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Micro-JLT GNSS™ User Manual
48 © 2019 Jackson Labs Technologies, Inc.
3.9.7 SYSTem:ISP
This command causes the Micro-JLT GNSS™ processor to reset into In System Programming (ISP)
mode for firmware upgrades. Please see
Chapter 4 for details on updating the firmware in ISP mode.
Initiating this command is equivalent to pulling the ISP# pin 1 on J1 or pin 1 on J4 low during
power-on. Both LEDs on D2 should dim indicating the unit is properly placed into ISP mode.
Once the system is placed into ISP mode it will need to be power-cycled or an ISP-Reset command
will need to be sent through the NXP ISP programming interface commands to establish a normal
operating mode.
3.10 SERVO Subsystem
This subsystem regroups all the commands related to the adjustment of the servo loop:
SERVo?
SERVo:DACGain
SERVo:EFCScale <float> [0.0,500.0]
SERVo:EFCDamping <int> [2,4000]
SERVo:SLOPe <NEG|POS>
SERVo:TEMPCOmpensation
SERVo:AGINGcompensation <float> [-10.0,10.0]
SERVo:PHASECOrrection <float> [-500.0,500.0]
SERVo:COARSedac <int> [0,255]
SERVo:1PPSoffset <int> <ns> [-5000000,5000000]
SERVo:TRACe <int> [0,255]
SERVo:FASTlock <int> [1,20]
SERVo:FALEngth <int> [100,20000]
3.10.1 SERVo:FASTlock <int> [1,20]
The FASTlock command enables the FASTLOCK mode, and sets its gain parameter. Fastlock works
by momentarily multiplying the EFCScale gain to a value determined by this SERVo:FASTlock
parameter. Gain values of 1x to 20x can be set, with a gain of 1x effectively disabling the
FASTLOCK feature.
By selecting gain values of > 1, the PLL loop parameter Proportional gain (SERV:EFCscale) will be
increased after power on, thus increasing loop aggressiveness and improving lock PLL time. It is not
desirable to maintain a high loop gain for longer than necessary to lock the PLL since high loop gains
come at the expense of increased phase noise (reduced short term stability). The FASTLOCK
mechanism will automatically reduce the FASTLOCK gain over a period of time specified by the
SERVo:FALEngth command, during which time the FASTLOCK gain is slowly decreased from its
initial value to 1.0x.