Cable AML Inc ITX02-2000 Manual De Usuario

Indoor Broadband Transmitter – ITX02-2000 

7 

IM402513-10  Rev – 

The ITX02-2000 Transmitter consists of the following circuits or modules: 

1.  MMDS Transmitter Driver  
2.  Power Amplifier  
3.  Power Supply System (three +12 VDC current sharing modules and one +24 VDC 

power supply) 

4.  Monitoring and Diagnostic Circuits - connectors and switches.   
5.  On-Delay Timer Assembly. 
6. Internal 

Downconverter. 

 

In addition, microwave isolators and filters are used as necessary to ensure the stability and 
purity of transmitted signals.  

The MMDS Driver is comprised of the following major functional circuits or modules: 

1.  Local Oscillator (LO) 
2. Upconverter/Mixer 

 

3. Filter 

Assembly 

4.  Microwave Low Noise Amplifier 
5. DC 

Diagnostics 

6. Power 

Supply 

 

The microwave local oscillator is a crystal oscillator and frequency multiplier encapsulated in a 
single enclosure.  The output of the LO provides pump power to the signal upconverter.  The LO 
is powered by a +12 VDC power supply.  The long-term frequency stability of the oscillator is 5 
parts per million per year. 

The translation from VHF to microwave frequencies takes place here.  The mixer is also called 
an "upper sideband upconverter".  The desired output of the upconverter is a signal at a 
frequency, which is the sum of the local oscillator and VHF input frequencies.  The upconverter 
also generates unwanted signals which have to be filtered out, among them the "lower 
sideband", LO leakage, and others. 

There are two filters.  The group bandpass filter is tuned to pass the upper sideband.  The notch 
filter is tuned to attenuate the local oscillator leakage without affecting the output signal.