Hi Paul,

Following-up on our conversation regarding best practices for changing the raw data logging rates, I wanted to share a couple of quick results from a logging test today.

Test setup:

• MicroMod Data Logging Carrier Board
• MicroMod Artemis Processor
• SparkFun GPS-RTK-SMA Breakout - ZED-F9P
• 6600 mAh LiPo
• GNSS Multi-Band L1/L2 Surveying Antenna (TNC) - TOP106

Configuration:

• Both systems are identically configured except for how the logging rates are set.
• The code is custom but has the DataLoggingExample4 from the u-blox library at its core.
• Both tests were conducted at the exact same time and were run for 1 hour.
• Results screenshots below are taken from Emlid's new and very handy tool "Emlid Studio" for processing .ubx data, which runs RTKLIB under the hood.

Test 1:

• Measurement and navigations rates set to one second

Code:

gnss.setNavigationFrequency(1);

Results:

• Very typical output for my location.
• Several uninterrupted connections to GPS and GLONASS satellites.
• Many L2 only signals.

Test 2:

• Measurement rate set to 1000 ms and navigation rate (ratio) set to 15.

Code:

gnss.setMeasurementRate(1000);  // Set the measurement rate to 1 second (1000 milliseconds)
gnss.setNavigationRate(15); // Set the navigation rate (ratio) to 15 to produce a solution every 15 s

Results:

• It's immediately clear that something is up.
• It appears that in many cases it was not possible for the receiver to achieve an L2 lock.
• Many of the L2 only signals are also missing.
  

Discussion

• It's appears that L2 performance is severely degraded when increasing the navigation rate to 15.
• I have tried difference combinations of receivers, processors and antennas to ensure that this isn't a hardware issue.
• I'm currently waiting on the NRCan PPP outputs from the above two RINEX files. I'm very curious to see what the results will be.

I'll update this issue later on!

Cheers,
Adam