MSM7712 View Datasheet(PDF) - Oki Electric Industry
Part Name
Description
MFG CO.
'MSM7712' PDF : 20 Pages View PDF
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Modulator radio requirements are:
• 6-bit DAC, clock at 32 MHz (offset binary).
• Anti-alias filtering to extract the 24-MHz alias
(24 MHz IF will be -10 dB on 8 MHz fundamental from DAC output)
• Gaussian filtering, to translate CP-FSK into G-FSK, in accordance with the IEEE 802.11 specification
(SAW filter at 240 MHz IF recommended)
Demodulator
The MSM7712 features a digital baseband demodulator, requiring an external discriminator. The
MSM7712 supports two modes:
• 1Mbit/s 2-ary FSK
• 2 Mbit/s 4-ary FSK.
Both modes require a 1-Mbit preamble of 80 bits of reversals and 16 bits UW for acquisition of carrier and
timing. The modem can then be switched to 2 Mbit/s if following headers require. Features of the
demodulator include:
• Diversity switching control for two antennas.
• RSSI threshold wake-up of demodulator
The demodulator offers three possible interfaces to a limiter/discriminator radio. The supported inter-
faces are:
• Analog data slicer (1Mbit/s only)
• Post discriminator 4-bit ADC (offset binary)
• Post discriminator 1-bit ADC (provisional)
The demodulator’s radio requirements are:
• 1 Mbit: 20 dB S/N from discriminator 10-5 BER (802.11 specifies sensitivity of 10-5 for 80 dBm)
• 2 Mbit: 30 dB S/N from discriminator 10-5 BER (802.11specifies sensitivity of 10-5 for 75 dBm)
• Discriminator linearity of ±5% required for specified 2 Mbit/s operation.
• 4-bit discriminator-to-ADC ranging, to cover approximately ±360 KHz.
• Carrier acquisition for analog slicer option within 4 µs, yielding a duty cycle better than 60:40 for a
square wave (demodulation provides signal for carrier lock switch once preamble detected.
• RSSI threshold decision within 4 µs of antenna switching.
• 3-state ADC output during transmit (bus is shared with TxDAC).
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Oki Semiconductor
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