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yeakharr
05-24-2008, 03:50 AM
က်ေနာ္ အရမ္းသိခ်င္ေနလို႕ပါ..သိတဲ့သူးမ်ား ၀င္ေရာက္ေဆြးေႏြးေပးၾကပါလို႕ေတာင္းဆိုပါရေစ..
က်ေနာ္ လိုခ်င္တာက
က်ေနာ္မွာ တကယ္လို႕ ပိုက္ဆံ အလုံေလာက္ ရွိတယ္ဆိုပါစို႕
GSM station တစ္ခုကို တည္ေထာင္ခ်င္တယ္..
ဒီလိုဆုိ က်ေနာ္ ဘယ္ကြ်မ္းက်င္သူေတြကို ရွာရမလဲ.
ဘယ္လို ပစၥည္းေတြကို ရွိရမလဲ..
ဘယ္လို project ေတြ လုပ္ေဆာင္ရမလဲ..
ေနရာေရြးခ်ယ္ျခင္း။ေစ်းကြက္ ေရြးခ်ယ္ျခင္း
Antena ေထာင္ရမယ့္ အေနအထား
ဘယ္လုိအဖြဲ႕အစည္း နဲ႕ဆက္သြယ္ျပီး လုပ္ငန္းလုပ္ကိုင္ခြင့္လုပ္ျခင္းကအစ
.....
စရွိသျဖင့္
....
သိသေလာက္ေလးေပါ့ ..
နည္းသည္ျဖစ္ေစ မ်ားသည္ျဖစ္ေစ..
ေစာင့္ေမွ်ာ္လ်က္.
ေရခါး..
(အားလုံးအတြက္ ေမးေပးျခင္းျဖစ္သည္။အထူးသျဖင့္ က်ေနာ္ ကိုယ္တုိင္က အရမ္းသိခ်င္လို႕႔ပါ..)

mario
05-26-2008, 03:03 PM
GSM စနစ္နဲ႕ ပတ္သက္လို႕ သိသေလာက္ ၀င္ေဆြးေႏြးပါရေစ။ အင္တင္နာ ေထာင္ရမယ့္ အေနအထား ဆိုတဲ့ ေမးခြန္းအတြက္ပါ။

ဂ်ီအက္စ္အမ္ စနစ္ရဲ႕ အဓိက သေဘာတရားက Frequency Reuse လို႕ေခၚတဲ့ Frequency တစ္ခုတည္းကို ထပ္ျပန္တလဲလဲ အသံုးခ်ျခင္းျဖစ္ပါတယ္။
BTS( Base Transceiver Station) လို႕ေခၚတဲ့ မိုဘိုင္းဖုန္းအတြက္ စင္ကနယ္ေတြ ထုတ္လႊင့္ လက္ခံမယ့္ ေနရာ က အင္တင္နာေတြကို အသံုးျပဳမယ့္သူ အေရအတြက္ ေပၚမူတည္ျပီး ပါ၀ါခ်ိန္ေပးရပါတယ္။ အသံုးျပဳႏိုင္မယ့္ Frequency က အကန္႕အသတ္ရွိတဲ့အတြက္ အကယ္၍ အသံုးျပဳမယ့္သူ မ်ားလာရင္ အဲဒီေဒသတြင္းမွာ ပဲ BTS ေတြ တိုးခ်ဲ႕ျပီး ပါ၀ါကို ေလွ်ာ့ခ်ေပးရပါတယ္။ ဂ်ီအက္စ္အမ္ လက္ကိုင္ဖုန္းေတြမွာ ဘက္ထရီအကန္႕အသတ္ရွိတာေၾကာင့္က တစ္ခ်က္၊ ပါ၀ါအမ်ားၾကီး ထုတ္လႊတ္ရင္ အသံုးျပဳသူေပၚ အႏၱရာယ္ရွိႏိုင္တာ က တစ္ခ်က္ စတာေတြေၾကာင့္ ဂ်ီအက္စ္အမ္ ဖုန္းေတြဟာ အေ၀းၾကီးမွာ ရွိတဲ့ အင္တင္နာေတြက စင္ကနယ္ကို ဖမ္းယူႏိုင္ျခင္းမရွိပါဘူး။ အဲဒါေၾကာင့္ ဂ်ီအက္စ္အမ္ စနစ္တစ္ခု တည္ေဆာက္ဖို႕အတြက္ အင္တင္နာေတြ အမ်ားၾကီး လိုတယ္ ဆိုတဲ့ အေၾကာင္းကိုေတာ့ ေျပာျပပါရေစ။

ေနာက္မွ ဆက္ေဆြးေႏြးပါဦးမယ္။

july79
06-14-2008, 08:33 PM
Hello,
I'm just a new user. I'm so bad in typing in Myanmar font. So, please let me write in English. I'm so interesting in GSM base station. But till now, I don't know it exactly yet.
In order to build the GSM base station is so difficult but if you have so many specialists such as, filter designers, hardware specialists for GSM base station, antenna specialists, and so on,then you can buy the base station.
In general, to build the base station, firstly, you have to choose the region you want to install the base station. In that region, you have to know which kind of things are there. For example, the downtown region, water and forest. If in your region has just buildings, we need to calculate the design for building. If in your region has water or forest, the design calculations for base station are so different. Every design has their exact own design calculations.

In designing the antenna systems for GSM, first we need to know which frequency bands we want to use. Generally, the GSM use 900MHz frequency band or 1800MHz frequency band. But in order to design antenna, we need to know the antenna specifications i e. the VSWR ratio, beam width, beam pattern,Gain, bandwidth, and so on. You may see the different kind of antennas with different specifications in the market. The normal frequency bands we use in normal general GSM are 824MHz to 960MHz for GSM 900, 1710 to 1880 for GSM 1800. The frequencies band we want to use are determined by the antenna specifications of VSWR ratio. The antenna designer have to design the antenna which frequency bands the base station wants to use.

After getting frequencies assigned, we need to design the beam width. The beam width is so important for the base station.
Generally, the beam width are 120 degree, 90 degree, 60 degree, and 45 degree. The antenna designer have to design to get the nearest beam width in order to use 360 degree region. If base station antenna has the beam width of 120 degree, we need to install 3 antennas for 5 or 10 KM region. If the antenna has 90, 4 antennas are needed, if 60 degree, 6 antennas and if 45 degree, 8 antennas are needed.
After getting antenna design for VSWR, Beam width, Gain and other specifications, we need to make array pattern. For base station, we have to design sinc pattern or cosecant square pattern so that all the people who are living in 5 KM region can get enough electromagnetic wave signal. I'm going to show which are cosecant square pattern if you are so interested in GSM BTS antenna.

PS. All the antennas have 2 polarizations, horizontal polarization and vertical polarization. In GSM we need to use Vertical polarization. So, in beam width, we need to design to get vertical polarization.
Sometimes, GSM handset can use horizontally because of the reflected waves which strike the building or other reflected objects.
I'm not the specialist in GSM BTS antennas, so if I make mistakes in my post, then please forgive me.
thank you so much,
july79

kosaw
06-26-2008, 03:40 AM
ကို july79 ခင္ဗ်ား။
ကို july79 ရဲ႕ ေဆြးေႏြးခ်က္မ်ားဟာ စိတ္၀င္စားဖို႕ေကာင္းပါတယ္။ ျမန္မာtyping မျမန္ဘူးဆိုေပမယ့္ ျမန္မာလိုေလး ဘာသာျပန္ေပးရင္ ပိုျပီးေတာ့ ဖတ္ျဖစ္ၾကမယ္ထင္တယ္ဗ်။ ျဖစ္ႏိုင္ရင္ ျမန္မာလိုေလး ေဖာ္ျပေပးပါလားဗ်ာ။
ေလးစားစြာျဖင့္.....

july79
07-07-2008, 05:38 AM
Hello,
if anyone who is interested in how electromagnetic wave travel, then please download that website.
best regards,
July79


http://www.myanmarengineer.org/index.php?ind=downloads&op=download_file&ide=38&file=emanim_setup.rar

ssl
08-06-2008, 02:24 PM
Hello,
if anyone who is interested in how electromagnetic wave travel, then please download that website.
best regards,
July79


http://www.myanmarengineer.org/index.php?ind=downloads&op=download_file&ide=38&file=emanim_setup.rar


yes .. first of all, i wanna say thx so much. I've aldy downloaded it and now i'd like to know how can we use it and which field is mainly used ???

Best Rgds,
ssl ...

july79
08-08-2008, 05:47 AM
Hello ,
So sorry for my late reply. The link I gave is just to see clearly how electromagnetic waves travel. As antenna theory says, antennas have Electric fields (E) and Magnetic fields(H). If Electric force is vertical to Earth's surface, it's vertical polarization. If not, it's horizontal polarization.
So, the antenna designer have to decide which field he will use in his antenna.
In generally, horizontal polarization is use in TV transmissions and FM because horizontally polarized waves have less losses even the antenna is located in dense forest. But horizontal polarization has more losses if the man-made interferences happen, eg, the airplane or car near antennas.
But for GSM and mobile communication systems, especially vertically polarization waves are used because vertical polarization is less effected by the man-made interferences such as car or airplane. But in vertical polarization, dense forest losses effects are more.
Please forgive me if I have mistakes in my letter.
Best regards,
July79

mzarne
10-25-2009, 03:43 AM
ညီေလးေရ
နိဳင္ငံပိုင္စည္းပြားေရးဥပေဒ 1989ကိုသာရွာဖတ္ပါ။ဆက္သြယ္ေရး ဥပေဒဆိုတာလည္းရွိတယ္လို့ေၿပာတာဘဲ။ရွာလို့ေတာ့ တိတိက်က်ကိုမေတြ ့ေသးဘူး 1885 နဲ့ 1934 တုန္းကဆိုလား။
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အင္တာနက္မွာေဖာ္ၿပေနတာက နည္းပညာအတြက္ အညြန္းေတြပါ။ပိုက္ဆံက ရင္းနွီးရတာ အရံွဳးအၿမတ္ မေသၿခာဘူး။
ဒီမွာၾကည့္ၾကည့္ပါ ဗဟုသုတေပါ့-http://www.vintelecom.com/products.asp?bigclassname=voip
ဟာသေလးေပါ့
ဆီအထြက္တိုးဖို့ေနၾကာကိုစိုက္ၾကစို့တဲ့
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