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Feature and Application :
¡@¡@RF (Radio Frequency) technology is utilized more and more widely on account of its superior performance. There are increasing numbers of RF appliances and users, while the RF Bands (Frequencies) are limited. Consequently the problem of frequency interference is getting progressively more rigorous.With solid knowledge and experience in RF wireless communication, and in the computer industry, we adopted the following solutions for the RF wireless mouse and keyboard, in order to ensure the best performance.

27 MHz ISM Band
 
¡@¡@The 27 MHz is a universally unlicensed ISM (Industrial, Scientific, Medical) Band. The wireless mouse/keyboard in this band can be used all over the world - hence, it minimizes manufacturing or marketing obstacles such as material replenishment, production, and inventory. Furthermore, the wireless mouse/keyboard of the 27 MHz band can avoid irritating interferences by wireless appliances of popular local ISM bands (such as the 900 MHz, 433 MHz, 315 MHz, etc.). These bands are widely applied to many appliances, some of which possess high- output power.
Multi-Channel
 

¡@¡@Multi-Channel solution enables simultaneous usage by multiple users in the same area. Furthermore, it provides additional channels for users to choose from, in the case of interference from other telecommunication signals.

 
FSK Modulation
 
¡@¡@Advanced FSK Modulation Scheme, IF (Intermediate Frequency) Process, and Synthesizer Technology are used to cut the limited bandwidth into 12 optional channels. Anti-interference performance is outstanding, whether the noise is from adjacent channels or from externals.
Multi-Security Code
 
¡@¡@Adopting the concept of RF channel Auto-scanning, up to 4096 digital ID codes are added to avoid interference between the same channels. Meanwhile, Self Detect and Update Decoding SDUD is adopted to minimize transmission error (BER).
2.4 GHz ISM Band
 

¡@¡@The 2.4GHz is a universally unlicensed ISM (Industrial, Scientific, Medical) Band. The wireless product in this band can be used all over the world - hence, it minimizes manufacturing or marketing obstacles such as material replenishment, production, and inventory. It also has enough bandwidth to have a high data rate communication.
Furthermore, the wireless product of the 2.4GHz band can avoid irritating interferences by wireless appliances of popular local ISM bands (such as the 900 MHz, 433 MHz, 315 MHz, etc.). These bands are widely applied to many appliances, some of which possess high-output power.
DSSS and FHSS
 

¡@¡@DSSS (Direct Sequence Spread Spectrum) and FHSS (Frequency Hoping Spread Spectrum) increased the data accuracy and redundancy. DSSS and FHSS improve the data loss and interference problem.
About DSSS
 
¡@¡@DSSS is a technic for bandwidth spreading by direct modulation of a data modulated carrier by a wide band spreading signal or code. This data modulated signal is to modulate the signal a second time using a very wideband spreading signal. This second modulation is usually some form of digital phase modulation, although analog amplitude or phase modulation is conceptually possible. The spreading signal is chosen to have properties which facilitate demodulation of the transmitted signal by the intended receiver, and which make demodulation by an unintended receiver as difficult as possible. These same properties will also make it possible for the intended receiver to discriminate between the communication signal and jamming. If the bandwidth the spreading signal is large relative to the data bandwidth, the spread-spectrum transmission bandwidth is dominated by the spreading signal and is nearly independent of the data signal. Actually, bit 0 will represent by an orthogonal code of several
number of chip (PN pseudo random code). Bit 1 will represent by an orthogonal code of several number of chip of it's complement. We will modulate this number of chips to the transmitter. We called it spreading the data. After received by the receiver. Receiver will de-spread this chip into data. It recovers the modulated signal to number of bits. It also rejects the jamming signal finally.
Data spectral of non-spreading before modulate
Data spectral of spreading after modulate
After dispreading the data
After IF matching filter power transfer function

Output of IF filter
Generally application : WLAN

About FHSS
FHSS is a technic for widening the spectrum of data modulated carrier is to change the frequency of the carrier periodically. Typically, each carrier frequency is chosen from a set of frequencies which are spaced approximately the width of the data modulation bandwidth apart. The spreading code in this case does not directly modulate the data modulated carrier but is instead used to control the sequence of carrier frequencies.Because the transmitted signal appears as a data modulated carrier which is hopping from one frequency to the next, this type of spread spectrum is called frequency-hop spread spectrum. In the receiver, the frequency hopping is removed by mixing with a local oscillator signal which is hopping synchronously with the received signal.
hopping data with spread

recover data of hopping
Generally application : Bluetooth

CSMA-CA

CSMA-CA (Carrier Sense Multiple Access- Collision Avoided) is a protocol to let multi-user can work with the same channel simultaneous. It will increase number of user. Anti-interference performance is outstanding, whether the noise is from adjacent channels or from externals.