RS2 Survey Inaccurate Data

Hi guys,

I recently acquired two RS2 units and been testing them out. For test, I set up a base station and rover nearby a NGS survey marker, and took 165 seconds reading on the rover set up on tripod. I went back to RTKlib for post processing. I used a nearby CORS unit ( 14km from my site) as my base station during PPK. The data I obtained from PPK, and the data on the NGS data sheet are 1.2 ft apart, and the difference in ellipsodial height is 2.58 m. Can someone please see what I am doing wrong. I used three different CORS station, but same result. I am worried that I may have gotten a defective unit. Here are the data and observation I used and got.

Using RTK (fix) W 77°18’20.60309", N 38° 50′ 27.74746" , 96.31393091(m)
After PPK - W 77°18’20.55367", N 38° 50′ 27.68867" , 101.3667(m)
Offical NGS data-W 77° 18’ 20".54110, N 38° 50′ 27.69358", 98.782(m)

Please see the google drive link for project files. Any help with this would be highly appreciated.
https://drive.google.com/drive/folders/1UE3PS1GMOSD-QkSB7KhRJuBxfGoLTFKx?usp=sharing

Simple system report
app version: 2.22.5-r0
'wifi_status, interface: wlan0':
- wifi_mode: infrastructure
- ip: 192.168.1.137
  is_added: true
  is_connected: true
  is_visible: false
  mac_address: C0:84:7D:39:C2:21
  security: wpa-psk
  ssid: GEWifi
  uuid: 9ef736d7-5c82-4c2e-bd49-b265d41425c2
base mode:
  base coordinates:
    accumulation: '2'
    antenna offset:
      east: '0'
      north: '0'
      up: '0'
    coordinates:
    - 0
    - 0
    - 0
    format: llh
    mode: single-and-hold
  output:
    enabled: false
    format: rtcm3
    path: tcpsvr://:9000#rtcm3
    type: tcpsvr
  rtcm3 messages:
    '1006':
      enabled: true
      frequency: '0.1'
    '1074':
      enabled: true
      frequency: '1'
    '1084':
      enabled: true
      frequency: '1'
    '1094':
      enabled: false
      frequency: '1'
    '1124':
      enabled: false
      frequency: '1'
bluetooth:
  discoverable: true
  enabled: true
  pin: '***'
constraints:
  lora:
    frequency:
    - - 902000
      - 928000
correction input:
  input2:
    enabled: true
    format: rtcm3
    path: lora
    send position to base: 'off'
    type: lora
  input3:
    enabled: false
    format: RTCM3
    io_type: tcpsvr
    path: :9028
device: null
logging:
  base:
    format: RINEX
    started: false
    version: '3.03'
  correction:
    format: RTCM3
    started: true
  debug: false
  interval: 24
  overwrite: true
  raw:
    format: RINEX
    started: false
    version: '3.03'
  solution:
    format: LLH
    started: false
lora:
  air rate: 18.23
  frequency: 915000
  mode: read
  output power: 20
position output:
  output1:
    enabled: false
    format: nmea
    path: bluetooth
    type: bluetooth
  output2:
    enabled: false
    format: llh
    path: :9001
    type: tcpsvr
rtk settings:
  elevation mask angle: 15
  glonass ar mode: 'off'
  gps ar mode: fix-and-hold
  max horizontal acceleration: 1
  max vertical acceleration: 1
  positioning mode: kinematic
  positioning systems:
    compass: true
    galileo: true
    glonass: true
    gps: true
    qzss: true
  snr mask: 35
  update rate: 1
sound: null



Hi Ashim,

Sorry for the delayed answer.

I’ve looked through your data. I can see that 92% of the solution is in Float status in PPK. For now, it’s difficult to tell what causes these results.

It’d be essential for me to check the following data:

  • the photos of the setup
  • the position log

This information would help me to check the placement of the units, understand if there were any issues in RTK and what the solution status was during the survey.

Hi Luidmila,

Thank you for you reply. I realized most my values were in float but during ppk , I will averaged the values from fix positions only to get my postion. Attached is the position log, but unfortunately I do not have any photos of my setup, but I have attached a picture from google maps that would show approximate location of my rover and base.

ROVER_solution_202007172103_LLH.zip (4.6 KB) BASE_solution_202007172056_LLH.zip (12.8 KB)

Hi Ashim,

Could you please specify how the base was placed for RTK? Have you used averaged single approach or the corrections from the CORS station?

On the 3d screenshot from RTKPost, I can see that you used RINEX Header Position in the Base Station settings. To get the absolute centimeter-level accuracy, you need to input the actual position of your CORS station. This information should be easily found, for example, on the CORS network website. Please, share the base position with me as well so that I could post-process your files too.