FDMDV plus Video
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Richard Peterson
Nov 1, 2011, 1:29:09 PM11/1/11
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Hello
all,
Group members who use FDMDV may be interested in an
experimental technique that adds simultaneous video to the voice
signal.
The technique, known as "FDMDV plus Video",
provides low-resolution video (36 lines) at 1 frame/sec (like surveillance
video). The video software is a modified version of ZL2AFP's "Analog OFDM"
NBTV. The video software is run simultaneously with HB9TLK's software
currently used for FDMDV.
Separate PC's are used for transmitting and
receiving (I use laptop PC's with 1.6 GHz minimum clock speed).
The 15-subcarrier FDMDV signal is increased to 64
subcarriers total, requiring a baseband bandwidth from 0.38 to 3.7 kHz for
transmitting and receiving (good with newer Ten Tec, FlexRadio and some other HF
transceivers). Unlike FDMDV alone, the operator should not transmit FDMDV
plus Video unless all frequencies from 14236 to 14240 kHz are checked and found
not to be in use!
The signal has a high peak-to-average power ratio
(PAPR), and requires high linearity in the transceiver's AF and RF transmitting
stages. Depending on your transceiver, external amplifiers may be required
to obtain the required linearity. I use a PA-100 and HF Packer 2 linear
from HF Projects (K5OOR), giving 20-30 watts output (the HF Packer has the
PSU-36V mod for operation from 36Vdc).
Tony, K2MO, has included PathSim simulations for
the FDMDV plus Video signal (without voice) at his YouTube pages:
The simulations are computer-to-computer, and show
the effects of propagation on the video portion of the FDMDV plus Video
signal. Because an actual RF link is not used for the simulation, the
effects of frequency drift in the transmitter and receiver are not
simulated. Also, because the video software is run without the FDMDV
software, the effects of interaction between the video and FDMDV subcarriers are
not simulated.
Software and information on FDMDV plus Video (an
840Kb zipped folder) can be downloaded from:
Read the text file "FDMDV plus Video Info"
first.
More information is found at:
If you're interested, you're invited to join the
Yahoo! group.
73, Rick Peterson,
WA6NUT
Rick Peterson
Feb 25, 2012, 6:11:41 PM2/25/12
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Hello all,
My previous post (11/1/11) introduced "FDMDV plus Video", which adds video to the FDMDV signal.
The early version of the video software had a problem with corruption of the FDMDV signal by the adjacent video subcarriers. An update to the video software corrects this problem by changing the video subcarrier spacing from 43.0664 Hz to 37.5 Hz, exactly half the spacing of the FDMDV subcarriers (thus retaining orthogonality in the composite signal).
I've posted a demo screenshot video of the new version to YouTube at:
73, Rick, WA6NUT
My previous post (11/1/11) introduced "FDMDV plus Video", which adds video to the FDMDV signal.
The early version of the video software had a problem with corruption of the FDMDV signal by the adjacent video subcarriers. An update to the video software corrects this problem by changing the video subcarrier spacing from 43.0664 Hz to 37.5 Hz, exactly half the spacing of the FDMDV subcarriers (thus retaining orthogonality in the composite signal).
I've posted a demo screenshot video of the new version to YouTube at:
http://www.youtube.com/watch?v=StQ_OIwocFU
73, Rick, WA6NUT
Rick Peterson
Feb 25, 2012, 6:13:22 PM2/25/12
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On Tuesday, November 1, 2011 11:29:09 AM UTC-6, wa6nut wrote:
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