Setup Manual

Device View Description
R&S
®
Tx9
207Operating Manual 2109.9110.02 ─ 07
Name Description Value range Access right
Guard Time (regulator) This value defines for how many hours the signal pro-
cessing should continue running without synchroniza-
tion if the reference connection fails. The Guard Time is
active only if the "Freq Stability" was "Good" at the time
of the failure. The longer the time selected is, the
poorer the accuracy of the transmitting frequency will
become. In addition, the time of transmission of the sig-
nal shifts. If this uses up the guard interval, reception
problems occur in single‑frequency networks.
0 to 24 hours Maintenance
Jitter Correction (Guard
Time)
When using an external reference source with high jit-
ter, activating this function can provide better frequency
stability. With "Good" reference signals, this function
should be disabled as the regulator takes significantly
longer to attain its maximum frequency stability. When
the internal GPS is used, this function is enabled auto-
matically.
On, Off Maintenance
4.11 Switchless Combiner
The switchless combiner couples the RF output signals of two racks and feeds the total
power to the antenna. If a rack has a power drop, the switchless combiner ensures
maximum output power at the antenna by a continuous shift of the phase angle.
Operating principle
The switchless combiner consists of two 90-degree couplers and an RF tube of varia-
ble length (referred to as a trombone). Changing the length makes it possible to gener-
ate a variable phase shift between the two inputs. If there is a complete power drop at
an input, the power of the other input can be fed to the antenna without loss. If there is
a partial power drop at one of the two inputs, the power dissipation in the absorber is
minimized by adjusting the phase angle.
Commissioning
During commissioning, the position of the trombone has to be calibrated for different
phase angles. To do so, connect an external power meter to the absorber of the
switchless combiner.
The calibration process consists of the following work steps:
●
Start the calibration process.
●
Set the switchless combiner to "local".
●
Switch the signal of input 1 off.
●
Press the up/down buttons on the switchless combiner to set the trombone so that
the power dissipation at the absorber is minimal.
●
Press "Save Position"
.
●
Switch the signal of input 1 on and of input 2 off.
●
Press the up/down buttons on the switchless combiner to set the trombone so that
the power dissipation at the absorber is minimal.
Switchless Combiner