This site is maintained in order to present a seismometer project as an educational project for schools and students. The goal of the project is to build an inexpensive but highly precise seismometer, which offers high resolution and live data representation over the internet.

The project is divided in its entirety into three parts, of which the first one is the computer science part (software), another part is the electrical engineering part (electrical hardware), the third and last part consists of mechanical engineering (mechanical hardware: casing and fixture of the sensors).

The seismometer essentially consists of a geophone sensor, an analog-to-digital converter (ADC), a control unit and a casing. During the project time, different approaches will been tried out; they will be documented in the following posts. The project started in January 2019 and is work in progress. If possible, the project shall be extended to a 3D ultra precise seismometer, which is connected to the international IRIS network. IRIS is a consortium of over 100 US universities dedicated to the operation of science facilities for seismological data. IRIS programs contribute to scholarly research, education and earthquake hazard mitigation [https://www.iris.edu].

The best way to follow the project is to read all posts below in chronological order.

If you like the project or have questions or remarks, use the field for comments under each post. Please always stay polite. It should be self-evidently that hateful or impolite posts will be deleted from the administrator without hesitation [“I am paying for this microphone, Mr. Green!” as Ronald Reagan said…]. If you are a teacher or student, who wants to build a seismometer for your school class or for yourself, don’t hesitate to get in touch with me over Email.

From time to time I will post small update messages at the status section below.

 

Thank you very much for visiting my page.

Dr. Jürgen Abel

Email: 

Specification

Status

The current version V0.2 of the seismometer is a proof of concept of the seismometer, which is able to visualize first data.

Setting up the seismometer into the soil has started together with some improvements.

The next weeks I will publish the results, probably until end of december 2019.

Projected installation date

The projected date for installation in the ground is december 2019.

Resolution

ADC raw resolution: 32 bits

ADC noise free bits: 20 bits

Sampling rate

400 samples per second

Geophon Sensitivity

28.8 V/(m/s)

Next tasks

Using interrupts for the measurements.

Posts

Using interrupts for measurements

Posted on 02.12.2019

0
In the past, the voltage measurements of the ADS1262 were recorded in a polling loop. A polling loop is the simplest form for performing repeated measurements. The loop reads a measurement and then waits for a certain time, e.g. 2 ms. It uses the sleep command, which does not block the CPU from processing other threads. However, this solution is still not very good

Increasing the ADC precision

Posted on 28.11.2019

0
Besides the missing reliability of the Raspberry Pi, which could be solved by switching the power input to the GPIO pins, there was one point, which disturbed me a lot the last months: The high level of noise at the input of the ADS1262. To keep things simple I measured the input noise by short cutting the pin AIN0 and AONCOM. The measeared value
During the development of the software, I noticed several times that the raspberry didn’t interact after the ADC program was running for one day.Since the seismometer needs to work many days outside without manual operation at the raspberry, this gave me some worries.Therefore, I took a peek at the log file /var/log/syslog and I found out that there have been hundreds of “Under-voltage detected!
The ADS1115 from the last version had 16 bit resolution, which is a little few for a good seismometer. Most commercial seismometers use 24 bit resolution ADCs. Therefore, different ADCs have been looked for with a higher resolution, before much code is developed, which would have been to be rewritten because of a different ADC, exspecially if the ADC uses a different interface bus.After
The beta version V0.1 of the seismometer is based on the Raspberry Pi. The ADC is a ADS1115 analog-to-digital converter with a resolution of 16 bit. The geophon is the SM-24 geophon. This version is still very simple and only a raw proof of concept. But it is able to visualize already some geophone data. Hardware Raspberry Pi The Raspberry Pi model 3B is
Now we are going to setup the Raspberry Pi with Midnight Commander (MC), the Network File System (NFS), the powerful PostgreSQL server, a PASCAL IDE, some tools, I²C and SPI. Hereafter, PC means a PC with a LINUX operating system, here KUBUNTU 14.04 is used. Heat Sinks In order to run the Raspberry Pi in continuous operation and for overclocking, it is advantageous to
Since of its limitation the ESP32 solution was no longer pursued. Looking for a more powerful alternative, the Raspberry Pi became the first choice, as it was used before in robotic projects. The Raspberry Pi offers many advantages and possibilities: SSD connection using an USB 3.0 to SATA converter, LINUX as an operating system, several PASCAL IDEs, several SQL servers, web servers and much
The first version of the seismometer is based on the micro controller ESP32. The ADC is a ADS1115 analog-to-digital converter with a resolution of 16 bit. The geophon is a SM-24 geophon from Sensor Nederland B.V.. ESP32 The ESP32 is a 32 bit micro controller loaded with a lot of utilities. The version used here is a board based on the SX1276 LoRa chip