Cost-Efficient Multi-GNSS Station with Real-Time Transmission for Geodynamics Applications

Round 1

Reviewer 1 Report

Dear authors,

My conflicts of interest are:

(1) I am currently installing low-cost tectonic GNSS stations in Greece (using GFZ's MCGS and MaRam's tinyBlack instruments).

(2)  I have recently submitted an EU-RIA proposal on the topic of low-cost GNSS station densification (including development of open source software/firmware for running these stations).

Nevertheless, I feel that I am able to carry out an objective review of the manuscript.

Here is my review:

The authors present a variety of time series and evaluation metrics of these time series, for a few different receiver-antenna combinations.  Two of these stations are low-cost and use the authors' developed systems for logging and sending the data.

The authors pay very careful attention to describing the their processing strategies at the appropriate level of detail.  Likewise, the description of the station designs for UBLO and SEPT are easy to read and clear.

Overall, the data shown are very clearly agreeing with the statements made by the authors in the text.  The low-cost SEPT station indeed performs remarkably well in comparison to more expensive, commercially available geodetic receiver and antenna combinations.  This is a very important message for the scientific community to understand, and it is the major significant result of the paper.  There are a few minor comments that I will explain below, but I think that this paper is well written and highly relevant to the audience of this journal.

Minor comments:

- The title uses the phrase "All-in-one".  I think this is not quite accurate for the current design.  The antenna is separated from the rest of the station components  via the antenna cable.  There is a separate solar panel, and there is a separate box containing the rasberry, receiver, etc.  Also, the title could be more specific to mention this is a multi-GNSS station design.

- L61-72:  Suggested improvement for this paragraph is to mention that many GNSS constellations are tested, in combination and in isolation.

- L88: Small antenna.  Yes it is small - I agree.  But it could be useful here for the maybe less-informed reader to state that this is small in comparison to the commonly used antennas for scientific/tectonic GNSS stations.

- Figure 1: Does the 4G modem require a SIM card? Are the authors able to share with readers the approximate cost for sending the data at 1Hz over 4G?

- Figure 1:  I see two plastic boxes (one on the monumentation pole and another under the solar panel).  Later in the manuscript (L139), it is explained that there is an antenna splitter.  Therefore, does one box contain UBLO, and another box contain SEPT?

- L139: It should be stated here if the two stations, SEPT and UBLO, are using the same antenna location shown in Figure 1.

- The link to the gitlab seems to be empty:  https://gitlab.oca.eu/maurinv/septentrio_mosaic_receiver  - I think it is a very good idea to make this software open source (as I understand from the manuscript text).

- The paper uses SOPH and NICE as the comparison stations for more expensive station types.  In Figures 6,9, and 11, we see the residuals (after detrending) for these stations.  Since the authors have used 30 stations in France and neighbouring areas (at least for the daily solutions), could the data from these other stations be used as comparison to SEPT and UBLO?  My point is that, from Figure 1, the site of SEPT looks great.  There is bedrock, a seemingly robust monumentation, and it looks like enough elevation for eliminating much of the multipathing.  Could it be that the monumentation at SOPH and NICE are not such good quality?  Of the 30 stations used in the processing, the chances are that the site conditions at a few of these locations is exceptionally good.  Therefore, it could be interesting to list the residual (WRMS cm) of the detrended NEU time series for these other non-low-cost stations, especially the sites with the lowest WRMS residuals.

- I was unable to find the link to the supplementary figures listed in the manuscript.

Author Response

Please see the attachment: reply_to_reviewer1.pdf

Author Response File: Author Response.pdf

Reviewer 2 Report

Dear authors,

Please find attached my report.

Regards!

Comments for author File: Comments.pdf

Author Response

Please see the attachment: reply_to_reviewer2.pdf

Author Response File: Author Response.pdf

Reviewer 3 Report

The authors present a new prototype for a dual-frequency geodetic station, which seems to offer new possibilities for geodynamic scopes. The topic is quite interesting, allowing also small communities to perform geodetic-class measurements with affordable costs. The manuscript is well structured, and the writing style is straight forward and easy to follow.

Comments for author File: Comments.pdf

Author Response

Please see the attachment: reply_to_reviewer3.pdf

Author Response File: Author Response.pdf