Single Channel GPS Source

Single Channel GPS Source

Last updated: September 2, 2009

This section is only applicable to the lab applications and the test application with a required feature license.

Description

The Single Channel GPS Source function allows you to generate GPS signals to calibrate the GPS receiver of the mobile.

GPS system employs 37 satellites in orbit to provide positioning services. Satellite GPS signal has 3 components: L1 (1575.42MHz) / L2 (1227.60MHz) carrier signals, ranging codes and navigation message. Two kinds of ranging codes are defined: coarse/acquisition (C/A) code for normal positioning and precision (P) code for finer positioning purpose. The L1 is used to carry the C/A code with 1.023Mcps spreading rate, while L2 is usually used to carry the P code with 10.23Mcps spreading rate. For each satellite, a unique Space Vehicle Identifier (SV-ID) is assigned and will be used to determine the phase of spreading code for this specific satellite. The navigation messages usually contain positioning parameters.

Normally P code and L2 are only designed for military use, so the test set only simulates single satellite signal containing C/A code carried by L1 with default navigation messages, and pseudo random sequence data for the calibration of GPS receivers.

   
NOTE
The GPS feature is only available in the CW operating mode.

   

GPS Info

The following diagram shows the GPS parameter information.

  • GPS RF Generator Frequency:

    Since the test set only simulates single satellite signal containing C/A code carried by L1, the frequency is fixed at 1575.42MHz. It's a non-configurable parameter.

  • GPS Power:

    This parameter defines the cell power of GPS signal. The power range of GPS signal is -125dBm to -70dBm.

       
    NOTE
    The power range that you can set on the test set is affected when there is an Amplitude Offset.

       

  • GPS Satellite ID (SV ID):

    This setting defines which satellite is generating the GPS signal.

  • GPS Navigation Message Type:

    This setting defines the actual navigation message that will be transmitted on GPS frame. If Default Navigation is selected, the GPS frames is filled with the default navigation message defined in the GPS standard. If Raw is selected, the GPS frames is filled with PN sequence.

  • GPS Raw Payload Pattern:

    This setting defines the data type that will be transmitted on GPS frames when Raw data payload is selected. You can select PN9 or PN15.

  • GPS Baseband Filter Type:

    This setting defines the filter that will be used to filter the GPS baseband signal when the GPS signal is generated. A Gaussian or Rectangle filter with 10 MHz bandwidth is supported in this feature.

GPS Parameters

The following table lists all the configurable GPS parameters.

Parameter

GPIB Command

RF Gen Configure

CALL[:CELL]:RFGenerator:CONFigure

GPS Power

CALL[:CELL]:RFGenerator:GPS:POWer:AMPLitude

GPS Power State

CALL[:CELL]:RFGenerator:GPS:POWer:STATe

GPS Power & State

CALL[:CELL]:RFGenerator:GPS:POWer[:SAMPLitude]

GPS Satellite ID (SV ID)

CALL[:CELL]:RFGenerator:GPS:SVID

GPS Navigation Message Type

CALL[:CELL]:RFGenerator:GPS:NMESsage

GPS Raw Payload Pattern

CALL[:CELL]:RFGenerator:GPS:RAW:PPATtern

GPS Baseband Filter Type

CALL[:CELL]:RFGenerator:GPS:BFILter

GPS RF Generator Frequency

CALL[:CELL]:RFGenerator:GPS:FREQuency

GPS RF Generator Frequency 2

CALL[:CELL]:RFGenerator:GPS:FREQuency2

How Do I Set up the GPS Feature?

The following procedure details how to access the GPS feature.

  1. Press the CALL SETUP key.
  2. Press Operating Mode ( F1 ) and select CW .
  3. Press RF Gen Configure ( F10 ) from the Control Parms menu, then select GPS menu.
  4. Press GPS Parameters ( F9 ), Use the knob to highlight the parameter and change the value.

Related Topics


CW