Clarion M10 Series Manual de usuario descargar pdf (Pagina 4)

C-SPEC CORPORATION WIRELESS PRODUCTS

FIFO being independently employed and capable of storing a maximum

length ethernet frame of 1518 bytes. Eight buffers are used to hold ethernet

frames received via the wireless medium and eight buffers are used to hold

ethernet frames received from the wired medium. On an Upload when all

eight buffers are used, a collision signal is generated to force the ethernet

card into its exponential back-off algorithm for flow control. If generation of

the collision is not selected via the configuration process, then no collision is

generated and the Upload is ignored. On an Upload, the MerLAN M10

provides the following:

Detection of the preamble of the ethernet frame followed by the frame

sync pattern

Suppression of the ethernet preamble and frame sync for RF

transmission since these portions are meaningless for wireless

transmission

Generation of a collision signal if an upload commences and there is no

buffer available

Forward Error Correction encoding of the data when that option is

enabled through the configuration process

Generation of the header information for the RF MAC and RF physical

layer

Spread spectrum carrier sense before transmission with preference given

to reception

Data and spread spectrum modulation onto a carrier of 2.4 GHz and RF

transmission

A data transfer is called a Download when the MerLAN M10 conveys a

frame from its buffered memory through the MAU port to the ethernet

device. On a Download, the MerLAN M10 provides the following:

Detection of and time alignment to the received radio signal

Demodulation of the physical header and MAC frame

Forward Error Correction decoding when the unit recognizes that the

received frame is FEC encoded by reading the physical header

Checking the 32-bit CRC generated by the ethernet card which uploaded

the frame

conversion of the serial stream to bytes for storing in the buffered

memory FIFO

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Clarion M10 Series Manual de usuario Pagina 4