From: owner-ammf-digest@smoe.org (alt.music.moxy-fruvous digest) To: ammf-digest@smoe.org Subject: alt.music.moxy-fruvous digest V14 #3797 Reply-To: ammf@fruvous.com Sender: owner-ammf-digest@smoe.org Errors-To: owner-ammf-digest@smoe.org Precedence: bulk alt.music.moxy-fruvous digest Friday, March 20 2020 Volume 14 : Number 3797 Today's Subjects: ----------------- Infrared Thermometer Non-Contact Temperature ["Terry" Subject: Infrared Thermometer Non-Contact Temperature Infrared Thermometer Non-Contact Temperature http://thermosense.pro/U7f-6r-TMfi1uYRsbbd7VqOE-NOUERJcCWzD__haFysc14PA http://thermosense.pro/AhUD8QuvTThHusg9ppnqnQ5tgrlmUEXb0Yq6_dlS_JhSpOSU A typical satellite has up to 32 Ku-band or 24 C-band transponders, or more for Ku/C hybrid satellites. Typical transponders each have a bandwidth between 27 and 50 MHz. Each geostationary C-band satellite needs to be spaced 2B0 longitude from the next satellite to avoid interference; for Ku the spacing can be 1B0. This means that there is an upper limit of 360/2 = 180 geostationary C-band satellites or 360/1 = 360 geostationary Ku-band satellites. C-band transmission is susceptible to terrestrial interference while Ku-band transmission is affected by rain (as water is an excellent absorber of microwaves at this particular frequency). The latter is even more adversely affected by ice crystals in thunder clouds. On occasion, sun outage will occur when the sun lines up directly behind the geostationary satellite to which the receiving antenna is pointed. The downlink satellite signal, quite weak after traveling the great distance (see inverse-square law), is collected with a parabolic receiving dish, which reflects the weak signal to the dish's focal point. Mounted on brackets at the dish's focal point is a device called a feedhorn or collector. The feedhorn is a section of waveguide with a flared front-end that gathers the signals at or near the focal point and conducts them to a probe or pickup connected to a low-noise block downconverter (LNB). The LNB amplifies the signals and downconverts them to a lower block of intermediate frequencies (IF), usually in the L-band. The original C-band satellite television systems used a low-noise amplifier (LNA) connected to the feedhorn at the focal point of the dish. The amplified signal, still at the higher microwave frequencies, had to be fed via very expensive low-loss 50-ohm impedance gas filled hardline coaxial cable with relatively complex N-connectors to an indoor receiver or, in other designs, a downconverter (a mixer and a voltage-tuned oscillator with some filter circuitry) for downconversion to an intermediate frequency. The channel selection was controlled typically by a voltage tuned oscillator with the tuning voltage being fed via a separate cable to the headend, but this design evolved. Designs for microstrip-based converters for amateur radio frequencies were adapted for the 4 GHz C-band. Central to these design ------------------------------ End of alt.music.moxy-fruvous digest V14 #3797 **********************************************