Philips 221TE2LB/00 Service Manual page 90

90 221TE2L LCD
General Product Specification
4.4.5 FINDING A MULTIPLEX
The iDTV shall initiate a multiplex search, and the user shall be able to enter any frequency manually
and choose between 7Mhz and 8Mhz bandwidth. The iDTV shall then be able to find all DVB-T
modulated multiplexes with center frequencies +/-Bandwidth around the manually entered frequency.
If there are no multiplexes in the scanned spectrum, the user shall be told so via the UI.
The iDTV shall automatically scan the grids as specificed.
The iDTV shall be able to find both DVB-T multiplexes in an hierarchically modulated stream. The
multiplexes are referred to as the high and low priority streams. The iDTV shall handle these streams
as two independent multiplexes. For each of these multiplexes, a separate Transport Stream Service
List (TSSL) shall be created.
Service installation shall additionally locate analogue TV transmissions (PAL and SECAM) in the VHF
and UHF frequency bands (both off-air and cable channels).
Once a multiplex is found, the iDTV shall store the parameters needed to tune back to this multiplex
in the TSSL. These parameters are, at least:
1. The Center Frequency
2. The Bandwidth
3. Whether this was hierarchical, and if so, whether the LP or HP was choosen
4. Constellation
The multipex's reception quality is a function of the BEQ, QE and quality of the LP and HP if
appliciable.
Along with the tuning parameters of a multiplex, the iDTV shall also store the multipex's Reception
Quality in the TSSL.
This table shows that a algorithm to calculate the reception quality could be based on a combination
of C/N and BER
4.4.6 STORING ALL FOUND SERVICES IN THE MSL
The Master Service List is frequency oriented. It may be viewed as list of lists. The top level list, is a
list of frequencies. At each frequency, there are either one or two TSSLs depending on the
modulation. For a hierarchically modulated signal, there will be two TSSLs, one for HP and one for
LP. For a not hierarchically modulated signal, there will be just a single TSSL.
During initial install, when the MSL is empty, all of the TSSL's found during a complete scan are
stored in the MSL.
At an update installation, the MSL has already been filled with all of the TSSL's that were found after
previous scans. In this case, the TSSL will be merged in the MSL.
If the frequency in the new TSSL is not in the MSL, then the entire TSSL is added to the MSL
If the frequency in the new TSSL is not new, and the modulation is the same, the new TSSL will
replace the old one in the MSL.
If the frequency in the new TSSL is not new and modulation scheme is different, then the old TSSL (2
if it was hierarchical) is deleted and replaced by the new one. If the modulation scheme changed to
hierarchical, then two TSSL's will replace the single one that was there before.
© MMD 2010 Page 27 of 45