Filter
Top Products
Chapter 3 Visual User Interface
Receiver Status Screen Data
Operating and Programming Guide 3-13
When the manually initiated message follows the Holdover label, the
Receiver has been placed in holdover by the user. An explicit command
is required to initiate an exit from manual holdover.
When the 1 PPS TI exceeds hold threshold message follows the
Holdover label, the phase difference between the 1 PPS time output
signal and the internal GPS 1 PPS reference signal has exceeded the
user-entered holdover threshold value.
When the internal hardware problem message follows the Holdover
label, a measurement hardware error exists.
The Holdover Duration message indicates the duration that the Receiver
has been operating in holdover (and recovery). Thus, this message
gives you an assessment of the quality of the outputs. The longer the
Receiver is in holdover the more degraded the outputs become.
Power-up indicates that the Receiver hasn’t yet achieved GPS lock or
acquired satellites since it has been powered up. The Receiver is
measuring the internal reference oscillator’s frequency and adjusting it
to 10 MHz during this power-up period. Other queries can provide
insight as to the cause if the Receiver is remaining in powerup longer
than expected.
Reference Outputs
TFOM (Time Figure of Merit) indicates the accuracy of the Receiver’s
internal 1 PPS signal. A low TFOM value indicates a more accurate
signal. In the sample screen of Figure 3-6, a value of 3 is displayed,
meaning that the Time Error ranges from 100 to 1000 nanoseconds.
The following table lists the TFOM values that could be displayed and
the corresponding Time Error.
*
The TFOM values 0, 1, and 2 are not presently used in the Receiver. The Receiver will display
TFOM values ranging from 9 to 3, which is consistent with the specified accuracies of each product.
TFOM Value
Time Error
(in nanoseconds)
TFOM Value
Time Error
(in nanoseconds)
*0 less than 1 5 10
4
– 10
5
*1 1 – 10 6 10
5
– 10
6
*2 10 – 100 7 10
6
– 10
7
3 100 – 1000 8 10
7
– 10
8
4 10
3
– 10
4
9 greater than 10
8