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From: | Nirali Patel |
Subject: | [Discuss-gnuradio] No horizontal sync with ntsc tv reception |
Date: | Mon, 1 Oct 2007 13:55:30 -0500 |
Hi, I am working on ntsc tv reception as a precursor to hdtv
reception. I am using usrp_rx_cfile.py to capture samples to a file from the
TV_RX board and then playing back using usrp_tv_rcv_nogui.py. The picture
displayed does not seem to have horizontal sync (picture keeps moving from left
to right). I have tried setting different decimation factors, the best I can
use without overruns is a factor of 8 and the picture still rolls in horizontal
direction. My understanding was that the decimation factor would only affect
the horizontal resolution not the ability to sync, but I could be wrong. The
commands that I use for capture and playback are: ./usrp_rx_cfile.py –R B –d 16 –f 531.25M –s
tv1.out ./usrp_tv_rcv_nogui.py –f 531.23M –n –i
tv1.out sdl where 531.25 Mhz is the picture carrier of the ntsc channel
with lower band edge at 530Mhz. I have also tried using –f 533M to set the tuning
frequency to centre of the band but no significant change in picture sync. If anyone has experienced similar problem I would appreciate
the guidance. Does the antenna setting have any influence on h-sync? My office
is in the interior of the building so would it help to move towards the
exterior? Thanks in advance for any help. Nirali Patel |
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