Javad Maxor, Руководство пользователя

Страница: 25 / 142

www.javad.com Maxor User’s Manual 1-5
I N T R O D U C T I O N
Receiver Overview
–Five or more visible satellites for only GPS or only GLONASS; six or more
satellites for mixed scenarios.
–Current ephemerides and almanacs.
–Several algorithms to detect and correct faulty information.
Conclusion
GNSS users can use JNS GNSS receivers to collect data from a network of satellites and
control stations to triangulate precise points anywhere on Earth.
This overview simply outlines the basics of GPS and GLONASS positioning. For more
detailed information, visit the JNS website (www.javad.com).
Receiver Overview
When power is turned on and the receiver self-test completes, the receiver’s 20
channels initialize and begin tracking visible GNSS satellites. Each of the
receiver’s channels can be used to track C/A-L1, P-L1, or P-L2 signals. The
number of channels available allows the receiver to track all visible satellites at
any time and location. The antenna receives the different signals for processing.
An internal antenna equipped with a low noise amplifier (LNA) and the
receiver’s radio frequency (RF) device are connected with a coaxial cable. The
wide-band signal received is down-converted, filtered, digitized, and assigned
to different channels. The receiver processor controls the process of signal
tracking.
Once the signal is locked in the channel, it is demodulated and necessary signal
parameters (carrier and code phases) are measured. Also, broadcast navigation
data are retrieved from the navigation frame.
After the receiver locks on to four or more satellites, it is possible to solve the
so-called “absolute positioning problem” and compute the receiver’s
coordinates (in WGS-84 or another datum) and time. All this information is
stored in the receiver’s memory, which can be downloaded later onto a
computer and processed using a post-processing software package. When the
receiver is run in RTK mode, raw data measurements can also be recorded into
the receiver’s internal memory. This allows the operator to double check real-
time results obtained in the field.
Depending on your options, capabilities of the receiver include:
• Common Tracking