A SID stands for Sudden Ionospheric Disturbance. It refers to a rapid change in the ionosphere caused by intense solar radiation, usually from a solar flare. These disturbances are commonly…
Yes — there are several practical disadvantages of using a SAWBird H1 (or similar surface-acoustic-wave bandpass filter) compared with a cavity filter in RF front-ends, especially at VHF/UHF, narrow-channel, or…
Amplifier examples relevant to discussion below of receiver chains that involve amplifier before a cavity filter: Budget amplifiers: Better quality amplifiers: Even better and more expensive amplifiers: Description: Yes —…
A surprisingly effective improvement for hydrogen-line reception is optimising the feed illumination of the dish. Many amateur systems lose several dB simply because the feed does not illuminate the reflector…
One upgrade that often improves hydrogen-line observations more than adding extra amplifiers or filters is improving the frequency stability of the SDR. Use a stable reference (TCXO or external clock)…
A simple improvement many hydrogen-line observers use with the Nooelec SAWbird+ H1 can noticeably improve the received SNR without adding another filter. The trick: Reduce gain at the SDR input…
Short answer: sometimes yes, but only in specific situations. In many hydrogen-line setups it gives little improvement and can even slightly reduce sensitivity. What the SAWBird H1 already does The…
An anti-aliasing filter is a filter placed before a signal is sampled by an analog-to-digital converter (ADC) to remove frequencies that are too high to be represented correctly after sampling.…
The phenomenon is called Intermodulation, specifically third-order intermodulation when two signals produce a third frequency that falls into your band. How it works When two strong RF signals at frequencies…
Test data: https://www.astronomy.me.uk/wp-content/uploads/2026/03/260306_WT-A11988-Q06_1415-1425MHz_Test-Data.docx Test Curves: Batch of three filters ordered – test curves for all three below: Filters 1-3:
Admin