5 dtm-3237 protocol handler, 6 theory of operation, 7 list of abbreviations – DekTec DTM-3237 DVB-S2 Receiver User Manual
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DTM-3237 – OEM DVB-S2 Receiver with DVB-ASI Output
User Manual
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2. Using a controller on-board of the equipment that uses the DTM-3237 as co-processor board
for satellite reception. In this case I
2
C or LVTTL serial control port is a plausible choice for the
control interface, but USB interface can also be used. The I
2
C address and LVTTL serial control
port baud rate can be pre-configured through USB with Dtm3237Util. The factory-default I
2
C
address is 0x60 and the default LVTTL serial control port baud rate is 9600.
3. Stand-alone mode. The DTM-3237 is pre-configured and no dynamic control is applied.
Two control tools are available:
1. Dtm3237Util – Windows GUI tool to view status and control settings of the DTM-3237. The tool
can also be used to upload new firmware versions. Dtm3237Util is convenient for initial
configuration of the DTM-3237 and for experimentation with the DTM-3237.
2. DtmCmd – Command-line tool to send commands to the DTM-3237. Multiple commands can
be combined in a script to apply a group of settings in one go. DtmCmd is useful for studying
the low-level commands available for the DTM-3237. It is also useful to apply a pre-defined
group of setting values from a script.
1.5 DTM-3237 Protocol Handler
For developers that implement their own application controlling the DTM-3237, an open source
implementation of a protocol handler for DTM-32XX devices is available. It can be downloaded from
free of charge, and can be used royalty-free. It consists of two source files,
DtmHandler.c
and
DtmHandler.h
, which can be compiled and linked into your C or C++
application. Please refer to
DtmHandler.h
for information about how to integrate the protocol
handler in your application.
Note:
The command-line control tool DtmCmd is an example of an application that uses the DTM
handler. The source of DtmCmd is also available on the DekTec website. Please refer to
Appendix C for more information about DtmCmd.
1.6 Theory of operation
Essentially, the DTM-3237 consists of two subsystems:
A tuner, demodulator and stream processor, converting the modulated DVB-S(2) input signal to
a Transport Stream or L.3 Baseband frames on DVB-ASI;
A processor subsystem that handles all internal/external control (USB, I
2
C, LVTTL serial control).
1.7 List of abbreviations
ACM
Adaptive coding and modulation
APSK
Amplitude and phase-shift keying
ASI
Asynchronous serial interface. Shorthand for DVB-ASI.
BCH
Cyclic error-correcting codes, abbreviation comprises the initials of its
inventors names (inner FEC coding used for DVB-S2)
BER
Bit error rate
CCM
Constant coding and modulation
CNR
Carrier to noise ratio