evertz 7700ADA-EQ User manual

7700 Multiframe Manual
7700ADA-EQ Equalizing Analog Video Distribution Amplifier
TABLE OF CONTENTS
1. OVERVIEW......................................................................................................................................... 1
2. INSTALLATION.................................................................................................................................. 2
3. SPECIFICATIONS.............................................................................................................................. 3
3.1. ANALOG VIDEO INPUT............................................................................................................ 3
3.2. ANALOG VIDEO OUTPUTS ..................................................................................................... 3
3.3. ELECTRICAL ............................................................................................................................ 4
3.4. PHYSICAL................................................................................................................................. 4
4. STATUS LEDS ................................................................................................................................... 4
5. CIRCUIT DESCRIPTION.................................................................................................................... 5
6. JUMPERS AND USER ADJUSTMENTS ........................................................................................... 5
6.1. SELECTING WHETHER LOCAL FAULTS WILL BE MONITORED
BY THE GLOBAL FRAME STATUS......................................................................................... 6
6.2. SELECTING THE INPUT TERMINATION................................................................................. 6
6.3. SELECTING THE INPUT AC/DC COUPLING .......................................................................... 6
6.4. DC RESTORING (CLAMP) OPERATION ................................................................................. 6
6.5. GAIN ADJUSTMENT................................................................................................................. 7
6.6. CABLE EQUALIZATION OPERATION .................................................................................... 7
Figures
Figure 1: 7700ADA-EQ Block Diagram............................................................................................................... 1
Figure 2: 7700ADA-EQ Rear Panel .................................................................................................................... 2
Figure 3: LED and Jumper Locations.................................................................................................................. 5
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7700ADA-EQ Equalizing Analog Video Distribution Amplifier
REVISION HISTORY
REVISION DESCRIPTION DATE
1.0 Original Version Nov 02
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7700ADA-EQ Equalizing Analog Video Distribution Amplifier
1. OVERVIEW
The 7700ADA-EQ Equalizing Analog Distribution Amplifier is a general purpose amplifier for distributing
analog video signals. The 7700ADA-EQ features one balanced equalized input with four outputs. The
7700ADA-EQ amplifier has been designed to distribute a wide range of analog video signals. It can also
distribute other pulses and signals that are less than 2Vp-p.
The 7700ADA-EQ is housed in the 7700FR Frame that will hold up to 15 modules.
Features:
• 75 Ohm or high impedance input (jumper selectable)
• High common mode range and common mode rejection ratio (CMMR)
• Gain control
• Jumper selectable AC or DC coupling
• Jumper selectable fast or slow back porch clamp
• DC level control when clamp is enabled
• Cable equalizer adjustment range: 0 to 300m of 8281 or 1694
• Looping feature with external "T" connector
• Consistent input impedance if card power is lost
4 Analog
Outputs
Signal Analysis
Cable
EQ
DC Restore
Cable
Length
Sync
Slicer
Impedance
AC/DC
Coupling
75Ω
Clamp Pulse
Generation
Clamp On/Off
Balanced
Analog Input
Gain
DC Level
SD
Pres
HD
Pres
SYNC
LOW
SYNC
HIGH
LEVEL
HIGH
FAULT
Figure 1: 7700ADA-EQ Block Diagram
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7700ADA-EQ Equalizing Analog Video Distribution Amplifier
2. INSTALLATION
The 7700ADA-EQ comes with a companion rear panel and occupies one slot in the 7700FR frame. Figure
2 shows a picture of the rear pannel. For information on inserting the module into the frame see the
7700FR chapter section 3.
7700ADA-EQ
ANALOG
OUTPUT
A
NALOG IN
75 /HI-Z
Figure 2: 7700ADA-EQ Rear Panel
IN Input (isolated) BNC connector for analog video signals. The TERM jumper located on the
module near the back determines whether the input signal will be high impedance or
terminated with 75 ohms. (See section 6.2) The INPUT jumper located on the module near
the back determines whether the input signal will be AC or DC coupled. (See section 6.3)
OUT 1 to 4 There are four BNC connectors with equalized, level and DC adjusted copies of the input
signal.
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7700ADA-EQ Equalizing Analog Video Distribution Amplifier
3. SPECIFICATIONS
Note: At the time of printing, this product has only been qualified for use with standard definition signals. It,
however, has been designed to work with high definition signals. Frequency, phase response as well as
cable equalization will not be optimized at the upper frequency range of high definition video bandwidths.
All specifications, unless indicated, measured under the following conditions:
• 1 Vp-p video applied
• 75 Ohm card input terminated
• AC coupled
• DC restore clamp turned on with slow time constant
• DC level adjusted for blanking at 0V
• Gain adjusted for unity operation into 75 Ohm load
• Cable equalizer set to 0 length
3.1. ANALOG VIDEO INPUT
Standards: Any analog video format, up to 2Vp-p and 30MHz bandwidth
Connector: 1 BNC input per IEC 169-8
Common mode range: >6Vp-p
CMRR: >70dB to 1kHz
Signal amplitude: 2.5Vp-p max
Cable equalizer: 0 to 300m of Belden 8281 or 1694 cable
Impedance: 75Ohms terminated, 35kOhms Hi-Z (jumper selectable)
Coupling: AC or DC (jumper selectable)
Return loss: > 40dB to 10MHz, >30dB to 30MHz
Clamp range: >+/- 600mV
Fast clamp attenuation of 60Hz: >36dB
3.2. ANALOG VIDEO OUTPUTS
Number of Outputs: 4 Per Card
Connector: BNC per IEC 169-8
Output impedance: 75 Ohm
Gain control range: ± 5dB
DC level < +/- 100mV (with DC Coupling active and back porch clamp disabled)
DC level Control range: < +/- 200mV( with back porch clamp enabled)
Freq. Response: < ±0.05dB no equalization (to 5.5MHz)
< ±0.09dB for 5 to 100m Belden 8281 or 1694 (to 5.5Mhz)
< ±0.15dB for 100 to 300m Belden 8281 or 1694 (to 5.5Mhz)
Differential Gain: <0.17 % 0 to 300m
Differential Phase: < 0.19 deg 0 to 300m
C/L gain inequality: <+/-0.1% for all cable lengths
C/L Delay: <+/-2nsec
Output isolation: >42dB to 10MHz, >32 dB to 30MHz
Output return loss: >40dB to 30MHz
Noise performance: <-78dB RMS NTC7 weighting,
<-70dB RMS 15kHz to 5.5MHz
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3.3. ELECTRICAL
Voltage: + 12VDC
Power: 1.2 Watts.
3.4. PHYSICAL
Number of slots: 1
4. STATUS LEDS
The 7700ADA-EQ has seven LED Status indicators on the front card edge to show operational status of
the card at a glance. Figure 3 shows the location of the LEDs.
Two large LEDs on the front of the board indicate the general health of the module
LOCAL FAULT: This Red LED indicates poor module health and will be On during the absence of a
valid input signal, or if a local input power fault exists (i.e.: a blown fuse). The
LOCAL FAULT indication can also be reported to the frame through the FRAME
STATUS jumper.
MODULE OK: This Green LED indicates good module health. It will be On when a valid input
signal is present, and the board power is good.
There are five small LEDs that indicate the status of the input video.
SD/HD Video Presence Indicators The width of sync is measured to determine if video is present and if it
is NTSC/PAL-B or if it is analog high definition video. If sync is approximately 4.7µsec wide, the
green SD PRES LED is illuminated. If sync is approximately 0.6µsec wide, the green HD PRES
LED is illuminated. If neither sync size is present, both LEDs are turned off.
This technique will also successfully detect HD signals with bi-level sync generated by Evertz
DACs for applications with computer monitors. Other manufacturers DACs may not have the
same sync size so the detection may not work with these signals.
Sync High/Low Indicators The sync level of the processed video is measured to determine if its
amplitude is approximately correct. If sync is below 270mV then the amber SYNC LOW LED is
turned on and if sync is above 320mV then the amber SYNC HIGH LED is turned on. This
measurement takes place AFTER all of the card processing. This means that if the card is not
calibrated properly, the indicators will not represent the proper state of the video. This includes
improper setting of restored DC level, poorly equalized video and wrong gain settings.
!
These indicators will NOT indicate properly when the input video is AC coupled
AND the DC restore clamp is turned off.
Video High Indicator The level of the processed video is measured to determine if its amplitude is
approaching the 100% level. If in one field, the video is ever above 700mV then the amber
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VIDEO HIGH LED is turned on for a short duration. If the video is consistently too "hot", then
the light will always be on. This measurement takes place AFTER all of the card processing.
This means that if the card is not calibrated properly, the indicator will not represent the proper
state of the video. This includes improper setting of restored DC level, poorly equalized video
and wrong gain settings.
!
These indicators will NOT indicate properly when the input video is AC coupled
AND the DC restore clamp is turned off.
5. Circuit Description
The input signal enters the board through a BNC with isolated ground so that balanced input processing
may be done to remove any common mode hum that may have been added to the signal and ground
shield. On-board jumpers allow you to configure the input impedance and input coupling (AC/DC).
For video applications, the synchronization pulses are analyzed for position and size information. A clamp
pulse is generated from the sync information and a clamp signal is delivered to a DC restorer circuit that
positions the blanking level to ground. This feature can be enabled with a jumper, the time-constant of the
clamping action may be fast or slow and the DC level may be set with a card edge POT.
An adjustable gain stage feeds the cable equalizer that can adjust the frequency response to match the
attenuation of up to 300m of coaxial cable. One OP-Amp drives the four output BNC's with 75-Ohm output
impedance.
6. JUMPERS AND USER ADJUSTMENTS
J6
16948281
CABLE
J1
FRAME STATUS
ON
OFF
GAIN
EQ CTRL
CLAMP LEVEL
HD PRES
SD PRES
VIDEO HIGH
SYNC HIGH
SYNC LOW
J7
ON
CLAMP
J5
75R
HI-Z
TERM
J4
DC
AC
INPUT
(2)7700ADA-EQ
MODULE STATUS
J8
FASTSLOW
CLAMP
OFF
Figure 3: LED and Jumper Locations
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6.1. SELECTING WHETHER LOCAL FAULTS WILL BE MONITORED
BY THE GLOBAL FRAME STATUS
The FRAME STATUS jumper J1, located at the front of the module determines whether local faults (as
shown by the Local Fault indicator) will be connected to the 7700FR frame's global status bus.
FRAME STATUS: To monitor faults on this module with the frame status indicators (on the power
supply’s FRAME STATUS LED's and on the Frame's Fault Tally output) install this
jumper in the On position.
When this jumper is installed in the Off position local faults on this module will not
be monitored.
6.2. SELECTING THE INPUT TERMINATION
The input termination may be set via card jumper J5 to either 75 Ohms (default) or Hi-Z (34k Ohms). Set it
to Hi-Z when using a "T" connector to loop the signal through several device inputs.
6.3. SELECTING THE INPUT AC/DC COUPLING
The input may be AC or DC (default) coupled into the input-circuitry using jumper J4. Use AC coupling in
applications when the input signal has a large (>2V) DC level. In some non-video applications that do not
have DC information (i.e. digital AES audio), AC coupling can be used to remove any DC level that may
have built up in its transmission. The DC Restoring (clamp) circuitry will work with either AC or DC
coupling in video applications.
6.4. DC RESTORING (CLAMP) OPERATION
A clamp pulse is generated from the sync information and a clamp signal is delivered to a DC restorer
circuit that positions the blanking level to ground. This feature will work with standard definition analog
NTSC and PAL-B sync structures. Analog tri-level sync 1125-line high definition video (SMPTE 240M) will
also be detected and DC restored. In addition, most versions of bi-level sync that has been applied to
1125-line high definition video will be supported.
!
The clamp position and size will successfully DC restore HD signals with bi-level
sync generated by Evertz DACs for applications with computer monitors. Other
manufacturers DACs may not have the same sync size and the DC restoring may
not work with these signals.
The clamp action can be enabled with a jumper, the time-constant of the clamping action may be fast or
slow and the DC level may be set with a card edge POT. For non-video, applications disable the clamp
with the jumper (J7). For removing low frequency distortions (<1kHz) from clean video, use the clamp
time-constant (J8) in the FAST position. If the video has a sizeable amount of noise (i.e. a low quality off-
air signal) the fast clamp will generate a line-to-line level distortion (also called "piano-keying") because of
the noise. In this situation, use the SLOW clamp position of (J8). The CLAMP LEVEL POT on the card
front edge allows you to adjust the DC level that the back porch is being clamped to. This allows you to set
the output DC level to values other than back porch to ground.
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!
Do NOT turn on the clamp when distributing Pb and Pr signals. Standard
Definition and High Definition component Pb and Pr signals have waveforms that
extend below blanking level. The right level and duration of a negative going
video signal may be interpreted as a sync signal, enabling a clamp pulse in active
video. This will cause the DC restorer circuit to distort the video, creating a large
Average Picture Level (APL) change.
6.5. GAIN ADJUSTMENT
The GAIN POT on the cards front edge allows you to adjust the input signal level. Turning the POT
clockwise will increase the gain.
!
There is enough range on this control to counteract the video level error due to a
missing or double terminated coaxial connection. This will create a frequency
response problem due to the mis-termination.
TIP: Set the DC LEVEL before adjusting the gain. The Gain control amplifies the signal around ground.
By setting the back porch to ground first, you may avoide re-adjusting the gain.
6.6. CABLE EQUALIZATION OPERATION
With the cable equalizer EQCTRL POT set fully counter-clockwise, the cable equalizer will be set to the
"zero length". As you turn the POT clockwise, more cable equalization is added. To set the POT to the
correct position, perform the following calibration:
1. Supply the cable being equalized with a multiburst or horizontal sweep test signal.
2. Make sure the driving level from the test generator is calibrated to unity.
3. Set the cable type jumper (J6) to the type of cable you are using (either 8281 or 1694). If you are using
a different type, then use either setting.
4. Make sure the card input termination and the test gear is terminated properly.
5. Adjust the DC level if the clamp is enabled and calibrate the GAIN level POT for unity output at low
frequencies.
6. Adjust the "EQCTRL" POT until the 7700ADA-EQ output signal has flat frequency response.
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