How do I add 3 logarithmic numbers together?
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To add three logarithms with the same base: log(a) + log(b) + log(c) = log(abc) Example: log10(2) + log10(3) + log10(5) = log10(2 * 3 * 5) = log10(30) If…
Why do radio astronomers use temperature rather than dB or another measurement to measure noise?
Radio astronomers use temperature because the random electrical noise generated by a resistor is directly proportional to its physical temperature. This creates a natural link between thermal physics and radio…
Which battery should I use for the Parkside 12V cordless polisher/sander that I am using to make radio telescope mounts at LRO?
For the Parkside 12V cordless polisher/sander (the 75 mm model), there is little practical difference between using a PAPK 12 A3 and a PAPK 12 A4 battery. Both are 12…
What is difference between receiver temperature, spillover temperature, ambient temperature, background temperature in radio telescopes?
In radio astronomy, several different “temperatures” are used to describe sources of noise. They are all expressed in Kelvin (K) because radio noise power is conveniently represented as an equivalent…
Formula for Tsys calculation
Tsys = Trx + Tant Where: Tsys = total system noise temperatureTrx = receiver noise temperatureTant = antenna temperature (everything seen by the antenna) Expanded form: Tsys = Trx +…
Where would you point a hydrogen line radio telescope to get hot sky?
Calibration of radio telescopes usually uses cold sky and hot ground, rather than hot sky. However, for completeness here is hot sky. (Cold sky is best achieved by pointing at…
What SDRs will provide bandwidth 20 MHz suitable for millimeter work?
If you want a receiver with 20 MHz instantaneous bandwidth, there are only a few realistic options — and one stands out as the simplest choice. — Best simple answer…
What types of GUI inputs blocks are available in GNU Radio?
In GNU Radio, “GUI inputs” are mainly implemented through Qt (modern, default) or WX (legacy) GUI blocks, plus a few message-based controls in the flowgraph. They let you change variables…
I need to brace my satellite dish as it is flexing when moves. What materials are effectively transparent to radio waves at 21cm, with least absorption or defraction and least weight with minimal cost?
At the hydrogen line (21 cm wavelength, 1420 MHz), many common structural materials are essentially transparent provided they are non-conductive and not loaded with carbon or metal. For bracing a…