DTC Communications Inc. VMDTX100C 用户手册
11
PROGRAMMING
Transmitter Control Application
RF Output
This control is used to turn the RF output on and off. Turn the transmitter RF power on by selecting
COFDM.
COFDM.
Output Frequency (MHz)
The Output Frequency setting allows selection of TX output frequency in increments of 0.25 MHz within
the allowed tuning range of the unit. If the unit is set to a frequency that is not an integer multiple
of 0.25 MHz, the unit will be automatically set to the closest frequency that is an integer multiple of
0.25MHz. An error message will pop-up warning you that the frequency will not be exactly as specified.
the allowed tuning range of the unit. If the unit is set to a frequency that is not an integer multiple
of 0.25 MHz, the unit will be automatically set to the closest frequency that is an integer multiple of
0.25MHz. An error message will pop-up warning you that the frequency will not be exactly as specified.
RF Bandwidth (MHz)
The actual channel bandwidth that the wireless video link will occupy. The DVB-T compliant mode
requires a bandwidth setting of 6, 7 or 8 MHz. The narrowband mode bandwidth is either 1.25 or 2.5
MHz. Narrower bandwidths increase receiver sensitivity and extend the maximum distance of the link,
however video quality and latency will suffer. Normal default for good quality video is 2.5MHz. The
modulation bandwidth may be set to 1.25, 2.5, 6, 7, or 8 MHz.
requires a bandwidth setting of 6, 7 or 8 MHz. The narrowband mode bandwidth is either 1.25 or 2.5
MHz. Narrower bandwidths increase receiver sensitivity and extend the maximum distance of the link,
however video quality and latency will suffer. Normal default for good quality video is 2.5MHz. The
modulation bandwidth may be set to 1.25, 2.5, 6, 7, or 8 MHz.
RF Output Power
Output power selects one of two output power attenuator settings; low power or high power,
typically the low power setting is the larger of the two attenuator settings and is used, for
instance, if a power amplifier is added to the transmitter and the output power needs to be
lowered substantially to prevent overloading the input of the power amplifier.
Attenuation - High RF pwr (dB)
Output attenuation (dB) is the high power attenuator setting, and is set at the factory for
narrowband mask conformance*.
Attenuation Low RF pwr (dB)
Output attenuation low (dB) is the low power attenuator setting, and is set at the factory for
DVB-T mask conformance*.
Output power selects one of two output power attenuator settings; low power or high power,
typically the low power setting is the larger of the two attenuator settings and is used, for
instance, if a power amplifier is added to the transmitter and the output power needs to be
lowered substantially to prevent overloading the input of the power amplifier.
Attenuation - High RF pwr (dB)
Output attenuation (dB) is the high power attenuator setting, and is set at the factory for
narrowband mask conformance*.
Attenuation Low RF pwr (dB)
Output attenuation low (dB) is the low power attenuator setting, and is set at the factory for
DVB-T mask conformance*.
*The value is set at the factory for mask conformance across the full transmitted frequency and ambient
temperature ranges (assuming DTC-standard heatsink is attached for ambient temperatures >50 deg.C.
This control can be used to make minor adjustments to the output power level, but in normal operation
should NOT be changed from factory settings. (0 attenuation = full output power, greater than 0
attenuation = reduced power in 0.25 dB steps.)