How do I check the L-band reception status of my LD2/LD2S demodulator?
In order for the LD2 to provide a differential position and RTCM outputs, it must be locked to the correct communications satellite (referred to as “beam” or “channel”) for the current location.
The easiest way to check for lock is to observe the status of the Sync LED on the front panel.
If locked, the Sync LED will be steadily illuminated:
For more detailed information, and to determine which beam is selected, proceed as follows:
Repeatedly press *Page* until screen displays:
Press *Enter* and screen will display:
Press *Enter*, followed by *Page* to show:
Press *Enter* to access the Signal Status page:
This display is for an LD2 unit
This display is for an LD2S unit.
The displays show the following information:
- The text at the left of the top line IOR shows the name of the selected beam (satellite).
(The possible options are: AORW, POR, IOR, 25E, 109E and 98W. If Ch16 is selected the name entered in CH16 Edit page will be displayed)
- The remainder of the top line shows the signal quality.
- The LD2 displays a signal voltage (3.1V) and the BER (E-7).
Possible signal voltages are: 0.0v to 3.5v.
Acceptable values are: 2.0V to 3.5V
Possible BER (Bit Error Rate) values are: E-0 to E-7.
Acceptable valued are: E-5 to E-7.
Note: It is important to monitor the BER values.
It is sometimes possible to have high signal strength but a poor BER.
- The LD2S displays signal strength (40.2) in dB/Hz.
The possible range of signals is 32 – 48 dB-Hz
Values in the range 38dB-Hz to 47dB-Hz indicate a “good” signal
- The left of the bottom line shows the lock status (uuuu)
For correct operation, all four diamonds must be displayed.
(See table below for possible displays and their meanings.)
- The centre of the lower line shows the frequency offset (+000260Hz).
This will typically show values in the range +/- 3000Hz.
- The right of the lower line shows the service ID (ID-R or ID-V)
For correct operation this is ID-R for an LD2 and ID-V for an LD2S.
Note: Possible displays for the lock indicator are shown below. For correct operation, all four diamonds must be displayed.
||Reference Lock – Indicates that the internal synthesiser is locked and is independent of the received satellite signal.
||Symbol Lock – Indicates that symbol lock has been acquired.
||Carrier Lock – Indicates that carrier lock has been acquired.
||Frame Synchronisation – Indicates that frame synchronisation has been acquired.