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Satellite weak signal simulation using antenna placement and polarization in the lab

IP.com Disclosure Number: IPCOM000029439D
Original Publication Date: 2004-Jun-28
Included in the Prior Art Database: 2004-Jun-28
Document File: 1 page(s) / 43K

Publishing Venue

IBM

Abstract

This invention disclosure publication will describe a simple, low-cost and infinitely variable signal attenuator to simulate weakly received satellite signals for set-top-box debugging.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 53% of the total text.

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Satellite weak signal simulation using antenna placement and polarization in the lab

Some MPEG decoder picture artifacts will only occur when decoding weak and noisy satellite signals. If the artifact is only occurring in PAL and not in NTSC, then it is difficult to receive a live PAL signal from a satellite in the western hemisphere. A weak PAL signal, simulating a weak satellite signal, must be created in the lab to load into the front end of a set top box decoder in order to see the artifacts. A very fine adjustment needs to be performed to get the lab set top box system right 'on the edge' of just being able to decode the signal in order to see the problems. This invention quickly and inexpensively solves the problem of providing a fine adjustment of weak signals. Other ways of providing this weak-signal environment would be to use RF signal attenuators inline with the coax. However, in this particular situation, a DC current with a variable voltage had to be supplied to the set top box front end as though it was coming from the antenna preamplifier. Supplying this DC current and using the RF signal attenuators was difficult, but yet this invention made it quite simple.

     We use the distance between two coaxially fed 1/4 wavelength antennas and also the polarization of the two antennas to finely adjust the signal strength arriving at the front end of the set top box. This avoids the process of purchasing or finding an appropriate RF attenuator and trying to adj...