on the radio parts of the satellite project. Onboard are three radio systems in S, L and ISM bands. The DTUsat GS has a S, L and UHF band systems. An attempt to pick up the COM Tx from top of the tower was hindered by the iron fence surrounding the top and encapsulating visitors creating a Faraday cage.

Engineering model of DTUsat 1 and DTUsat GS relocated for a night in Rundetårn.

GS 3m Mast Flashes New Top Pipe

The top pipe of our 3m dish mast has been bend for some time. Further to that the COM distance test revealed that some tweaking was necessary. Hence it was: "Go 3m Mast Touch Up!". After a long day the DTUsat Ground Station 3m Dish Mast now features a shining new top pipe and should be ready for the next COM distance test.

Left image shows the 3m Dish Mast with the old top pipe and right shows the new straight top pipe.

COM on it's first field test

Equiped with a 15m mast from DX-Wire and the COM radio in stand alone configuration the first field test was conducted on 29. March 2012. The test marks the opening of a series of tests leading up to a long distance high altitude balloon test. We did get some data through but overall results were sparse. Lessons learned: Ground Station needs tweaking, wind and glassfiber telescopic masts equals trouble.

Among the conclusion were: the glassfiber mast acts a lot like a fishingpole in winds of 7-9 m/s.

Rocket Scientists relays the depeche

On Tuesday 30. August the Rocket Scientists running team participated in the DHL relay 2011. The worlds largest relay with 130.000 signed up and 100.000 completing. This years mixed team completed the 5x5km in 2h 8min 13sec.

One cake was released by Villads (19m 25s) who clearly beated René (20m 47s).

DTU Hosts 7th Intl. CDIO conference

And DTUsat is present, of course.

On the 21. of June 2011 participants of the CDIO conference held at DTU had the opportunity to get a first impression on the pedagogic strategy behind the DTUsat project.

Pictures giving an impression of the venue. The audience showed genuine enthusiasm towards the satellite project.

Rocket Scientists Rocks - again!

55min and 52 sec was the total time for the Rocket Scientist team participating in the 3x5km DTU Relay 2011.

Individual times were:

Ulrik Nielsen 17min 17sec

Martin Laage Kragh 18min 03sec

René Fléron 20min 32sec

Our nearest competitor came in 2min 34sec after us.

Feeling Radiant?

EPS took a dip in the gamma soup. Reportedly the refreshment had little effect.

EPS dressing up for the dive.

Rocket Scientists - Speeds Up

Team Photos, incl. photographer.

The DTUsat relay team, a.k.a. Rocket Scientist participated in this year DHL relay. The officiel team time this year: 1h 47min 41sec marking a 1min 27sec improve over last years time.


Individuel times:

1. 19min 27sec

2. 20min 49sec (project manager)

3. 21min 37sec

4. 22min 50sec

5. 23min 7sec


Releasing one cake.

GPPL Show Down Days

The DTUsat team has allocated time for assembling and testing the GPPL before Easter. First step: Optimization of transmitter.

Work in progress

Evaluating results. ...and yes it's small.

Track-a-Sat kit nails S-band communication

After several attempts and adjustments the Track-a-Sat kit finally picked up S-band communication from an orbiting satellite, thereby prooving that it is actually possible to receive 2,4GHz signals with the portable equipment. The pass of ECHO (AO-51) lasted approximately 10-11 min, signal was acquired at 8 degress elevation. Total duration of recording with signal(s) was 9min 22sec, with periodic loss of signal.

Below are some excerpts of the recording (AOS Acquisition of Signal, LOS Loss of Signal).

Yes, the white stuff is snow and no the bird feeder is not part of the equation.

Click on the buttons to hear excerpts of the pass.

BPSK Demodulator Award/Challenge

The two winners of the BPSK Demodulator Award/Challenge received cakes for their help to the DTUsat project. The challenge was announced on a GNU radio forum and on DTUsat webpage and ran worldwide. Below are pictures of the prizes and winners. Congratulations and thank you to Josh Blum (Ettus Research, California) and Peter Scott (OZ2ABA, Denmark).

The prizes are a "German Chocolate Cake" for Josh and Chocolate cake with chocolate chips and a Rhubarb Pie for Scott. Two DTUsat students help Scott celebrate his prize.

Rocket Scientists Rocks! - Update

Five DTUsat members (four students and Project Manager) participated in the DHL relay 5x5km today (1/9-09). With an official total team time of 1h 49min 8sec  the average run time was 21min 37,8sec. Or 4min 22sec pr. km.

According to our own time keeping the individual results are:

  1. 21m 27s (Project Manager)
  2. 21m 30s
  3. 23m 43s
  4. 20m 55s
  5. 21m 32s

This releases two cakes, as runner number 2 benefits from the doubt on time accuracy.

All the results has now been compiled. Rocket Scientists came in:

#450 of all teams all days (19891 teams completed the 5x5 km)

#5 of all DTU teams (170 teams signed up for the relay)

#1 of all DTU Space teams

Shaken not Stirred - updated

Well palms were sweaty today when DTUsat-II EM went on the shaker. So far no casualties :-) Tomorrow the final axis: Z but looks ok at the moment.

And here we are on the other side - only three nuts loosened and no subsystem casualties. Nothing that can't be fixed with a bit of glue/lock-tite or tightening. Some shaking spec's (we went for a WC scenario): Sinusodial 20-100 Hz, 12G. Random vibration: 24,8 Grms (pretty noisy). 

Click on the image to see a small clip (1,8Mb) of the sinusodial shaking in the Z-axis. The low frame rate of the camera causes aliasing.

Never say die!

With only five days left of the semester and no portable payload receiver equipment the long sought field test of the Ground segment Primary Payload seemed very far away. Two long extension cords constituted the primary items in a quick-fix. A stationary PC was converted into a "portable" thereby allowing us to perform the field test with the bird tracker. Despite it not being the final version we really wanted to present some in-field measurements before the summer holidays set in. In between heavy rain-showers (including thunder) and with less than perfect batteries 1200 meters was reached. That's about as far as we can go on Campus (click on the map). In reaching this milestone enthusiastic students and both Hinke A/S, Ettus Research LLC and More Electronics played important parts.

Cold as in Ice Cold

The DTUsat team has conducted the first Thermal Vacuum (TV) test in the test and integration facility. The system is still being refined; so far we've reached 1e-5 mbar and -40°C. The chamber has an in-situ sun simulator for thermal chock test and a thermally decoupled rotationel stage.

As the door to the climate chamber is opened water vapour in the air freezes on the outside of the vacuum chamber.

FL Smidth Roadrunners

In the world of natural science and technology the competition is fierce but most often unrecognized by the general public. The Shell Eco Marathon is an exception to that rule. With 200 teams from 30 countries winning two first prizes is an amazing achievement - congratulations! The DTUsat project shares three students with the roadrunners.

The green "go" flag is waved for the Innovator (1. Prize Lowest CO2 emission/km). The "family" portrait with the two prizes and DTU Dynamo 5.0 (1. Prize Longest distance/l in it's class, Internal Combustion Engine).

Challenge: BPSK Receiver for Gnu Radio

Dear Reader,


If you know how to make a BPSK receiver on Gnu Radio (preferably in GRC) and is willing to make the code not only will you be honoured on these pages but you will win a cake of your own choice.


The code has to run under Gnu Radio and on the USPR board, i.e. if it doesn't run on our set-up we don't need/want it.

We would prefer code in GRC, but that's not a strict requirement.

It has to handle 868 MHz, we have the USRP hardware for that already.

The code has to recover the transmitted data (we have the transmitter).

We do NOT need/want DBPSK demodulation.

Dead-line: 11. May 2009, Midnight CET.

The cake:

Various internet based shops around the globe offers cake delivery. We are willing to consider specific request, otherwise we'll try to find one close to you.

It could be something like this:

Beverly Hills Bakery.


Questions are welcome at: r w f - a t - s p a c e - d o t - d t u - d o t - d k

(omit spaces and dashes - you'll figure it out).

1. May WorkShop

The DTUsat WorkShop today brought about positive results and a convenient chance for some team-building, i.e. Hot-Dogs from the BBQ.

Thanks to a very fast respons from Ettus Research and our own very skilled SW student, we now have a 868 MHz capability.

Also the Sun Sensor Calibration Bench finally came up and running. The first Sun Sensors to be calibrated are the ones for TUM MOVE satellite. 

The Sun Sensor Calibration set-up and one of the first -70° to +70° measurements.

Enjoying Hot Dogs from the BBQ and finally the day ended with capturing in real-time the appology sent through the GSM net by the Project Manager to the kinder garden for not keeping track of time.

Test Receiver for the Bird Transmitters

In order to test the small transmitters carried by the birds we need a receiver. Finding a ready made one has prooven hard and we've given up on that. Our efforts on constructing one from scratch has also prooven fruitless, primarely due to lack of attention.

Finally it seems the solution is based on a SW defined radio using hardware from Ettus Research.

At present we do not have anything up and running but we'll keep posting on the issue as it progresses.

You been Owned

When bored why not nag our sister-project: FL Smidth Car (f.k.a. Øko-raceren). So here's some pic's for you to enjoy :-)

Yes, you've been owned ;-) More Pic's to come.

DTUsat X-Mas Event 08

This Friday the DTUsat Team held a small X-Mas event to celebrate the very productive fall semester and the approaching holiday. After a regular System Engineering meeting with our PI seasons sweets very produced featuring a first prize for the most creative one. The picture to the right shows the 3 finalists, with the Cuckoo nominated as the winner. The Cuckoo was created by our PI. Merry X-Mas and a Happy New year to all.


The three finalists. The Cuckoo by our PI won first prize.

Orphans of Apollo

Members of the DTUsat team went to the European premier of the film Orphans of Apollo directed by Michael Potter. The film describes a group of enthusiastic space entrepreneurs and their effort to salvage the MIR space station and open it up for commercial business.

DTUsat team members in the Planetarium with director Michael Potter. As a curiosa there are 3 ISU alumnis on this picture.

Q-Bird All Systems Check!

These last few days have been filled with good news. Following the birth of our FlatSat the Q-Bird (bird transmitter mark-I) has now undergone and passed an all-systems check. For the un-trained eye the picture to the right may not be a revelation but it is in fact proof that the Q-bird receives GPS signals. Before field tests can be done some further integration and SW coding is needed - present results however are encouraging.

DTUsat WorkShop

In order to get an extra amount of cross disciplinary work done we've set up a 3 days WorkShop in the TIF. After a slow start the first day, things are speeding up on day two and some nice milestones have been passed.

The overall goal is to get ready for the CDR.

Almost all subsystems has been present the last two days, on the picture to the right ACS SW is being debugged (successfully) by ACS HW (Thorbjørn) and SW (Martin) while project manager follows. OBC FlatSat version apparently took "a hit" while SW was developed for it. In the foreground with his back turned Teis is in the process of reviving it.

Exchange student from TUM

The last weeks we have had the pleasure of an exchange student from the MOVE team at TUM.

The student will work on finalizing sunsensors for the MOVE Cubesat.

The exchange was arranged through the informal network: European CubeSat Community. The network consist of European Cubesat Teams and was established during the days of the Vega Maiden Flight Conference at Estec in January this year.

Activities during the summer 08

The webpage has not been updated for a long time. Not due to project inactivity - on the contrary the team members have been busy all summer working on all but the DTUsat webpage. As the time for flight hardware fabrication is closing in efforts have been put into finalizing the DTUsat Test and Integration facility as well.