Auteur : radiotelescopelavillette

A simulation for Radio Telescope Training

When the radio télescope du Parc de La Villette rehabilitation is completed it will be possible to perform a remote control via Internet connexions. Using an astronomy software like « Stellarium » or « Skychart » it will be possible to connect the radiotelescope and choose a specific « radio source » then click on GoTo to ask the antenna to move toward the specified target and to perform a follow up while the Earth is slowly rotating. Then it will be possible to record the signal from the radio source in orfer to perform scientific observations.

Another part of the project includes contacts between hamradio stations far away from each other, thanks to signal reflection on the moon surface and back toward the Earth. For this scope the telescope must be oriented toward the moon and must follow its movement in the sky.

Third « mission » dedicated to the radiotelescope is to use the antenna for communications via geostationnary QO-100 hamradio satellite. We will take advantage of the high antenna gain even on 2.4 GHz due to its surface to use a limited amount of transmission power to enter satellite transponder.

For the present time, while the antenna motorization is being repaired, it is still possible to play with the telescope. By using a dummy telescope software, antenna movements are achieved by simulating telescope response to astronomy applications. The server transmits target coordinates to the software driver who computes necessary motors activation. The driver receives in turn the antenna position information from the simulator software as if the radiotelescope was actually moving. This information is sent back to the client astronomy software that displays telescope movement as if the antenna was actually moving.

Here is how to perform training with radiotelescope. Download and install Skychart astronomy software (https://ap-i.net/skychart/fr/start). On menu bar click on « Télescope » and « Paramètres du Télescope« . Click on menu « Télescope« , validate « Pilote INDI » and write in front of Serveur INDI the Internet telescope address : radiotelescope-lavillette.fr

The server port is 7624 by default. Click on « Connect and get device list« . In the window on line « Nom de télescope » should appear : « Radiotelescope – La Villette ». The box « Use the internal INDI gui pannel » should be validated. Click on Appliquer then on OK.

Go back to main menu and click on « Télescope » , « Connect le télescope« . In the new window click on « Connecter« . The red square should become green. In the same window click on INDI gui. A new window will open. Arrange and widen the windows down. On the sky map click on a « source » target and then click in menu « Télescope » on « Go To« . The telescope may refuse to move if the source is out of view. By clicking on numbers in the right it is possible to zoom. Once the antenna reached the target, the telescope switch to tracking mode. A demonstration of all commands explained previously may be visualized on this video : http://f6bvp.free.fr/VP/Film1.mp4

Let us know your remarks and observations. Good simulation !

Publicités

Antenne Parabolique

La parabole

Position géographique de la parabole

  • Az axe : 359° 58′ 14
  • P axe : 48° 57′ 06

Diamètre de l’antenne parabolique : 10 mètres. Les mailles du grillage sont de 11-12 mm.

F/D = 0,40

Ouverture du lobe de l’antenne  : environ 1° (sur la fréquence de la raie hydrogène atomique HI 1420,4 MHz ).

  • Gain théorique +40 dB. Rendement ?

La source 1440 MHz

Monture équatoriale

Les moteurs

  • moteur de poursuite monophasé : 25 tours/minute, 0,25°/min
  • moteur horaire triphasé :
    • grande vitesse : 180 tours/min, 30°/min,
    • petite vitesse : 45 tours/min, 6°/min, AH de -4 heure à + 4 heure
  • moteur déclinaison triphasé, 45 t/min, 6°/min, DEC de -30° à +55°

Schéma général du système de réception (non contractuel)

Earth – Moon – Earth (EME)

Another part of Stars Song project will consist in sending and receiving radio signals in telegraphy or telephony (Single Side Band) or digital signals toward the Moon. CAMRAS WebSDR in diffusing such radio signals sent by radioamateurs and reflected by the Moon. La Villette radiotelescope antenna should be equipped with a source cavity adapted to Earth-Moon-Earth (EME) frequency band around 1296 MHz. We are thinking of using digital transceiver (Transmitter – Receiver) Lime SDR, a device that has been selected by European Space Agency.

Capture d'écran 2018-02-18 02.44.54

All these operations are achieved by capturing radiowaves signals using a Software Defined Radio (SDR) receiver. Receiver is driven by a software driver that is presently under development by INDI developers.  Using INDI API for both sky objects targetting and recording will simplify development of both parts of our project, radioastronomy and hamradio communications.

Present SDR market has a few TRX (transmitter and receiver) offers such as LimeSDR. The choice of TRX model for EME (Earth Moon Earth, EME) is not yet fixed. LimeSDR mini will soon be tested. A driver for LimeSDR is still under beta test in INDI library.

 

Liaisons Terre – Lune -Terre

Earth – Moon – Earth ( EME )

Un des objectifs du projet « Le Chant des Etoiles » est d’effectuer des communications par réflexion sur la Lune en télégraphie ou BLU (Bande Latérale Unique). Cette activité consistera à envoyer et recevoir des signaux radio en mode télégraphie ou phonie en BLU par réflexion sur la surface de la Lune, comme par exemple ce message « Allo Moon ! » de la station allemande DF6NA .

Le WebSDR du CAMRAS diffuse de tels signaux en provenance de la Lune.

Nous devrons équiper le radiotélescope de la Villette d’une source adaptée à la fréquence EME 1296 MHz. Nous envisageons d’utiliser un émetteur récepteur Lime SDR qui a été sélectionné par l’Agence Spatiale Européenne.

Capture d'écran 2018-02-18 02.44.54

Toutes ces opérations nécessitent une fonction de réception qui est assurée par un récepteur radio logiciel (Software Defined Radio, SDR). Le récepteur est piloté par un driver INDI en cours de validation. L’utilisation de la suite INDI pour la poursuite de objets célestes et pour la réception simplifiera la mise en oeuvre de notre objectif d’observation radioastronomique et de communications radioamateurs.

Il existe sur le marché plusieurs TRX (émetteur-récepteur) tel que LimeSDR. Le choix du TRX pour les communications via la Lune (Earth Moon Earth, EME) n’est pas encore arrêté. Le LimeSDR mini nous semble intéressant. Un pilote pour le LimeSDR est en cours de développement en version beta dans la librairie INDI.

Simulation d’observation

Lorsque le radio télescope du Parc de La Villette sera complètement réhabilité, il sera possible de télécommander le radiotélescope à distance grâce à la connexion Internet. Avec un logiciel d’astronomie comme « Stellarium » ou « Cartes du Ciel » on pourra se connecter au télescope et pointer directement sur une « radio source » puis cliquer sur GoTo pour demander au télescope de se diriger vers la cible choisie et de la poursuivre pendant le mouvement de rotation de la Terre. A partir de ce moment on pourra enregistrer le signal radio de la radio source en vue de procéder à des observations à but scientifique.

Une autre partie du projet prévoit de procéder à des contacts entre stations radioamateurs très éloignées grâce la réflexion de signaux sur la Lune et retour vers la Terre. Le télescope sera alors dirigé en direction de la Lune et la poursuivra automatiquement pendant son déplacement dans le ciel.

La troisième « mission » assignée au télescope prévoit d’utiliser son antenne pour faire des communications via un satellite géostationnaire radioamateur. Nous profiterons du gain important de l’antenne pour n’utiliser qu’une faible puissance en émission.

En attendant, il est possible de s’entraîner à piloter le radiotélescope grâce à la mise en place d’un logiciel de simulation des déplacements en réponse à la commande effectuée dans le logiciel d’astronomie. Le serveur et le pilote qui calcule les commandes de déplacement selon les coordonnées des cibles sont les versions réelles définitives. Les moteurs de l’antenne étant en cours de rénovation, celle-ci est boulonnée en position de parking et le simulateur exécute des déplacements fictifs comme si les moteurs étaient activés. Le logiciel d’astronomie reçoit donc l’information de déplacement en retour comme si le radiotélescope bougeait réellement.

Voici comment procéder pour piloter le radiotélescope. Télécharger et installer le programme Cartes du Ciel (https://ap-i.net/skychart/fr/start). Sur la barre de menu cliquer sur « Télescope » et « Paramètres du Télescope« . Cliquer sur l’onglet « Télescope« , valider « Pilote INDI » et indiquer en regard de Serveur INDI l’adresse Internet du télescope radiotelescope-lavillette.fr Le port serveur est par défaut 7624. Cliquer sur « Connect and get device list« . Dans la fenêtre sur la ligne « Nom de télescope » vous devez voir apparaître : « Radiotelescope – La Villette ». La case « Use the internal INDI gui pannel » doit être validée. Cliquez sur Appliquer puis sur OK.

Revenez sur la barre de menu principale et cliquez sur « Télescope » , « Connect le télescope« . Dans la nouvelle fenêtre cliquer sur « Connecter« . Le carré rouge doit passer au vert. Dans la même fenêtre cliquer sur INDI gui. Une nouvelle fenêtre doit s’ouvrir. Arrangez et agrandissez les fenêtres vers le bas. Sur l’image un réticule vous indique vers où pointe le télescope. Cliquez sur une « source » puis cliquer dans le menu « Télescope » sur « Go To« . Le télescope peut refuser de se déplacer si la source est hors de vue. En cliquant à droite de l’image sur les différents nombre il est possible de zoomer. Une fois arrivé en position sur la cible le télescope passe en position poursuite. Une démonstration de toutes les commandes décrites ici peut être visualisée dans la vidéo suivante : http://f6bvp.free.fr/VP/Film1.mp4

Faites-nous part de vos remarques et observations. Bonne simulation !


Projects ongoing at la Villette radiotelescope

Three activities are programmed for radiotelescope project.

The first activity will be in agreement with initial project that had been elaborated at the time the instrument was designed thirty years ago : to study Hydrogen-Line of the Galaxy on 1420,4 MHz. By measuring the frequency of spectral line of atomic hydrogen depending on the galactic region will provide dressing a map of frequency shift proportional to radial velocity of targetted regions. Other more discrete radiosources can be studied. Paris Meudon observatory has studied la Villette radiotelescope observations possibilities of galactic hydrogen and various radio sources.

Primary observations will record galactic hydrogen signals from well known high power radio sources (Cygnus) received using a Software Defined Radio receiver. Received signals will be broadcasted via WebSDR.

One major interest of radioastronomy is the study of radiosources from pulsars. Some pulsars transmit signals with audible frequency due to their rotationnal speed. However, pulsar signals are very weak and it is not sure that these objects are within the telescope possibilities. 

The second activity will consist in sending and receiving radio signals in telegraphy or telephony (Single Side Band) or digital signals toward the Moon. CAMRAS WebSDR in diffusing such radio signals sent by radioamateurs and reflected by the Moon. La Villette radiotelescope antenna should be equipped with a source cavity adapted to Earth-Moon-Earth (EME) frequency band around 1296 MHz. We are thinking of using digital transceiver (Transmitter – Receiver) Lime SDR, a device that has been selected by European Space Agency.

Capture d'écran 2018-02-18 02.44.54

All these operations are achieved by capturing radiowaves signals using a Software Defined Radio (SDR) receiver. Receiver is driven by a software driver that is presently under development by INDI developers.  Using INDI API for both sky objects targetting and recording will simplify development of both parts of our project, radioastronomy and hamradio communications.

Present SDR market has a few TRX (transmitter and receiver) offers such as LimeSDR. The choice of TRX model for EME (Earth Moon Earth, EME) is not yet fixed. LimeSDR mini will soon be tested. A driver for LimeSDR is still under beta test in INDI library.

Capture d'écran 2018-02-20 20.58.53

The third goal of our project is to use the antenna for transmitting toward radioamateur transponder module P4A abord a geostationary Eshail-2. The satellite is now Qatar-OSCAR 100 and it is positionned at 25.9° East above equator. Transponder will be able to retransmit radio signals from hamradio stations from 1/3 of the globe (see footprint on above map).

This publication from Amsat-DL gives news about QO-100 hamradio geostationary satellite

New software driver and interface card for radiotelescope antenna remote control

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The radiotelescope antenna movements can be controlled from a local command pannel on the antenna plateform. However it is more convenient  to activate the radiotelescope from remote sites via Internet. This is why we are developping a driver that can activate antenna motors.  Control driver is based on the API (acronyme for Application Programming Interface) named Instrument-Neutral-Distributed-Interface control protocol (INDI).

We installed the driver and INDI library version 1.7 on a RaspBerry Pi under RaspBian Stretch Linux distro.

The software driver communicates with an interface card that can read antenna angular positions and activate motors. Driver is writen in C and C++ by Dimension Parabole software team (Patrick F1EBK and Bernard F6BVP). It communicates with INDI server using XTML messages upon receiving target coordinates from an INDI client. Astronomy client softwares such as Stellarium and Cartes du Ciel (Skychart) are compatible with INDI API and connect to INDI server via Internet. Experiments are also being performed with KSTAR application under KDE.

The interface card designed by KK6MK et F1EHN has been assembled by Laurent F6FVY. It is used for remote control of radiotelescope antenna motors. Recently the card has been repared by Patrick F1EBK who added an LCD display card useful for software debuging.

IMG_1194

However, although the repared card is able to control the antenna and read its position angles, it is not completely fitted to the radiotelescope for it can only activate four commands. At least three additional commands need to be added : two for fast movements in either AD directions and one for targetting rotation movement. This is why Alain F1CJN (Radio Club de Maison Lafitte) offered to study a new control card based on an ARDUINO micro controller that will be compatible with KK6MK-F1EHN card and will provide the extra necessary commands. INDI driver communicates with interface card through a serial link at 9600 bauds. It is controlled by software messages from INDI server, based on INDI API library set of functions. INDI server is listening on a dedicated port accessible by Internet. Telescope astronomy clients (Stellarium or Skycharts) connects to indiserver via Internet. Using such astronomy client a user can send an order to the radiotelescope for targetting a given radio source. Then another application will possibly activate an SDR receiver for detecting radio signals from space.

Interface card prototype is finished and working perfectly. The LCD screen displays Righ Ascention (AD) changing while antenna is moving. It also displays the commands sent by astronomy client software (PVP means Low Speed +). When the antenna reaches the target coordinates the software sends a command for switching to tracking mode. The antenna rotation is actually still simulated by hexadecimal coding wheels connected to the card. A more sophisticated optic coder telescope simulator is being developped using a Raspberry Pi and a multiport HAT card. The following pictures show the test-bed. Testing has been performed in Folie N4 building near the parabola while *DUUU radio station studio was broadcasting during the day of décembre 11, 2018.

On the left is the rack temporarily removed from the antenna plateform, equipped with prototype interface driven by Arduino micro controler,  a Raspberry Pi supporting 32 ports serial/parallel card, a card holding connections cable towards the rack connectors ; in its own box another RaspBerry Pi running INDI server and a software for optic coders simulation.

The prototype card screen displays command orders received from the driver and the angular values read on 12 ports of each angular position RA and DEC. During the test each of the 12 bits weight 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024 and 2048 are successively raised from 0 to 1. LCD screen displays values in hexadécimal. The test was succesively performed on RA and DEC, prouving that software driver is correctly decoding optical coder values and that wiring of connections was performed without error. Click here to look at test-bed video.

Amon supplementary control commands on the new card, are fast speed implementation toward Est and West and target tracking plus remote switch of separate radio preamplifiers or power amplifier. The two following picture show the preamp 1 ON and OFF commands acknowledgements.

img_1401

Patrick F1EBK is wiring the radiotelescope control system. Last improvement is on the simulator RaspBerry Pi power taken directly from the rack connection.

Antenna motorisation must be repared

The parabolic antenna can be moved along two main axis,  Right Ascension (RA) axis and  Declination axis (DEC), using three different electrical motors.

Antenna motorization is composed of three motors :

  • mono-phase tracking motor, 25 t/mm, tracking 0,25°/min
  • three-phase clock motor, 180 t/mn, 30° mn, 45 t/mn, 6°/min, from -4h to + 4h
  • declination three-phase motor, 45 t/mn, 6°/min, -30° à 55°

The equatorial mouting allows targetting objects in the sky according to its two coordinates RA and DEC, then follow the object while the Earth is rotating, using a low speed movement toward west to compensate the rotation.

Antenna movements can be initiated by pushing buttons on the command panel or by giving orders from a remote site using an astronomy application that sends the coordinates to be reached.

IMG_2658

Software driver computes the movement orders to be transmitted for motor activation. Several speeds and directions are available.  Movements toward east or west at low or fast speed or very low speed tracking toward west ; and positive or negative declination movements.

Reductors gears are positionned between the antenna wheel and the motors like in a clock mechanism or on a bicycle to reduce the actual rotation speed of the antenna.

IMG_2661

The above picture shows declination axis reductor. One can see the plate on the top where the first reductor took place. It has been removed in order to be repared.

Close view on gears covered by rust to be soon cleaned.

Command panel is displaying slow speed toward west direction activated by sofware remote control. Local-remote switch is in remote position and selector of local commands is in neutral position.

Absolute optoelectronic coders are connected to both rotation axis and transmit RA and DEC angles with a high precision (12 bits – 1/4096).

KK6MK-F1EHN-F6BSV interface card has been moved out of the rack during remote control tests. LED display reads Az for RA and El for DEC angles. A more complete interface card equiped with an Arduino micro controler is under development. This new card will replace the present one that can only handle four commands of low speed movements. It will also include more commands in order to be able to switch on and off some radio devices.

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View on the RA axis motor.

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Ellyan, François and Steve from Electrolab « rescue team » came to work at La Villette on september 30th and the antenna was soon well secured. This preliminary work was necessary in order to be followed by the motor reductors removal.

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While opening the second motor reductor cover a mixture of oil and water came out. The picture shows inside that the axis is invaded by rust. However, despite all efforts accomplished by the intervention team it has not been possible to completely remove the reductor. It is clear that a stronger extractor needs to be used on next procedure in order to remove the reductor from the antenna declination axis.

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On Septembre 30th, 2018 the radiotelescope antenna is now back to security position aiming at the zenit.

 
 

The main declination axis wheels are being cleaned while rust is removed using a metallic rotating brush.

Intensive efforts have been accomplished in order to remove the cover of second reductor after removing appropriate bolts and using a dedicated extractor manufactured by the colleagues from Electrolab. Inside the cover one can see the Archimede screw that was connected to the primary declination moto reductor. The a lower ring gear used to step-up the rotation with vertical gear is still in place. Once completely removed all pieces can be cleaned and serviced. We will then finish the cleaning of main and secondary gear wheels.