🔍 Key Concepts

• HF radiotelegraphy (A1A) emission and what A1A means • ITU/US maritime rules that set numerical bandwidth limits for different emission types • Difference between a fixed maximum bandwidth and a vague "minimum necessary" requirement

💭 Think About

• Look up the specific numeric bandwidth limit for A1A emissions in the maritime HF bands: is it given as a fixed kHz value or only as a general principle? • Compare the typical bandwidths used for narrow-band telegraphy (Morse) with voice SSB and CW to see which option is realistic for HF telegraphy. • Ask yourself: in regulations, when a maximum is specified, do they usually phrase it as a number or as "minimum necessary"?

✅ Before You Answer

• Confirm the definition of A1A (narrow-band, on-off keyed telegraphy) and its usual occupied bandwidth. • Check in the relevant ITU-R and national regulations for the exact numeric maximum authorized bandwidth for HF A1A in the maritime service. • Verify whether "minimum necessary" is used as a general principle or as a replacement for a specific numeric limit in HF telegraphy rules.