NOVAA Weather satellite WWW Server at UKM
ii. Management Software.
Basically, the UKM ground station is using two management programmes ( Quiktrakİ and Mega NOAAİ ) supplied by Timestep. Quiktrak is a satellite-tracking program, which located the position of the satellite in orbit. The software need to be configured before tracking the satellite with the Keplerian data, longitude, latitude and height above sea level for the city and ground station location ( QTH). Keplerian data contain the information about the satellite that we want the track such as name, satellite ID, inclination, mean motion, eccentricity and etc. they are available form a number of sources including ASR, AMSAT News Bulletins on PBBS, AMSAT Nets and others. NASA supplies tow line compact notation elements as well. The main menu of the program contains several functions and the most important function which are used in this case are as follow.
Schedule - after this selection is made the program proceeds to print out to the screen in tabular form a schedlr of ht passes ( apparitions ) over the location given by the latitude longitude height set of numbers entered in QTH or city information above. Table 1 shows and example of the schedule. The Acquisition of signal ( AOS) EPOCH is the data time of the beginning of the pass of the selected satellite. Loss of Signal ( LOS) EPOCH is the data and time of the end of the pass of he selected satellite. MAX is the time of maximum communications range. AZ is the azimuth of the satellite at the time of the maximum communications range. DX/EL is the elevation of the satellite in degrees at the time of the maximum communication range. The maximum communication range will then occur at either AOS or LOS depending on which is closer to an apogee.
Table 1. satellite for satellite NOAA 14 for ground station 9MUKM form epoch 6th Aug 97 16:11:16 GMT.
| DATE |
AOS
hh:mm:ss |
MAX
hh:mm:ss |
LOS EPOCH
hh:mm:ss |
DX/EL |
AZ |
ORBIT |
| 06AUG97 |
181903 |
182509 |
183115 |
13 |
102 |
13418 |
| 06 AUG97 |
195805 |
200539 |
201313 |
41 |
282 |
14419 |
| 07 AUG97 |
070321 |
071104 |
071847 |
50 |
76 |
13425 |
| 07 AUG97 |
084535 |
085124 |
085713 |
11 |
257 |
13426 |
| 07 AUG97 |
180747 |
181310 |
181832 |
8 |
102 |
13432 |
| 07 AUG97 |
194556 |
195338 |
200120 |
58 |
281 |
13433 |
| 08 AUG97 |
065129 |
065858 |
070628 |
36 |
77 |
13439 |
| 08 AUG97 |
083253 |
083921 |
084550 |
15 |
257 |
13440 |
| 08 AUG97 |
175643 |
180104 |
180526 |
5 |
103 |
13446 |
| 08 AUG97 |
193343 |
194130 |
194916 |
81 |
276 |
13447 |
| 08 AUG97 |
211830 |
212133 |
212436 |
2 |
286 |
13448 |
| 09 AUG97 |
063936 |
164649 |
065401 |
26 |
76 |
13453 |
| 09 AUG97 |
082011 |
082711 |
083410 |
22 |
258 |
13454 |
Real Time 1 Sat - this function is for real-time tracking of the satellite. It has either graphic and text modes of operation. Fig. 2 shows an example of the graphic mode.
Figure 2: Real Time tracking satellite NOAA 14 for ground station 9MUKM from epoch 6th Aug97 16:37:12 GMT
(the satellite position is in indicated by A and the ground station in UKM is indicated by B)
Mega NOAA is a program for all LEOs . it will automatically synchronize to an image and store the complete image. when the image is being received it is displayed in completer but-low resolution format on the screen. This is to allow the whole image for 15 minutes to be shown. It starts to receive the satellite image after the Timestep pro-scan receiver has detected the satellite and indicates with the sound 'tic-tic".
NOAA Image Format [4]
The advanced very High Resolution Radiometer ( AVHRR) provides data for real time transmission to the NOAA local read-out services, termed High Resolution Picture Transmission ( HRPT). The primary objective is to provide visible, near infrared and thermal infrared spectral radiation bands. The AVHRR is a cross-track scanning system similar to the VHRR, but features four or five spectral channels, compared to just two for the VHRR NOAA-12 and NOAA-14 which is currently on orbit has five channels.
The multi-spectral radimeter of the operational NOAA satellite rotates at two revolutions per second or 120 revolutions per minute . One line of composite image data is transmitted with each revolution of the radiometer, so the basic line rate for these satellites is two lines per second. Each second represents 1000 millisecond ( ms ) and the basic line of NOAA data are 500 ms long . each 500 ms line of image data is made up of two different types of image data Infra-red information for the first 250ms and visible-light data for the second 250ms. There are a number of other distinctive elements to each line. The signal portion that represents the actual image is assumed to be an 8 -step grapy scale, running from black at the left to white on the right. Fig. 3. shows the video format for NOAA satellite. Each IR line begins with seven cycles during which the sub-carrier level swings form white to black and black to white. These seven transitions occur at the rat of 832 Hz. The r4ain of pulses appears as a fine seies of vertical black- and white bars in te sync pulse and can be shown on the display. IR line-sync pulse produces very distinctive 'tic-tic ' sound signal when it has reached full quienting in the station receiver. The visible-light segment immediately follows the IR line sequence. It begins with a seven -pulse sync sequence. These pulses occur at a 1040Hz rate and create a sequence of vertical black-and-white stripes down the leaf edge of the image. these stripes appear slightly narrower than their IR equivalent
Figure 3: Video formats for NOAA satellite
