Jackson Labs Micro-JLT GNSS, Руководство пользователя

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Micro-JLT GNSS™ User Manual
Setting the FASTLOCK gain to 2 for example will result in the Proportional gain value stored in the
SERVo:EFCscale parameter to be multiplied by 2x initially after power on.
This dynamic gain is slowly reduced until the gain is back to 1.0x, the value stored in the
SERVo:EFCScale parameter.
For example:
if we set SERVo:FASTlock to 2, and SERVo:FALEngth to 3600, and SERVo:EFCScale is set to 0.7
Then initially the unit will multiply the EFCscale by 2x, and an effective EFCscale value of 1.4 is
applied to the PLL loop.
This increased gain value difference will be reduced every second by 1/3600, so that the gain after
two seconds would be: 1.3998, until after 3600 seconds the gain has been reduced back to its long
term value of 0.70 as stored in the SERVo:EFCscale parameter.
Disabling the FASTLOCK mode is accomplished by setting the SERVo:FASTlock to 1. This will set
the dynamic gain to 1.0, effectively disabling the fastlock feature.
This command has the following format:
SERVo:FASTlock <int> [1,20]
This command will query the state of this command:
SERVo:FASTlock?
3.10.2 SERVo:FALEngth <int> [100,20000]
This command adjusts the length of time during which the FASTLOCK feature is active, please see
the command SERVo:FASTlock above.
The length can be set from 100 seconds to 20000 seconds. The Dynamic FASTLOCK gain is slowly
reduced until it reaches a gain of 1.0 after the FALEngth period of seconds. During this time the PLL
loop gain is increased by the amount specified in the SERVo:FASTlock parameter, which will result
in a faster initial phase lock to UTC after power-on, while giving the lowest possible noise floor (best
short term stability) during normal operation.
This command has the following format:
SERVo:FALEngth <int> [100,20000]
This command will query the state of this command:
SERVo:FALEngth?
3.10.3 SERVo:COARSedac <int> [0,255]
This command sets the coarse DAC that controls the EFC. The Micro-JLT GNSS™ control loop
automatically adjusts this setting. The user should not have to change this value, however it is very
useful to measure loop stability when experimenting with alternate SERVO parameters by inserting
a large frequency step into the OCXO, then monitoring the behavior of the PI loop as it corrects for
the synthetic frequency error.
This command has the following format:
SERVo:COARSedac <int> [0,255]
This command will query the state of this command: