The front panel - the man-machine interface (MMI) - should be on the north side of the unit, with respect to the antenna calibration.

Almost universally, GNSS receivers with integrated antennas are calibrated with the MMI being the north reference point. It is confusing to surveyors that the Sparkfun units are an exception to this widely-followed convention. The unique orientation of the Facets makes it more likely that surveyors will mis-align the Facet when setting up a base or collecting static data.

Besides convention, there is a good reason for having the MMI on the north of the receiver.

The sun, for people in the north hemisphere, doesn't shine from the north. If the MMI is on the north side of the GNSS receiver, it is easier to read and less likely to be washed out by the sunshine. There are more people living in the north vs the south hemisphere, so putting the MMI on the north side of the receiver maximizes the MMI visibility for more people.

See also issue #12.

The screw holes for the screws that hold the Facet (GPS-19029) housing together are too narrow to allow most of my small screwdrivers to reach the screw. These are screw drivers that properly fit the screw heads.

This is important as I need to open the case in the field to retrieve lost SD cards.

It's very difficult to insert and remove SD cards when there is a cable plugged into the USB-C connector. There just isn't a lot of room for fingers to grasp the tiny microSD card.

I have two GPS-19029 Facets.

As linked to from the Facet product page
https://www.sparkfun.com/products/19984
I'm looking at
https://cdn.sparkfun.com/assets/d/2/a/b/0/SparkFun_RTK_Facet_-_External_Connector_Schematic.pdf
With a rev date in the title block of "12/3/2021 11:58am" and a version of "V12".

In the section of the schematic showing what I believe to be the JST Radio and Data connectors, I have the following observations:

1. I believe the "Serial Config, NMEA Out" connector is what the hookup guide calls the "Data" connector, but this isn't explicit.

2. The hookup guide doesn't mention using the Data connector for Serial Configuration. I always use the USB-C for serial configuration. The schematic calls it a "Serial Config..." connector.

3. Why are there two "Serial Config, NMEA Out" connectors on the schematic with the pin numbers flipped?

4. I believe the "External Radio, RTCM In/Out" connector to be the "Radio" connector as described in the hookup guide. Not explicit but close enough to be obvious.

5. Why are there two "External Radio, RTCM In/Out" connectors on the schematic with the pin numbers flipped?

6. According to the hookup guide, the V+ pin on both the radio and the data connector are current limited by a PTC to 600ma. Do both connectors share the same PTC (F1) ? That is, is the sum of the V+ current provided by the data and radio connectors limited to 600mA? This isn't explicit in the hookup guide and the schematic is unclear on this point.

I'm able to make the cables I need using the info in the hookup guide, so the issue is not an impediment for me.

Front panel and operation status LEDs need to be visible from below and in bright sunlight.

Units from other vendors generally angle the front panel downward, design the case so the LEDs are visible from directly below, and/or use very bright LEDs.

See also #10.

Emlid RS2 - panel angled downward.

Trimble R12i - bright and large LEDs visible from directly below.

Topcon - front panel angled downward.

Carlson BRx5: Very bright LEDs and nothing on the case to block LED visibility from directly below. The LEDs protrude slightly to aid visibility from below.

To support very long term logging, add SD DET and power control, and big decoupling caps.

Performing logging tests here on the firmware. Have the Facet plugged into power. Sitting on my kitchen table at a tilt because it is resting it's weight on the USB cable.

I spend more time learning, debugging, and upgrading this device than actually using it. Therefore having it on my desk with a USB cable plugged in for power or serial IS IN FACT my primary use case :)

T.

The 4-pin JST-GH Radio port connector on the Facet is both less common, difficult to make or source cables, and fragile. The TTL serial levels are fine for drone telemetry-style radios, but do not work with more powerful radios commonly used in the surveying industry. In the field, small tree branches pull on the tiny wires and yank the pins out of the JST connector shells.

I suggest replacing it with a more common connector and/or a more robust connector for which cables are readily available and/or easily constructed. The TTL vs RS232 level issue needs discussion too.

If one is using serial telemetry radios (eg SparkFun LoRa Serial, Holybro, or RFD900 radios), the 4-pin to 6-pin cables are less common. I've had to purchase drone cable kits and frankenstein cables by swapping shells when Sparkfun is out of stock on the 4-pin to 6-pin JST cables.

The simplest but less robust change would be to replace the current 4-pin JST radio connector with the more common 6-pin version. It seems the drone community has settled on 6-pin connectors for telemetry radios and 6-pin to 6-pin cables are commonly stocked by multiple vendors and are also commonly included in cable kits sold for drone builds.

If one is using more powerful radios, building a custom cable is time consuming, and almost without exception the more robust cables used for more powerful radios put a lot of weight on the JST connector....and out comes the duck tape. Yuck.

More powerful radios generally required RS232 levels, so I find myself making cables with the SparkFun Max3232 breakout board incorporated into the cable. Not hard but very time consuming. In the surveying industry, generally the more powerful radios have a DB9 (RS232) cable available.

For the more powerful radios used in the surveying industry, a solution that can be used to connect the Facet to an external radio using a DB9/RS232 connector would be very welcome.

Other options for the radio port include

• USB: As far as I can tell, every vendor of 900MHz telemetry radios seems to include a USB port or a USB cable with their radios. Robust enough, well-proven, common, easy to get cables for. Not terribly expensive. But the Facet would need to be a USB host. There are USB to TTL serial and USB to RS232 serial cable available.
• LEMO style connectors. Common in the surveying industry. Very robust. Expensive and hard to for a hobbyist to source parts to build cables for. But widely used in the surveying industry
• RJ connector. Very inexpensive and cables can be made with $15 tools. Most of us have made these cables for telephony and network applications. Cisco network devices have used RJ connectors for serial consoles 'back in the day' so these cables are widely available. Would need to be RS232 levels.

Add a highly-visible indicator, observable from below, which shows that logging writes to the SD card are happening.

Static logging is a long-term operation, 2, 4, or even 8 hours. It is important to be able to verify that logging is actually happening after the Facet is setup. It is disheartening to find a setting was misconfigured or even the SD card wasn't properly inserted.

While the logging icon on the OLED display is very useful, the OLED display is often not visible.

1. It is very common to have a GNSS receiver up on a 2m pole. It's not uncommon for the pole to be on a mark that is projecting 0.2m above the ground. That puts the OLED display over 2.2m up in the air, well above eye level for most people.
2. The OLED display is easily washed out in bright sunshine.
3. The OLED display is slightly recessed, making it harder to read from low vertical angles. This is good as it protects the display, but the logging icon in in the lower part of the display.

Many commercial survey GNSS receivers use a bright blinking LED to indicate that logging is active. The LED is visible in sunshine and visible from a low vertical angle.

My Workbench

Facet 19029 (the one before the carrying case)

Feature Request

Redesign the Facet housing to support slant measurements of height above the mark. It's physically impossible to measure directly with a tape measure from a survey mark to the reference point of the GNSS housing (the bottom) when using standard survey tripods (heavy duty "legs", not a pole or bipod setup) due to the width of the head on standard survey tripods.

This is an issue with most commercial survey-grade GNSS receivers. Many commercial survey-grade GNSS receivers provide a secondary measurement mark for "slant measurements", where the tape is held at an angle from the survey mark on the ground to the edge of the diameter of the GNSS receiver. Many commercial survey data collectors allow the input of
a. the slant measurement - the length of the tape at an angle from the survey mark to the "slant" mark on the edge of the receiver.
b. the offset from the slant measurement to the phase center or bottom reference mark (I forget which at the moment.)
c. the diameter of the receiver at the slant measurement mark.
and the data collector uses a simple triangle formula to calculate the actual height of the antenna phase center above the survey mark on the ground.

Specifically, this includes

1. Increase diameter to allow a tape measure to run in a straight line from the mark to the case without touching survey tripod head or the tribrach. Standard survey tripods ("legs", not a pole & bipod setup) have a wide head and the current housing diameter is too small - one would have to bend the tape. Some manufacturers (eg. the Hemisphere 320/Carlson BRx5 have tabs (aka "ears") on the housing that increase the effective diameter and give clear place to measure from (or even hold the hook on the end of the tape). See Carlson's KB1042 (link below) for a diagram.
2. Put a slant mark on the housing (that the rubber bumper moves around needs to be resolved.)
3. Make the bottom of the Facet ROUND so that the slant height can be measured with a tape from any location and have a consistent radius. The current hexagonal bottom means there is no one radius.
4. Publish the radius of the housing at the slant mark
5. Publish the vertical offset from the slant mark to the ARP (the Antenna Reference Point, the center of the bottom of the housing; NOT the APC, as the APC moves with frequency and SV elevation and position.)
6. Create a diagram showing the radius and vertical offset from the slant mark to the ARP.

OR it might be easier to just use a thin round disk of sheet metal with sufficient diameter between the Facet and the Tripod and slant measure to that. Hmmm. Similar to https://www.sparkfun.com/products/17519 (ground plane) but with a hole large enough for the 5/8x11 tripod screw.

References

https://www.ngs.noaa.gov/AERO/Genspecs_A/Volume%20A_Attachment%2011-19.pdf
(Multiple docs in this PDF, Scroll down to "Attachment 13" page 3)

This document contains a great example of a diagram showing the radius and slant offset to the ARP.
https://web.carlsonsw.com/files/knowledgebase/kbase05.php?action=display_topic&topic_id=1042

https://kb.unavco.org/kb/article/introduction-to-gnss-antenna-set-up-methods-for-campaigns-71.html

The green power indicator LED on the FACET only shows when the battery is charging due to external power being supplied.

It would be very useful to have an indicator to show when external power is connected, regardless of the state of the internal battery.

When setting up the base for a long work day, it is often necessary to connect external power, especially if using RTK radios, more especially if the radios are transmitting at more power than 100mW. It is important to be able to confirm that the external power is properly connected to ensure the work day will not be interrupted.

Currently, if the internal battery is fully charged, there is no indicator to confirm that the external power is connected properly. If the user thinks the external power is properly connected, but it actually is not, the base will shutdown midday due to the internal battery depleting, interrupting RTK work and static collection.