Promax US TV EXPLORER II, User Manual

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USER’S MANUAL. US TV EXPLORER II
01/2008 Page 63
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With the aim to have a reference about the signal quality, it is considered that a
system has a good quality when it decodes less than one non-correctable error for
every transmission hour. This border is known as
QEF ( Quasi-Error-Free ) and it
corresponds approximately to a BER after Viterbi of 2.0E-4 BER (2.0x10
-4
). This value
is marked on the measurement bar of the BER after Viterbi and therefore, BER for
acceptable signals must be at the
left side of this mark.
Next it is shown the tuning frequency and the frequency deviation in MHz
between the tuned frequency and the one which optimizes the BER ( i.e. Freq: 1777.0
+ 1.2 MHz ).
Finally it is shown a status line with information about the detected signal. The
possible messages that can appear and its meaning are shown in the following list. The
messages are exposed from less to more fulfillment of the
MPEG-2 standard:
No signal received
Any signal has been detected.
Signal received
A signal is detected but it can not be decoded.
Carrier recovered
A digital carrier has been detected but it can not be decoded.
Viterbi synchronized
A digital carrier has been detected and the Viterbi algorithm is synchronized, but
too many frames arrive with non correctable errors. It is not possible to quantify
the BER.
MPEG-2
Correct detection of a MPEG-2 signal.
5.14.8 Digital TV: Measuring MER
Once determined the suitable parameters for 8-VSB , QAM Annex-A , QAM
Annex-B or QPSK/8QPSK signal reception, it will be possible to measure MER , press
[12] key until it appears the MER measurement screen.