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Chapter 5
5.3.15 SPLLBW Configure Phase-Lock-Loop Bandwidth
1.
This command can fundamentally change the way that the receiver operates. Do not alter the default
settings unless you are confident that you understand the consequences.
2.
When you change this command, the selected channel loses lock and the locktime for its tracking
satellite is reset to zero.
3.
The PLL is 3rd order.
This command sets the PLL low-pass filter bandwidth for one signal channel.
A time filtered square of the signal carrier phase tracking loop error signal is used to track the performance of
this tracking loop. This value is used as the variance of signal carrier phase measurements. The threshold
specified by this command is compared with the loop variance to determine when the signal tracking lock time
is reset. The resetting of the signal lock time is used to indicate that conditions exist in which a cycle slip might
occur.
The time filtering that is performed on the loop variance determination is controlled using the third argument of
this command. This value is used to compute the first order time constant that provides a noise equivalent
bandwidth for the specified bandwidth. The filtering equation used is:
new value = e
where
ΔT = the PLL sampling rate, and
ω
= 4 × filter constant
Syntax:
SPLLBW PSIGCHAN
Field
Field
Name
1
header
2
psigchan
3
bw
Example:
SPLLBW 0 1.0
68
× (old data) + (1 - e
-ΔTω
BW
Valid Values
This field contains the Abbreviated ASCII command name. See Section 4.1
on Page 34.
The parameters should be applied to
0-31
this signal channel.
PLL low-pass filter bandwidth in Hz.
0.5-15
) × (new data)
-ΔTω
Description
EuroPak-15ab Receiver User Manual Rev 1
Commands
Message ID: 801
Binary
Binary
Format
Bytes
Offset
H
0
Ulong
4
H
Float
4
H+4
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