Real-World Technology NIMs
Real-World Technology Ltd
Network Interface Modules
Click here for the big picture (thanks Mitel Semiconductors)
RWT is now working with customers on a range of Network Interface Modules,
for Satellite, Cable and Terrestrial applications.
The NIM is the Channel Receiver or Front-End Module of a digital set-top box, taking the RF input,
tuning, filtering, downconverting, digitising and demodulating it, performing carrier and symbol clock recovery
and forward error correction operations, and delivering the MPEG transport stream to the transport demultiplexer.
The RF input is an analog signal whose frequency range and modulation characteristics differ
according to the delivery system.
In the DVB world:
- For Satellite (DVB-S), frequency range (from LNB) is 950 to 2150 MHz and modulation is QPSK
- For Cable (DVB-C), frequency range is 45 to 750 or 862 MHz and modulation is QAM
- For Terrestrial (DVB-T), frequency range is 470 to 862 MHz and modulation is COFDM
As an example of our work, the above picture shows a compact satellite NIM developed by RWT for
GEC Plessey (now Mitel) Semiconductors,
to promote GPS's 5-chip satellite front-end solution. The NIM can be built in module form as shown,
or integrated onto the main board of the set-top box. The photo shows the board, which measures
96 x 40 mm, without the tuner shielding in place. Mitel are unique in offering the tuner devices
as well as the demodulator and decoder silicon, and they are currently in licence discussions with
a number of receiver manufacturers, world-wide. A new version is currently in development for 1-45 MS/s,
featuring a brand new demodulator device from Mitel.
Mitel satellite NIM Features and Outline Specification:
Functionality
- Complete front-end solution
- L-Band in, MPEG2 transport stream out
- 20-30MSymbols/s
- Fully DVB compliant
- I2C software control
Mechanical/production
- Only 40 x 96mm
- Can be installed like a traditional RF tuner module
- Design can be implemented directly on motherboard
- Standard surface mound technology on one side only of PCB
- Production alignment free
- Standard production tolerancing used throughout
- Two-layer FR4 PCB
- Simple test methodology
Support
- Complete evaluation kit available
- Windows-based evaluation software supplied
- Full support package including PCB layout files
- Generic 'C' code available for production applications
Commercial
- (Contact Mitel Semiconductors)
Specification
- RF input range 950MHz to 2.15GHz
- Input dynamic range (operation) -70 to -20 dBm
- Input dynamic range (no BER degradation) -65 to -25 dBm
- Image rejection (typ) 45dB
- Input noise figure (max) 12dB
- Input impedance 75 ohms
- Input return loss (min) 8dB
- LO tuning increment 125kHz
- Second IF 479.5 MHz
- IF bandwidth (3dB) 36 MHz
- MPEG transport stream output parallel, 3.3V TTL
- Software control I2C fast mode compliant;
Tuner controlled via VP306 or direct from micro;
I2C-controlled general purpose I/O available
for control of LNB polarisation and band selection.
- Symbol Rate 20-30 MSymbols/s
- Viterbi and R-S parameters as DVB specification
- LNB/Polarisation control: Transparent to LNB voltage, 22kHz and DiSEqC
- Dish alignment output: AF tone
- Connectors: RF - F type, 44-pin 2mm pitch edge connector
- Supplies (typ): 3.3V @ 350mA; 5V @ 375mA; 28V @ 3mA (all at 27.5 MS/s)
- Dimensions (approx) 96 x 40 x 22.5mm
-- Please note this is only one example of an RWT NIM design
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