What is facsimile?

The transmission of printed pictures for permanent display on paper.

It is the generic name for the FAX machine. It meant that you can send by telecommunications lines system an exact duplicate of what you have.

The Radiofax, or weatherfax, or WEFAX, are transmissions of images in grayscale, somewhat like the slow-scan TV. For more info and pictures of faxes, please see the HFUnderground site for the article "Maritime Fax Transmissions"

The site Furuno shows examples of Weather Fax machines, with details.

Also, see M0TAZ site for the article "Receiving HF Weather Fax"

For more info, please see Wikipedia's article on FAX

Reference: NAVTEX/FAX specifications and use are listed in the Code of Federal Regulations, Title 47 Chapter I Subchapter D
Part 80 - STATIONS IN THE MARITIME SERVICES

Since applicable regulations are in a number of places, please use CTRL-F and search on the word "NAVTEX" to look up applicable regulations.

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What is the standard scan rate for high-frequency 3 MHz - 23 MHz weather facsimile reception from shore stations?

120 lines per minute

The scan rate is dependent on the rotational speed of the drum with the graphic being scanned. The 120 lines per minute is the most widely used standard in various radio transmissions, including ham radios.

For comprehensive information on this topic, please see SSTV Handbook site, for the pdf document entitled Facsimile — Radiofax Please use CTRL-F and search on key words, such as "120" or "lines" for relevant references.

Also, see Wikipedia's article on Radiofax

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

1 kHz at -6 dB.

Looks like this one is great just to memorize, since it is just a piece of data to remember, anyway.

For additional info, please see Electronics Notes site for the article on Quartz crystal band pass filters as a lack of filters would produce pictures with inappropriate dots resulting from unfiltered signal noise.

For regulations in this area, please see the Code of Federal Regulations, Title 47, Chapter I, Subchapter C, Part 74, Subpart E,
§ 74.535 Emission and bandwidth.

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Which of the following statements about NAVTEX is true?

Receives MSI broadcasts using SITOR-B or FEC mode.

From wp2ahg:

NAVTEX (Navigational Text) receives Marine Safety Information (MSI) broadcasts.

SITOR-B (Simplex Teletype Over Radio) is a FEC (Forward Error Correction) broadcast mode.

Marine Safety Information is available from all three sources:

• Navigation Telex (NAVTEX)
  
• SafetyNET
  
• Radio Telex (HF NBDP)

Weather updates, info regarding unsafe conditions, even distress calls are received, as there is always monitoring for such information.

For US Coast Guard MSI info see:

US Coast Guard NAVTEX MARITIME SAFETY BROADCASTS

Also see Wikipedia's article on NAVTEX.

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Which of the following is the primary frequency that is used exclusively for NAVTEX broadcasts internationally?

518 kHz.

NAVTEX is the NAVigational TEXt. Navigational and weather forecasts and warnings, and any relevant safety information are sent to ships. It is run by the US Coast Guard. NAVTEX is also used by GMDSS.

NAVTEX sends messages on 518 kHz and also on 490 kHZ. The English-only International frequency is the 518 kHZ. Regional or local broadcasts in any language are made on 490 kHz. It uses the NBDP, which is the narrow-band direct printing.

For more information see:

See Wikipedia's article on NAVTEX

Solid info on the Siranah site, in "Sail Away" section called NAVTEX Safety Information.

Also see the National Weather Service site for the National Weather Service Marine Products via NAVTEX article.

US Coast Guard NAVTEX MARITIME SAFETY BROADCASTS

Also, see Marine Insights article on NAVTEX On Ships: Working, Types Of Messages And Advantages

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What determines whether a NAVTEX receiver does not print a particular type of message content?

The subject indicator matches that programmed for rejection by the operator.

The NAVTEX uses "Subject indicator characters" to categorize different message groupings, including to accept or reject messages. Also, "serial number of messages" can be assigned, such as "00" which would print the message automatically.

The receiver can be setup to ignore specific messages, such as repeated messages, and various informational notices not specifically relevant to the vessel.

For more details, please see Wikipedia's article NAVTEX.

To see a NAVTEX unit with printer, please see the Furuno site, for the NAVTEX RECEIVER (with printer) Model NX-700A and
its product document in pdf.

For details relating to receiving messages and printing, please see Furuno Operator's Manual NAVTEX Receiver, Model NX-700A/B

Should the documentation for this unit become unreachable, please search for a "NAVTEX receiver with printer, to become familiar with an actual working model.

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