HILNA HF w/ AGC User Manual
Rev ‐
8
4.1.1
AGC SETTINGS
REFVALdddd is used as the reference value for the AGC. The AGC loop compares the current RSSI value
to the stored REFVAL and makes a decision whether or not to adjust attenuation. The rate at which it
adjusts attenuation is based on the ATACKddd and DECAYddd settings. The value of the ATACK / DECAY
settings is approximately 0.5 dB per count. This determines the maximum step size that the AGC loop
can make each iteration. A low ATACK / DECAY value results in longer ATACK / DECAY times, whereas a
larger value results in faster times. The AGC settings are described in Table 8.
Table 9: AGC Settings
Op Code
Parameter
Range
Description
REFVAL
dddd
0000 ‐ 1024
Sets the AGC servo loop value (given in RSSI
A/D counts)
ATACK
ddd
000 ‐ 254
Sets the AGC Attack rate
DECAY
ddd
000 ‐ 254
Sets the AGC Decay rate
Op Code
Parameter
Range
Description
HYSTER
ddd
000 ‐ 254
Sets the AGC Hysteresis
SPEED
d
1 ‐ 7
Sets the Timer Scaling
The SPEEDd command controls the timer scaling. Lower speed values result in the loop running faster,
whereas higher speed values result in the loop running slower. This allows for additional control over
the attack and decay times. Table 9 shows the approximate time for completing one iteration for each
SPEEDd setting.
Table 10: SPEEDd Iteration Times (Approximate)
SPEED
Time (mS)
1
0.61
2
0.60
3
2.22
4
4.44
5
8.85
6
17.70
7
70.90
