Bluetooth is a high speed, low powered wireless linktechnology that’s designed to connect phones or otherportable equipment together with little to no workrequired by the user. Unlike infrared, Bluetooth doesn’t require line of site positioning to work.Current prototype circuits are contained on a board that is 0.9 cm square, with a much smaller circuit board being developed.When one Bluetooth device comes in contact with another, they will automatically exchange addresse and details of capability. Then, they can establish a 1 MB link with security that they will use asrequired. The protocols involved with handle both data and voice, with a very flexible topography.The technology achieves its goal by embedding tiny,non expensive short range tranceivers into the devices available today. The radio operates on the 2.45 GHz frequency band, and supports up to 72 KBps, along with three voice channels.Each devices offers a unique 48 bit address from the IEEE 802 standard, with the connections being point to point or multipoint. The max range is 10 meters, although it can be extended to 100 meters by increasing the power. The devices are also protected from radio interference by changing their frequencies, also known as frequency hopping.What’s important, is the fact that Bluetooth devices won’t drain battery life. The specificationtargets power consumption of the device, limiting the drain on the battery. The radio chip willconsume only 0.3mA in stand by mode, which is less than 5% of the power that standard phones use.Bluetooth will also guarantee security at the bit level. The authentification is controlled by the user via a 128 bit key. The radio signals can be coded with anything up to 128 bit. With the frequency hopping, Bluetooth is already very hard to listen into.The baseband protocol is a combination of both
circuit and packet switches. Slots can be reserved for synchronous packets as well. Each packet will be transmitted in a different hop frequency.
Normally, a packet covers a single slot although it can be extended to cover up to five slots Bluetooth can also support data channels of up to
three simultaneous voice channels. Therefore,it’s possible to transfer the data while you talk at the same time. Each individual voice channel
will support 64 KB.From a technical standpoint, Bluetooth is very different indeed. It’s the best wireless method in the world, surpassing even infrared. For communication on the go, Bluetooth is indeed very hard to compete with.
वैज्ञानिकों को इंडोनेशियाई वर्षावन के अंदरूनी हिस्सों में एक ऐसा मेंढक मिला है जो अंडे देने के बजाय सीधे बच्चे को जन्म देता है. एशिया में मेंढकों की एक खास प्रजाति 'लिम्नोनेक्टेस लार्वीपार्टस' की खोज कुछ दशक पहले इंडोनेशियाई रिसर्चर जोको इस्कांदर ने की थी. वैज्ञानिकों को लगता था कि यह मेंढक अंडों की जगह सीधे टैडपोल पैदा कर सकता है, लेकिन किसी ने भी इनमें प्रजनन की प्रक्रिया को देखा नहीं था. पहली बार रिसर्चरों को एक ऐसा मेंढक मिला है जिसमें मादा ने अंडे नहीं बल्कि सीधे टैडपोल को जन्म दिया. मेंढक के जीवन चक्र में सबसे पहले अंडों के निषेचित होने के बाद उससे टैडपोल निकलते हैं जो कि एक पूर्ण विकसित मेंढक बनने तक की प्रक्रिया में पहली अवस्था है. टैडपोल का शरीर अर्धविकसित दिखाई देता है. इसके सबूत तब मिले जब बर्कले की कैलिफोर्निया यूनीवर्सिटी के रिसर्चर जिम मैकग्वायर इंडोनेशिया के सुलावेसी द्वीप के वर्षावन में मेंढकों के प्रजनन संबंधी व्यवहार पर रिसर्च कर रहे थे. इसी दौरान उन्हें यह खास मेंढक मिला जिसे पहले वह नर समझ रहे थे. गौर से देखने पर पता चला कि वह एक मादा मेंढक है, जिसके...
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