Signal Strength

[Ron Pollitt]

I have noticed a lot of messages referencing the signal strength of member's STB's for various stations. (i.e. I'm receiving WTMJ at 85% or WDJT at 65%).
 I have an odd STB (Sensory Science) which I really like for OTA reception but it just gives me a horizontal bar to measure signal strength with no calabration as to percentage.  Does your boxes come with a strength meter built in?  Does any one know if I could add a metering device within the RG6 line that would be more accurate.  Just wondering....didn't want to be left out of the fun.  Grin
Ron
 

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SensoryScience HDT100 STB
NEC 42" Plasma Monitor
Lance 4-bowtieUHF Antenna
Channel Master UHF Preamp
Charter Cable(no HDTV )

[Gregg Lengling]

Okay a little bit of science and little bit of nonsense.  Most of our units (my DTC100 and HiDTV Pro) have a numerical signal strength...the HiDTV has it superimposed on a bar graph.  There is no way you can put a signal meter into the coax because it would just measure all the energy the antenna is receiving.  

This is how a signal meter works.

Receivers receive all signals but then beat a synthesized signal against the amplified signals in a mixer...this develops a product that falls within the bandbass of the receiver IF (intermediate frequency) and then is demodulated.  There is a developed voltage (signal strength) in the mixer stages that are used for 2 purposes.  1 purpose is to reduce the gain of the preamplifier in the receiver to prevent overload (distortion and harmonics) from strong signals.  Thus it reduces the voltage to the preamp in the receiver to do this.  Signal strength meters just take this voltage and use it as an indicator of received signal strength.

This is not a real number, such as the FCC mandated 22dBu contour coverage requirements, but just an arbitrary number to allow you to see in relation to other signals, how they compare to each other.

Hope this helps.


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Gregg R. Lengling
RCA P61310 61" 16x9
HiDTV Pro 2 computer reciever card
glengling@ameritech.net

[Ron Pollitt]

Thanks,  I knew I would be sorry for asking that question.  Grin!  Probably, just a hamster on a miniture treadmill.
Ron


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SensoryScience HDT100 STB
NEC 42" Plasma Monitor
Lance 4-bowtieUHF Antenna
Channel Master UHF Preamp
Charter Cable(no HDTV )