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  • Antenna Reception Articles

    by Published on 11-29-2009 02:21 PM  Number of Views: 2710 
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    RF Front End

    Did you know that every digital system has what is termed as an “RF Front End”?

    They do! The RF front end refers to the signal reception portion of any communication system – both analog and digital systems. The RF front end consists of the antenna and the cables that deliver the signal to the receiver. With satellite the antenna is the dish, and with OTA broadcast it is the TV antenna.

    Each individual’s in-home system performance is determined by how well the signal is received at the RF front end. It is the integrity or quality of the arriving signal delivered to the receiver that will determine the performance of any digital system.

    The goal of a properly designed system is to maintain the integrity of the signal as it is received, decoded, and presented. Everything about these systems (performance, reliability, and picture quality) is dependent on the quality of the signal you have to work with.
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    by Published on 11-13-2009 12:31 PM  Number of Views: 3357 
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    Signal Quality is a factor with DTV reception!!

    I have spent literally the last 4 months doing field strength tests in our market with some very interesting discoveries about the DTV signal itself. It seems signal quality is a BIG factor that can determine ease of reception of DTV signals, and signal quality is something that the Station Engineers actually control to a certain extent.

    Not all reception problems are directly related to an end users antenna, low signal levels, or reception equipment in all cases. A transport stream reader can tell a lot about a signals quality, and that may be the key to a lot of the reception issues that viewers are seeing.

    Many stations still do not have the equipment needed to monitor the quality of their signals due to the high costs of the equipment itself. High error vector magnitude, bit error rates, modulation error rates and high SNR ratios are all killers of reliable reception for some DTV signals. Signal quality can vary drastically between different broadcasters in any given market.
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    by Published on 10-29-2009 11:30 AM  Number of Views: 3041 
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    Originally Posted by JER
    Its been my general feeling for quite a while now that for many people reception problems are usually related more to signal quality than signal strength.

    The above post by FoxTV indicates how complicated the signal environment can be and how difficult it can be to resolve these kinds of problems without a truck load of test equipment.

    Probably the simplest way to avoid a lot of these problems is to get the antenna outside and to avoid amplifiers.

    Putting the antenna outside helps reduce the impact of household noise sources. It also dramatically increases signal level and reduces the effect of indoor multi-path.

    While amplifiers increase signal level, they always add something (e.g. noise, harmonic distortion, and inter-modulation distortion) that's not actually on the air. A cheap amp can easily saturate on a strong in-band or even out-of-band signal and generate a wide spectrum of "crud" that makes it impossible to detect anything with the receiver. By starting off without an amp, you can make a better determination of what your true signal situation is like. Then, if you're missing some weak stations you can add the amp and see if it really helped.
    JER, I agree with your thoughts on amplifiers. I think they are overused to the point of causing problems instead of solving them. An amplifier is the last thing I would recommend to try and solve reception issues. This is based on my last 3 or so months doing field strength tests in our market that has very mountainous terrain. I have received signals from ours, and other transmitters in this rough reception terrain at 75 miles out, and still had plenty of signal head room for good reception using a Clear Stream C2 or in some cases a C4 at only 20 feet elevation.

    I have seen this same scenario at many different locations in our rigorous signal testing project. I use a Rhode & Swartz FSH-3 TV Analyzer for RF signal analysis, along with a Sencore DTU 236 transport stream analyzer to look for echo strength and amplitude, and for echo timing to see how far out on the time line the echos are in highly problematic areas. It seems that most of the multi path issues are from reflective objects that are relatively close to the receive location instead of miles out as in analog.

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