INDEX :

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
8. P and S wave example

• Quick guide to setting up WinSDR

version 2 - 26 pin connector

version 2 - DB25 connector

version 3 - 26 pin connector

version 3 DB25 connector

version 1

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

 http://www.seismicnet.com/gps/gps18.html
 

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.

Earthquake P & S waves example