The SETI Net antenna consists of a 10
foot dish and twin rotors
each with 180° of movement. The
rotors are stacked,
using a specially built adapter so that the combined they
can position the antenna
nearly any where in a 360°
and 90° degrees elevation.
Controlling the Antenna
Start the control panel if needed and click on the
Antenna Controller icon (top left). If the antenna
comes on with a different view than above click on the right
facing arrow on the bottom and it will open up.
- When you start the SETI Net antenna controller by double
clicking on the icon you are presented with this image.
Turn the subsystem on by setting the Main Power ON/Off
switch. This enables the motors and clears the
software ready for operation. Press the
button and if the antenna is not already at its mechanical
stops it will start to move toward them.
It may be that the incorrect serial port has been selected
by the last user. In this case the antenna On/Off
switch will automatically switch back to off. Use the
Com Port menu (top left) to change to another port and try
again. Usually the port is either 3 or 4.
- Notice that all the gauges slam to zero when you start
homing. When you reach home they will go to there
mechanical stop positions. The minimum elevation is
currently set at 6 degrees. This is shown by the
yellow band on the Elevation Set gauge. The Azimuth
Set gauge moves from 180 degrees (straight south) to 355
degrees (almost south again). The mechanical stops on
the azimuth system determines the maximum position.
When you achieve home the status bar (bottom of the
controller) will show 'Ready for Operation'. The
yellow needles will all be enabled ready to move the antenna
as you wish.
- With the antenna system on and the homing operation
complete you simply 'tug' a yellow needle, with a left mouse
click and hold, to the desired position. As the
antenna ramps up to slew speed you will see the second
needle move to show the current antenna position. You
can tug either of the 'Set' needles (Az or El) or the motor
needles. All needles keep up with each other.
When the antenna reaches the desired position it will ramp
down and stop.
- If you shut down the motors, with the main power switch,
you can turn on the simulation software that mimics the
operation without moving the antenna. This is useful
when the antenna is off line for repairs or when you want to
simply get used to the operation panel. In simulation
mode try moving the Azimuth dial to about 210 degrees.
This forces the antenna to go 'over the falls' where it
turns itself completely around in Az and El to reach this
- It is possible to start the antenna without going through
the homing operation. After turning the Main Power to
On you can press the Quick Start button rather than the
'Home' button. The system will load the motor control
logic with the last known position and then go to the ready
Band Pass Filter
- See the description below
Watching the Antenna Move
You may watch the antenna respond to your commands.
To do this start a new browser and open
Select the button for Audio/Video and use the
Username - guest and password- guest.
The antenna was developed by the Haystack Observatory
(part of MIT) for use as a continuum and spectral line observations in
the L-band (1.42 GHz.
||122.5 inches (311 cm)
|Depth of dish (x)
||20 inches (50.8 cm)
||46.85 inches (119 cm)
|Gain @ 4.2 GHz
|Gain @ 1.4 GHz
|Weight with mount
||3.5 Degrees (L-band)
The focal length of the dish based on dish geometry is
46.85 inches. From the
of the feed horn dimensions the focal length should fall inside
the lip of the feed horn by 1.46 inches.
The Head End electronics are contained
in a watertight box riding on the back of the Horn. It
is mounted as near to the feed probe as possible to minimize
loss in the system. It houses the Low Noise Amplifier
(LNA), the band Pass Filter (BPF) and various other relays
and amplifiers. The remote sensor thermometer (the
white box) is not normally part of the Head End electronics.
LNA - The Head End Electronics
contains the all important LNA and
BPF. The LNA is the white with black
label object in the middle. You can see the 'N' type
connectors on the left side of the LNA making a right turn
down to the probe pickup inside the horn.
BPF and Bypass relay - The 30 dB
Band Pass Filter is the black device at the top marked
'Combline Filter 1.425 GHZ'. Its the BPF that sets the limit
on the portion of the band that reaches the receiver.
The BPF is required to eliminate out of band signals from
distorting in band signals. If strong out of band
signals are allowed to enter the receiver they mix with
in-band signals and produce images that may show up anywhere
in the band.
The receiver will tune from 1 GHz
(100,000,000Hz) to 2 GHz. You may tune the
receiver any where in this band. Notice that if you wish to view the Global
Positioning Satellites (GPS) at 1575.42
MHz you will have to shut off the BPF because this frequency is above the BPF cut
off. You can bypass the filter from the Antenna
control panel (middle of screen).
Band Pass Filter Bypass
Band Pass Filter Characteristics
The BPF can be bypassed engaging the microwave
relay (top right in the picture). It is switched in
and out of the circuit by software command from the
Control software ('Band Pass Filter switch'). For SETI
work the BPF is set in line. For Radio Astronomy this
filter is bypassed for maximum signal.
The BPF relay is controlled by a Kerr module
mounted out of sight on the lid of the weather proof Head
End Electronics case. Its this Kerr module that makes
the connection to the computer using an Category 5 cable.
This is the same sort of cable that is used, with RJ45
connectors, to interconnect computers and routers for
internet use. This cable is actually operating using a
variant of the standard RS-232 protocol (RS-422) to
control the relay and the twin motor control modules in the
Line Amplifier - This little device
(marked RCA in the picture) is wide band and is intended to
make up the loss expected from its output to the input of
the receiver. This is a run of about 50 feet and
consists of high quality semi-ridged co-ax.
Notice the use of copper colored 'hard
lines' to connect the components. At this frequency (1420
MHz) losses need to be minimized by the use of this type of
'plumbing'. A hard line is a copper tube filled with
Gor-Tex material and a solid inner conductor of copper.
The ends of the copper tube are terminated with low loss
'SMA' type connectors. Hard lines are expensive and
difficult to work with but necessary at this frequency.
ICOM IC-R7000 Receiver with installed DRM
Receiver Control User Interface
You may tune the receiver to (almost) any
portion of the band from 1 GHz to 1.5 GHz using the user
interface. To get the receiver on line do the
Start the control panel if it needs it and click on the
Receiver icon (top). If the receiver comes on with a
different view than above click on the right facing arrow on
the bottom and it will open up.
- Toggle the On/Off to the on position. If your very
lucky you will see the software search for the receiver and
find it. If your not so lucky you will see the
software fail to find the receiver and suggest that you
change the port setting. The receiver is generally on
either port 3 or 4. The port it is connected to
is dependant on how I have the station configured at the
Select Digital Radio Mondale (DRM) mode for normal SETI or
RA work. This mode makes use of a small module that I
installed in the receiver that taps into the receivers 455
KHz IF and converts that to a 20 KHz wide audio signal.
Its this 20 KHz signal that is routed to the Sound Blaster
card and used in all SETI searches. The other modes
operate but unless you are listening to the audio directly
from the SETI Net web site you will not see a difference.
- Notice that the leading digit is missing from the display.
This is always a '1' and can be assumed. On the actual
receiver hardware the selection of the lower band (100 KHz
and 999 MHz) and the upper band (1 GHz to 1 GHz) is done by
a push button on the front panel. This is not
controllable by software so it is always set ON (upper
band). The trailing two digits are also missing on the
display. This is because the receiver cannot tune in
increments less that 100 Hz.
The result of this is that when you see a
display like '765,432.1' as in the above display you are
receiving at 1,765,432,100 HZ. This may be referred to
as 1765.4 MHz or 176.432 MHz.
If you set the Control Panel 'Update'
switch to On this last digit will show itself as a '1'.
Switching that last digit off does not effect the receiver
but does cause the software to assume that the receiver has
been switched to the lower part of the band (below 1 GHz).
- The large spinner knob can be used to adjust the
frequency as needed. One complete revolution will change the
frequency by 1,000 Hz (1 KHz). You can also set the
frequency by pressing the up/down arrows under each digit on
the frequency display.
Other controls and
indicators - Theses should all be left in there
default condition and are supplied for your amusement only.
- Click to save space on your display.
download and install a copy of this software on your
computer. This would allow you to tune you own R7000
for general purpose use.
from the standard sound system on my mother board to
Creative Sound Blaster X-FI Xtreame PCI Express card.
It has a much better noise floor than the original.
You can set the Tone Generators frequency
and amplitude and if your attempting to synthesize a SETI
signal you can cause the tone to chirp down in frequency by
a specified amount. If you are synthesizing a very low
level SETI signal you can add attenuation to the signal to
get it down very close to the noise floor. Chirp is a
technique described in the Water Hole section.
Most of the controls of the Tone Generator
are self explanatory and can be understood by doing more
than anything else. Try setting the unit to 10 kHz
(Frequency Range - Wide, Sweep Speed - Manual, Manual
Frequency - about 1/2 way) then start the Spectrum Analyzer
and you should see the note on the screen.
The system is setup with Virtual Audio
Cable (VAC) so that the Tone Generator audio to be
routed to the Spectrum Analyzer. More on this in the
section on Audio Connections.
You can download a Tone Generator for your
The Spectrum Analyzer is the key component
in the station operation. Its task is to accept the
raw audio digital data from the sound card and convert it to
the time domain for further analysis. It also contains the
Waterfall and the detection logic to alert you when you have
discovered the worlds first ET.
Start the control panel if it needs it and click on the
Spectrum Analyzer icon (top). If the SpecAna comes on
with a different view than above click on the right facing
arrow on the bottom and it will open up.
- Change the Spectrum Size selector from its default
position of 8192 to a smaller number like 1024. Notice
that the spectrum display freezes and 'Run' switches to Off.
Set it back On and the display will start running again.
Notice that the display is much more 'jittery' at a spectrum
size of 1024. Switch to 16k on the Spectrum Size
control and restart the SpecAna. Now it is much slower
but the display is much finer grained. Its slower
because it simply takes longer to process a 16,000 point
array than a 1,024 array.
Notice the Hz/Bin number next to the knob on
the Spectrum size control. At 16k it is a little less
than 3 Hz/bin. More about bins and spectrum size
Start/Stop/Record - Hit the Run button. If you have
the receiver up and running turn it on the Spec Ana (the Run switch on
the right) and you should see the output of the receiver in
the time domain. Use the Vertical Sensitivity control
to set the signal so that it fills about 1/2 the screen and
add 1 or 2 seconds the Integration Period control. You
screen should look something like the one in the example above.
Toggle the waterfall button and the spectrum will appear as
a waterfall. The waterfall is set to be as wide as you
have the Spectrum Size set for. That is if you set a
Spectrum Size for 8192 bins you will have a waterfall that
is 8192 pixel wide.
- Starts recording the incoming audio as a WAV file and the
waterfall as a JPG. when you stop the capture
operation the WAV and JPG files will be created and tagged
with your SML. The file names are created
automatically based on the Date and Time.
Home Gamers Please Note:
If you don't see any noise it could be that you don't have an active
input selected for recording.
This is done in Windows Vista and Windows 7 by
right clicking the Speaker Icon (bottom right of
you Windows Desktop) and choosing 'Recording
On my machine it looks like this. Make sure
your input device is selected as the default, that
it has a green check mark beside it and that it is
active (green volume bars).
Part of the SpecAna
The Waterfall is where the detection takes place. Its
job to to maintain a buffer in memory that represents the
values collected in each bin of the Spectrum Analyzer FFT
operation. It gives you a peek at this buffer on the screen as
shown below. .
- The Waterfall is built into the Spectrum
Analyzer. To see it in operation do the following:
Set the SpecAna Spectrum Size control
Run the SpecAna
Press the 'Water' switch next to the
-You should see a display something like shown above.
In a waterfall display your looking at the same display that
is presented on the SpecAna except that each pass through
the array of time domain data is presented as a single
colored line across the width of the waterfall. Each
pixel of the line represents one bin of data and is color coded
to indicate the relative amplitude of the signal found in
that bin. Cooler pixel (bin) colors are toward the red
end of the spectrum, hot towards the blue end. When one
line is color coded and written to the window the display
shifts down one line and repeats the process. The result is
a display of that portion of the spectrum where time runs
from top to bottom and frequency from left to right.
-The number of pixels used is equal to the size of
the spectrum size so this waterfall in this example is 2,048 pixels wide.
If you increase the SpecAna Spectrum Size the waterfall
expands to accommodate it. The width quickly expands
past the right side of the display but a scroll bar appears
below the display to allow you to move right.
- This bar is located at the top of the Water Window but can
be dragged off to allow you to scroll the Water Window and
still keep the tool bar. This bar indicates that a
signal somewhere in the window has exceeded to the
parameters necessary to be defined as a 'Hit' when the green
LED comes on and the bin (pixel) position where the carrier
signal can be found. Other controls in this tool bars
will be defined later.
display interaction - If you are tuned to a
portion of the band where there is a signal you should see
the 'ETDetected' LED go green and the bin (pixel) that
holds the signal show up next to it. If you move the
mouse to the Waterfall and put it over the alarm bin you
should see a dotted vertical line show up in the SpecAna
display that corresponds to this same position. This
operation is less than perfect because of the processor time
needed and the dotted vertical line may jerk into position
rather than show a smooth operation. More on the other
settings operations later.
The Control Panel currently requires several pieces of code
running (like a MySQL database) before it will even start.
For this reason I don't recommend downloading it to your
system. If you are interested in running the CP I will
put some effort into making it startup better.
The Control Panel integrates all the other
SETI Net modules and allows you to make visible or dismiss
each module from view during operation. This is important,
particularly when using a computer with a single monitor, to keep the
confusion of multiple modules running at the same time to a
minimum. The Control Panel also ties together certain
functions of modules for a larger picture of what is going
Some of the icons
in the Icon Bar (across the top of this screen) might be
familiar. Left to right:
||Controls the information going to
the SETI Net web site front page.
||Allows SETI Net to Auto Tweet its
||Defines the Min/Max of Az and El
and the No Fly Zone of the rotors
||Frequency and mode setup for the receiver and 10
kHZ bump button
||Press to see the current database
||Select and connect to the database
||Make the Spectrum Analyzer visible
||Show/hide the waterfall
||Show/hide and control
||Generates and tags the JPGs and WAVs with SML
||This is what I hear when a Hit comes in (go
ahead and play it)
Each icon is
live - that is if you click it the underlying module will
spring up for you to control. When you have the module
set the way you want it another press will dismiss it and a
double click will keep it in view.
Start up -
If the CP is not visible on your screen click the Control
Panel icon that looks like a dish antenna or find the CP
from the start menu. If all
goes well you will the screen above.
dB - This
is a MySQL data base that keeps track of 'hits' in the
system. Each time the system ET Found light (in the
Waterfall control panel) lights the details of the station
operation is added to the data base. This allows the system
to skip known when there address space is searched again.
Chirp - The
ability to chirp the receiving system is the principal
method of discrimination of local, terrestrial, signals and
those from outside of the Earth. The Chirp system is simply
turned on or off here and the current chirp value reported.
The Hz/Sec shows the current frequency change computed for
the antenna direction. The Fractional Frequency is a total
of the chirp since this session was started and the Bin
Shift is the number of bins the waterfall display has been
moved to account for the chirp. More on chirp in the
discussion on Detection Logic.
Receiver Freq - This
panel reports the current frequency of the R7000 receiver.
It does not take into account the bin shift or chirp. Its
operation is TBD and may be removed.
Stare Time -
This panel sets up the total time that the system will look
(stare) at a particular space address and what the operation
is after the stare time is finished. Set the Stare Time
spinner to the number of seconds to stare and select the 'On
End Stare' radio button selection for the next operation.
Generally this is set to 'increment Freq' where the receiver
is bumped up to the next 20 KHz segment of the space address
and the stare operation automatically restarts. The 'inc
DEC' and 'Inc RA' are non operation at this point. The
'Stop' selection simply stops the automatic increment of
receiver frequency at the end of the stare period.
This is the Next to last operation performed when a search
run has been configured and is ready to go. The Update
switch turns the Sky
on and keeps the station
parameters up to date in the File
last thing to
do to start a run is to press on the State Control button so that it
turns green. The Control Panel will ask you where you would
like to save the data resulting from a 'Hit' and after you
have selected a suitable directory.
The search will start.
(Part of the Antenna module)
This module is used to
set the default conditions of the antenna in use. Its
settings are used by the File Manager to report the setup
when data is collected. Normally there is no reason to
change any of these setting.
The antenna Mount
module allows you to adjust the following items:
All Sky is the type used currently meaning that the
antenna can cover most of the sky from 360 of Azimuth to
90 degrees of elevation. The other possibility is Drift Scan where the antenna is
pointed at a fixed Az/El and the sky allowed to 'drift'
by. If the mount points straight up its called a Bird Bath.
Angles - This value is set by the Sky Map Module is is
shown here for reference only
No Fly Zone -
Min/Max azimuth and Min/Max and elevation is entered in
this moule. This
is used to compute the directional setting of the
antenna and of the image on the Sky Map. If you
hit the Reset button you will notice that the Az max
entry changes to 185 and the Az Min to 180. This
does not mean that you can not move the antenna in
degree zone. The Elevation Min/Max is shown by the
red arrows and side bars.
Beam Width - The
frequency (nominal) is entered here to be used to
calculate the beam width. The default is 3.66
Changing one parameter
effects the others and can become confusing so when
all else fails - hit the Default button to return to a known
(Part of Control Panel)
This module is used to send the current operating parameters
to the base page of the SETI Net web site (www.SETI.Net).
Turn it on and your current search information is displayed
on SETI Net
The File Manager is a key element of SETI
Net. Its task is to keep track of all the station
parameters and convert them to the SETI Markup Language
(SML). When the station captures a signal SML data is inserted into
the WAV file and the JPG image to make a complete record of
what was going on when the hit occurred. It shows who was at the
controls, where the antenna was pointed, the time, and a
myriad of other details that add meaning to an otherwise
file of noise. You can, and should, change at least
the Title Page to show your name and any observers with you.
After all this will make a record of who actually made the
first discovery of ET so make it your own.
Since the station configuration is saved
with the data generated a future user would be able to
search the station
section of this web site for any WAV or JPG files and then
extract any particular parameter needed automatically.
For example all the Hits the were found between 1420.66535
and 1437.230 could be found in the archive WAV or JPG files.
If you wanted to calculate the system noise temperature
during a particularly setup you could use the embedded SML
as input to these calculations.
The File Manager has six
areas to enter data, Title Block, Antenna, Receiver,
Waterfall, Block Diagram and SML
- This is the main screen that needs personalization for
your observation session. Change what you need but
remember that Station Location should stay the same
(after all that is where the antenna is even if your
running it from some other part of the globe).
File |SML | SaveAs to save a copy of your first changes.
I usually call it 'Prototype.SML'. Continue
changing the data in your prototype until you are happy
with it. Save early, save often.
- The Antenna tab is a place to put all the technical
details of the antenna, its size, current position
(automatically updated) the gain of the LNA and all the
other items that are needed to identify this equipment.
- The Receiver tab collects all the parameters that are
necessary to identify the receiving parameters.
- This tab displays the JPG file when loaded. This
screen takes care of itself.
- -This is essentially the same as the System Block
Diagram. Its used as a hint when laying out you own
SML file. The block diagram is of my own station
but should be general enough to relate the parameters to
- The generated SML is shown in this tab. Notice
that it is coded in XML. The
Language is detailed in this section of the web
- Just before you start a search session open the File
Manager and personalize the Title Page. This is
how you do it:
Select the Title Block Tab
Change the Title, Operator Name,
add an Observer if you have on, put any notes you
would like to preserve with the file in the single
line note area
Select the SML File 'SaveAs'
button and make up a name for your prototype SML File.
the Antenna Tab and make the changes
necessary. Do the same with the
you go along.
have several receivers save a prototypes file for
each one under a different name. That way you only
have to enter the details once.
Some of the information in the File
Manager is updated automatically like the date and time.
The SETI File Manager software allows you to
capture the essentials of your SETI station and save that information
inside the data
file that you generate. Since the information is inside the JPG and
WAV files it cannot get lost and will make it possible to identify the
station configuration, pointing angles and other engineering information
from when the SETI data was collected.
To learn the basics of the File Manager its best to play with it. Do the
Create A New SML File
The File Manager starts with a
built in SML set. Use it to
build a personal SML file for yourself. For more information on SML
the SML file in a convent file are by clicking on
"Save As". The SML is stored in a file with the extension .XML
This allows the file to be recognized by other standard XML processing tools.
Modify the current SML by changing any data in any of the boxes.
View the raw SML by pressing the "SML" tab. This is
the data that will be stored with your WAV or JPG files.
Attach Your SML To A Wave or JPG File
Using the File Manager open any wave file. You will have many on you
computer so use the Windows built in search function to find a suitable one to play with. In
the WAVE File area (bottom right) select "Open". Then
navigate to your wave file. Select the file and press the Open button.
The File Manager will ask you if you would like to use any SML
already inside the wave file. if you say 'Yes' any SML in the file comes
into the File Manager and overwrites the current SML. No - and only the wave data comes in.
If there is no SML in the file it will tell you so and switch to the 'merge'
Your wave file is now loaded and has been
'tagged' with the SML data.
or 'SaveAs' and store it.
That's all there is to tagging a wave file with SML.
SETI Station Use
other tabs in the generator (Antenna, Receiver
and Data Set) and make the changes that describe your SETI station.
Save the final SML file for later.
Search using your standard system software and
resulting WAV file.
Tag the file with your station profile.
Your file can then be sent to other Argus stations or exchanged
with any other user. The file can be played back as if it were live data
and the station conditions at the time of collection are frozen with the data.
How File Tagging Works
A Wave file is made up of several 'chunks'. First is a RIFF chunk that
that identifies the file as a Resource Interchange File Format.
Second comes a Format chunk that identifies the configuration of the
wave data in the file (Stereo or Mono, 8 Bit or 16 bit, sampling rate etc).
Next comes the Data chunk that contains the actual data. At the end of
the long Data Chunk there may be a chunk that identifies the name of the
tune or the record producer etc. This chunk is not a requirement.
The File Manager adds a final chunk, the SML chunk, where
the SML data is stored.
You can SML tag wave files and still use them normally. For example
you can tag the Windows Start wave file and it will still sound correct on
JPGs don't use 'chunks' but do allow comments. The JPG comment
field, at the top of the file, is where the File Manager stores the SML.
As with WAVs tagging a JPG will not change the way it is displayed nor will
anyone know about the existence of the SML data unless they have the
The SETI Net Astronomical Clock is the heart of the
system. It calculates the various equations of
time necessary to keep the antenna pointed and locked to
a place in the sky and to cause it to move to a new star
location when requested. When running from the
Control Panel the operation of the clock is transparent
The clock can also be used stand alone
on your computer. You can use it to find where a
star is in the sky and what Azimuth and Elevation
setting it would take to point to it.
Setting up the clock
Start - The clock starts running as soon
as you start it. It displays Julian day,
Universal Coordinated Time (UTC) and Greenwich
Sidereal Time. These are calculated based on the
clock in your computer.
Location - Enter you latitude and
longitude. I use Google maps to find mine.
As soon as you enter these two values the clock
calculates your Local Sidereal Time (LST)
Pointing - Hit the 'Mount' button
on the right side and the information for your
antenna mount can be entered.
Sky Map - Show your star
and antenna pointing location graphically.
(part of Clock and Antenna)
The Sky Map gives you a visual indication of
the portion of the sky you can see from your location. It was built from a Mercator
projection of the night sky modified so that Declination bars
are shown running up the middle and Right Ascension bars
from right to left.
This type of map allows an
object that is spherical to be shown as if is flat.
This introduces distortions in the top and bottom of
the image but makes it possible for me to use the
map in SETI Net. The night sky which is a
sphere above you is shown as a flat projection in
the Sky Map.
The result is that the Milky Way (the blue band)
has a curve to it.
With the Sky Map you can see the position of
the major constellations of the sky in both Azimuth and
Elevation or Declination and Right Ascension. The
DEC/Ra is fixed in the sky and the Az/El changes as the day
progresses. You set the Sky Map to your location using
the stand alone Clock and Mount.
For SETI Net the location is built in.
SETI Net -
Start the control panel if it needs it and click on the Sky
Map icon. You should see the Mercator projection of the sky
shown above. If both the Radio and the Antenna are on
line and if you select 'Update' on the Control Panel you
should see the Horizon line and the Mechanical Stop.
Other wise you will just see the sky.
- Move your mouse of the map and notice the change in the
top status bar. This bar calculates the position of
your mouse pointer as you move through the Sky Map. It
shows you the following:
Ra - The Right Ascension of the
mouse. This is calculated from the current date
and time as reported by the SETI Net computer the the
location of SETI Net in latitude and longitude.
You can think of Ra as the movement across the horizon
(its not really that but its a way to keep your sanity).
This is indicated in Hours | Minutes | Seconds and
milliseconds with zero hours on the far right and 23
hours, 59 minutes on the left.
DEC - The Declination indicator
is also calculated from the date/time and the location
of SETI Net on the globe. You can think of DEC as
the up/down movement of the SETI Net antenna.
Again its not really up/down but it can be visualized
that way. DEC
is calculated in degrees with zero degrees in the middle
of the Sky Map running up to +90 and down to -90.
DEC is indicated in Degrees | Minutes | Seconds
HA - This is the Hour Angle of
the mouse position. Hour angle is an intermediate
value used during the calculation of the DEC and Ra and
is shown for interest only.
pixX and pixY - These are the
pixel positions of the mouse pointer. They are
used in the calculation of the other values and have no
value other than interest.
- The current Antenna position is shown on the left side
bottom of the Sky Map. Changing the antenna position is done
by mouse left click.
- This sets a point in the Sky Map as your star
selection. Make your star selection with a right
click. The Star and Antenna positions are show in
major units (Hours in the case of Ra and Degrees for DEC)
and decimal portions of those values. This is
different than the mouse position indicator which is in
hours, minutes, and seconds, and allows you to work with
- Move your mouse to any place in the Sky Map and Right Click the
mouse. From then on the current star selection is
shown in the bottom right of the Sky Map. Left click any
place on the Sky Map and the antenna starts to move to that
Locators - If you loose
track of where the antenna star is you can press the left
side icons and see the current
- If you set this switch on the
antenna will start to move to your current star selection
and when it reaches it it will maintain this position for as
long as the star remains above the horizon line. This
is useful for long integration time searches. A green
LED will come on below the switch indicating lock condition.
Of course if you are using the stand alone clock this switch
has no effect.
Lock switch and LED does not show when running the clock
- The antenna cannot turn a complete 360 degrees. At
355 degrees it hits a mechanical stop to keep it from
strangling its control cables. The antennas minimum
elevation is +6 degrees but it does go up to +90 degrees.
These two values are used to compute and display the
mechanical stop figure on the Sky Map. It looks like a
misshapen triangle because of the distortion caused by the
Mercator projection. If your command the antenna to
move to the right of the mechanical stop the antenna will
'turn itself inside out' or 'go over the falls' by rotating
though 90 degrees of elevation. Don't do this
operation very operation as it puts maximum strain on the
antenna rotor motors.
- The horizon is of course a straight line when you look out
your window but because of the Mercator distortion is
appears as a sine wave in the Sky Map. The area below
the line is below the horizon and of course you cannot move
the SETI Net antenna lower than the 6 degree minimum elevation.
The horizon line moves across the Sky Map,
from right to left, as the day progresses. It carries
the Mechanical Stop with it so that when it meets the SETI
antenna the system causes the antenna to 'go over the falls'
and continue to track its star position on the right side of
the mechanical stop. This is an impressive thing to
see as the antenna turns its inside out to reach the new