Model QM-1.0 Long-Period Seismometer Electronics.

Welcome to The Inexpensive Seismometer Project, an attempt reduce the cost and complexity of amateur seismic systems.

This page is about my project to build simpler and less expensive amateur long-period seismometers by using microprocessors and other new chips, such as switched capacitor filters. Long-period seismometers are useful for detecting and analyzing distant teleseismic activity (worldwide). For more general information on other types of seismometers and links to web resources, see my main seismometer page. Click here for information on my short period system.

Current Long Period Seismometer Electronics Status:
The latest QM-1.0 long-period processor improvements include:

• DIP 1, debug zero test, normally off, use to center range, if on then tracking off, set serial output to zero by zero pot.
• DIP 2, debug zero test, normally off, use to center range, if on then tracking off, set serial output to 32767 by zero pot.
• DIP 3, set sampling rate, if on and 1,2,4,5,6 off, then 34 samples/second (QM-4.5 default)
• DIP 4, set sampling rate, if on and 1,2,3,5,6 off, then 18 samples/second
• DIP 5, set sampling rate, if on and 1,2,3,4,6 off, then 12 samples/second
• DIP 6, set sampling rate, if on and 1,2,3,4,5 off, then 8 samples/second (QM-1.0 default)

See for latest updates to this page.

QM-1.0-3074 Exterior.

QM-1.0-3074 Interior.

QM-1.0-3074 circuit board, enclosure, pickup coil and magnet.

Here is the circuit schematic. Note that my short period QM-4.5 seismometer printed circuit board is identical to the QM-1.0 board except for passive component value changes to reduce the lowpass filtering to 4.5 Hz. The QM-4.5 is designed to work with a 4.5 Hz Mark Products geophone.

• From at Bailey's Crossroads, VA (about 10 miles West of Washington, DC):
  Seismometer: EV-17 1 Hz vertical sensor with QM-1.0 electronics
  Location: on a basement slab in a noisy office building
  Orientation: Z (vertical).
  Time Base: Abouttime gets occasional web time updates, Rightime corrects PC clock.
  PC and Software: Athlon 850, Win98, Amaseis, Rightime, Abouttime, Winquake.
  • January 12, 2002 04:53:53 UTC, Magnitude 6.3 quake 90 miles (145 km) ENE of Iraklion, Crete, Greece:
    distance estimated by Winquake as about 8650.9 km or 5372.2 miles from Bailey's Crossroads, VA.
    I created a Amaseis export data file so that I could transfer the data to WinQuake for further analysis, and here is the Winquake time series data display. The S wave peak is strong, but the P wave can not be detected. The FFT spectral data plot shows that the received seismic signal power was spread from 0.1 to 1 Hz. The Columbia University 1/22/02 display from an online short period seismometer Columbia University LCSN seismic observatory in New York state showed a seismic signal similar the the EV-17. These results show how the QM-1.0 circuit board can be use with variety of low frequency sensors in addition to the 9 k ohm coil that is generally used as a Lehman with Lehman seismometer designs. The EV-17 had a resistance of 5 k ohms and the standard QM-1.0 design generated a voltage gain of 2000. Click here to download the time series data file in .SET format. Note that the time base is fast by about 40 seconds.

  • February 22, 2002 19:32 UTC, Magnitude 5.7 quake on California-Baja California Border Region,
    distance is estimated by Winquake as 3510 Km or 2180 miles from Bailey's Crossroads, VA,
    Winquake time data display, Winquake map, and Winquake readable time series data file.
    Note: P and S not visible.

• From at Bailey's Crossroads, VA (about 10 miles West of Washington, DC):
  Seismometer: Lehman with 18 second period and QM-1.0 electronics
  Location: on a basement slab in a noisy office building
  Orientation: E-W.
  Time Base: Abouttime gets occasional web time updates, Rightime corrects PC clock.
  PC and Software: Athlon 850, Win98, Amaseis, Rightime, Abouttime, Winquake.
  • January 13, 2001 17:33:32.38 UT, Magnitude 7.8 quake OFF COAST OF CENTRAL AMERICA,
    ~3000 km from Bailey's Crossroads, VA. Winquake time data display
    . Note: time base not correct, P and S markers not correct.

  • January 26, 2001 03:16:40.50 UT, Magnitude 8.0 in SOUTHERN INDIA,
    ~13,000 km from Bailey's Crossroads, VA, Winquake time data display
    . Note: time base not correct, P and S markers not correct.

Here is my latest short-period, single-board, single-channel seismometer design :

• Board is designed to work with a 9 k ohm pickup coil.
• Board can be configured for other pickup coils.
• Revised low-noise circuit board is availaible as of December 5, 2005.
• Hammond 1590P diecast enclosure is included for pcb shielding.
• Shielded 9' cable with connector connects the geophone to the circuit board.
• Amplification is single stage, low noise, 1100x voltage.
• Amplifier chip: AD8628 auto-zero low noise, precision, rail-to-rail output, op amp.
• Low-pass filter is an 8 pole bessel filter set by capicitor to a 5 Hz cutoff.
• Filter chip: MAX7401CPA 8th order, lowpass, Bessel, switched capacitor filter.
• A to D: 8 channels onboard microprocessor, each 16 bits covering a 0-4.85 volt range.
• Microprocessor: 8 bit, 4 mHz PIC14000 with 16 bit A/D, replace chip to upgrade software.
• Microprocessor software: burned into PIC14000, controls A to D, time integration, etc.
• Voltage regulator chip: micropower LP2950ACZ-5.0 with very low dropout voltage.
• Serial output rate is adjustable (by DIP switch) from 8.7 to 33.5 samples per second.
• Serial output 10' cable with DB9 female connector for PC COM port.
• Serial extension cables (DB9 M/F) up to 100' are usable for remote sensor locations.
• Serial output rate is 9600 baud, 8N1.
• Serial output ASCII records vary from -32767 to +32767, 0 is zero velocity.
• Power is derived from the PC serial port, and the board turns on when connected.
• Power on board is single-supply 5 volts, current is less than 4 ma @ 5 volts.
• LED Power On indicator blinks at output sampling rate.
• You download the latest Amaseis (freeware) for data logging, helicorder display, data export, etc.
• You download AboutTime (optional/freeware) for time synchronization via Internet.
• You download RighTime (optional/free trial) if you need to adjust Win95/98 PC clock.
• You download WinQuake (optional/free trial) for seismic data analysis.

• RF Pickup This RF Pickup problem seems to have been fixed by the metal enclosure, the revised circuit board, and the low-noise AD8628 opamp. The beta test unshelded units showed spikes when ham gear, cell phones, portable phones, or radio telephones were used near them. This was reduced ~10x by two board changes: the cable between the geophone and the circuit board was replaced by a foil shielded cable, and the LT1677 low noise op amp was replace by the much less RF sensitive TLC2201CP, and then by the autozero AD8628. Low pass filtering of the serial derived input power was installed, but it does not seem to cause much improvement due to the excellent voltage regulator performance. No RF pickup was detected from the output serial cable. Now waiting for more input from the field.

• Microprocessor Firmware Upgrades Each PIC14000 is One Time Programmable (OTP), so the chip must be replaced in order to upgrade to the latest firmware. This is easy to do since the 28 pin chips are socketed. The same firmware is used for long period, short period, and strong motion circuit boards. Here is a history of firmware bug fixes and improvements:
  • v010516 - Increased the maximum sampling rate from 19 SPS to 23.7 SPS. Note: faster sampling rates are available if the PIC does not sleep during the A to D, and if the A to D is set to 14 bits or 12 bits.
  • v010516 - Bug corrected that incorrectly saturated the A to D values when they reached +32767 or -32767.
  • v010516 - Bug corrected that caused a small variation in the sampling rate depending on the signal amplitude.

• Amaseis Software The following have been noted when using Amaseis with the QM-1.0 system:
  • Getting Started with Amaseis:
    • To get started with Amaseis and the QM-1.0 requires two editing changes to the AS1.INI file that is found in the C:\AMASESIS directory. You must use a text editor like the Windows NOTEPAD to add the line DEVICE=INFILTECQM1 on any line in the file, and you must set the COM=1 line to whatever COM port is free on your PC and has a DB9 connector.
    • Under the SETTINGS/HELICORDER pull down menu you will find a DECIMATE entry box. If you are running Amaseis on a slow computer you may want to change the DECIMATE=1 default to a number greater than one. This will speed up the redrawing of the display. But it may cause you to miss spikes.
    • Under the SETTINGS/HELICORDER pull down menu, typical values are GAIN=30 and LOW PASS=1 (Hz). Sometimes you can get see quake signals clearer by reducing the LOWPASS to lower 0.1 Hz to reduce the effect of the omnipresent wave noise (microseism) at 0.12 to 0.2 Hz. DAYS TO RETAIN RECORDS does not delete data records, so you will fill up your hard drive unless you delete some of the daily and hourly data folders that Amaseis creates. LINES PER HOUR=1 is generally left unchanged.
    • You can delete all the data files by exiting Amaseis, using Windows Explorer to highlight the C:\AMASEIS\2002\ folder and then hitting the DELETE key. Amaseis will recreate this folder when you restart it.
    • Under the SETTINGS/DATA VALUE menu, you can see the data values coming out of the A to D. This can be quite useful for debug.
    • If you plug the QM-1.0 serial cable into PC serial port, the LED on the board will not light up unless Amaseis has been started and is trying to read the COM port. In general, COM ports are not energized until some program tries to read them. Once Amaseis has tried to read the port, it will be energized even if Amaseis is terminated. There are some computers that do not have +12 on their COM ports, and they will not have the power to run the QM-1.0 board. If Amaseis can not find the COM port you have specified in the AS1.INI file, it will show a COM port not found error message when you start Amaseis. However, if the error is "No Data", then the COM port was found by the QM-1.0 was not connected to it. Try other COM ports and see if the LED lights up. You may have to get a connector changer from Radio Shack if the only available COM port is not a DB9 connector.
    • To examine some data more closely, block it with the right mouse button down, and then click on the menu button that looks like a wave. This will display a detailed view of the selected data. Under the FILE menu, select SAVE to create a data file for analysis by WinQuake. Note that this data selection does not generally work until Amaseis has recorded an hour of data. Use the PEPP (.SET) data format option.
  • Possible Amaseis Problems:
    • On the hour, Amaseis recomputes the sampling rate in samples per second (SPS) based on a default 5 second average of the number of input samples received. 5 seconds may not be long enough to accurately determine the QM-1.0 SPS. The program author modified the program so that INITSAMPLESEC=5 may be modified by editing the AS1.INI text file. INITSAMPLESEC=30 or 60 seconds should reduce this error well below 1%.
    • When data is saved in a file for input to WinQuake, the only data format that seems to work is PEPP which produces a .SET file ending. The work around is to only save .SET files.
    • When data is saved in a file for input to WinQuake, much of the file header is scrambled. The work around is to fix up the file header in WinQuake and resave the file.
    • Note that the .BMP format that Amaseis uses to store screen shots generally produces rather large files, and you may want to use a file conversion program to convert them to smaller .GIF or .JPG files.
    • When you exit Amaseis, it sometimes opens a series of error messages. The workaround is to just keep clicking on them till they disappear. No problems seem to be created by this abnormal exit.

• You can pay by check, money order, credit card or PayPal. The assembled QM-1.0-3704 include a 9k ohm pickup coil salvaged from a 220V relay, a diecast aluminum enclosure, and a General Tool 370-4 alnico horeshoe magnet. The kit KQM-1.0-3704 includes the all the parts, but you assemble them. To start recording, all you need is to download the Amaseis software and plug the QM-1.0 serial cable into your PC serial port.

  OPTIONAL EXTENSION CABLE: You may want to consider a serial (DB9 M/F) extension cable if your PC is a long way from your Lehman/geophone. The QM-1.0 has a built-in serial cable that is about 10 ft long, and a cable to the pickup coil that is about 6 ft long. I have some serial extension cables that are 10 ft to 100 ft long.

  PRICES:

  __ASSEMBLED long-period seismometer electronics in diecast aluminum case for RF and thermal shielding
  1 QM-1.0-3704 assembled/tested pcb, in case, 10 ft cable, coil, magnet @ $295
  

  __KIT long-period seismometer electronics with diecast aluminum case for RF and thermal shielding
  1 KQM-1.0-3704 bare pcb, components, case, 10 ft cable, coil, magnet @ $195
  

  __MISC PARTS
  1 QM-370-4 General Tool horseshoe alnico magnet, 22lb/9.97kg pull, fits 9k ohm coil @ $25
  1 QM-02712 10ft DB9 M/F Extension Cable @ $10
  1 QM-09452 25ft DB9 M/F Extension Cable @ $20
  1 QM-09453 50ft DB9 M/F Extension Cable @ $30
  1 QM-17612 100ft DB9 M/F Extension Cable @ $50
  

  __SHIPPING
  1 Shipping within the US by USPS Priority Mail with insurance @ $10
  1 Shipping outside the US by USPS Global Priority Mail with insurance @ $25
  

  MAIL ORDERS: Print out our Order Form (text) and fill out your order and calculate the cost. Mail a check or money order payable to Infiltec to:
  

  Infiltec Seismometers
  108 South Delphine Avenue
  Waynesboro, VA 22980
  
  phone: 540-943-2776
  fax: 540-932-3025
  

  email: .

  FAX CREDIT CARD/PAYPAL ORDERS: you can order by credit card (MV/VISA/AMEX) by printing out our Order Form (text) and faxing it back to me. We do not charge your card before we ship.

  PAYPAL ORDERS: (for orders shipping within the US only)

  QM-1.0-3704 assembled/tested pcb, in case, 10 ft cable, coil, magnet @ $295 + $10 Shipping in USA = $305

  KQM-1.0-3704 kit: pcb, components, metal case, 10 ft cable, coil, magnet @ $195 + $10 Shipping in USA = $205

  QM-1.0-3704 assembled/tested pcb, in case, 10 ft cable, coil, magnet @ $295 + $25 Shipping outside the USA = $320

  KQM-1.0-3704 kit: pcb, components, metal case, 10 ft cable, coil, magnet @ $195 + $25 Shipping outside the USA = $220

  AVAILABLITY: It generally takes about one month to build and test your system, after I receive your order. You do not need to make a PayPal payment before I inform you that I am ready to ship your system.

  WARRANTY: Your money back if you are not satisfied for any reason. Just return the system in reasonable shape for a full refund. If the system is defective, please ship it back for a no-charge repair. If you build a kit and it does not work properly, we will fix it for $25 plus shipping if you return it to us.

  TUNE UP: Any time I make improvements to the microprocessor software and/or circuit, you can return the board for these upgrades for $30.