Table of Contents
Advertisement
RC2000A Dual Axis Antenna Controller Appendix I
Signal Strength Peakup
113
1.2.4 What to do if Problems are Found
For a type (iii) problem in the absence of type (i) or type (ii) problems. the pot adjustment procedure can
be performed again using the transponder/satellite where saturation was encountered as the 'on
satellite' signal.
For type (i) or type (ii) problems, it may be possible to adjust the Threshold values up or down. For a
given AGC input (receiver), if type (i) problems are encountered for one band and type (ii) problems are
encountered for the other band, the insertion of pads (attenuators) or amplifiers in the IF line can
sometimes help.
If problems persist the usual culprit is gain flatness. An amplifier's gain vs. frequency characteristic, or
gain flatness, is the variation of the amplifier's gain with changing frequency. The ideal response is to
have a flat gain characteristic (the gain does not vary with frequency).
There are four places in a satellite receiving system that may have gain flatness problems that can
affect the peakup operation. These are the LNB, the coaxial cable connecting the LNB to the receiver,
line amps (or bullet amps) inserted in the 950 - 1750 MHz IF, and the receiver's IF or AGC stages. If a
spectrum analyzer is connected into the receiver's block IF line, the gain flatness of the LNB and any
line amps present can be observed. When the antenna is pointed away from any satellite, the spectrum
analyzer displays the received noise, which should be constant with frequency. If the display is not
horizontal then some gain variation with frequency is present. The type (i) test above is essentially a
test of gain flatness.
Most gain flatness problems can be traced to a problem with the coaxial cable connecting the antenna
to the receiver (sometimes called a 'suck-out') or to bullet amplifiers. Some bullet amplifiers have been
observed to have really terrible gain flatness characteristics.
2.0 Signal Strength Peakup
This version of the software includes optional support for a signal strength peakup function after an auto
move to a satellite. The software version number indicates whether or not the software installed in a
given controller supports the peakup function. The controller displays it's software version on power-up.
Controllers that have a software version number that ends with '5', '6', '7', '8', or '9' support the peakup
function. Controllers that have a software version number that ends with '0', '1', '2', '3', or '4' do not
support the peakup function. This section pertains to controllers that support the automatic peakup
function.
2.1 Enabling Peakups and Configuring Peakup Parameters
To use the peakup feature several controller CONFIG mode items have to be configured properly and
peakups have to be enabled.
2.1.1 Enabling Peakups
To implement the peaking function the controller requires an analog input voltage that varies with
received signal strength (0 to 10 volts DC max range). This voltage is typically provided by a receiver or
modem AGC (Automatic Gain Control) circuit. The interface of this analog voltage to the controller is
described in section two.
On controllers that support the peakup function, peakups can be enabled via the Peakup Enable
CONFIG mode item. When enabled, peakups will follow an automatic move either initiated via the front
panel or via certain commands received via the controller's serial port.
Peakups initiated by the user via the controller's user interface occur at the conclusion of automatic
move commands. At the completion of the automatic move, if peakups are enabled and the Peakup
related CONFIG mode items are valid, a peakup is initiated. Note that invalid Peakup related CONFIG
mode items will result in display of a flashing 'PEAKUP CONFIG' alarm message on the bottom row of
the controllers LCD.
Research Concepts, Inc. • 5420 Martindale Road • Shawnee, Kansas • 66218-9680 • USA
www.researchconcepts.com
Advertisement
Table of Contents
Troubleshooting
