Field day prototype test
(Thanks to GRC (Grupo Radioamadores Cascais)
The intention to enter the world of satellites and space at low cost, led us to develop a driver for the program Orbitron able to command two rotors of moderate price, thus, making a system for the following of Satellites, Moon, Sun etc. The complete system of components hardware are purchased from the market and should not exceed € 400.00.
With the use of reasonable gain antenna, the system optimizes the contacts from horizon to horizon and frees your hands.
The system consists of a software driver that can be downloaded on the link page above.
This Driver extracts every moment the Azimuth and Elevation of the satellite selected in Orbitron and sends them to a micro-controller board that will control the rotor-controllers through a system of LEDs indicators PCBs installed over the rotor-controllers.
We are preparing a manual that explains how to assemble all the kit, install it and operate.
In the following lines we describe the development of the idea for a Mule prototype being that, in the end, we will have a system with 3 Printed Circuit Boards (PCBs) with all the electronics so, it just will be needed to assemble the parts according to the instructions manual.
DIVER FOR THE ORBITRON
Aspect of the driver inside the ORBITRON
button is active
the driver is openned .
It is desirable, before the passage of any satellite, to do the compensation and synchronization .
The total cost of the System wil be about 400.00 €.
- 2 rotors MASTERROTOR B747 AR303 to acquire in your local the market. (They are for € 50.00 each in Portugal.)
Our KIT with
(Packaging & shipment included).
Note: you will bee billed of VAT in your country customs
- Tripod or garden umbrella for about € 30.00. Purchase it on your local market. We got our from Leroy Merlin
- For the power supply use any 12V 2A . We used an old PC powe supply . Or get one for about ~30,00 €
- Time and patience to assemble the kit cost (€?).
the end of
comulative Azimuth error will happen
However, this error does not affect the tracking of satellites with antennas openings of +- 6º at -3dB which are just the type of antennas we use for VHF and UHF for Amateur Satellite Comunications .
- The antennas should be installed so that, the center of gravity of the boom must stay on the elevation rotor, to avoid slippage.
Use of an easy and friendly tracking
2 - Low price
4 - To modify rotors, it is only necessary to open the azimuth rotor and saw the two locking pins.
5 - The system can be synchronized and do not winds cables around the mast.It makes an automatic "Unrolling".
6 - The placement of the Led PCBs is simple: just remove the buttons and the contacts of the controllers and place there the PCBs.
7 - The system allows anyone with minimal investment and ability to enter the LEO satellite communications
8 - The system can be also be remotly controlled by entering the remote PC over the Internet..
Hardware and software
- 2 ROTORS with Controllers(type MASTERROTOR B-747 or AR-303), 1TRIPOD (Quadripod), 1 TUBE with 1.5m
2 PCB/s with position LEDs for the Azimuths and elevations to mount in the controllers.
PCB Mother Board equipped with
We have built our prototype on a wooden board.
- One tripod or an umbrella garden base
- An old PC power supply can be used where we take the 12 volt ~ 2 A minimum.
- 5 Flat Cables with 16-conductor with 2 x ICD16 female connectors to connect the microcontroller PCB and the Led position PCBs.
- 2 x 10 meters of cable UTP CAT5 4 pairs to send the control voltages to the rotors. With 2 Power connectors and one DB15 male connector.
( You can avoid the multipin connectors, connecting the cable directly to the Rotors terminals 1,2,3).
The program BB_TRACKER is a Driver that runs under Windows and is inserted in the Orbitron configuration.
The driver receives data from Orbitron and sends them to the PCB equipped with a microcontroller that commands the controllers of the rotors for the azimuths and elevations.
The rotors and the controllers have synchronous motors.
For azimuths, we made a printed circuit board with 60 position green LEDs in circumference at 6 degrees angles (Sectors of 6º) which are sufficient to maintain tracking of satellite antennas with lobes of + - 3 degrees @ -3 dB.
The elevation PCB have 15 LEDs corresponding to 15 sectors of 6º.
In the rotating disk of the controllers we installed a photodiode which detects the LED light stopping in the center of the respective sector.
The software always calculates the shortest route around 360 degrees and walk accordingly.
The program also warns that will carry out a reset of turns for compensation, in order to avoid winding the cables around the support of the antennas.
- Extracts the data through the protocol DDE (Dynamic Data Exchage) in a Satscape string format.
- Inserts data in the reading windows for viewing.
- Processes the data from windows comparing the values with the ranges of sectors and sends a related signal to the angle-LED where the Micro should send the rotor, the LED lighting sector
- The software also compares current data with the previous one to know which way is shorter to move the rotor (CW or CCW). It also calculates the number of sectors CW and CCW to where the rotor will be sent. It calculates the travelling of the azimuth rotor to notice to do a RESET and avoid cable turns around the mast.
- Even after turning off the PC, the data of the Last Position of the antenna is stored.
- In the case of the Last Antenna Position values indicated by the program does not match the actual orientation of the antenna, it is because something has been forced.
(when in orange)
It uses a Software Driver running with Orbitron, a microcontroller in a PCB accessed by the PC USB port, which controls the modified Controller Box.
The Software Driver receives data from Orbitron processes it and sends the commands to the microcontroller which, in turn, sends data control to the Rotor Controller.
HOW IT WORKS
The concept is to replace the original controller button with an hardware which simulates the manual operation.
This is done replacing the rotable controller dish with a PCB with leds which represents the centre of angle sectors.
In the white plastic rotable dish we put a photodiode which detects the activated led and stops.
We divided one complete turn of 360º in 60 sectors of 6º each for the azimuths and 90º 15 sectors for elevations.
The reason for the sectors is to permit an antenna pause between +- 3º of satellite passage inside a 6º arc.
For example: the sector 5 will be between 24º and 30º and the antenna will be pointed in the midle 27º during the passage.
As soon as the satélite azimuth is out of the sector, the software driver sends a command to the microcontroller to activate the next sector led and the (white plastic) dish of the controller runs 6º and stops.
SOFTWARE DRIVER FUNCTIONS FOR THE ORBITRON
The driver catches the data from Orbitron with the DDE protocol in the Automatic mode or catches data from the windows in the Manual mode.
The movement of the azimuth rotor is free from any mechanical limitation so, it will be possible to turn more than 360º around without being interrupted in the middle of a satellite pass .
that automatic resets occurs during the satellite passage, the RESET button
In the Manual operation, the Azimuth and Elevation are inserted in the windows to command the antenna position.
The SINC button is to synchronize the physical antenna position with the system data. It can occur with heavy wind or data loss and the software position do not corresponds to the physical antenna position.
HOW WE DEVELOP THE PROTOTYPE
HOW TO MODIFY THE ROTOR CONTROLLERS
Contacts removed Aligning the PCB
Marking holes for the leds Drilling of small holes
Placing the 60 LEDs on the disk of the azimuths AND 15 LEDs on the disk of the elevations. Phototransistor and shrink sleeve
Sleeve placed on phototransistor Pin where to put the phototransistor
Phototransistor placed . Screws were removed because are not necessary. The sleeve stands the fototransistor. Photodiode will run down and around the leds.
15 Elevation diodes placed. ( Note:Each diode representes the center of a sector of 6º ) Flat cable 16 connected to the Microcontroller PCB
For Azimuth we have 60 sectors ( 60 leds) divided in four quadrants of 15 sectors. Four flat cable 16 wil connect diodes to the microcontroller PCB
Note : These two PCBs are a prototype design and will be replaced by the new comercial PCBs shown above.
Assembled system to put in to a metalic box
All Relais, and wires, will be placed in a single PCB after this prototype
HOW TO MODIFY THE AZIMUTH ROTOR
Remove the blocking pins in the gear to allow more than 360º rotation
of the Azimuth
to allow more than 360º rotation of the Azimuth rotor
This is the
gear of the rotor shaft
This is the gear of the rotor shaft
Exterior microswitch installed in the Azimuthe Rotor. The cam (ledge) switches on the stop at zero. The Brown and Brown/White wires belongs to the UTP CAT5 cable.
Wiring the UTP cable to the rotors. In both rotors, connections are the same.
Connectors used and glued to the rotors to allow easy transportation. Soldering the female pins of the connestors
Note : These numbers are the numbers of the Pin connectors and the number of the DB15 Pin also. They are note the numbers of the Rotor terminal.
seen in the picture before;:
The Blue cable will connect to the pin 2
The Orange to the pin 1
The Green to the pin 3 .
The Brown and White/brown wires will connect to the microswitch opened contacts in both rotors.
Soldering the two UTP cables (Azim.and Elev.) to the DB15 male connector Soldering the internal wires to the female of DB15 connector
Back view of the prototype Box.
BB_TRACKER, Antennas, Rotors, Tripod, Mast and Radios ready for a Satellite Field Day...
73 have a nice work