			E.M.E System
			------------

		Jean-Jacques F1EHN / F6KSX group


Contents :
----------
	1. Introduction :
	2. Specifications :
		2.1 Software/Computer
		2.2 Interface
		2.3 Considerations on an automatic tracking system
		2.4 Installation and run
		2.5 Installed files
	3. Initialization software "EMESETUP.EXE" :
	4. Control software "TRACKING.EXE" :
		4.1 Description
		4.2 Automatic tracking
		4.3 Automatic positioning
		4.4 Manual positioning
		4.5 Noise measurements with the sun or the radiosources
	5. Tracking interface PC - Antenna - Receiver :
		5.1 Description
		5.2 Building
		5.3 Connection
	6. Conclusion :


1. INTRODUCTION :
-----------------

This system is primarily suited for EME operation. Moreover, it helps to 
manage traffic procedures in real time and to calibrate the station 
(Measurements of received levels, tracking of radio-sources, 
angular correction ...)

This system is divided into :
- An initialization module ( callsign, location, serial port, endstop...) 
called by the control software.
- A control module capable of handling an EME station in real time 
( Automatic tracking of sources, periods, Doppler, signal level ...).
- A hardware interface between the control software and the EME station 
(Motors, angles monitoring, receiver...).

2. SPECIFICATIONS :
-------------------

2.1 Software / Computer :

The software runs on an IBM PC or compatible with a CGA or Hercules monitor 
and 640 KBytes of RAM.               

The delivered files are already compiled, directly executable and can make 
use of the math coprocessor on request.
	
Remark : This software needs two RS232 ports : one to connect the interface 
and one to the mouse (it is optional).

2.2 Interface :
	
- 5 Volts single supply.
- The inputs are TTL compatible and enabled on high level.
- 4 relays ( 2A max ) are used to drive azimuth and elevation motors 
(Up, Down, CW, CCW).        

2.3 Considerations on an automatic tracking system:

- Angular resolution:

Several automatic tracking software and their interfaces are available in 
the radio-amateur domain (like Instant Track,VK3UM ....). Most of these 
systems are based on a 8 bit digital accuracy. The best position measurement 
possible with these systems is :
		360 degrees/2**8 = 1.41 degree, 
which is fine for 144 MHz antennas or small 432MHz arrays. 
With bigger systems, losses due to the pointing error would be tremendous 
(-3dB angle for 16 yagis 7l is close to +/- 2 degrees).

The described system uses a 16 bit format for both the software and the 
interface.
The obtained resolution is then : 360/2**16=0.0055 degree. The error due to 
this system is therefore negligible compared with the overall error in the
tracking system. The only limitation is due to the transducers used to 
determine the antenna's position (High resolution potentiometer + 12 bit ADC, 
optical encoder ...).

- Angular accuracy:
	
The accuracy of the position measurement is limited by the backlash, the 
measurement resolution (above-mentioned), the station's calibration, 
mechanical and electronic drifts of the system, capabilities of the computer, 
calculation  errors.

backlash: Often due to the reduction gear assembly of the elevation and 
azimuth motors. This backlash may cause a "pumping" on the antenna's position. 
The most important backlash is existing between the antenna and the angular 
transducer. This backlash translates directly into a position error.

-Station's calibration: At first, angular transducers must be set in azimuth 
(0 and 360 degrees) and elevation (0-90 degrees with a vertical level). 
Then, the setting should be done into a well known direction. 
The control software allows an accurate setting on sun noise. A setting on 
a moon signal (with large fluctuations) or with a compass (not accurate) is 
not correct. The measurement of sun noise is also fine for checking the 
station's sensitivity at times.

-Mechanical and electronic drifts: These drifts can be estimated by tracking 
the sun and by checking the maximum sun noise elevation and azimuth. 
This can be cured by software (see 4.1 'Antenna window').
Generally speaking, these drifts are due to mechanical twisting, offset 
variations (thermal problems), transducer non-linearities, bad verticality 
of the mast or tower. The inaccuracy in position is variable.

-Computer's capabilities: The elapsed time between two calculations of the 
moon's position is equivalent to the mechanical backlash in the reduction gear 
assembly. The error is then proportional to the speed of rotation. 
For example with a 8MHz 80286 PC the approximate computation time is 0.3 
second. If the rotation speed of the antennas is 1 degree/sec then the backlash 
due to the computer is 0.3*1=0.3 degree. This backlash may result in a "pumping" 
effect.

Remark : This "pumping" effect is mastered by the software (hysteresis 
parameters in the setup menu). 

-Calculation's error: All calculations are performed in double precision mode 
and make use of the coprocessor when present (emulated otherwise). 
The automatic tracking works with the interface with 16 bit words. 
Only the resolution of display has been reduced (position of moon and sources). 
Computed positions of both moon and sun have been compared with those 
calculated by "bureau des longitudes de l'observatoire de Paris". 
No significant error has been noticed.

2.4 Install / Run :

- Make a directory in your hard disk
- Copy all files from the floppy disk in this directory
- Make a batch file or type cd\eme_directory and type the application name
EMESETUP.EXE or TRACKINGEXE.

2.5 Installed files :

EMESETUP.EXE :  Initialization software
TRACKING.EXE :  Control software
HOME.DAT :      Example of EME station data file
F1EHN.DAT :     Example of F1EHN station data file
NO_COM.DAT :    Example of data file (without the COM port) 
DXCCPREF.DBR :  DXCC Prefix data base
TRACK.INI :     Screen configuration file
F1EHN.TCV :     Example of Tracking Correction Values file associated to 
		F1EHN.DAT
READ_EME.TXT :  English notice
LIS_EME.TXT :   French notice
			
3. INITIALIZATION SOFTWARE "EMESETUP.EXE" :
-------------------------------------------

- The introduction screen is displayed for about 1,5 seconds.

- After, choice a data file  "*.dat" :

Select a file ("double-click" or "click" + O.K) to edit it, or press "NEW" to 
create a new data file.

Remark : It is quicker to read an old file, to modify it and to save it with 
another name. 

All parameters are stored in a ".dat" file. It is possible to give several 
names in order to store several configurations (Expeditions, stations... ).

- EME Setup screen displays all parameters :

Remark: COM1 and COM2 ports are available in the DOS version. 

- Use the "Help" button to obtain the help.
- Use the "Save" button to save the file after your modifications. The 
program stores the parameters if they are right or displays an error message. After, enter a new right value.
- Use the "Save as ..." button to save the file with another name after your 
modifications. The program stores the parameters if they are right or 
displays an error message. After, enter a new right value.
- Press the "Quit" button to stop EMESETUP.
- Press the "Tracking Setup" button to display the TRACKING parameters. 

Remark : The "Tracking setup" screen is not displayed if the serial port 
does not exist.(COM=0). 

Example : Azimuth configuration 
	Mode = BIN, Range = 300, Offset = 30, CCW=45, CW=315

4. CONTROL SOFTWARE "TRACKING.EXE" :
------------------------------------

4.1 Description :

- The introduction screen is displayed for about 1,5 seconds.

- After, choose a data file  "*.dat" (Home.dat button is enabled if the 
home.dat file exist) :

Remark : If you use the interface, you must plug on now.

- Select a data file ("double-click" or "click" + O.K) . Press "Home.dat" 
button to select "Home.dat" file.
 
- if you wish to quit "TRACKING", press "Cancel" button , and select "Quit" 
in the "File" menu.

- "TRACKING" main screen :

Remark : If you run "Tracking" without interface (COM=0), the "Antenna" and 
"Signal level" windows are not displayed and the "Control" menu is disabled.

- "File" Menu :
	New : to change the ".dat" file
	Parking : to park the antenna automatically
	Quit : to quit "TRACKING"

- "Sources" Menu :
	To choose a source

- "Traffic" Menu :
	To adapt the traffic (period duration, First or second period)

- "Control" Menu :
	Az/El position : to point the antenna automatically
	Auto Track : Enable or disable the automatic tracking
	Normal level : Absolute measurement of the received signal level 
	(Offset = 0)
	Reset level : Relative measurement of the received signal level  
	(Offset = mean value)

- "Windows" Menu :
	Open or close  the select windows
	Save Track.ini : save the screen configuration.

	Remark : It is possible to drag the windows in the principal screen 

- "About" Menu :
	Gives some informations about the software

- "U.T.C" window :
	Displays the date and time (TU)

- "Source" window :
	Displays the source position 

- "Traffic" window :
	Displays :
		- Traffic periods (Rx/Tx),
		- Extra loss (Loss/Perigee) due to the actual distance 
		between moon and earth 
		-Doppler frequency shift caused by the earth rotation 
		and moon/earth speed
		- Frequency
	Remark : The label Rx/Tx blink for 10 seconds before each new period. 

- "Antenna" window displays :
	- the antenna position
	- the rotate wise
	- the antenna parameters (Tracking, Endstop, Parking...)
	Remark : If you use a angular correction file, the window caption is
	'Antenna + tcv' (tcv: Tracking Correction Values).
	To use an angular correction file :
		- Edit the existent file with the DOS Editor
		- Modify the values
		- Save the file with the same prefix of the file *.dat used + 
		the suffix '.tcv'.
		Ex: f1ehn.dat file uses the f1ehn.tcv file.

- "Signal" window :
	Displays :
	- the peak value of the received signals (echoes measurement)
	- the average value of the received signals (noise measurement)
	- the offset measurement.

- "Station<=>DX" window :
	The Station<=>Dx parameters are calculated from a DXCC prefix 
	typed by the operator. 
	The window displays :
	- the moon position for the DX station
	- the Doppler frequency shift between the station and the DX station
	- the polarisation offset  between the station and the DX station
	- the distance between the station and the DX station
	Remark : These parameters are updated for each traffic period. 
	The "Station<=>DX" window is invisible if the selected source is different 
	of the moon.

4.2 Automatic tracking :

Select the "Control" menu and click on "Auto Track". The antenna rotate 
automatically towards the source position. The drive starts when the angle 
between the target and the antenna is greater than the "hysteresis start" 
value. The drive stops when the angle between the antenna and the target is 
greater than the "hysteresis stop" value. The drive stops when the angle 
between the antenna and the endstop is zero.        
	
4.3 Automatic positioning :

Select the "Control" menu and click on "Az/El Position". Enter the azimuth 
and elevation values. The antenna rotates automatically towards the new 
position.     

4.4 Manual positioning:

The High, Low, Right, Left cursors control the antenna position. Press the 
key to start the motor (High = High, Low=Low, Right=CW, Left=CCW). Press 
again the key to stop the motor.

Remark: The cursors keys are enable if the "Antenna" window is active
(Clik on this window to activate it).

4.5 Noise measurements with the sun or the radiosources :

The tracking of a radiosource allows the checking of an EME station by 
looking at the difference in level between a noise source and a quiet source.
The antenna beam is towards a quiet sky ("Sources" menu ,"Cold sky" 
Ra=9h30 Decl=40deg). In the "Control" menu, select "Reset Level" to display 
a zero average value of the sky noise. The antenna beam is towards the sun 
("Sources" menu, "Sun"). Read the sun noise excess in the "Average signal 
level" window. The measurement accuracy depends of the signal level 
measurement setting.

5. TRACKING INTERFACE PC - ANTENNA - RECEIVER :
------------------------------------------------

5.1 Description :

The diagram (see appendix) describes the principal interface functions. 
The timing diagram and the electrical schematic are in the appendix.

The level converter RS232/TTL uses a MAX232. The interface is built around 
a specialised circuit for asynchronous protocols like RS232 (UART HD6402).
The parameters of the port are set by "TRACKING.EXE" to : 9600 bauds, 8 bits, 
1 stop bit , no parity. 

The received messages are decoded by 2 PROMs (256*8). 
The "CONTROL" PROM interfaces :
	- the motors 
	- the Rx/Tx information 
	- the RS232 test (The LED "Clock" blinks if the RS232 line is correct) 
The "ENABLE" PROM takes care of :
	- the RS232 BUS (TX mode)
	- the input ports. The received level byte (0 = 0 dB, 255 = 51 dB) is 
	directly forwarded and the Az/El channels (16 bits : Binary or BCD mode) 
	are forwarded with 2 bytes. 
	
It is possible to parallelise some interfaces by RX Bus and Tx Bus. It is 
necessary to change the addresses in the PROM's. The "master" card with UART+MAX232 
make the RS232 connection and the "slave" card is built without UART and MAX232. 
This system allows some future designs (future version) such as power 
measurement, polarisation control, some antenna arrays, digital signal 
processing control ...

5.2 Building :

The components location is in the appendix. There are not other 
comments needed to build this interface. It has a single 5V supply 
with a DC current of  500 mA max. It runs with both technologies : 
HCMOS and TTL. The interface has no trimmers. The accuracy of the 
whole system depends mainly on the accuracy of the sensors and on 
the quality of the mechanical structure of antenna.

5.3 Connection :

The RS232 connection is to be found in appendix. The input ports are compatible 
TTL and are described in appendix.

- Example of sensors :
	The interface has no sensors. 
	- Linear potentiometer (0.2 % linearity) and 12 bits analog to digital 
	converter (ADC)
	- Linear potentiometer (0.2 % linearity) and Digital VoltMeter (DVM) 
	with Binary or BCD mode
	- 12 bits or more optical position sensor. 

The interface supplies clock signals for the sensors. 
In binary mode, the unused bits (LSB) must be grounded.
In BCD mode , the both MSB (400 and 800 deg) must be grounded.  
		
A schematic of 12 bits ADC used by F6KSX is in the appendix. 
3 ADC are used for the elevation, the azimuth and the signal level. The EME 
System is used in binary mode with : Range = 360 deg. Offset = 0 deg for 
azimuth and Offset = -2 deg for elevation to be able to track at the horizon.

6. CONCLUSION :
---------------

The system described allows easy and accurate, manual or automatic, control 
of antenna arrays. This great help frees the EME operator which in turn 
improves the efficiency of the EME station.

The both programs (EMESETUP and TRACKING) in the both version (DOS and 
Windows)  can be sent against a self-addressed and unformatted floppy 
3,5"/1.44MO.
I can also program empty PROM's on request.
I shall be glad to help the interested OMs. My address :         

Jean-Jacques MAINTOUX  F1EHN
24 rue de Villacoublay
F78140 VELIZY
FRANCE
