It can be caused by your TV receiving a local station broadcasting over the air and via the cable system at the same time. Make sure you are using good quality RG-6 coax cable and good compression fire-resistance cable fittings. Replace any low quality cable splitters or combiners with high quality units. Make sure they are tight also. This will also cure another cause of ghosting, signal reflection inside a poor cable.Ghosting can also be caused by multi-path interference on an antenna system.
This is especially true in an urban environment with lots of hills and tall buildings. To combat this, use a very directional antenna aimed directly at the desired station.Herringbone Pattern ?A herringbone pattern is caused by radio frequency interference from other stations transmitting on the same channel or adjacent channels, powerful radio signals, computers, etc. Another common cause is being equidistant from two transmitters operating on the same channel.
In short, this can be caused by just about any sort of RF radiation at the correct frequency. Really great shielding found on high quality cables helps to combat this. If you are getting this interference while modulating an A/V source on a certain channel, try switching to a different channel.Poor Upper Channel Reception ?Poor Upper Channel Reception is caused by poor signal strength on the upper channels. Use an amplifier with a tilt compensator that allows adjustment of the upper channels relative to the lower channels. This will prevent overdriving the lower channels while providing the upper channels with enough gain.
Also, check to see if all components in the RF system are rated to at least 1GHz and RG-6 or RG-6Quad shield cable is being used throughout.Bio: Steve Faber has almost 15 years in the custom installation industry. He is a CEDIA certified designer and Installer 2 with certifications from both the ISF and THX. His experience spans many facets of the industry, from the trenches as an installer and control systems programmer, and system designer, to a business unit director for a specialty importer of high end audio video equipment, a sales rep for a large, regional consumer electronics distributor, and principal of a $1.5M+ custom installation firm. He currently is senior sales engineer for Digital Cinema Design in Redmond, WA.