1. Garmin OEM GPS 18LVC Firmware update
  2. Garmin OEM GPS 18LVC 9 pin plug wiring
  3. PSN-ADC Serial Board  version 1
  4. PSN-ADC Serial Board version 2
  5. PSN-ADC Serial Board version 3
  6. One to Four channel amplifier / filter board.
  7. Gain adjustment, amplifier board

Firmware Upgrade Information:
Garmin is now shipping a new version of their OEM GPS 18 LVC receiver. The new receiver, the GPSx 18 LVC, has better sensitivity then the older model. The new receiver required a minor change to the PSN-ADC-SERIAL firmware to operate properly. Version III ADC board users should use firmware version 1.2. Version II ADC board users should use firmware version 2.8. To upgrade the firmware, download the appropriate zip file, unzip, copy the .hex file to your WinSDR install directory and then follow these directions..(also link to downloads). Version III ADC boards started shipping with firmware version 1.2 December 8 2008.http://www.seismicnet.com/serialatod.html#NewFirmware

  • Quick guide to setting up WinSDR

Important driver update

FTDI Driver for PSN-ADC-USB Board

Download this driver if you have the new Ver3_USB board


Garmin OEM GPS 18LVC

information on PSN- Boards and pictures credit http://www.seismicnet.com/

Version 1 PSN board


Ver2_ board_DB25

version 1


version 2 - 26 pin connector


version 2 - DB25 connector





version 3 - 26 pin connector


version 3 DB25 connector


version 3 USB connector - 26 pin or DB25


Gain Adjustment:

  • Each channel has a two-pin jumper that controls the gain of the first op-amp. With the jumper in, the gain of the board will be ~145 to ~1700. This range should be used with sensors that have a high output voltage, like a geophone. With the jumper removed, the gain range is ~600 to ~6000. This input range should be used with sensors that produce less of an output voltage.
  • Each channel also has a variable gain stage with a range of 1x to 10x. The gain trim pot for each channel is marked "Gain" next to the part. When setting up your system, the user should first try the board with the gain jumper removed and the gain pot turned to minimum (fully counter clockwise). If there is too much signal the jumper should be inserted and the gain pot adjusted if needed.
  • If there is still too much signal you will need to reduce the voltage from the sensor by using a resistor divider (schematic). Each channel as a 10k resistor to ground unless you specified a different input impendence. This resistor can be used as one leg of the divider. The other resistor is placed in the signal path. A 10k resistor will reduce the voltage by 2 and a 100k resistor will reduce the voltage by 10. If you have a long wire between the sensor and the input to the board the resistor in the signal path should be placed near the Amp/Filter board.

9-Pin Serial Connector Pinout

The Garmin GPS18x LVC receiver is shipped from the manufacturer with a small JST test connector. This connector is removed and a 9-Pin RS-232 female connector is soldered to the end of the cable. This is done so the receiver can be plugged into the 16 Bit PSN-ADC-SERIAL Analog to Digital Converter board. Below is the pinout and wire color of the 9-Pin connector

Pin 1 - One pulse per second output. This is the DCD or Data Carrier Detect line. (Yellow Wire)
Pin 2 - Serial Data Output from the Receiver (White Wire)
Pin 3 - Serial Data Input to the Receiver (Green Wire)
Pin 4 - + 4.0 to 5.5 Volts DC Power Input (Red Wire) Note 1
Pin 5 - Ground (Black Wires) Note 2
Pin 6 - Not Connected
Pin 7 - Not Connected
Pin 8 - Not Connected
Pin 9 - Not Connected
Note 1: USB Power Option. USB +5VDC connected to pin 4
Note 2: USB Power Option. USB Ground connected to pin 5


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