Drake EH24A/EH24A ASI - Manual (Page 17)

Setup and Programming (continued) 17
GRAY ENCODING:
This menu is only available when QAM modes QAM-16A through QAM-1024A, are selected.
The choices are DVB and DAVIC. Gray Encoding is normally not used for video data.
QAM SYMRATE:
Preset or Manual: If PRESET is selected, the symbol rate will be automatically set to the
‘normal’ rate based on the QAM mode that is selected and assuming a 6 MHz wide QAM channel. If MANUAL is
selected, pressing the right or left arrow buttons will allow selection of symrates from 1.000 thru 7.000 MSym/Sec.
QAM SYMRATE:
This menu item only appears of ‘Manual’ is selected in the previously described menu item. It
allows selection of the output QAM baudrate or symbol rate. Set as required by the set top box.
INTERLEAVER:
This menu item only appears if QAM-64B, QAM- 256B, or QAM-1024B is selected and provides
the means to set the QAM modulator interleaver. Choose among the available selections based upon your system
/ set top box requirements. For typical 256-QAM DigiCipher II CATV systems, I128, J1 is the most commonly
used interleave setting but many other choices are available. This menu does not appear in the adjust mode if
the QAM mode is A (DVB) as there is only one choice in the DVB standard.
OUTPUT FORMAT:
For normal operation, select NORMAL. For system level set up, choose CW to provide a
CW carrier at the center frequency of the output channel for use in leveling a system when a QAM power meter
is not available. To disable all RF output, select STANDBY. In the CW mode, the CW carrier can be measured
on a spectrum analyzer without a need to apply a bandwidth correction or it can be measured with an analog
meter tuned to channel center. The CW power measured will equal the channel QAM power when the modulator
is returned to NORMAL output mode. Usually QAM signals are set 5 dB to 10 dB below analog NTSC channels
when balancing a system.
PRBS menu entries are used for testing purposes only and should normally not be selected by the user.
OUTPUT CHANMAP, OUTPUT CHANNEL
: Select the desired EIA CATV channel output using these two menus.
RF LEVEL:
Select the desired RF output signal level. The available range is between +45 dBmV and +56 dBmV,
selectable in 0.5 dB steps. The output accuracy is ± 1 dB.
SETUP:
ENDODER xx
ENCODER SELECT:
The LEFT and RIGHT buttons allow the user to scroll through the encoder numbers for each encoder
installed in the EH24A as well as the EH24A itself. Use the LEFT and RIGHT buttons to select the encoder to be programmed.
VIDEO:
This menu entry allows the user to select between SVIDEO and COMPOSITE video input for each selected
encoder.
FORMAT:
Either MPEG2 or MPEG4 H.264 may be selected as the output format for the selected encoder using
this menu item. Encoder 2 on a given SDE24/SDE24A has no option. It is forced to MPEG2.
BITRATE:
This menu item allows the user to select the bitrate. The choices are from 1 to 8 Mbits per second.
INPUT:
This menu allows the user to select between the NTSC or PAL video formats.
RESOLUTION:
The resolution of the video output of each encoder may be selected from this menu item. The
choices range from 720 x 480 thru 353 x 240 as shown on the software flow chart on page 10.
BRIGHTNESS, CONTRAST, SATURATION and HUE
: These menu items allow the user to assign each of these
parameters of the output video values from 0 to 255.
AUDIO ENCODER:
The SDE24/SDE24A includes audio encoders for Dolby Digital Stereo commercial encoding or MPEG1
Layer 2 audio encoding (MP2). In the USA, the majority of applications will use Dolby Digital (referred to within EH24A
settings as " AC3") but if your network is using Annex A (DVB) set top boxes, they may require the MPEG audio selection.
Some TVs and set top boxes will decode either mode but be sure to set the encoder to the mode used by other program-
ming on your system to insure complete compatibility. The AUDIO ENCODE(R) menu allows you to select either AC3 or MP2.
Use the up/dn arrow keys to toggle between the two settings.
MAX AUDIO IN:
This menu entry allows the user to set the maximum audio input which may be input to the selected
encoder. The choices are 1 Vrms or 2 Vrms.
AUDIO GAIN:
The audio output level can be chosen from this menu item by selection of the appropriate gain. The
values range from + 15 dB to - 15 dB. Audio output can also be completely eliminated using the ‘MUTE’ selection.