Lacerta M-GEN User manual

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LACERTA M-GEN
Stand-Alone AutoGuider
User’s manual for Firmware 02.50
Created by Zoltán Tobler
Last updated: 27 November 2017
Table of contents
1 ABOUT THE HARDWARE..............................................................................................................................2
1.1 PARTS OF THE DEVICE ....................................................................................................................................2
1.2 POWERING THE DEVICE ..................................................................................................................................4
1.3 ELECTRICAL CHARACTERISTICS .....................................................................................................................5
1.3.1 Specification of the HC and Camera .....................................................................................................5
1.3.2 Imaging specification of the Camera.....................................................................................................6
1.4 TURNING ON AND OFF THE DEVICE.................................................................................................................7
1.5 UPDATE MODE.............................................................................................................................................8
1.6 HARDWARE TYPES..........................................................................................................................................8
2 NEW FEATURES IN FW. 02.50.......................................................................................................................9
2.1 PREVIOUS VERSION CHANGES.........................................................................................................................9
3 ABOUT THE USER INTERFACE.................................................................................................................11
3.1 BUTTONS AND LEDS....................................................................................................................................11
3.2 MAIN CONCEPTION OF THE USER INTERFACE...............................................................................................11
3.2.1 Menus ..................................................................................................................................................12
3.2.2 Variables (parameters)........................................................................................................................12
3.2.3 Profiles ................................................................................................................................................14
4 PARTS OF THE SOFTWARE, FUNCTIONAL UNITS..............................................................................15
4.1 AUTOGUIDING FUNCTION (AG) ...................................................................................................................15
4.2 AUTOEXPOSURE FUNCTION (AE).................................................................................................................16
4.3 RANDOM DISPLACEMENT (DITHERING)FUNCTION (RD) ..............................................................................16
4.4 FILESYSTEM (FS) .........................................................................................................................................17
4.4.1 When is the file written? ......................................................................................................................17
4.5 COOPERATION OF THE FUNCTIONAL UNITS...................................................................................................19
5 MENU TREE.....................................................................................................................................................20
5.1 SCREENS AND FUNCTIONS DETAILED............................................................................................................21
5.1.1 AutoExposure (AE) screen...................................................................................................................22
5.1.2 AutoExposure program list screen ......................................................................................................24
5.1.3 Random Displacement (RD) screen.....................................................................................................27
5.1.4 Misc. screen.........................................................................................................................................29
5.1.5 Power off screen..................................................................................................................................35
5.1.6 Guiding menu screen...........................................................................................................................36
5.1.7 Guider setup screen.............................................................................................................................37
5.1.8 Star Search screen...............................................................................................................................38
5.1.9 Live View screen..................................................................................................................................40
5.1.10 Guiding screen...................................................................................................................................42
6 MORE DETAILED ABOUT... ........................................................................................................................54
6.1 ... CCD BINNING...........................................................................................................................................54
6.2 ... THE NEW IMAGE PROCESSING METHOD ...................................................................................................55

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1 About the Hardware
1.1 Parts of the device
The “LACERTA M-GEN Stand-Alone AutoGuider” (referenced as LMG) consists of the
following parts:
Handcontroller (referenced as HC). It has the whole user interface (buttons,
indicator LEDs, LCD) and does the main functions like Autoguiding, Random
Displacement, AutoExposure etc.
The display is a graphic, 128x64 dot negative LCD with backlight. Previous
versions have red while the new ones come with amber (orange) color due to the
much better contrast.
Note that there is a protector film on the display window, You must remove it
before the first use! This is quite invisible in dark when the LCD backlight is on,
some can let it on to protect the window from scratching and remove only if too
much scratch is visible yet.
The connetor panel is located at the bottom of the HC box:
These are the following from left to right:

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oCanon EOS compatible shutter output (3.5mm stereo jack conn.)
oCamera port (RJ-45 type female conn., can be used any (max. 2m) UTP
cable too but the supplied cable is preferred. Note: NEVER try to use a UTP
cross cable!)
oDC power input (5.5/2.1mm size) (12V nominal, 9-15V), tip positive
(polarity-protected)
oST-4 compatible autoguider output (RJ-12 type female conn.)
oPC communication port (USB-B mini 5-pin conn.)
Camera (head). This is a special device, can be used only with the LMG
Handcontroller. It’s function is imaging and doing several image processing steps.
To attach the Camare to the guider telecsope there is a 4-5mm thick T2
inside screw. Any T2→1.25” adapter can be used for 1.25” (31.7mm)
focusers. There is a 1.25” filter thread inside the T2 panel to attach some
filter or “dust preventor”.
At the back of the Camera there is the same type of connector as on the
HC (RJ-45 female).
The sensor is a high sensitivity monochrome CCD from Sony (with
ExView HAD technology). Due to its exremely low dark current (dark
noise) and the enhanced sensitivity in near infrared it doesn’t need cooling
and saves energy. These with the low readout noise gives the ability of
guiding on very faint stars or using small guidescope. The small pixel size
allows using shorter focal length for guiding compared to other systems.
(The CCD part number is ICX279AL-E.)
Note: ont the CCD there is the protector film by default. You must remove
it before the first use! Cleaning the CCD’s glass is done as for any other
optical surfaces. Avoid scratching! Don’t let any electrically conducting
material or liquid fall into the circuit, on the CCD and its pins. (The foam
around the CCD gives some protection.)
Supplied cables (this may vary):

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o1 piece of Camera cable, similar to a straight UTP cable. Used to connect
the Camera with the Handcontroller. It’s length is around 1.8-2m.
o1 piece of “ST-4 autoguider” cable (white) to connect the Handcontroller
and the mount with ST-4 compatible autoguider input. About 1.5 meters of
length.
o1 piece of USB-A (PC side) / USB-B mini5 (HC side) cable to the
connection with the PC. Used to update Firmwares, download data files or
control the HC.
o(Some release include an EOS shutter cable with 2.5mm and 3.5mm stereo
jack ending, 2m length. (Can be used directly for Canon EOS 550D for
example.))
1.2 Powering the device
In normal use: (during autoguiding)
The device needs a nominal 12V DC power source on the HC’s DC input connecor, which
is tip positive. This is essential for the Camera for imaging. 9-15V is also accepted but don’t
use higher voltage than 15V (peak voltage max. 18V)! The output power of the DC supply
must be minimum 2W (at 12V) but the supply may source higher currents than 160mA for a
short time (about 0.1s).
Be careful choosing the type of the DC power source, it MUST BE well stabilized or a
constant source. A battery, stabilized DC or switching regulator should be used! An
unfiltered, only AC-rectified power (which has a heavy transformer in it) may not supply the
device properly, this could lead to sudden reset/turn-off of the device or even damage the
input circuitry! (For example a 220V-input and 12V / 800mA-output rectified power supply
could easily source over 20V peak voltage at low load, which is harmful for the device!)
“Logic only” mode: (USB connection: Firmware update etc.)
If the Camera is not connected or will not be used for imaging the USB bus can also
supply the device’s logic circuit. All those functions are accessible that don’t need analog
power (imaging). Works for example: Autoexposure program, data file downloading,
Firmware updating but autoguiding (star search, LiveView etc.) will not.
NOTE: new type devices (boot version ≥$14) may fail to update the Camera’s firmware
if the USB voltage is well lower than 5V. In this case, power the device also from its DC
input!
When the device gets power input (DC input or USB cable is plugged in) a short flash of
the four LEDs indicates this. The flash is also present at the Firmware update process when
the device is reset before the next update step.

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1.3 Electrical characteristics
1.3.1 Specification of the HC and Camera
Values for HC with BOOT version $14 or above.
Note: All DC input current values are for a nominal 12V input. These currents
change with the input voltage.
Min.
Typical
Max.
unit
Notes
DC power supply
9
12
15
V
7
Active input current (no light)
(full light)
96
160
mA
1,3,4,5
109
160
mA
1,3,4,5
HC only input current (no light)
(full light)
27
mA
1
33
mA
1
Power-down mode with USB
w/o USB
10
mA
6
mA
ST-4 out. pull-down current
5.3
mA
6
Shutter out. pull-down current
1.1
mA
6
1 with connection to PC via USB
3 ‘active’ means an active Camera (autoguiding or LiveView)
4 the value changes as some parameters do (gain, exp.time)
5 there is a fuse in the HC
6 for a TTL low input level (below 0.8V @ 5V)
7 the peak input voltage MUST NOT exceed 20V!
Values for HC with BOOT version $13 or below
Min.
Typical
Max.
unit
Notes
DC power supply
9
12
15
V
7
Active input current
110-116
200
mA
1,2,3,4,5
HC only input current
27
mA
1,2
Power-down current with USB
without USB
9
mA
6
mA
RED display backlight
0
30
mA
AMBER display backlight
0
7
mA
ST-4 out. pull-down current
1.1
mA
Shutter out. pull-down current
0.5
mA
1 with connection to PC via USB
2 older devices may draw about 8mA more current due to the MCU
(see the table above for the other notes)
Note.: values shown gray are only informational and derived from the
design.

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1.3.2 Imaging specification of the Camera
ADU means: Analog to Digital conversion Unit (= a digital step)
e-means: electron
RMS means: standard deviation (statistical); Root Mean Square
Min.
Typical
Max.
unit
Notes
CCD active pixel area
752 × 582
pixel
3.65 × 2.7
mm
CCD pixel size
4.85 × 4.65
μm
Imaging depth
8
bit
Image conversion speed
2M
pixel/sec
max.
Conversion (min. gain (2))
(max. gain (9))
44
e-/ADU
1
1.75
e-/ADU
1
Readout noise at min. gain (2)
22
e- (RMS)
1
Readout noise at max. gain (9)
5.9
7.1
8.5
e- (RMS)
1,2,4
Average dark current
3.2
e-/px/sec
1,2
Pixel capacity
10k
e-
1
Operating temperature
-10
60
°C
3
1 the value is only informative but measured on some instances
2 at 23ºC CCD temperature
3 violating the limits is the responsibility of the User
The CCD and its environment heats itself a little bit if active (good for anti-dew).
The power dissapated in the HC is also rather useful than problematic.
4 typical value (mean) measured on 22 pieces of ‘random’ Camera instances.
The mean of deviation of this value between the instances is only 0.29 e-.
The limits were measured in some “extreme” instances.
The gain of the CCD’s analog output signal is called ‘gain’ generally and can be set in
the HC as a parameter. The scaling of this is defined so that 2 steps means one
magnitude difference in sensitivity. The full scale (from 2 to 9) cover 3.5 magnitudes
(×25). The table below shows the physical imaging parameters for each gain value
(approximately):
gain
conversion
(e-/ADU)
pixel saturation
(e-)
1
70.0
16700
2
44.0
10500
3
25.7
6650
4
17.5
4200
5
11.0
2650
6
7.0
1670
7
4.4
1050
8
2.77
665
9
1.75
420
Note: gain 1 is not available from FW v2.00 due to
possible early pixel-saturation

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1.4 Turning on and off the device
After the device is first supplied with power source it goes to sleep (power-down) mode,
nothing can be seen and there are no output signals. The cables can be safely plugged in or
out.
Turning ON the device:
Press ESC button! The program will start in application mode if the HC contains valid
Firmware. The version of it is displayed for 2 seconds, then the first screen appears (see
later). You can skip 2 sec. waiting with pressing ESC one more.
If the device does not contain valid Firmware (or it was faulty) it starts in update
mode, which is shown on the LCD. In the center of the display there is a “NO FIRMWARE”
text indicating the case.
If ESC is pressed continuously for more than 1 second the device starts in update
mode (1.5). Using this starting procedure is not required because the updater (PC
application) will force to restart the device in this mode. If You happen to enter this
mode, hold down SET for 1 second and the Firmware will try to start. This works until the
device communicates through USB, after this only an USB command can start the
firmware (using PC application).
From Firmware ver. 1.21 (or later) the device starts on the date and time settings
screen and the filesystem’s screen after that. This is needed to make You remember to set
or check the correct date and time at every startup and select a file to open if You want to
store data about the night (guiding, events etc.). If You don’t need these functions, two
more ESC keypresses after startup leads directly to the main menu.
Turning OFF the device:
In application mode: Navigate back to the main menu (with pressing ESC some times)
and select the power off item. It is essential to power off this way because it stops every
functional part properly (Camera), closes the open file and stores the parameter settings.
WARNING: simply plugging out the power cable is not recommended, mainly if the
Camera is actively working! Data loss or corruption in the open file or in the stored
parameters may occur.
If the device is in update mode and there is no operation in progress (mainly
Firmware update), You can power-off the device with detaching the power cable(s). (Be
sure there is no operation in progress shown by the PC application.)
WARNING: never plug out the power/USB cable during Firmware update! Doing so
can damage the boot program and it may be required to reconfigure the device at factory
(it’s not the part of warranty).

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1.5 UPDATE mode
Also known as BOOT mode. The device always starts in BOOT mode by pressing ESC,
but doesn’t start the firmware if You hold ESC button for more than 1 second. If there is no
valid firmware on the device, UPDATE mode will start anyway with the text ‘NO
FIRMWARE’.
This mode is used to update the Firmware or download/refresh stored parameter data. The
PC application may make the running Firmware to enter this mode (even during autoguiding),
but from Fw. 2.20 it is allowed to do so, the open file will be closed and parameters get
stored.
1.6 Hardware types
There are two types of hardware of this device (HandController and Camera). The newer
will show a little X right to the ‘UPDATE MODE’ text to indicate the new hardware type.
Besides the HC will show a BOOT version of $14 or above and the Camera BOOT version of
$14 or above as well. (See PC app.’s manual how to check this.) Lower BOOT versions
indicate ‘old’ hardware.
Note that the new hardware can not run Firmware version older than 2.00 due to the
hardware change. Uploading such an old firmware will succeed but the HandController will
display ‘WRONG FIRMWARE’ in update mode.
The difference between the two hardvare types are the following:
the new can be turned on by remote (USB) while the old can not;
the new can be used with a (supplied) 6-wire cable while the old works only with a
8-wire one;
the new can’t run a Firmware below 2.00;
Types of the supplied camera-cables:
8-wire black “telephone” (flat) cable with black connector (Cbb)
6-wire yellow silicone-covered cable with black connector (Cyb)
8-wire yellow silicone-covered cable with white connector (Cyw)
same as Cbb but producted after the year 2014 (Cbb2)
any straight UTP Cat5e cable (any color), < 3m (U)
The table below is important only if You want to use different HC and Camera (not from
the same device pack). The HC and Camera is advised to be used always from the same pack,
the following configurations would work only:
Cbb
■──■
Cyb
■──■
Cyw
□──□
Cbb2
■──■
U
■──■
old HC, old Cam.

─



new HC, new Cam.
()




old HC, new Cam.
()
()
()
()
()
new HC, old Cam.
X
─
X
X
X
─= not working
()= must be working but not guaranteed
X=not working. The devices may be damaged!

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2 New features in Fw. 02.50
oExclusive AG output mode has been extended with variable dead time and it is
applied between each AG signal change. (This is a workaround for some mounts
that can be stuck in one direction while AG signal ‘suddenly’ changes to the
opposite way.)
oA constant 0.2s AG signal idle time is inserted between RD movement and AE
exposure end. (This is the same workaround for some mounts that don’t need
exclusive AG out mode but still could be stuck at dithering.)
oFixed bugs in PC App:
CSV format selection (separator and decimal point mode) is fixed.
When calculating PE, day step (23:59 to 0:00) is handled well.
2.1 Previous version changes
From 02.42:
oA ‘factory reset’ possible from Fw., for all the variables in the device. (at Misc. /
Mode settings / …)
oSomewhat better star search results at high binning modes.
(An AutoExposure pause bug has been fixed in 2.41 release meanwhile.)
From 02.40:
oThe polar alignment feature is now available for mounts without DEC axis.
oOptional “focusing mask warning” feature for AutoExposure to avoid telescope
time to be wasted because of the forgotten (not removed) mask.
From 02.30:
oA precise polar aligment function/screen is available. The method is the
‘declination drift’ or ‘Schneier’ method.
From 02.21:
oFixed bug:
‘Disable direction’ type backlash compensation worked buggy.
From 02.20:

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oAutomatic shutdown (power-off) possible at a given time.
oDEC backlash “elimination” is possible. Two methods are offered.
oCalibration data can be restored after deletion, until a new calibration is done.
oFixed bugs:
Calibration: is more precise at high exposure time; fixed ‘random
characters written’on the screen for some rare error.
Exclusive AG out mode was wrong for the manual mode.
From 02.12:
oAstro Photography Tool is able to inform M-Gen about the externally controlled
exposure, so that M-Gen saves guiding positions to create guiding diagrams.
o(Mech./star) emulation mode is available. (It has been developed only for testing
indoor.) More on this at the switch’s description.
oAfter a calibration has failed / been stopped, the mount is restored to its starting
position (no backlash is assumed).
oFw. version show on main menu header; DC input voltage can be seen at guiding
screen page 5/5, inside “more..” item.
oFixed bug:
LiveView mode timed out if using at least 4x4 binning and more than ca. 3
seconds exposure.

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3 About the user interface
All the screenshots in this document may be one of a previous firmware release and are
only for demonstration purposes. The only exceptions are the ones that are detailed written
about, in the screens’ paragraphs. These have a colored border.
3.1 Buttons and LEDs
On the front panel of the HC there are 6 buttons and 6 so-called indicator LEDs next to
them. The buttons are for navigation and controlling of the device while the LEDs indicates
some action of it for visual checking.
These are the following:
oESC
Functions: back, cancel or exit.
Main function: exiting from the current screen.
blue LED indicator: shutter focus line active - feedback (default).
oSET
Functions: enter (into sub-menu), choose,set, activate,start editing.
Main function: activating the selected item on the screen.
green LED indicator: shutter exposure line active –feedback (default).
oUP, DOWN (arrows)
Functions: select prev./next item, inc./dec. digit (in editing mode), DEC manual
guiding.
Main function: navigation between the screen’s items.
red LED indicators: DEC axis correction output line(s) active. (Shows what is
physically on the autoguider output).
oLEFT, RIGHT (arrows)
Functions: changing the value of the selected item, (select prev./next item,)
moving the cursor (in editing mode), RA manual guiding.
red LED indicators: RA axis correction output line(s) active. (Shows what is
physically on the autoguider output).
3.2 Main conception of the User Interface
The display and controlling of the device is menu-based. By default there is always an
active screen, holding one selected item on it (for most of the screens). The selected item is
always shown inverse. (This is something like a cursor for the actual screen items.) The
selected item can be activated by pressing the SET button. Activating means entering to
editing mode (to change its value) or doing some function. By default You can change the
selected item (~”move the cursor”) with UP and DOWN buttons and in some cases LEFT and
RIGHT could also be used.

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This “screenshot” below shows the main menu with the “Exposure” item selected on it:
Certain items behave differently. There are number, time and text types etc. Text type
items can lead to a submenu or are to do some function (like a button), while other (number or
time) types store a value that could be edited/changed and are called parameters or variables.
These are to setup, parametrize the device, to control its behaviour.
3.2.1 Menus
The HC has a fixed menu tree structure. From the main menu every submenu is
accessible with a subscreen at the end that is for some specific function. If an item leads to an
other (sub)screen it is called menu item.
Exiting from a screen is done with ESC button. When entering into a subscreen, the
selected item is memorized to set it as the selected item if You go back with ESC.
3.2.2 Variables (parameters)
There are many types of items on the screens. If an item holds a value its called variable
or parameter. Their value can be changed in editing mode. For demonstration there are some
example:
Example
A variable item is selected on the screen.
By pressing SET You can enter editing
mode (if it is allowed to be changed). The
bracket around the edited item indicates
the editing mode.
SET
Beginning of editing.
In this mode there is always a cursor that
selects one digit and is shown inverse. To
move the cursor on the digits LEFT and
RIGHT buttons can be used.
LEFT
Moving the cursor.
To change the value of the selected digit
use UP and DOWN buttons. Use
autorepeat of the buttons for faster
changing of the digit value.
UP
(more times)
Increasing a digit.

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To store the new value press SET again.
The new value immediately takes place
in most of the cases. Doing so we also
leave the editing mode.
SET
Storing the new value.
To discard the new value edited (to hold
the old one) press ESC. This exits editing
mode.
ESC
Discarding the new value.
The editing process is always done on a temporary variable so it does not affect anything if
You start an editing and then exit from it with ESC. During editing the device uses the
old/original variable value.
Types of the items or parameters:
Decimal
An integer value representing something (meant in some unit or indexes different
modes). Consists of fix number of digits (all these digit characters are shown
inverse when selected as above in the example), has limits (minimal and maximal
value). (If a limit is violated in editing mode by changing a digit’s value the value
is set to that limit independent of the edited digit.)
The example above shows this type of parameter.
Real
Real value with two-digit fractional part. Edited the same as for the decimal type.
Between the integer and fractional parts there is a dot character.
For example:
The selected “AG speed RA” item in this screen
is real-type with a value of 0.5.
Time
The default time-type variable is always meant in 0.1 sec unit and is displayed this
way.
For example:
The selected “exp.time” item on this screen is
time-type with a value of 3 minutes and 15.2
seconds.
In editing mode it behaves as the decimal type except that some digit’s maximum
is only 5 (ie. 59 for the minutes) and there are dot and double dot characters
between the digits.

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Text
This type can not be edited as the other. Holds a fix text or the ‘value’ (state) of it
can be changed with the SET button. So the text can show the value or state of a
parameter.
Can be a so-called button item that does/starts
some function. Can be a submenu item to enter a
new screen (down in menu tree).
For example the main menu consists only of this
type of items.
Can be a so-called switch that can be altered by
the SET button. (This is a two-state parameter
item.)
For example: enabling functions or modes are
controlled by this type of items. Commonly a ‘-‘
character indicates the OFF and a ‘’ char. the
ON state.
Can be a special parameter that can have a few
number of fix values, displayed as a text.
For example on LiveView screen this item can
have only the “max.”, “avg.” and “havg” values.
The value of most of the parameters or variables are stored into EEPROM (non-volatile)
memory of the HC at power-off. At the next power-on they are initialized from here.
3.2.3 Profiles
Profile means the value of a set of variables / parameters, these are called profile
variables. The value of these can be set in each profile independently. Changing the active
profile will change the value of all these profile variables.
There are 3 separate profiles (number 0, 1 and 2). The active profile can be changed in the
misc. menu screen. If doing so the old profile setting is stored into memory and the new one is
loaded into the profile variables. The change of these takes effect immediately and so there
may be a question to stop the current autoguiding because all the guiding parameters are
profile variables.
A profile can be interpreted as a ‘trimmed’ set of parameters for each guiding solutions,
for example profile 0 for a guiding telescope, profile 1 for off-axis system and so on.
Non-profile (global) variables are not affected by a profile change. The parameters of the
AutoExposure program are of this global type for example. Profile variables are generally for
those variables that are needed for autoguiding.

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4 Parts of the software, functional units
There are some well defined functional units in the device. In the next sections You can
read about these functional units for the sake of a better transparency.
4.1 AutoGuiding function (AG)
The main function of the device is Autoguiding. It has its own process (runs
independently of the other (including the User Interface)), handling the Camera is it’s job
exclusively so the program of the Camera is the part of this functional unit.
The guiding star’s image is processed by the Camera. The guiding program in the HC uses
the calculated star position to control the mount with the ST-4 compatible autoguider port.
There is a dedicated screen for Autoguiding, on which everything can be controlled that
directly affects guiding. This is the guiding screen, can be reached with two SET keypresses:
(Main menu) Guiding →(Guiding menu) Current guiding →
Guiding screen is indicated by a “GUI” text in the top right corner and a 48x48 pixel
window monitoring something on the left of the screen. There are more pages of this screen,
more on this later.
Important notes:
oIf the Camera is active and there is a star in its guiding window (an area on the
CCD field), it will follow the star with repositioning the guiding window even if
the autoguiding is not started. Because of this the monitored image of the guiding
star (within the 48x48 pixel window) may be shown as replaced ‘immediately’ but
this does not affect anything, it is only made by display.
This star following is a part of the software, can’t be turned off.
If the followed star is lost (gets too dim by clouds or jumps out of the guiding
window by a mechanical push), the guiding window stays and waits for the star
appearing again in it (no automatic re-search is done). The user may search for the
star again (with LiveView or Star Search).
This could happen often if You touch and push the mount / telescope (or the
DSLR) by hand and it is not stable enough. After this the star may stabilize in its
old position (in guiding window) but the window may be repositioned as it wanted
to follow the star and that’s why the star is lost.
If autoguiding is active, the guiding window is stationary, does not follow the star,
since it should stay near the center. At permanent star lose no automatic re-search
takes place.
oIf You started to use the Camera once, do not just pull out the Camera-cable, for
example to detach the Camera from the guide scope. Stop the Camera before. (See
5.1.10 page 5).

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The Firmware handles sudden lose of the Camera but it is not safe to power-off it
that way, it might damage some circuit part in the Camera.
4.2 AutoExposure function (AE)
The Autoexposure functional unit is also a separate part of the software. On its dedicated
screen can be set up, started and stopped etc. The shutter signals generated by this functional
unit appear on the 3.5mm stereo jack output connector and can be directly connected to a
Canon EOS 550D or similar DSLR with such a shutter input (“open-collector” line). The
AE’s function is to shutter Your DSLR synchronized with the device’s functions.
The AE program runs totally independently of the other units by default. In this case it can
be used as a single automatic shutter device too, can be powered only from USB as well. The
only case when the AE is synchronized with other functional units is the Random
Disaplacement function enabled and the Autoguiding active.
The shutter program has two operational modes:
oNormal mode (default): all the shutter program parameters can be set and used
(wait time, mirror lockup time etc.), the DLSR shutter is controlled fully by the
LMG device.
o“AstroTimer” mode: this mode is mainly for cooperating with the external shutter
device called AstroTimer but other external device may be used.
In this mode the device does not generate shutter signals but other: the shutter
output is only active when the Random Displacement function is moving the
telescope, so it indicates the time when the external shutter device must wait.
In this mode there is only one parameter that can be set, the time period between
two RD movements. It is shown as the ‘exposure time’ of the program.
4.3 Random Displacement (dithering) function (RD)
Also known as “dithering”. It’s goal is to move the telescope (with relocating the guide
star) randomly between the imaging exposures, avoiding to image the object time to the same
sensor surface each time. This has several advantages:
Some untouched or ‘termporary’ hot pixels can be eliminated automatically at the
combination (‘averaging’) of the single frames. These pixels will be located at
different position on each frame relative to the object (after registering /
alignment).
Similar to this, overcompensated pixel caused ‘black holes’ are eliminated also
and the noise effect of ‘wrong’ dark frame subtraction is smoothed.
The non-uniformity of pixel sensitivity causes extra noise pattern that can be
suppressed (smoothed) too.
Using very short focal length objective and a sensor with Bayer-matrix color filter
can cause false coloured star spots as they are easily imaged into a single pixel. By
moving the image over the filter matrix will lower this ‘color noise’.

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On photos taken without RD some small pattern of the background noise is a typical
effect. This may be caused by the changing gravitational flex in the system (using a guide
scope and a separate imaging telescope) or image movement (rotation) around the guiding star
due to not enough precise polar alignment.
Some effect of using a ‘noisy’ flat field is also smoothened by RD.
RD works together with the Autoexposure and Autoguiding functions, if enabled. At
disabled state it does not affect any part.
RD can be triggered through the USB interface, enabling an external program (for
example Astro Photography Tool) to dither with the MGen synchronized.
4.4 Filesystem (FS)
As its name shows it is a data storage function of the device. There is 2.088.960 bytes of
free Flash memory for the files’ data.
In the filesystem there can be a maximum of 16 file entries. Only one of those can be
opened at a time, which is accessed by all the processes (for data inserting). The open file
stores several types of data –dependent of the parameter settings- to store one or more night’s
events to make statistics, search for ‘bugs’ or just check the accuracy of the autoguiding (or its
parameters). May be used to optimize Your parameters ‘offline’.
The files have their own menu, where details can be seen (size, dates, downloaded state),
new file can be created, file deleted, opened or closed. It is advised to download these files to
PC as frequently as possible (with the PC application) to make enough free space for the
forthcoming nights.
There is a date and time settings screen, where the realtime clock (with date) is to be set.
This is essential for timestamping the files’ data to a proper identification of the stored data
later. After power-on this screen appears, after then the file menu when You can open a file,
for example the last opened or a new one. (If You skip opening a file, every function will
work but no data will be saved.)
4.4.1 When is the file written?
If a file is open, the following events/conditions triggers data to be saved into it:
A new star position measured, while AutoGuiding is enabled and AutoExposure is
in the exposure state: the ‘drift’ data is stored (RA/DEC offset). The stream of such
data will create guiding diagrams and data into the HTML output file.
Note that this is stored even if the MGen was informed that there is an external
exposure going and the AE is idle in the MGen. (For example by APT.)
A new star position is avalable while AutoGuiding is NOT working and the ‘save
pos’ switch is on: (See 5.1.10.5) the X-Y coordinate of the star is saved. These are
mainly used to record data for generating PE curve.

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AutoExposure state changes.
Some variable value’s change.

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4.5 Cooperation of the functional units
The three main functional parts (AG, RD, AE) need to work synchronized if the RD is
enabled. This communication is shown below in a simple diagram (the time axis goes
downside):
Some behaviour read from the diagram:
If the RD is disabled (“Requiring new position” will fail) there is no
synchronization between AE and AG.
The RD as a program must be enabled only at one moment (the only horizontal
line), the movement is done using parameter values at that time moment. Changing
the parameters (or enabling/disabling it) any other time will not affect anything.
The Autoguiding works in a special mode when a displacement is in progress. It
starts to autoguide to the new position automatically with the current parameters
but the guiding is stopped right after both of the correction signals (axes) got
inactive at least for a moment since the start of the movement. The new star
position (that is not the exact calculated position) is then measured for max. 2
seconds and the guiding is continued in that position and the Autoexposure is left
to go on. (This method shorten the displacement time and gives more for imaging).
Autoexposure
(AE)
Random
Displacement (RD)
Autoguiding
(AG)
Wait state
(„w”)
Program start
Requiring new position
Start moving to
new position
Autoguiding active
Special mode
“Autoguiding” for RD
On new position
Autoguiding active
Start Exposure
(„m” or „E”)

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5 Menu tree
The menu is structurized around the function units. From the main menu You can access
these main functional units’ control screens, besides other subscreens and menus.
Here is a drawing of the important part of the menu structure.
(screenshots are only illustrations, actual fw. may differ)
To navigate in the menu use SET and ESC buttons. SET is to enter a subscreen while ESC
is to exit the current one. The previous screens and their selected items are stored in a stack,
by going back to them will hold the previous selection. By entering a new one will have the
default item selected on it.
Blue arrow shows an extra possibility to change directly between Guiding and
AutoExposure screens. This is called ‘long ESC’, ESC button pressed continuously for more
than 0.5 second.
To go to the main menu press ESC more times.
Main menu
Autoexposure
Guiding menu
Random Displ.
Misc. menu
Guiding
LiveView
StarSearch
Guider setup
…
Power off
…