AMIS-53050 Datasheet, PDF (71/107 Pages) AMI SEMICONDUCTOR – Frequency Agile Transceiver

AMIS-53050 Frequency Agile Transceiver
Data Sheet
Automatic Threshold Optimization in Sniff Mode
An option available in the sniff mode config register will enable the AMIS-53050 to automatically adjust the energy threshold of the
AMIS-53050 to optimize the sensitivity of the sniff mode. The target number of wake-ups (register 0X2F) allows the user to specify a
value for the number of false wake-ups the AMIS-53050 is allowed with the selected configuration of the sniff mode (by bits [4:3] in the
SNIFF_CONFIG register) number of sniff cycles.
As an example:
If the number of sniff cycles is set to 500 (sniff config [Bit 4:3]),
If the target number of false wake-ups is set to 50 (target number wake-ups),
Then over the course of the next 500 sniff cycles the radio is triggered falsely by energy:
More than 50 times, the threshold will be increased to reduce the sensitivity,
Less than 50 times, the threshold will be decreased to increase the sensitivity.
Using this option to set the threshold for energy detection can have a dramatic impact on the life of battery powered devices. The AMIS-
53050 will adjust to changing levels of background noise while still maintaining maximum sensitivity and will not waste power by
continually waking and processing background noise.
Additionally, the energy threshold setting can be monitored by an external host controller. The amount the threshold will increase or
decrease is based on Table 57, with the order of the rows in the same order as the AMIS-53050 will evaluate the conditions.
Table 57: Auto Threshold Adjust
Condition
Select the number of sniff cycles as the test period
Enter the desired number of false wake ups per
period
Then if wake ups/period > target
Then if wake ups/period < target
Adjustment
Note: a false wake up is when the receiver detects energy but fails to detect the ID in the
packet
Threshold is increased
Threshold is decreased
The threshold of the AMIS-53050 can vary over a wide range from one device to the next, due to design, manufacturing tolerances, and
environment changes; such as temperature and voltage. This automatic threshold optimization can be used to adjust the threshold by
monitoring the level of false wake ups due to background noise. The adjustment in this fashion can reduce the effects of design and
manufacturing on the threshold setting of the AMIS-53050.
Register descriptions:
Target- Set a value for the allowed number of false wake-ups desired.
Target Threshold
The number of false wake ups occurring during a period of time is used to automatically adjust the energy threshold in the sniff
operation. This allows the AMIS-53050 to automatically adjust its input level to compensate for, manufacturing, components,
environment, temperature and/or voltage.
Table 58: Target Wake Ups - 0X2F [47]
Bit Name
Comment
7:0 _{Target [7:0]}
The number of wake-ups that the sniff circuit will try to adjust the threshold to not have
more false wake-ups or less missed signal detections. This register allows the number to
be 0 to 255, but this number should always be less than the number of sniff count (sniff
config bit 4:3).
AMI Semiconductor – Jan. 07, M-20639-002
71
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