Model QM-4.5 Geophone Short-Period Seismometer.

Detailed information on the Infiltec QM-4.5-L15B short period
seismometer designed to work with a Mark Products 4.5 Hz geophone.

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INTRODUCTION:
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 short period seismometers by using microprocessors and other new chips, such as switched capacitor filters. Short period seismometers are useful for detecting and analyzing local seismic activity (within a few hundred miles or closer). 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 long period system, and click on here for my strong motion accelerometer system|. The latest design of the QM-4.5 has lower noise levels and can achieve teleseismic detections down to 0.01 Hz.
System Status: QM-4.5 Systems are in use in Panama, Portugal, Chile, and the US.
March 2006 Status:
The latest QM-4.5 long-period processor improvements include:
an improved low-noise circuit board layout,
a lower noise AD8628 auto-zero amplifier,
revised PIC 14000 firmware with improved zero tracking,
DIP switch selection of sampling rates,
a diecast aluminum enclosure for better EMI and thermal shielding, and
completed kit instructions
See for latest updates to this page.

PICTURES OF QM-4.5-L15B Short-Period Seismometer:

(Click on thumbnails below for full screen images)
QM-4.5-L15B exterior.

QM-4.5-L15B interior.

QM-4.5-L15B circuit board, case and 4.5 Hz geophone.

Here is the circuit schematic. Note that my long period QM-1.0 seismometer printed circuit board is identical to the QM-4.5 board except for passive component value changes to reduce the low pass filtering to 1 Hz. The QM-1.0 is designed to work with a 9k ohm pickup coil and moving magnet.

PERFORMANCE OF QM-4.5:
- From at Bailey's Crossroads, VA (about 10 miles West of Washington, DC):
  Seismometer: Mark Products 4.5 Hz horizontal geophone system with QM-4.5 electronics
  Location: horizontal geophone on carpeted floor of 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: AMD Athlon XP 2500+ cpu, Win98, Amaseis, Rightime, Abouttime, Winquake.
  - 2005 December 05 12:19 UTC
    Magnitude 6.8 - LAKE TANGANYIKA REGION: 11,954.0 km from Bailey's Crossroads, VA
    Winquake power spectral analysis display note quake signal at 0.05 Hz and microseism peak at 0.2 Hz.
    Winquake data analysis display (jpg image) with HP=0.045 and LP=0.065 filtering
    USGS Preliminary Earthquake Report
    Note: this is the first teleseismic detection with the improved QM-4.5-L15B system with a low-noise pcb, low-noise AD8628 opamp, and shielded enclosure. The noise level on this geophone system is often low enough to see the microseism peak at about 0.2 Hz.
  - 2005 July 26 04:08:35 UTC
    Magnitude 5.6 - WESTERN MONTANA: 2994.1 km from Bailey's Crossroads, VA
    Winquake data analysis display (gif image) with HP=0.03 and LP=1.0 filtering
    USGS Preliminary Earthquake Report
  - 2005 July 24 15:42:05 UTC
    Magnitude 7.2 - NICOBAR ISLANDS, INDIA REGION: 14722.5 km from Bailey's Crossroads, VA
    Winquake data analysis display (gif image) with HP=0.03 and LP=1.0 filtering
    USGS Preliminary Earthquake Report
  - 2005 July 23 20:09:05 UTC
    Magnitude 5.5 - NEAR THE COAST OF NICARAGUA: 3121.1km from Bailey's Crossroads, VA
    Winquake data analysis display (gif image) with HP=0.03 and LP=1.0 filtering
    USGS Preliminary Earthquake Report
  - 2003 January 22 02:06:36.0 UTC
    Magnitude 7.8 - COLIMA, MEXICO: 3397 km from Bailey's Crossroads, VA
    Amaseis 24 hour display (gif image) with 1 Hz lowpass filtering - background noise is from local auto traffic and occasional RF interference spikes
    Winquake data analysis display (gif image) with 1 Hz lowpass filtering
    Winquake power spectra display (gif image) with no lowpass filtering
    Winquake geographic display (gif image) from USGS position and time information
    Comment: only P wave detected
  - 2003 January 20 08:43:06.0 UTC
    Magnitude 7.2 - SOLOMON ISLANDS: 13,500 km from Bailey's Crossroads, VA
    Amaseis 24 hour display (gif image) with 0.1 Hz lowpass filtering
    Winquake data analysis display (gif image) with 0.1 Hz lowpass filtering
    Winquake power spectra display (gif image) with no lowpass filtering
    Winquake geographic display (gif image) from USGS position and time information
    Comment: neither P nor S wave detected.
  - 2002 January 12 08:26:52 UTC
    Magnitude 5.7 - SW OF HAMILTON, BERMUDA: 1300 km from Bailey's Crossroads, VA
    Amaseis 24 hour display (jpg image)
    Amaseis data analysis display (jpg image)
    Winquake data analysis display (gif image)
    WinQuake geographic display (gif image) using NJ and AL seismometers for position determination
    time series data file (PEPP data format)
    Note that WinQuake allows the S and P wave arrival times to be tagged. The location of the sensor together with the S and P wave time difference can be used to create a WinQuake map showing circles indicating possible quake locations. The small square box on the map shows the USGS calculation of the position of the quake, and there are circles from my location in Bailey's Crossroads, VA (blue) as well as data from amateur seismometers in New Jersey (yellow) and Alabama (green) that WinQuake combined to create this map.
  - 04/18/2002 16:08:36 UT
    M6.6 NORTHERN CHILE: 7358 km from Bailey's Crossroads, VA
    Winquake data analysis (gif image)
    WinQuake geographic display (gif image)
    time series data file (PEPP data format).
- From Dave Booth in Saugus, CA (~40 miles North of LA)
  Seismometer: Mark Products 4.5 Hz horizontal geophone system with QM-4.5 electronics
  Location: Buried in coffee can in back yard.
  Orientation: N-S.
  PC and Software: Amaseis, Winquake.
  - 2/22/2002 19:32 UT
    M5.7 CALIFORNIA-BAJA CALIFORNIA BORDER REGION: 351.8 km from Saugus, CA
    Winquake data analysis display (gif image)
    Winquake geographic display (gif image)
    Time series data file (PEPP data format).
  - Latest quake detections from Dave's Seismograph Web Pages.
- From Ron Giachetti in Spokane, WA
  Seismometer: Mark Products 4.5 Hz horizontal geophone system with QM-4.5 electronics
  Location: on basement slab.
  Orientation: N-S.
  PC and Software: Amaseis, Winquake.
  - 02/18/2002 18:42:29 UT
    M3.2 NORTH OF MOUNT RAINIER: 342.6 km from Spokane, WA
    Winquake data analysis display (gif image)
    Winquake geographic display (gif image)
    time series data file (PEPP data format)
    COMMENT: P was visible but S was not.
  - Latest quake detections from Ron's Seismograph Web Pages.

QM-4.5 SPECIFICATIONS:
Here is my latest short-period, single-board, single-channel seismometer design :
- Printed circuit board (PCB) is designed to work with one Mark Products 4.5 Hz geophone #L15B.
- PCB works with either a horizontal (most available) or vertical geophones.
- Enclosure: Hammond 1590P diecast aluminum, 4.75x2.61x1.42 inches (121x66x36 mm)
- Shielded 9' serial cable with connector connects the geophone to the circuit board.
- Amplification is single stage, low noise, 1900x voltage.
- Amplifier chip: AD8628 auto-zero low noise, precision, rail-to-rail output, op amp.
- Low-pass filter: 8 pole Bessel filter lowpass cutoff set by capacitor to a 4.15 Hz.
- Filter chip: MAX7401CPA 8th order, lowpass, Bessel, switched capacitor filter.
- A to D: 16 bit covering a 0-4.95 volt range.
- Microprocessor: 8 bit, 4 mHz one time programmable PIC14000 with 16 bit A/D.
- Microprocessor software: burned into PIC14000, controls A to D, time integration, etc.
- Voltage regulator: micropower LP2950ACZ-5.0 with very low dropout voltage.
- Serial output rate is adjustable (by DIP switch) from 8 to 33.5 samples per second.
- Serial output 6' 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, where 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 sampling rate.
- You download 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.

PROBLEM REPORTS:
- RF Pickup As of 12/05/05 this problem seems to have been fixed by the metal enclosure, the revised circuit board, and the low-noise AD8628 opamp. The first 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. 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. A total elimination of RF pickup may require mounting the circuit board and sensor in a metal box.
- 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-4.5 system:
  - Getting Started with Amaseis:
    - To get started with Amaseis and the QM-4.5, all you have to is to plug the QM-4.5 into your PC serial port, and then start the Amaseis program. The first time you start the program you will have to set the DEVICE and the COM port in Amaseis. Pull down SETTINGS & DEVICE, select INFILTECQM1 for the QM-4.5. Amaseis defaults to COM port 1, but if you get an error message about the COM port, or an error message that says no data was found, theb pull down SETTINGS and COM PORT and select another serial port. You must restart Amaseis to change the COM port.
    - 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. DECIMATE does not change how data is stored on your computer hard drive, only how the display looks and how fast it can be redrawn.
    - Under the SETTINGS/HELICORDER pull down menu, typical values are GAIN=5 and LOW PASS=5(Hz). If you are looking for distant quakes, you may want to set your LOW PASS=1(Hz) and GAIN=20 so that you filter out some of the nearby noise. 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\2005\ or \2006\ data folder, or the month folders under the year \1\ to \12\ 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 Analog to Digital converter. This can be quite useful for debug.
    - If you plug the QM-4.5 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-4.5 board. If Amaseis can not find the COM port you have specified, 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-4.5 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.

ORDERING:
- You can pay by check, money order, credit card or PayPal. To start recording, all you need is to download the Amaseis software and plug the QM-4.5 serial cable into your PC serial port.
  OPTIONS: You may want to consider a serial (DB9 M/F) extension cable if you want to bury the geophone to reduce background noise pickup. The QM-4.5 has a built-in serial cable that is about 10 ft long, and a cable to the geophone that is about 6 ft long. I have some serial extension cables that are 10 ft, 25 ft, 50 ft, and 100 ft long.
  
  PRICES
  __ASSEMBLED short period seismometer mounted in diecast aluminum box for RF and thermal shielding
  1 QM-4.5-L15B assembled/tested pcb, diecast enclosure, 10' cable, L-15B geophone @ $159
  __KIT short period seismometer with diecast aluminum box for RF and thermal shielding
  1 QM-4.5-L15B kit: pcb, components, diecast enclosure, 10' cable, L-15B geophone @ $114
  __OPTIONAL PARTS
  1 QM-L-15B Mark Products 4.5 Hz Geophone (used but tested working) @ $40
  1 QM-ADXL103 accelerometer chip and components mounted on DIP8 board for QM-4.5 mounting @ $30
  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 USA by USPS Priority Mail with insurance, per seismometer @ $10
  1 Shipping outside USA by USPS Priority Mail with insurance, per seismometer @ $25
  --------------------
  
  MAIL ORDER: Print out our Order Form (text) and compute the cost of your order. Mail the completed form with a check or money order payable to Infiltec:
```
Infiltec Seismometers
PO Box 8202
Falls Church, VA 22041-8202

Phone: 703-820-7696
Fax: 703-671-9350
```
  Email: .
  CREDIT CARD ORDERS: you can order by credit card (MV/VISA/AMEX) by printing out our Order Form (text) . We will not bill your credit card until the order is shipped.
  PAYPAL ORDERS:
  QM-4.5-L15B assembled short period seismometer system shipped within USA ($159 + $10 = $169)
  
  KQM-4.5-L15B kit short period seismometer system shipped within USA ($114 + $10 = $124)
  
  QM-4.5-L15B assembled short period seismometer system shipped outside USA ($159 + $25 = $184)
  
  KQM-4.5-L15B kit short period seismometer system shipped outside USA ($114 + $25 = $139)
  
  Do not make a Paypal payment before your order is ready to ship.
  AVAILABLITY: It generally takes about two-four weeks to build and test your system, after I receive your order.
  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.
  TUNE UP: Any time I make improvements to the microprocessor firmware and/or circuit, you can return your board for these upgrades for $30.
  LATEST IMPROVEMENTS:
  051101: laid out pcb and had prototypes made.
  051020: found diecast box by Hammond (#1590) that provides EMF and thermal shielding.
  030131: reduced adc noise level by increased power supply noise bypass
  021126: increased SPS to 35 by PIC firmware modification, plus more uniform sample spacing

FUTURE PLANS:
- DONE-Draw circuit schematic.
- DONE-Lay out circuit board and fabricate.
- DONE Provide do-it-yourself kits including circuit board and parts.
- DONE- Develop a version of the system that encloses the electronics and sensor in a shielded box.
- Develop data logging software that automatically records significant events.
- Do you have suggestions? Please send them to .

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Seismometer Page.