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8/6/2019 IHY User Manual 191P4MHz Ver01
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Indian Institute of Astrophysics - Public Outreach
A two element radio interferometer for observations of Sun at 191.4
MHz
User manual Version 3Introduction:
International Heliophysical Year (IHY) is an United
Nations program spread over the years 2007 and 2008. The thrust area
is to study the Sun, Earth's magnetosphere and the interplanetary
medium as a coupled system. One of the major components of IHY is the
Public Outreach Education Program through which the knowledge on Helio
spheric Physics would be disseminated to the general public and more
importantly, to inspire the next generation of space scientists who
are still in schools and universities. In this connection, the Indian
Institute of Astrophysics (IIA), Bangalore has initiated several
activities through its Public Outreach (PO) program. One among themis to provide hands on observing experience in radio astronomy to
interested and motivated science and engineering graduate students in
the country by providing necessary antenna and receiver system to
their institutions. The above set up developed by the radio astronomy
group of IIA can be used to observe radio emission from the solar
corona at 191.4 MHz.
Contents of the 'kit':
1. Log periodic Antenna 2 nos.2. RG 8U coaxial cable (50 m length) 4 nos.
3. 1st stage Amplifier + high pass filter 2 nos.
4. 2nd stage stage Amplifier 2 nos.5. Analog receiver 1 no.
6. RF (LC)Filter 191.4 4MHz 2 nos
7. IF Filter 10.7MHz 30KHz 2 nos
8. Digital receiver 1 no.
9. Power supply 1 nos.
10.IHY Data acquisition CD 1 nos.
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BLOCK DIAGRAM OF IHY SYSTEM
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The radio 'kit':
The observing set up consists of two Log periodic antennas tuned
to receive radio frequency (RF) signal at 191.4 MHz. Each antenna
has an independent analog receiver chain for processing theincident RF signal and subsequent down conversion to the
intermediate frequency (IF) using the super heterodyne principle.
Figure 1 shows the block diagram of the antenna and receiver
system. The RF signal incident on each antenna goes through the
following series of operations before it is transmitted to the
receiver building,The filtering of terrestrial AM broadcast and
other spurious interference signals prevalent at low frequencies
using a high pass filter with cut off at 50 MHz. These otherwise
might saturate the amplifier(s) in the receiver chain,1st stage
amplification by about 30 dB gain in a commercial broad band (0.5
500 MHz) amplifier,transmission of the filtered, amplified RFsignal over a distance of about 50 m via RG 8U coaxial cable 2 nd
stage amplification by about 30 dB gain, identical to the 1st
stage,Then transmission of the filtered, amplified RF signal to
the receiver room via RG 8U coaxial cable over a distance of
about 50 m. A total length of 100 m RF cable is used for each
antenna since this helps to place the two antennas well spaced
apart and obtain interference fringes with good contrast. The
signal attenuation in the cable is about 12 dB at 191.4 MHz.
In the receiver room, the RF signal from each antenna is first
passed through a band pass filter of center frequency (fc)=191.4MHz and bandwidth ( f)=6MHz, to minimize the contribution from
interfering signals at other frequencies. The insertion loss in
the filter is about 9 dB at 191.4MHz. The filtered signal is
given to RF amplifier,amplifier gain about 30dB gain. Then mixed
with a local oscillator (LO) signal of frequency 180.7MHz for
down conversion of the RF signal from the antenna to 10.7 MHz (IF
signal).The output of the mixer is passed through a Band pass
filter fc= 10.7 MHz with the bandwidth f = 1 MHz to further
minimize the contribution from spurious signals and then
amplified by about 30dB gain Finally amplified signal is given to
Quadrature,output of quadrature will give 0'(cosine) and90'(sine). The output of the above signal is given to digital
receiver. In that receiver comparing the two signal sampled and
correlated (with the similar signal from the 2nd antenna) in the
digital receiver. The latter has also provision for integrating
the correlated data before passing it on to the computer for
storage.
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Indian Institute of Astrophysics - Public Outreach
1.Block Diagram of Digital Receiver
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Digital correlator board Electronic schematic diagram:
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Log periodic antenna:
In This log periodic Antenna operating range in frequency of 183MHz to
193MHz,over a bandwidth of 10MHz and gain of antenna is 7dB,The
antenna is made of aluminum tubes(Arms)and booms, For this range
frequency operation we have to choose the boom length,arms length andseparation of arms, below table showing the length of Arms and
spacing between the dipole.
Length of Arms Spacing between Dipole
Dipole 1 30.4cm Dipole 1 & Dipole 2 28cm
Dipole 2 33.2cm Dipole 2 & Dipole 3 29.3cm
Dipole 3 36
For any transmitting or receiving antenna we should match the system
impedence,For that we have to measure the VSWR(voltage standing wave
ratio).it is ratio of maximum voltage to minimun voltage along the
transmission line.For measuring VSWR we have to use spectrum
analyzer.below diagram showing the VSWR of the (183MHz to
193MHz)logperiodic antenna. For better signal VSWR should be less than
2 and return loss should be more.
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Measurement :
RF FILTER(TUBULAR) OUTPUT:
PARAMETERS EAST SIDE WEST SIDE
Centre Frequency 191.4MHz 191.4MHz
Insertion Loss 9dB 9dB
3 dB Bandwidth 6MHz 6MHz
Frequency and Level @191.4MHz and -55dBm @191.4MHz and -56.5dBm
RMS voltage 3.2mv 2.6mv
RF AMPLIFIER(MAN) OUTPUT:
PARAMETERS EAST SIDE WEST SIDE
Gain of the Amplifier +30dBm +30dBm
Frequency and Level @191.4MHz and -25dBm @191.4MHz and -26.5dBm
RMS voltage 50mv 94.5mv
VSWR 1.5 1.5
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Indian Institute of Astrophysics - Public Outreach
RF MIXER(SBL)OUTPUT:
PARAMETERS EAST SIDE WEST SIDE
Insertion Loss 6dB 6dB
Frequency and Level @10.7MHz and -31dBm @10.7MHz and -34.5dBm
RMS voltage 67mv 34mv
LO OUTPUT:
PARAMETERS EAST SIDE WEST SIDE
Frequency and Level @180.7MHz and +8dBm @180.7MHz and +8dBm
IF FILTER(TRILITHIC)OUTPUT:
PARAMETERS EAST SIDE WEST SIDE
Centre Frequency 10.7MHz 10.7MHz
Insertion Loss 1dB 1dB
3 dB Bandwidth 1MHz 1MHz
Frequency and Level @10.7MHz and -32dBm @75MHz and -35dBm
RMS voltage 25mv 9mv
IF AMPLIFIER(MAN) OUTPUT:
PARAMETERS EAST SIDE WEST SIDE
Gain of the Amplifier +28dBm +28dBm
Frequency and Level @10.7MHz and -5.5dBm @10.7MHz and -7dBm
RMS voltage 476mv 156mv
VSWR 1.5 1.5
IF QUADRATURE(PSCQ):
PARAMETERS EAST SIDE WEST SIDE
Insertion Loss 3dB 3dB
Frequency and Level @10.7MHz and -8.5dBm @10.7MHz and -10dBm
RMS voltage 220mv 160mv
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Installation
System requirements:
Desktop or Laptop with Microsoft windows XP(P III,IV).
Please maintain the screen resolution 1280X1024 or maintain
maximum resolution.
USB port.
How to install the system
1. Mount the two log periodic antennas separated by a distance ofabout 50 80 m, depending on the distance to the receiver room and
the available length of RG 8U cable.
2. Connect 15 V power supply to the amplifiers near the antenna end
as well as in the receiver room.
3. Connect the 1st stage amplifiers to the output from the twoantennas.
4. Take two nos. of 25 m length of RG 8U cable and connect the
output of the above two amplifiers to one end of each of them.
5. Connect the input of the two 2nd stage amplifiers to the otherend of the aforementioned two RG 8U cables.
6. Connect the output of the two 2nd stage amplifiers to the inputof the analog receiver unit in the receiver room using the
remaining two nos. of 50 m length of RG 8U cables.
7. Connect the two IF outputs from the analog receiver to thedigital receiver.
8. Connect 5 & 5 V power supply to the digital receiver.
Connect the output of the digital receiver to the USB port of the
Laptop/Desktop using the interface cable.
Hardware Installation procedure :
The DAQ Software installation program consists of a series of easy to
follow dialogs that lead you through the installation procedure. To
install the Measurement Computing DAQ software, do the following.
Insert the Measurement Computing Data Acquisition Software CD in your
CD drive and wait for the installation program to start.
If the installation program does not start automatically, use
Windows Explorer to browse to the root of the CD, and
double click on and follow the following steps:
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The MCC DAQ dialog opens.
Then press INSTALL
Then press NEXT and follow it.
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Then press INSTALL to install the program.
Running InstaCal and adding
your hardware
This section explains how to run InstaCal and add the USB BOARD
to the InstaCal configuration.
1. To run InstaCal, click on Start All Programs Measurement
Computing InstaCal .
InstaCal's main form opens.
Then automatically a window appears like bellow
click ok to add the USB board.
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If instacall doesn't start automatically then please follow the
following procedure to add board:
2. Click the right mouse button on the PC Board List, and selectAdd
Board from the pop up menu.
The Board Selection List dialog opens.
Running InstaCal and adding your hardware
3. Click on the USB tab.
4. Scroll down to select USB BOARD , and then click on theAdd
button.The USB BOARD is added to InstaCal's main form.
Now that you have added the USB BOARD you can use this form to
configure and test the USB BOARD.
Installing the data acquisition software:
Double click setup.Exe file from the acquisition CD and follow the
instructions to install data acquisition software...
Then please follow the pop up instructions to install...
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How to start the IHY data acquisition:
1) After successfully installing IHY Data acquisition software CD
an IHY icon will appear on the desktop automatically.
2) Check all the power supply is on.
3) Double click the IHY icon to start data acquisition.
4) The initialization screen will appear on the screen as shown
below.
5)Choose the appropriate source and the observation time in hrs and
then press OK to start acquisition as shown below.
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6) The Data acquisition screen will appear on the screen asshown above.
Data Storage & File name format:
1) User can choose the Directory where data can be stored as
mentioned above.
2) In that directory a folder named IHY will be created
automatically where the observed data files will be saved.
3) The file name format and example is as given below
Format :IHYyyyymmddHHMMSS.source
Example :IHY20080817035932.SUN
extension of the file name represents the first three characters
of the observed source name.
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Tips & Hints:
1) Restart computer after installation of the software.
2) Check the power supply connections before the system is switched
'ON' for observations.
3) It is always better to carry out a trial run every day for a few
minutes before commencing the regular observation.
4) Ensure that the power supply (both AC as well as DC) is 'OFF'
while checking the analog and digital components in the system.
5) Please disable anti virus , screen savers, power mode, automatic
updates etc... in the computer that is used for data acquisition.
They might disturb the observations.
6) Avoid running other applications in the data acquisition computer
(either in the background or foreground) while the observation is
'ON'.
7) Avoid seepage of rain water inside the 1st and 2nd stage RF
amplifiers which will be out there in the 'field'. Keep them in a
dry environment and at a height of about two feet from the
ground.
8) Carry out observations everyday between 10 AM (START) 3 PM
(END), to the maximum possible extent.
9) The raw data will be stored in ASCII format in the computer hard
disk. It can be plotted either using MATLAB or MS EXCEL software
or any other graphics routine.
Some of the quantitative results that can be obtained upon analysis of
the data obtained are:
A comparision of the daily fringe amplitude (particularly when
the Sun is 'undisturbed', I.e when there is no solar flare
activity) for a period of time will give information on the
variation in the radio emission from the background solar corona
at 191.4MHz and the appearance/disappearance of discrete
structures in the solar atmosphere like coronal holes, streamers,
etc.
An estimation of the angular separation between the adjacent
fringes give information the baseline separation between the two
antennas. Note that the fringe separation is proportional to d
radians, where 'd' is the baseline separation between the
antennas and '' is the wavelength of observation.
Radio burst emission data obtained during a solar flare/coronal
mass ejection can be analyzed to obtain information on plasma
parameters of the associated region in the solar atmosphere.
Recommended