Technical Instruction
Table Of Contents
- Nautel Limited
- MODULE EXCHANGE SERVICE
- 6.1 INTRODUCTION
- 6.2 WIRING LISTS NOT PROVIDED
- 6.3 PRINTED WIRING PATTERNS
- 6.4 WIRE COLOURS
- 5.5 WIRING LISTS PROVIDED
- 7.1 INTRODUCTION
- 7.2 COMPONENT VALUES
- 7.3 GRAPHIC SYMBOLS
- 7.4 LOGIC SYMBOLS
- 7.5 REFERENCE DESIGNATIONS
- 7.5.1 Types of Inputs/Outputs
- 7.5.2 Logic Level/Convention
- 7.7 IDENTIFICATION OF SCHEMATIC DIAGRAMS
Page 3-8 VSHD Exciter Technical Instruction Manual
Issue 2.0 Section 3 Operation
- IBOC Injection (Upper): for FM+HD and HD modes, enter value, in dB, between -20
and -10 dB for the IBOC injection level of the lower sideband of digital carriers. This
value determines the relationship between the digital carriers power and the analog
carrier power. Example: -20 dB indicates that the total RMS power of the digital carriers
will be 1/100 of the total RMS power of the analog carrier. -10 dB indicates that the total
RMS power of the digital carriers will be 1/10 of the total RMS power of the analog
carrier.
NOTE
The actual digital sideband power is 3 dB less than that indicated in the upper or lower IBOC
Injection fields; Example: if -20 dBc is entered in the upper and lower IBOC Injection fields,
the upper and lower digital sideband power levels are actually -23 dBc; this way, when
added, the resultant total digital power level is -20 dBc.
For symmetrical sideband transmission: if -14 dBc IBOC Injection level is desired (total digital
power of upper + lower sidebands is 4% of analog carrier power), set the upper and lower
IBOC Injection levels to -14 dBc.
For asymmetrical sideband transmission, account for the fact that the actual sideband power
level is 3 dB less than that shown. For example, if the upper digital sideband IBOC Injection
level is entered as -14 dBc, the actual power level will be -17 dBc. This is equally true for the
lower digital sideband.
- HD PA Volts: for FM+HD, HD and DRM+ modes, enter value, in volts, between 30.0 V
and 53.0 V (default is 53.0 V). This value sets the drain voltage applied to the PAs in the
RF power modules, from their associated power supplies. This value affects
IBOC/DRM+ performance. Larger values result in an improved spectrum, but decreased
efficiency. Conversely, smaller values result in improved efficiency, but degrade the
spectrum. Typical values are between 35 V and 50 V, and depend on many variables
such as power level, frequency and injection level. You can also use the HD Optimizer
feature in the front panel UI to maximize your transmitter’s performance (refer to the VS
transmitter`s Operations and Maintenance manual).
- HD PowerBoost Priority: for FM+HD only; select either MER (modulation error ratio or
signal quality; default setting) or Efficiency.
Selecting MER minimizes the aggressiveness of the HD PowerBoost function and
makes maximizing MER the priority. Transmitter efficiency and power capability will be
reduced as a result.
Selecting Efficiency maximizes the aggressiveness of Nautel’s HD PowerBoost process,
an advanced peak-to-average power ratio reduction algorithm that prioritizes efficiency
and power capability when reducing the peak-to-average ratio, while ensuring that the
MER of the transmitted HD signal meets transmission requirement.
NOTE
HD PowerBoost is now standard as of VS SW 4.4. Transmitters shipped prior to VS SW 4.4
that haven’t been upgraded may get 3 dB foldback and associated license alarms if “Priority
Efficiency” is selected. Nautel recommends upgrading the software to VS SW 4.4 or later.