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Main / SDI audio embedding and deembedding / PEXT-3325

PROFLEX™ PEXT-3325 multistandard deembedders accept the SDIembedded input, up to four audio channels are deembedded along with PAL/SECAM/SDI video.

PEMB-3325 module occupies one slot in the PROLFEX 1U/3U racks so that up to four receivers fit into a 1U rack and up to fifteen into a 3U rack.
If paired with PEMB-3305, the PEXT-3325 deembedder allows for the following modes of operation:

The output audio signal may be of any standard: an analog, AES or combination of both. These modificatiuons are designated the following model indexes:

• four analog balanced outputs (24-bits ADC) - the "AA" index, (f.e. PEXT-3325AA)
• two analog balanced outputs and one balanced AES/EBU outputs (4 channels totally) - the "AE" index, (f.e. PEXT-3325AE)
• two balanced AES/EBU outputs (4 channels) - the "EE" index, (f.e. PEXT-3325EE)

At a deembedding side the audio format must not necessarily coinside with the one at the source (f.e., an analog input signal embedded is deembedded in the AES/EBU).

Both the deembedder (PEXT-3325) and the intended embedder (PEMB-3305) are featuring the PAL-monitor output with the OSD of the bar-graph audio level meters (quasi-peak and VU).

PEXT-3325 features

• multiformat outputs (SDI/PAL/SECAM)
• built-in VITS generator
• high quality PAL/SECAM encoders
• signal loss indicator
• automatic detection and indication of an embedded audio in an input SDI signal
• automatic cable equalizer on SDI input
• built-in 1kHz test generator
• EDH status indicators
• audio group selection for deembedding
• audio remapping (user-configurable assignment of audio groups to the physical output channels)
• bargraph audio level meter (quazi-peak and UV) OSD on PAL monitor output
• an analog, AES/EBU or combination of audio outputs
• 10-bits video DAC
• 24-bits audio DAC
• optional +6dB audio gain on analog audio outputs

• Inputs
  • SDI input
    

    Number of inputs		1
    Input impedance and connector type		75 Ohm, BNC
    Automatic cable equalizer		up to 100 meters of Belden 8281 or similar cable

• Outputs
  • SDI output
    

    Number of outputs, standard compliance	2 reclocked, ITU-R BT.656
    Embedded audio	supported
    Output impedance	75 Ohm, BNC connectors
    Return loss	better than 18dB at Ft
    Amplitude	800mV±10%

  • PAL/SECAM output
    

    Number of outputs				2
    Output impedance				75 Ohm, BNC
    Luminance channel frequency response
    SECAM	1.0MHz	2.0MHz	3.0MHz	4.0MHz	4.286MHz	4.8MHz	5.8MHz
    	±0.1dB	±0.1dB	±0.5dB	-6±2dB	-16±2dB	-3±1dB	-0.5dB
    PAL	0.3dB up to 5.8MHz
    2T pulse K-factor				<0.5%
    Diff phase				<1%
    Diff gain				<1%
    S/N ratio (weighted)				63dB
    Chrominance error			PAL	<2%
    			SECAM	complies with Rec.470 ITU-R and GOST 845-92
    Chroma to luminance delay				<5ns
    Sampling				10 bits

  • PAL monitor output with audio level bargraph meter OSD
    

    Connector type	BNC
    Amplitude	1000±20mV at 75 Ohm
    DAC	10 bits
    Frequency response	<3dB up to 5,5MHz

  • Analog audio output
    

    Connector	DHS-26F
    Output impedance	<50 Ohm
    Output type	balanced
    Output headroom	+18dB
    Dynamic range	100dB
    Distortions and noise	less than 0.006%
    DAC	24 bits
    Sampling rate	48kHz, synched to video signal

  • Digital audio output
    

    Output type	transformer balanced
    Connector type	DHS-26F
    Amplitude	3v at 100 Ohm

General description

PEXT-3325 simplified schematic diagram

PEXT-3325 accepts the SDIembedded input. SDI input is equalized, decoded into a 10-bits 4:2:2 stream which is processed by a video/audio processor. The video/audio processor deembedds up to four audio channels. Output audio may be an analog ("AA" model index), digital AES/EBU ("EE" model index) or combination of both formats ("AE" model index). The video signal is made available as analog composite video (PAL/SECAM) or digital (SDI) video.

PEXT-3325 rear panel view

Controls and indicators

All the controls and indicators are located at the module's frontal board.

The operation mode is selected by toggling the MODE button, the editing is done by pressing the UP and DOWN buttons.

The following modes are available:

• GROUP SEL - an audio group number selection for embedding
• VITS - the test signals insertion ON/OFF (composite output only, TV lines#: 17, 18, 330 and 331)
• VU METR - an audio bar-graph OSD placement and scale controls
• ASSIGN - an audio remapper (the output channel pair "A" and "B" deembedded audio assignation)
• TON - 1kHz test signal ON/OFF in an output channel
• GAIN - an output audio gain presets (±6dB in 0.2dB increments)
• GAIN MINUS - lit when an audio gain in a selected channel is negative
• VIDEO STD - output signal's standard selection (PAL/SECAM/SDI)
• LOSS - an input signal loss indicator
• EDH DET - lit when an input SDI signal contains valid EDH packets
• EDH MIN/HOUR - lit if two or more EDH errors were detected within one hour/minute interval, both LEDs blink if an SDI input is lost
• AUD DET - lit when an input SDI signal contains valid AUDIO data packets

Configuring the PEXT-3325 deembedder

The audio group number selection:

Toggling the MODE button select the GROUP mode. Pressing the UP and DOWN buttons select an audio group number (01, 02, 03, and 04 groups are available). The AUD DET LED is lit solidly if an audio is detected in a selected group, it blinks if there is no audio in a group.

The VITS insertion in the TV lines #17, #18, #330 and #331:

Toggling the MODE button select the VITS mode. Press the UP button to enable and the DOWN button to disable the VITS insertion:

• oF - the VBI test signals are OFF
• on - the VBI test signals are inserted into the 17th, 18th, 330th and 331st lines

PLEASE, NOTE!
The VITS insertion is not possible into the SDI output signal, the main display shows the "--" marks.

Selecting the VU METR modes:

Toggling the MODE button select the VU METR mode. Pressing the UP and DOWN buttons adjust the position of the VU-meter OSD. Pressing the MODE and DOWN buttons simultaneously switches the OSD off (the indicator shows "On" -> "OF"). Pressing the MODE and UP buttons simultaneously selects the VU-meter scale mode:

• EBU scale, 0dBfs corresponds to +18 dBU (indicator shows "FS")
• quazi-analog scale, 0dBU corresponds to 0,775VRMS (indicator shows "db")

The channel-to-output assignment (the audio remapping):

Toggling the MODE button select the ASSIGN A mode. Pressing the UP and DOWN buttons select a channel for the "A" output: the leftmost digit on the main LED display shows the channel number for the left channel of the output stereo pair, the rightmost digit on the main LED display shows the channel number for the right channel of the output stereo pair. Available combinations are 1/2, 2/1, 1/1, 2/2, 3/4, 4/3, 3/3 and 4/4.
Pressing the MODE button again select the ASSIGN B mode. Pressing the UP and DOWN buttons select a channel for the "B" output in the similar way.

The 1kHz test tone operation:

Toggling the MODE button select the TON A mode. Pressing the UP and DOWN buttons enable or disable the test singal in desired channel:

• oF - the test signal is OFF in all channels
• Lr - the test signal is ON in the left and right channels
• L - the test signal appears in the left channel
• r - the test signal appears in the right channel

The audio gain adjustments:

Toggling the MODE button select the GAIN A mode. The UP button increases the gain by 0,2dB steps, the DOWN button decreases it. The indicator shows the current gain level, the GAIN MINUS is lit when the gain is negative. Press the UP and DOWN buttons simultaneously to reset the gain to the default 0dB level. Press the MODE button to access the GAIN B mode which adjusts the stereo pair "B" in similar fashion.

The output signal format selection:

Toggling the MODE button select the VIDEO STD mode. Pressing the UP and DOWN buttons select the desired output standard:

• Sd - SDI output signal (270Mbps)
• PL - PAL
• SE - SECAM

Both the OUT A and OUT B are affected by this setting. The X5 jumper allows to override this setting for the OUT B output. In the "SDI" position the X5 jumper forces the SDI output format at the OUT B output. Placing the X5 jumper into the "VAR" position restores the software control over the output B standard.
PLEASE, NOTE!
The "CS" on the main display means that the composite signal (PAL or SECAM) is being transmitted in an un-decoded form, the output standard alteration is not possible.

The remote control and monitoring

The “PROFLEX” modular system provides the remote controls and monitoring capability. An optional CPU module installed in a rack connects to an IBM PC via the proprietary protocol and software package.