UK Community Base Station


The Laboratory of Geometronics(LOG) maintains a Trimble 12-channel Super Community Base Station that logs its antenna position determinations for Differential GPS (DGPS) positioning of a rover operating within 300 miles from Lexington, Kentucky area. UKCBS antenna position was surveyed to an accuracy less than 2 centimeters 2-d RMS horizontal and vertical.

Since September 1993, UKCBS has provided NAVSTAR GPS data for DGPS to the public free of charge. UKCBS GPS data are stored in hourly files in the self-extractable data format .EXE and are available for download ten (10) minutes after the hour. Although UKCBS data files are collected every hour of the day and every day of the year, only the latest ninety (90) days' hourly files are available for downloading. UKCBS station position and other parametric values are tabulated in UKCBS Position & Parameters.


UKCBS data can be downloaded through three methods:

1. Direct FTP through this link

2. FTP linking through the IP address:
LOGIN: anonymous
PASSWORD: your e-mail address


The Laboratory of Geometronics, University of Kentucky, provides
this GPS Data Service as a convenience for the general public. No
responsibility is assumed for damages or other liabilities due to
the use or misuse of this service.

UKCBS Position & Parameters

The file name scheme is Uymmddhh.EXE where:

U is the first letter of the CBS file - also called the BASE ID
y is the last digit of the year - 6 for 1996, 7 for 1997, etc.
mm is a 2-digit month number - 01 for Jan., 10 for Oct., etc.
dd is a 2-digit day number - 01 for the first day of the month etc.
hh is a 2-digit hour indicator. The hour is based on GPS time. 00 for the first
hour through 23 for the last hour of the day.
.EXE is always the extension/suffix of the CBS file name.

While measurements for all satellite in view are not recorded, UKCBS logs
synchronized measurements which contain full pseudorange and carrier phase
data. Synchronized measurements can be used for differential correction
(Measurement Space Correction) only if you have Pfinder version 2.5 or
later(with MCORR300 ver3.43).

If you use PFINDER v2.40 or earlier(with MCORR300 ver3.04 or earlier)
for differntial correction, you must use the SYNC2RAW standalone
utility program to convert synchronized measurements to raw measurements
before performing differential correction with the UKCBS data files.

Table of Parameters
Software-PFCBS V2.68
Firmware-NAV & SIG Proc.:3:08
Output Path C:\PFCBS\DATA
Auto Log Enabled
Autolog Time Start 00:00
Duration 23:59
Auto Exit Disabled
RTCM Disabled
Logging Rates Position 3
Measurement 0
Synced Msmt 3
Clock Offset 0
Clock Time UTC
Velocity 0
Reference Stn LAT 38-01-58.1010 N
LON 84-30-21.1750 W
ALT(HAE) 283.830 m
Antenna Type compact dome
Antenna Height 0 m
File Option Append File if Restart
Parameters Dynamic Static
Ele Mask 5
SNR Mask 6
PDOP Switch 6
PDOP Mask 6
Fixed Mode 2D/3D
Filter Constant 0.005
Health Action Heed SV health
Enable SV All
Baud 14400-2400
Parity No
Data Bits 8
Stop Bit 1
Full Duplex
Terminal ANSI
Protocol Any one of choice

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