Customer Service Center
Spirent KB Article
Doc ID: FAQ11936
Email Article Link
GSS6400, GSS6425: Why does my receiver reject the recorded signal during playback?
Normally the carrier phase of a GNSS signal is derived from the transmitting satellite's highly stable atomic clock.
This wave comes to the Earth and is picked up by a receiver with a relatively low grade TCXO.
The receiver however knows this and has a model built in that allows the carrier phase to be recovered.
With the GSS64xx product the carrier phase is recorded using a TXCO but is then played back using an OCXO
This helps minimise any further degradation in carrier phase reproduction
However the receiver connected to the GSS64xx output will still be using its TCXO (and model) to recover the carrier phase.
If the receiver filter used to 'analyse' the carrier phase is set very tightly then it is possible that the receiver perceives the carrier phase measurements to be too 'degraded' / outside 'expected' ranges
Possibly as a result of the two TCXO’s involved in recording the signal and then receiving the recorded signal?
The receiver therefore rejects the carrier phase observations at most of the epochs and this can potentially lead to signal dropouts.
If the receiver rejects one signal type more than another it may be due to different filtering 'rules' / 'techniques' being applied to the different signals
For example, the receiver may be more stringent with the GPS carrier phase measurements than for the GLONASS measurements?
Contact the receiver manufacturer to determine if it is possible to change the filter setting or reduce / disable ‘carrier smoothing’.
Product : General Navigation,GNSS,GSS6400,GSS6425