User's Manual

RTL8187L
Datasheet
Wireless LAN Network Interface Controller 27 Track ID JATR-1076-21 Rev. 1.2
Offset# Bit# Symbol Description
4 7:0 SQ Signal Quality.
The SQ is a measure of the quality of BAKER code lock, providing an effective
measure during the full reception of a PLCP preamble and header.
8 31:0 TSFTL A snapshot of the TSFTR’s least significant 32 bits.
12 31:0 TSFTH A snapshot of the TSFTR’s most significant 32 bits.
11.2. Loopback Operation
Loopback mode is normally used to verify that the logic operations have performed correctly. In loopback
mode, the RTL8187L takes frames from the transmit descriptor and transmits them up to internal Rx logic.
The loopback function does not apply to an external PHYceiver.
11.3. Tx Encapsulation (With RTL8187L Internal Baseband
Processor)
While operating in Tx mode, the RTL8187L encapsulates the frames that it transmits according to the
Differential Binary Phase Shift Keying (DBPSK) for 1Mbps, Differential Quaternary Phase Shift Keying
(DQPSK) for 2Mbps, and Complementary Code Keying (CCK) for 5.5Mbps and 11Mbps modulators. The
changes to the original packet data are as follows:
1. The PLCP preamble is always transmitted as the DBPSK waveform and used by the receiver to achieve
initial PN synchronization.
2. The PLCP header can be configured to be either DBPSK or DQPSK and includes the necessary data
fields of the communications protocol to establish the physical layer link.
3. The MAC frame can be configured for DBPSK, DQPSK, or CCK.
11.4. Rx Decapsulation (With RTL8187L Internal Baseband
Processor)
The RTL8187L continuously monitors the network when reception is enabled. When activity is recognized
it starts to process the incoming data. After detecting receive activity on the channel, the RTL8187L starts
to process the PLCP preamble and header based on the mode of operation.
The RTL8187L checks CRC16 and CRC32, then reports if CRC16 or CRC32 has errors. When using the
40-bit WEP and 104-bit WEP module for decryption, the RTL8187L also checks the Integrity Check Value
(ICV) and reports if the ICV has errors.