What is the allowed frequency tolerance for...

Question 1 / 27070d2gsTh8ZL2bKpaxbePKR

Question 1 of 27070d2gsTh8ZL2bKpaxbePKR

What is the allowed frequency tolerance for the DSC carrier frequencies?

Back

Question 1 of 27070

Q

What is the allowed frequency tolerance for the DSC carrier frequencies?

🔍 Key Concepts

• Digital Selective Calling (DSC) technical requirements in GMDSS equipment standards • Difference between absolute frequency offset in Hz and relative accuracy in parts per million (ppm) • ITU / IMO performance standards for VHF/MF/HF DSC transmitters

💭 Think About

• First decide whether the requirement is usually expressed as a fixed number of hertz or as a relative error (parts per million) for modern synthesized radios • Think about how much error is acceptable so that coast stations and ships can still reliably decode DSC calls on very narrow-band channels • Compare what a ppm requirement would mean in hertz at a typical DSC frequency (for example around 2 MHz or 8 MHz) to see which options are realistic

✅ Before You Answer

• Check whether DSC equipment standards specify frequency tolerance in ppm rather than just in hertz • Convert the ppm options to hertz at a representative HF or VHF frequency and ask: would this stay inside the channel and meet DSC decoding requirements? • Verify in current GMDSS/DSC equipment specification or relevant ITU‑R recommendation what numeric tolerance is given for the DSC transmitter carrier

Question 1 of 27070

Q

What is the allowed frequency tolerance for the DSC carrier frequencies?

A

10 Hz

B

20 Hz

C

5 ppm

D

10 ppm

Question 1 / 27070d2gsTh8ZL2bKpaxbePKR

Question 1 of 27070d2gsTh8ZL2bKpaxbePKR

What is the allowed frequency tolerance for the DSC carrier frequencies?

Back

Question 1 of 27070

Q

What is the allowed frequency tolerance for the DSC carrier frequencies?

🔍 Key Concepts

• Digital Selective Calling (DSC) technical requirements in GMDSS equipment standards • Difference between absolute frequency offset in Hz and relative accuracy in parts per million (ppm) • ITU / IMO performance standards for VHF/MF/HF DSC transmitters

💭 Think About

• First decide whether the requirement is usually expressed as a fixed number of hertz or as a relative error (parts per million) for modern synthesized radios • Think about how much error is acceptable so that coast stations and ships can still reliably decode DSC calls on very narrow-band channels • Compare what a ppm requirement would mean in hertz at a typical DSC frequency (for example around 2 MHz or 8 MHz) to see which options are realistic

✅ Before You Answer

• Check whether DSC equipment standards specify frequency tolerance in ppm rather than just in hertz • Convert the ppm options to hertz at a representative HF or VHF frequency and ask: would this stay inside the channel and meet DSC decoding requirements? • Verify in current GMDSS/DSC equipment specification or relevant ITU‑R recommendation what numeric tolerance is given for the DSC transmitter carrier