Amateur telemetry reception from ARTSAT2 interplanet probes: DESPATCH and Shin-en2.

Authors: Piotr SP5ULN, Michał SQ5KTM, Piotr SP5MG, Łukasz SQ5RWU.

Introduction

Bands above 50MHz are often treated only as local FM communication channels. Here and there in the radioamateur environment, the opinion is repeated that in this frequency domain nothing particularly interesting is happening, excluding only rare cases of sporadic E layer. By denying this thesis, quite a large group of radio amateurs (which include, among others, Authors) focuses its activities around UKF and higher, using such experiments as:
– satellite communications;
– listening for out of horizontal signals in bands above HF (signals reflected from the upper atmosphere layers ionised by meteors, eg signals generated by the Graves radar in France, or TV signals from Sweden or Russia);
– reception of telemetry from stratospheric balloons (amateur and so-called “weather” and their search after touchdown);
– receiving signals from weather, scientific, academic and amateur satellites;
– communications via aircraft reflexes;
– EME communications;
– other new and interesting challenges, including those related to hardware constructions.

One of the interesting activities of this kind was the reception of a telemetry from the space probe 4M (Manfred Memorial Moon Mission). Amateur transmitter was attached to the last stage of a Chinese rocket probe Chang’e-5 flying on the trajectory leading to the Moon and back to Earth. Start of the mission was on 10/23/2014, and the probe 4M last time was received on 11/11/2014. The first ever amateur interplanetary spacecraft was broadcasting data in modified digital mode JT65. It were telemetry data and texts commemorating prof. Manfred Fuchs. SP5ULN was among 29 (officially registered) stations on the Earth which received and decoded these signals. The maximum distance from which SP5ULN managed to receive and decode signals from 4M was 267,000 kilometers. The equipment used for this purpose was not as sophisticated as you would expect, and it is described on SP5ULN page at QRZ.COM (http://www.qrz.com/).

Japanese Interplanetary probes transmitting on amateur bands

The above described radio adventure inspired and motivated for the next challenge, but this time a more ambitious and therefore requiring collective action. 11/30/2014 was announced in Tanegashima Space Center as a date for the launch of Japanese Hayabusa2 mission. Hayabusa2 is a robotic space probe to explore the asteroid 1999 JU3 and return a sample of the matter from its surface. In December 2020 those samples will be delivered to Earth. The rocket also had on its board two other space probes with transmitters operating in the amateur bands (as well as several other scientific space probes).

The first of these – Shin-en2 was weighting 17kg and its overall dimensions were 490x490x475mm (http://www.shin-en2.jp/index_E.html). It was built by the students of Kagoshima University in Japan. It had on its board a linear transponder 2m/70cm (which was unfortunately disabled just before the launch) and a transmitter operating in the digital mode similar to JT65, transmitting telemetry data on frequency 437.385MHz with the power of 800mW.

The second space probe was ARTSAT2:DESPATCH (“DESPATCH” – DEep SPace Amateur Troubadour’s Challenge http://despatch.artsat.jp/en/Main_Page) weighting 32kg and its overall sizes were 500x500x450mm. It was powered only by non rechargeable battery (2500Wh). It was built to broadcast data using a modified CW emission on frequency 437.325MHz, with 7W of power. This space probe was the result of the work of about 70-person team from Tama Art University, and The University of Tokyo.

Both space probes were to be put into solar orbit at a distance of 0.7-1.3 a.u. from the Sun (which is approximately the distance from the Sun to the Earth +/- 0.3 a.u.; a.u – astronomical unit is equal to about 150 million kilometers).

ARTSAT2 was the realization of a very original concept. The shape of the probe (a three-dimensional spiral) was designed by artists as a sculpture and was made using a 3D printer. Information from the probe was planned to be transmitted in three consecutive phases: at first full telemetry (phase 1) until the distance from the Earth did not exceed 180 thousand km (about 10 hours from the launch), then the generative poetry (phase 2) until distance from the Earth did not exceed 1,860,000 km (about 110 hours from the launch), then (phase 3) only the temperature inside the probe (until the end of battery power).

Sent by the probe in the second phase poetry was generated by the on-board computer and was inspired by the data from the on-board sensors. It was not a replay of previously written verses, poetry was generated live by the on-board computer probe.

An interesting element of the mission was to establish a collective ARTSAT2 receiving of the probe signal by radio amateurs scattered around the globe. In a view of the expected distances in which the space probe was supposed to be received, counted in the hundreds of thousands of kilometers, and later in the millions, the creators of the space mission assumed that the individual listening stations will only fragmentary receive signals transmitted from space. Therefore, each received signal had to be sent to the operators of ARTSAT2 along with precise timestamps. There, the information was reconstructed to the complete data frames and decoded.

Design and building of a ground station

By happy coincidence of various circumstances, on the roof of Industrial Research Institute for Automation and Measurements (PIAP institute) in Warsaw (Poland), where research is carried out (among others) associated with reception and analysis of radio signals from an orbit, mesh dish parabolic antenna with a diameter of 4.5m appeared just before the start of the Hayabusa2 probe. In mid-November 2014 antenna was mechanically sited on the roof, with running rotor and all wiring. At this time there were no other installations associated with the planned research activities. This occasion was used to obtain the approval of the management of the PIAP institute for temporary use of this installation for amateur radio experiments. Also there was a permission for use of radio laboratory equipment (with help from radioamateurs who are PIAP Institute employees).

Such opportunity does not happen often, so the project initiative group (SP5ULN, SP5MG, SQ5KTM, SQ5RWU) started the preparatory work. There was very little time – the scheduled launch was on 11/30/2014, but the first mail in this regard was sent by the originator SP5ULN on 11/24/2014. Quick analysis indicated that almost all equipment was somehow available, there was a chance to built the ground station fast enough, except that there was no dish feed for 70cm band.

Building a dish feed illuminator in a few days was a real challenge. A review of available information on the design of dish feeds and discussions on the local FM channel led quickly to the conclusion what type of dish feed was within reach, taking into account dependence of its performance parameters from mechanical accuracy and the availability of materials. Building it was like a race. SP5MG made it. After just few days he delivered working and tuned dish feed. Interesting link on such dish feeds: http://www.2ingandlin.se/Feed_comp_432_MHz.html .

Other critical preparatory work for the project included among others:
– delivering antenna coax cable and other wiring to the proper place (where radios, rotor controller and computes were to be situated),
– development of a method how to find the focal point of the antenna,
– design and making of a mechanical holder for the dish feed at the focal point of the antenna,
– installation of dish feed, with preamplifier and all necessary wiring.

Among members of the team (supplemented at the moment by SQ5DRC, SQ7GMO and other volunteers) other tasks were divided and assigned, which included:
– development of rotor control software (SQ5RWU – the program was fetching data from the Shin-en2 website and sending them to the software controlling the rotor),
– the analysis of signal encoding method for ARTSAT2,
– development of software to decode the data received from the probes (SQ5RWU – method of encoding a signal from ARTSAT2 was published, but then it turned out that the information was wrong, while the encoding methods of Shin-en2 telemetry was not available),
– development of a method to record received signals with time stamp accuracy of less than 1 second (due to needs of JT65 digital mode in the case of Shin-en2 and taking into account the requirements of collective reception ARTSAT2),
– gathering all the necessary equipment (several devices were borrowed from friends. i.e. 70cm preamplifier).

It was also necessary to take care of the mechanical balance of the antenna after installation dish feed and a preamplifier, to calibrate the azimuth and elevation readings on the rotor controller, to perform a test run of the antenna mechanics, to make test measurements and commissioning of RF path, to run all additional subsystems tests (i.e. the recorder of signals with exact time stamps).

As can be seen the logistics of preparation and technical content were quite complex, and for all this in practice only one week was available. All works were performed during private time. The end of a very tight schedule was on Sunday 11/30/2014 with the morning meeting at the place where the ground station was supposed to be built, in order to mount the dish feed on the antenna and make the test run of all subsystems, and finally to test the whole setup. It turned out that it was possible to complete all tasks in eight hours, including a few hours on the roof at freezing temperatures. In the meantime, it turned out that Hayabusa2 is to be launched a day later, but in practice only on Sunday it was possible for all team members to gather in one place at one time, so no action was stopped.

During preparation works we had few problems to solve and obstacles to overcome. For example, for a while it seemed that our antenna system has an offset of 30 degrees in azimuth. It was not the best news, because it would mean that the focal point of the antenna is blurry, and that the antenna does not work the with entire surface. But it turned out that the problem arose from false readings in the controller of the rotor, which quickly was fixed.

On 30/11/2014 Sunday afternoon, the ground station was assembled and tested (including the use of real radio signal simulating ARTSAT2 beacon, made by SQ5RWU and installed few kilometers from the station).

Launch of Hayabusa2 was postponed several times. Finally the mission was launched on Wednesday 03/12/2014 at 04:22 UTC.

Waiting for the first signal (night 3/4.12.2014)

Initially, the ground station team focused on trying to receive ARTSAT2. Both space probes (ARTSAT2 and Shin-en2) every day (or better to say in our situation: every night) were within the range of our location on the globe from about 7:45p.m. to about 2:15a.m. local time. The maximum elevation of about 8 degrees above the horizon was every night around 11:25p.m. This meant sleepless nights, but the enthusiasm and hope among a team allowed to push this to the end of the problems queue. More troubling questions were:
– whether the space probes will work?
– whether the dish feed will be effective?
– whether the equipment in the station will work properly?

Until the very last moment it was not known whether the whole effort will not be wasted, but everyone at the station were sure that the stake was high.

Before the space probes risen over the horizon (precise settings were available on Japanese websites), motivated by anxiety we made experiments with listening of beacons from long distances (i.e. at distance 366km). These tests gave positive results, especially in comparison to other stations equipped good Yagi antennas. Dish feed was working, but did it work good enough to receive data from far outside the Earth’s orbit?

It is worth mentioning that the task of operating ground station the team faced was quite extensive. During the reception of signals from space probes it was necessary to do the following simultaneously:
– supervision of the parabolic dish antenna (camera on the roof provided live images) and its rotor controller,
– radio operations: tuning, selection of filters and gain, Doppler shift compensation (if necessary),
– storing data (screenshots, movies, time-stamped records)
– browsing the Internet in search of any information about the current status of the two probes (i.e. whether they are operational, whether they changed frequency, does anyone receive them, …)
– making our own attempts to decode the received signals,
– other ancillary works.
It was enough work for at last 4 people at a time.

Space probes have come into the range of the Japanese stations and first reports in the Internet appeared. So the probes were working, now the only question was whether our station was good enough to receive anything. Distance already exceeded 300,000km. Around 7:30p.m. local time we all were focused on our tasks, but the tension was seen and heard. At the time of emergence of the space probes on the horizon, station was operating in full swing. After a while, on the waterfall screen we saw a clear signal of ARTSAT2, and we even heard sound of it. We enjoyed it with the happy shouts, but very soon returned to work. We knew that every bit of the received information is valuable. Accompanying us observers asked: “do you always celebrate success in so muted way?”. We enjoyed this success, but everyone had so much work that it wasn’t time for excessive exaltation.

The received signal was strong and stable, but after a few minutes it disappeared. Was this the end? Any attempt (radio settings, change of the frequency, antenna movements) did not produce any effect. We tried to pick up Shin-en2 and succeeded, which was some consolation.

Then the Internet have gained new information. We found out that the probe ARTSAT2 overheated (in a vacuum there is no convection, thus putting the heat to the environment is very difficult) and, consequently, the security system operated and caused transmission cycle of 20 minutes on and 50 minutes off. Operators of ARTSAT2 published schedule of transmitter work. We set alarm clocks (for “five minutes before” and “now”) and started listening to Shin-en2. In our original plans, this probe was not taken into account, but now we had 50 minutes only for it. It turned out that the reception of the transmitter at 0.8W of power at a distance of 300,000km was not a challenge for our station.
Example movie footage of Shin-en2 reception is available at the following web address:
https://www.youtube.com/watch?v=rmVW_LKShAg

Received signals almost on a regular basis we were sending to both Japanese space probes operators. Their response was very positive. It turned out that our station was receiving the strongest signal. It was good confirmation that our work has paid off and all the elements of the RF path have been working properly.

After midnight, when azimuth exceeded 180 degrees, signal strength decreased and later we picked up nothing. Both space probes were moving away from the Earth very quickly, almost 400,000km per day, or more than 16,000km per hour. The disappearance of signals could mean that this is the end of the capabilities of our hardware. Last reception of ARTSAT2 was at a distance of 320,000km.

Then doubts arose whether certainly our dish feed was at the focal point of the antenna. Before 3:00a.m. station was cleaned, and we agreed to do next day a series of experiments with the selection of the position of the dish feed in search of focal point of the antenna. The next day we all went to work in the morning, which was challenging considering that in practice most of us could sleep for only three hours. We were full of doubts about the further reception of both space probes..

The second night, 400.000km farther (4/5.12.2014)

We met a little earlier than last time, and using the signal from a nearby repeater and PIAP institute laboratory equipment, we set the antenna characteristics. Significant help in this task, among others, we have received from Konrad SQ5DRC. We were moving around dish feed position and setting antenna characteristics. In such a way we were looking for sharpest characteristics (the narrowest beam) and the strongest signal. We assumed that using this method we could find exact position of the antenna focal point, and so obtain stronger reception of space probes. But it turned out that the old saying is true: “perfect is the enemy of good”. After more than an hour we set everything back to its original position, which turned out to be the best one.

That night a challenge for our station was set at the distance two times greater than that separating Earth from the Moon. This night ended with the result of 742,179km and it was then the highest score in the world! We received two probes: ARTSAT2 and Shin-en2. Japanese operators of ARTSAT2 probe sent us congratulations. We assumed that the next night will probably be the last one. Next day attempts were to start with a distance of more than 1 million kilometers.

Another nights, another records

Nights 5/6.12 and 6/7.12 brought more records: 1.1 million km and 1.5 million km for both space probes. After each of those nights we discussed whether to come back next night to the station, because each day distance was greater by another 400,000km. But we made the next attempts and in some way we were surprised that we were still in game. These distances were already becoming difficult to imagine, and slowly we started to change from using kilometers to light seconds.

We started to feel physical fatigue. It is not easy to sleep for 3 hours, work normally during a daytime, then work in our ground station until 3:00a.m – and so on day by day. At the end of the night 6/7.12 we had had enough. However, the next morning, it turned out that the station in Argentina received ATRTSAT2 from a greater distance than we did. That was what we needed, motivation appeared and we took the challenge.

The fifth night (7/8.12.2014)

Next session we started full of doubts. Each day it was 400,000km more. This time it was already 1.9 million km. We made it!

At that time, ARTSAT2 has already entered the third phase. The signal was supposed to be sent in the 3 seconds periods. Amount of the time with the carrier on, in relation to the time when there was no signal, was the input data to the formula published by the Japanese ARTSAT2 operators. It allowed to calculate the temperature inside the probe. But what we received was not entirely in accordance with these assumptions. Luckily we had constant communication via the Internet with Japanese space probe designers. They confirmed that this is a signal of ARTSAT2. It turned out that the published documentation was a little bit incorrect, and the period of the transmitted information was not 3 but 5 seconds.

Based on data from our station, temperature inside the ARTSAT2 probe was estimated at 55 deg. C. It was quite warm. We also received Shin-en2, but the signal was very weak. We had to look for marks on waterfall diagram and compare it with the model and previous records. It was only 0.8W received from a distance of 1.89 million km!

The sixth night (8/9.12.2104)

Arriving to our ground station just before the 8:00p.m. has become routine. Also a second phenomenon occurred every day – every day of the space probes were about the distance from Earth to the Moon more than the previous day. That evening we were almost certain that this is the end, and that receiving anything from a distance of more than 2 million km is too much for amateurs. These distances we were associating with a NASA’s Deep Space Network, and not with the efforts of a group of enthusiasts. Nobody said it aloud, but we knew that this time it may end up on a social meeting.

And then it turned out that we still receive ARTSAT2. Shin-en2 unfortunately no, though some traces were visible on the waterfall diagram. This night we finished with an amazing result 2.316759 million km, or 7.73 light seconds!

On the basis of our data ARTSAT2 inside temperature was calculated to be almost 60 deg. C. Since two days we were the only station on Earth receiving anything from probes. In this context, the hobby began morphing into the real mission and we felt responsibility.

Also we have done successful experiments with additional preamplifier at the receiver. Since that time, we started to use it permanently.

The seventh night – the last one (9/10.12.2014)

This time it was really hard. Received signal was so weak that before we anywhere announced its reception, we sent our data to operators of ARTSAT2 space probe asking for their verification. The next day came the official answer:
“[…] Confirmed your data. The frequency is OK (<100Hz) and the duty ratio is 50%. We are sure it is the Despatch’s beacon signal:-)”.

We did not receive anything from Shin-en2 probe.

Our result was to receive readable telemetry data from ARTSAT2 from a distance of 2.715228 million km, which is more than nine light seconds. This was the record distance, before we received that night a few other ARTSAT2 signals. There is a chance that it is a world record in the discipline of the amateur long distance reception of space probes – in terms of decodable signals, not only any registration. It also was the third day, when we were the only Earthlings receiving a signal from the ARTSAT2 probe.

That night we decided that we end the project. We were sure that we had no chance to deal with another 400 thousand km – of which probe was traveling each day. We worked for 7 nights, it was a big challenge for us (and our families). We were so tired that we did not even made a commemorative photo.

Movie recording of this session is available at the following Internet address:
https://www.youtube.com/watch?v=3uW1ZQYuqFo

Conclusions

Despite the colossal effort, seven nightly shifts (and it all was after the marathon preparations), it was a memorable and interesting adventure. A unique experience was the opportunity to see live reception of the space probe signals from a distance of almost 3 million km.

When we started to receive data from a large distance, the signal appeared from time to time. We had the impression that it was reaching us only when the number of propagation parameters played in a positive way for us. When one or more of them tuned away, our reception was disappearing. It seemed like looking through a garden hose with a length of 3 million kilometers, which was bending in all directions, but from time to time by accident was straightened and it allowed to look for a moment until its end.

Signal from our antenna was interrupted by increased background noise at azimuths greater than 180 degrees – we do not know what was the noise source. It should be underlined here that we acted on elevations from zero to only eight degrees above horizon. Probably interference from terrestrial sources played a big role. Perhaps the use of a filter placed at the antenna could improve the situation.

A very good way to store the received data was the use of a program recording audio and video directly from the screen and the computer’s soundboard input. It is also important to store such data such as: frequency, the rotor position, time and date, time pulses per second.

Our achievement has been recognized by international amateur radio organizations, space agencies employees, astronomers. Signals of that we had received through phone calls, Facebook and e-mails. It turned out that with such a project, an important role was played by the direct relationship with the internet media. Our mini press office run by SQ5KTM at the end of each day was preparing an information package, which included bilingual information note, photos and screenshots. We wanted to not only to make our work results public, but also to ensure regular and appropriate messages (i.e. to avoid inaccuracies in reports on various sites and blogs etc.). Furthermore a very important was ongoing communication with Japanese operators of both space probes, especially in terms of collected data transfer (tens of gigabytes finally). Also it was useful for confrontation of a theoretical models with the real observations of received telemetry.

An interesting is probably the fact that if we count the hardware units and software used, the latter could give greater number.

There were also several reports of reception ARTSAT2 from a distance of the order of 4.7 million km, but most likely these signals were not decodable (but this we do not know for sure).

Our efforts and successes have rebounded fairly wide coverage on the Internet. Here are a few selected web addresses:
– AMSAT-UK:
http://amsat-uk.org/2014/12/09/despatch-2m-km-record/
– AMSAT bulletin:
http://amsat.org/pipermail/ans/2014/000823.html
– ARRL:
http://www.arrl.org/news/polish-radio-amateurs-receive-3d-printed-artsat2-despatch-qsl-card
Operators of our ground station during all of the nights were: Piotr SP5MG, Piotr SP5ULN, Lukasz SQ5RWU and Michal SQ5KTM (from the left on the photo). We received great technical support from Arek SQ7GMO and Konrad SQ5DRC. Also we got the help from PIAP Institute employees (but of course afterhours, in their private time). Guests visiting our station: Tomasz SP5XMU, Krzysztof SQ5NWI, Jacek SQ5AAG and few other not licensed people.

Guests visiting our station: Tomasz SP5XMU, Krzysztof SQ5NWI, Jacek SQ5AAG and few other not licensed people.

Photo on the left: QSL cards sent to us form ARTSAT2:DESPATCH project managers, printed on 3D printer, confirming our participation in a project and reception distance.

Technical appendix

In this section we will describe used by us hardware and software. It will be shown on photographs.

Signal was coming directly from dish feed to preamplifier. Than coax cable was running down to the station. Mechanical holder of dish feed is also visible here.

Main screen:
Right Upper corner – waterfall diagram showing received signal.
Right bottom corner – radio controlling software.
Left upper corner – program fetching data from the Shin-en2 website and sending them to the rotor control program, written by SQ5RWU.
Left bottom corner – rotor control program.

General view of important parts of the ground station.
In the background: on the left – images from camera on the roof (antenna view); in the middle – main screen; laptop on the right – main computer with audio & video recording functions.
Closer: on the left – PR activities and communications with Japanese space probe’s operators, laptop on the right – sound recordings.
Other computer outside the picture – internet monitoring (mainly Japanese space probes web pages) and other auxiliary functions.