What would be the bandwidth of a good...

🔍 Key Concepts

• Weather facsimile (WEFAX) uses frequency-modulated tones to send picture information over HF radio. • A crystal lattice band-pass filter is chosen so it passes the signal you want but rejects nearby interference and noise. • Think about the typical audio frequency range of an HF weather fax signal (from black to white tones) and what filter width is needed to pass that range cleanly.

💭 Think About

• Which choice is wide enough to pass the full fax audio tone range without distorting the picture, but not so wide that it brings in unnecessary noise or adjacent signals? • Compare the bandwidth values: which one is closest to the known audio spectrum used by HF weather fax (around the low‑hundreds to a couple of kilohertz)? • If the filter is too narrow, what would happen to the image quality? If it’s too wide, what happens to noise and interference levels?

✅ Before You Answer

• Check the typical audio frequency range for HF weather fax (for example, approximate low and high tone frequencies). • Confirm which bandwidth would include that entire range at the -6 dB points without cutting off important parts of the signal. • Eliminate options that are much wider than necessary for an audio fax signal (more like a full SSB voice or wider) and those that are so narrow they would clip significant parts of the tone range.

What would be the bandwidth of a good crystal lattice band-pass filter for weather facsimile HF (high frequency) reception?

500 Hz at -6 dB.

6 kHz at -6 dB.

1 kHz at -6 dB.

15 kHz at -6 dB.

🔍 Key Concepts

💭 Think About

✅ Before You Answer