Note: FReDNet RAW files are Ashtech raw files and share the following naming: UnameAyr.doy

example: UZOUFA02.174 was collected from ZOUF, doy 174, year 2002

RINEX files:

The first proposal for the "Receiver Independent Exchange Format" RINEX was developed by the Astronomical Institute of the University of Berne for the easy exchange of the GPS data collected during the large European GPS campaign EUREF 89, which involved more than 60 GPS receivers of 4 different manufacturers.

Most geodetic processing software for GPS data use a well-defined set of observable:

• The carrier-phase measurement at one or both carriers (actually being a measurement on the beat frequency between the received carrier of the satellite signal and a receiver-generated reference frequency).
• The pseudorange (code) measurement, equivalent to the difference of the time of reception (expressed in the time frame of the receiver) and the time of transmission (expressed in the time frame of the satellite) of a distinct satellite signal.
• The observation time being the reading of the receiver clock at the instant of validity of the carrier-phase and/or the code measurements.

Usually the software assumes that the observation time is valid for both the phase AND the code measurements, AND for all satellites observed.
Consequently all these programs do not need most of the information that is usually stored by the receivers: They need phase, code, and time in the above mentioned definitions, and some station-related information like station name, antenna height, etc.

The Description of RINEX [Gurtner et al, 1989] states that any receiver-dependent calibrations (delays) have to be applied to observable, any intentional internal offsets removed, but neither the code nor the phase observable are to be corrected by the influence of satellite or
receiver clock offsets. The time tags are defined in GPS time (not UTC).

There are two important pieces, of information which are (or may be) receiver or antenna dependent:

1. Phase measurements performed on the original or the squared carrier. Ambiguities (and cycle slips) have to be formulated on either full-cycle or
   half-cycle level.
2. The (average) phase center eccentricity for a specific antenna type, an information which is important as soon as different nstrument/antenna
   types are to be combined

RINEX files consist of a header section containing station/receiver/antenna related information and a main body with the actual data. The files have a maximum record length of 80 characters and are written in ASCII to guarantee an easy exchange between different computer systems.
As soon as the data are exchanged in such a receiver-independent way only the provider of the data has to have available the means to interpret the instrument's raw data and format it into RINEX. Moreover, only the author of such a translator program has to really understand the definitions and the formats of the original raw data. Theoretically one such program per receiver type is necessary. This implies of course that every processing software accepts RINEX as standard (or optional)input format.

RINEX defines 6 different file types:

FILE	NAME
Observation Data File*	aaaaddds.yyo
Navigation Message File	aaaaddds.yyn
Meteorological Data File	aaaaddds.yym
GLONASS Navigation Message File	aaaaddds.yyg
GEO Navigation Message File	aaaaddds.yyh
Satellite and Receiver Clock Date File	aaaaddds.yyc

* You could also find the following file name: aaaaddds.yyd which indicates compressed Observation Data File (Hatanaka compression)

where:

• aaaa = alphanumeric 4-character station identifier;
• ddd = day of year (doy);
• s = session;
• y = year of observations;