User's Manual Part 1

CL1TC-4 400W DVB-H Transmitter Commissioning and Operation
Product Manual, Rev. 1 44
5.5.1.1 Broadcast Mode
The transmitter normally operates in broadcast mode,
allowing it to transmit a broadcast
signal and run all protection loops and ALC. It receives a transport stream signal, or
generates an internal test signal and transmits an OFDM signal for terrestrial broadcast. In
this mode, all transmitter functions are automatically maintained by the modulator
controller.
To operate in broadcast mode, the following conditions must be met:
• The transmitter must be receiving an input signal and be locked to the input stream
(if the modulator is in test mode, the input signal presence is ignored).
• The ALC loop must be running.
• For Single Frequency Network (SFN) operation, the system must have a GPS signal
lock with no alarms (if the modulator is in test mode, the GPS signal presence is
ignored).
• There must be no modulator alarms.
• There must be no HPA alarms.
5.5.1.2 Standby Mode
In t
his mode the transmitter output is muted by turning the HPA RF switch off and muting
the modulator output.
The operating conditions in Standby Mode are:
• AC power is supplied to the modulator and HPA
• The HPA RF switch is off
• The modulator output is muted
5.5.2 Modulator Operating Modes
The five mo
dulator modes are: Normal, CW, Test 1 (Carriers Removed), Record and
Playback.
In Normal mode, the modulator generates a complete DVB-H waveform. CW and Test 1 are
special test modes not used in regular operation. The CW mode generates a narrow-band
frequency tone and the Test 1 mode suppresses a set of OFDM carriers in the center of the
band (useful for checking for interference, factory configurable). Record and Playback are
described in Section 6.4.1
.
5.6 Indicators and Controls
T
he transmitter main subassemblies have individual indicators and controls used in normal
operation. This includes:
• DVB-H Modulator
• HPA