User`s manual

100-M0056X2B 24 of 28
www.cobham.com/gms
Output Power: Up to100mW (programmable) [200mW on some models]
Connector: SMA-F
Note: Transmitters should not be powered on without a load. Doing so could cause
the output PA to stop working. A proper heat sink is also required.
8.6 Modulation
Modulation Type: COFDM w/ QPSK, 16 QAM or 64 QAM
FEC: ½, 2/3, ¾, 7/8
Guard Intervals: 1/32, 1/16, 1/8, 1/4
Spurious: 50dBc
Number of C-OFDM Carriers: 2k
C-OFDM MER: > -45dB
Standard: DVB-T compliant
8.7 Power
MDT (Frequency 1 to 6GHz In-Bands
DC Input Voltage Range: 9 to 15 VDC
Power Consumption: 10Watts
8.8 Physical Dimensions (without mating connectors)
MDT (Frequency 1 to 6GHz In-Bands
Size: 3.25 in. (W) x 4.5 in. (D) x 1.76 in. (H)
(8.26 cm x 11.43cm x 4.47cm)
Weight: 13.4 oz
(380.5grams)
8.9 Environmental
Operational Temperature: -10 to +70 °C
Humidity: Up to 100% (non-condensing)
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9.0 The D/C (Down Converter)/IF frequencies explained
9.1 If Frequencies
• MDR-B receivers (and many other digital receivers) are capable of receiving direct frequencies in
the range of approximately 49 MHz to 861 MHz. If the transmitter is not in this range then a
down-converter is used to convert the frequency to this range. The frequency out of the down-
converter is called the IF (intermediate frequency) which is fed to the receiver.
Down-converters have a LO (local oscillator) which is mixed with the transmitter frequency (MDT-
B) and converts it to the IF frequency. MDR-B receivers need to know the LO (local oscillator) of
the down-converter and is factory programmed with this information. It then automatically
calculates the IF frequency once the RF (transmitter frequency) is entered. Thus as the desired RF
frequency is dialed in on the MDR-B the IF is taken care of automatically. For example, if the
transmitter frequency (MDT-B) is set for 2000 MHz, then the MDR-B can be set for 2000 MHz (it
automatically calculates the IF frequency based on pre-programmed LO information of the down-
converter). The IF frequency changes as the RF frequency changes, the LO remains constant.