Pioneer ARP3476, Руководство по обслуживанию

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PDP-5020FD
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5 6 7 8
A
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F
Generation of block noise
Factory
Depending on how block noise is generated, obtain the DTV tuning status.
(Two-page screen data, as indicated on the right)
Obtain the DTV tuning status for QAM256 and QAM64, regardless of whether noise
is generated or not. With a terrestrial- broadcast wave, obtain the status for VSB8 only.
Then, if noise is generated at a certain frequency but not generated at another
frequency even though the modulation method is the same, obtain the statuses for
both frequencies.
Timing of obtaining a status is 60 sec after the beginning of measurement.
Resetting of a measurement value can be done with the "
k
" or "
l
" key.
Is generation of noise dependent on the modulation method?
Screen example of DTV Tuning Status (Two-pages)
Check the modulation method with which block noise is generated.
QAM256 QAM64 VSB8
How to check the frequency and modulation method and how to obtain the status
• Is generation of block noise dependent on the frequency/modulation method?
→
Check the "Frequency" and "Modulation" items.
• Is the input level high enough?
→
Check the "IF AGC" item.
• Is the signal quality high?
→
Check the "C/N," "Error," and "BER" items.
Is generation of noise dependent on the frequency?
Press the Factory key.
INITIALIZE
Press the Mute key three times.
DTB SERVICE MODE
Press the "
j
" key twice then the Enter key.
Digital Tuner Service Menu
Press the "
l
" key to select YES for MODE SHIFT then hold the Enter key pressed for several seconds.
Digital
Select Digital from the menu then press the Enter key.
DTV Tuning Status
Select DTV Tuning Status from the menu then press the Enter key.
Check the frequency at which block noise is generated.
All channels Only at a certain frequency Not generated
Frequency
Check the frequency.
Is block noise generated at a particular frequency or on all channels?
If only at a particular frequency, a wireless LAN or another ambient electromagnetic disturbing
wave, such as a terrestrial-broadcast wave, may disturb the reception. If on all channels, the Assy
may be defective.
→
Replace the Assy and check the status to see if the symptom is cleared.
Modulation
Check the modulation
method.
With a cable modem, is block noise generated with QAM256 or QAM64 or both?
If noise is generated with either of them, the signal quality of the transmitting device may be low.
If noise is generated only with QAM256, the reception level or the C/N value may be low.
If noise is generated with VSB8, multiple paths may be the cause.
FEC LOCK
Check the status of the
demodulation IC. Check if LOCK is indicated.
Even if block noise is generated, LOCK is indicated if a picture is displayed.
IF AGC
Check the IF AGC
voltage.
Is the IF AGC voltage level high enough? The following table provides an indication of the level.
QAM256
QAM64 VSB8
less than 50 less than 55 less than 60
If the levels fall into the above ranges, usually noise is not generated (use the above ranges only as a guide.
They vary depending on the frequency).
If noise is generated even though the signal level is sufficient, ambient electromagnetic waves or multiple paths may
be the cause.
If the levels of all channels are low, the level of signal input to the ANT connector may be low.
Check the input signal level with a spectrum analyzer.
C/N
Check the C/N value.
Is the C/N value high enough? The following table provides an indication of the level.
QAM256
QAM64 VSB8
more than 30 more than 25 more than 18
If the level falls into the above ranges, usually noise is not generated (use the above ranges only as a guide.
They vary depending on the frequency).
BER(Pre)
Check BER of a
PreFEC error.
Was a PreFEC error actually generated? The following table provides an indication of the level.
QAM256
QAM64 VSB8
less than 1.000e-06 less than 1.000e-06 less than 1.000e-04
If the level falls into the above ranges, usually noise is not generated (use the above ranges only as a guide.
They vary depending on the frequency).
BER(Post)
Check BER of a
PostFEC error.
Was a PostFEC error actually generated? The following table provides an indication of the level.
QAM256
QAM64 VSB8
0.000e + 00 0.000e + 00 0.000e + 00
If the level falls into the above ranges, usually noise is not generated (use the above ranges only as a guide.
They vary depending on the frequency).
If noise is generated even though the value is in the range of 0.0E-00, an error may be generated at the B.E. block
(after the demodulation TS is output).
Time Measurement time
Accumulated measurement time
Uncorrected Error
Check the count of a
PostFEC error.
Was a PostFEC error actually generated? The following table provides an indication of the level.
QAM256 QAM64 VSB8
0 0 0
If the level falls into the above ranges, usually noise is not generated.
If noise is generated even though the error count is zero, an error may be generated at the B.E. block
(after the demodulation TS is output).
Corrected Error
Check the count of a
PreFEC error.
Was a PreFEC error actually generated?
QAM256
QAM64 VSB8
Indication - - -
Details on how to confirm the factory DTV tuning status