How to properly measure Sigfox signal strength with the CheckFox?
In measuring the Sigfox coverage you try mostly to measure several things:
- Does the predicted coverage match the actual coverage ?
- Will a reference device work at the installation spot ?
- What is the attenuation between reference measurement and final destination ?
- What is the reliability of the reception over time ?
- Does my HW device work as well as a reference device ?
Please always use a reference device. Completely unusable are any development kits.
Black Box emits at 16dB(ETSI) so it gives little bit skewed results, Sensit 2.0 and CheckFox are fine.
Also please keep in mind that Sigfox is susceptible to fading in motion. Do all the measurements while stationery. If you want to do measuring while driving, take the fading and the position of base stations in relation to the vector and speed of movement into account while evaluating it.
We developed the following methodology and checklist that you can print out and use as guidelines.
Aim of the measurement:
- A Coverage
- B Final place coverage
- C Attenuation
- D Reliability in time
- E Own HW performance
Name of the person and his qualification:
ID of the reference device used:
Date: Time: Place:
Photos stored at:
Any remarks: (extreme weather etc.):
- Ensure that you are using reference device
- Check the antenna not being loose and using a proper antenna
- Check the device voltage
- Take a photo of the device
- Decide what you want to measure and how you will evaluate the results
- Place the device 1.3 m above ground under open sky at least 1m from any obstacle
- Hold it with vertical antenna and don't move. Ideally place the device on a tripod but car or holding it in hand should be fine.
- Take a photo of the device
- Take a photo of the environment
- Ensure you have a GPS fix
- Select Outdoor at 1.3 meter (4.3feet) Reference - REF in Main menu
- Select how many Messages you want to send
- Ideally repeat the measurement three times shifting the device in a triangle by 8-9cm (lambda/4),
- Check in the Dashboard that the predicted coverage matches roughly the measured coverage. In case the predicted coverage is much worse, please contact immediately the local Sigfox operator, provide him with photos and GPS position
- Assess the results of the A aim.
Final installation place measurement
- Do Reference measurement
- Do Between the steps measurements (Indoor for indoor installations, Outdoor Ground Level for Underground (parking sensors) installations. Always take a photo.
- Select your final location
- Take a photo of the device and the environment
- Select location in Menu and select FInal destination measurement or Final with delay in case the final destination is behind closed doors or the device needs to be lowered on a string. The measurement starts in 30 seconds.
- Assess the results of the B Final place coverage aim.
- In the Dashboard compare to Reference measurement and asses the C Attenuation. Subtract the SNR
- Make a time series measurement at the Final destination with either 10 min intervals or hourly intervals
- Assess the D Reliability in time by accessing the message lost
Own HW performance
- Do the Final installation place measurement with the reference device
- Take a photo of your Own HW in Final destination
- Do the Final installation measurement with the final device
- Assess the E Final HW performance. Look especially at message loss and how many repetitions of the device you see. If you see only 1 repetition in most cases the battery design is bad, and battery doesn't have enough power to emit second and third. Or the device antenna is detuned and does not perform properly.
- Does the actual coverage match the predicted one ? same-better-worse
- Does the reference device work in the Final installation ? yes-no-little bit
- What is the attenuation of the Final installation in comparison with Reference measurement ? give number between 0 and 70
- How is the long term reliability of messages ? excellent-good-bad
- How my HW performs ? in comparison with reference: better-same-worse-far worse