Hardware - Geometrics Forum

How to change the default IP settings for a MFAM Ethernet Adapter?

Rui Zhang — Thu, 27 Mar 2025 19:28:00 +0000

1. Take out the micro-SD card and plug it into your computer.

2. Open the geometrics.cfg file using a txt editor, such as NotePad, inside the micro-SD (in case the file is missing, create a txt file and rename it to “geometrics.cfg”.)

3. The content of the "geometrics.cfg" file should have the following 3 lines for new IP parameters:

StaticIP=192.168.2.23

IPMask=255.255.255.0

TcpStreamingPort=2100

4. A sample geometrics.cfg file can be downloaded here: Sample geometrics.cfg file

5. Without the micro-SD card, the IP setting is the factory default.

STP files for MFAM

Gretchen Schmauder — Tue, 13 Feb 2024 21:31:11 +0000

Here are the CAD STP files for the MFAM Development Kit Housing, the MFAM Sensor Assembly, and the MFAM Basic Assembly. 64

Is it possible to extend the cables between the MFAM sensors and module?

Gretchen Schmauder — Thu, 08 Feb 2024 21:02:47 +0000

The cables between the sensors and the MFAM module are flexible circuit boards, and the length is limited to 20 inches. It is possible to remove the MFAM module from the Development kit box and then reconnect it using a ribbon cable. That would allow you to extend the MFAM module and sensors away from the Dev Kit box. Our engineers have tested it to 4 meters.
Below are some details about the ribbon cable.
The connector on the MFAM unit is Samtec FSH-110-04-F-DH. Its mating connector is Samtec SFMH-110-02-L-D-WT.
The easiest option for an extender cable between the MFAM and the Dev Kit is a pair of cable assemblies from Samtec www.samtec.com which has male/female mass terminate connectors put onto a ribbon cable.  These connectors plug directly into the MFAM I/O connector and also into the Development Kit.  We are comfortable with lengths to 10 feet total.  The samtec P/N for this cable is:  FFMD-10-T-60.00-01-F-N
The ‘60.00’ number specifies the cable length in inches (which equals 5 feet).  We have found that there is generally a 2-4 week lead, time since they are made to order and not an off-the-shelf part.
(There is another solution as well if you want to make adapter boards at each end (Dev Kit and MFAM).  The exact Samtec mates for the MFAM / Dev Kit connectors are made in PCB mount connectors only, so if you make simple small adapter board to adapt the samtec connector to another connector of your choice.  We've done this with ExpressPCB which is fast and inexpensive.  A board set from ExpressPCB is about $70 including shipping.  Our Engineering Team has a design and parts list they can send you if you're interested in going this route.)

What is the name of the antenna connector on WiFi and GPS boards inside the Dev Kit?

Rui Zhang — Wed, 20 Sep 2023 15:16:12 +0000

This connector style is called U.FL (UMCC).

For more details, please refer to more connector information.

What is the recommended bending radius of MFAM sensor flex cables?

Rui Zhang — Fri, 15 Sep 2023 19:05:03 +0000

One inch is the recommended radius limit for multiple bends. If you are looking for the bend-once and fix-in-place bend radius, it can be bended more. We have used ~ 0.5 inch before without breaking the connections inside.

What is the slew rate of MFAM?

Rui Zhang — Fri, 15 Sep 2023 17:15:22 +0000

About 0.5uT/ms in low heading error mode and 1uT/ms in low noise mode.

MFAM 1 PPS signal input, 10 MHz reference input and synchronization

Rui Zhang — Fri, 15 Sep 2023 17:07:15 +0000

The 1PPS pulse phase locks and synchronizes the sample interval to be in lock step with the GPS. Thus once locked there will always be 1000 samples per second, with the sample beginning time precisely lined up with the 1 PPS edge.

The 10 MHz input is for a different function. This input phase locks the 40 MHz master reference oscillator to the incoming 10 MHz, which is usually a GPS disciplined reference oscillator or atomic clock (in other words exactly 10 MHz). This phase locks the 40 MHz reference oscillator to exactly 40 MHz. The 40 MHz oscillator is the time base reference for calculating the Larmor frequency, and therefor the magnetic field value.

Even though the 40MHz oscillator is really good even without the 10 MHz input, there is some drift in the 40 MHz over time (mostly thermal drift and some aging). For some applications where they need to measure very low frequency and low amplitude changes in the magnetic field the 10 MHz input will allow drifts in the reference oscillator to be removed. Without that it would be impossible to distinguish between reference oscillator drifts and low frequency low amplitude changes in the magnetic field.

The connector for the 10 MHz input is SMB RF connector from Molex.

If you must simulate the 1 PPS signal in a GPS denied environment, please be aware of certain requirements of the 1 PPS signal.

1. The lock range for the 1 PPS input pulse is very narrow. The simulated 1 PPS signal must be within 100 ppm of an exact 1 Hz PPS signal (100us).

2. Timing jitter must be small (less than 0.5 ppm, 0.5us) too. If you are setting a GPIO pin on a microcontroller, there may be some concern about timing jitter due to interrupt latency or other processor tasks delaying the I/O pin toggle. Any rectangular waveform should work but the leading edge must be very close to 1 Hertz. It is the positive edge that specifies the 1 second rollover.

MFAM Development Kit IP Address

Gretchen Schmauder — Thu, 31 Aug 2023 17:01:50 +0000

The MFAM Development Kit is usually set to a fixed address of 192.168.2.2 (port 1000). The Ethernet port on the Windows PC must also be switched from DHCP to a fixed IP Address mode in order to connect to the Dev Kit. The procedure for doing this is described in the Dev Kit User Guide.

If there are more than one Dev Kits connecting through an Ethernet switch they cannot have the same address. Therefore it is possible to set the Dev Kit IP address to something other than the default.

192.168.2.3 and 192.168.2.4 firmware are included in the USB drive shipped with Dev Kit and can be downloaded here:

https://www.geometrics.com/product/mfam-developer-kit/

For other IPs, please contact Geometrics or reply to this post. You may need to install the Uniflash program from Texas Instruments.

What are the differences between the standard MFAM and the SX version?

Gretchen Schmauder — Tue, 22 Aug 2023 17:07:30 +0000

The only difference between the standard and SX version is the sensitivity is 4pT/rt-Hz and 20 pT/rt-Hz respectively.

Here is an expected response with the magnetometer moving past a generic magnetic projectile:

In this case the amplitude is about 1nT in total from peak to peak. The feature itself is quite distinguishable. This is assuming there is no noise in the system.

Here is what the data looks like with 4pT/rt-Hz noise:

You can see the general structure is still there but there is a little more wiggle on the trace that is associated with the noise of the system.

Here is the data with 20 pT/rt-Hz noise:

Again, here the structure is clearly visible but the data looks a bit noisier. With some signal processing technique, such as low pass filtering, noises can be further reduced. Please note that in real surveys, detecting 1nT peak-peak anomalies is always a big challenge even with the most sensitive magnetometers due to other noise sources, such as motion noises and environmental noises. Therefore, SX version is in general NOT the limiting factor for conducting surveys.

To understand this concept better, you can use the magnetic gradient tool developed by our partner in the UK, Geomatrix Earth Science.

Can I use an off-the-shelf GPS antenna?

Rui Zhang — Mon, 21 Aug 2023 17:18:57 +0000

The GPS antenna shipped with the MFAM Dev Kit is customized (with the magnet removed). If you want to buy another off-the-shelf GPS antenna, please make sure that it doesn't have a magnet in it.

If you need to place the antenna close to the sensors (<0.5m), please make sure to magscreen the antenna.