rfw102 ETC-unknow, rfw102 Datasheet - Page 10

• Manufacturer Part Number: rfw102
• Description: Rfw102 Transceiver Chipset Shortrang
• Manufacturer: ETC-unknow

Datasheet
October 2002
Rev. 1.03
Auto Correlation and Interference Handling
The SAW correlator functions as a matched filter building up a peak of energy when it correlates with its own
impulse response. This peak is a clear mark stating the correlator has detected its own correlation function.
Numbers and Figures:
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•
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Frequency Generation
The frequency generation circuit is a general-purpose element in the system. It is the only part of the system
that is active in transmit and receive modes, and is off in standby mode for energy saving reasons. Its
functions are to provide:
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The circuit consists of a SAW-resonator based oscillator (RFW488R), whose frequency is multiplied by 4 to
achieve the desired up-conversion frequency. The most important feature of this circuit is the fast wakeup
time (<35µs from standby to stability).
© 2002, RFWaves LTD.
The Insertion Loss of the SAW correlator is 19dB @ 488MHz, when fully tuned. Since it is a relatively
wide-band element (>30MHz over a central frequency of 488MHz gives Q≈14), tuning it is an easy task
– with a lot of tolerance to passives values.
Energy Preservation: When a 76ns shaped pulse interrogates the SAW correlator (40ns effective
pulse length) it produces a 750ns-spread sequence (see Figures above). Therefore, there is a loss of
additional 10*log (750/40)≈13dB.
The Equivalent Noise Bandwidth of the SAW correlator is approximately 20MHz.
A basic clock for the state machine
A source for the generation of an interrogating pulse to the SAW correlator
A source for the front end up/down conversion circuitry
-0.01
-0.02
-0.03
-0.04
-0.05
0.05
0.04
0.03
0.02
0.01
0
0
Figure 6: Spectral Density - Measured
Figure 7: Autocorrelation
0.5
Autocorrelation
Time [µs]
1
1.5
RFW102 ISM Transceiver Chipset
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