Merchant Marine radio program

[Richard Freedland]

On April 3, NPR aired a program about the merchant marine. Regrettably (but not surprisingly), no mention was made of radio officers.  Here is a link:

How the mariner shortage could impact maritime security
https://one.npr.org/i/1268875255:1268875257

Sent from my iPhone.

[Bougard Michel (Gmail)]

Hello Richard,

The shortage of mariners, in particular of radio-officers or marine electronic engineers, will happen when satellite communication will be cutted by enemies countries.

Despite the GMDSS compulsory equipments, the actual GMDSS operators are not able to maintain a veery long distance radiocommunication in emergency or war conditions.

M.Bougard,

Old Belgian merchant navy and offshore industry radio-officer.

+

[D.J.J. Ring, Jr.]

Not only that, Michel, but the shore side radio facilities are either very small or do not exist. For example, the nations in West Africa always had terrible watchkeeping on 500 kHz and even worse on HF, I'm guessing are totally dependent on satellite based systems.

One nation that had an outstanding  HF system was France. I remember as recently as 1990 copying their communication hubs in their excellent world-wide system.

They had CW markers from their installations most of which are shown on this map.

If anyone has the URL of a website giving details of their old system, I ask for them to send it to this email list.

Avec ma gratitude et mon appréciation,

David Ring N1EA

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[Jeremy Allen]

Hi all,

As I see it, there are 3 systemic problems with using the HF terrestrial components of the GMDSS which would be needed if that satellite systems are compromised.

1) At-sea operators are woefully out of practice in using HF.

2) Shore stations are understaffed for any extensive use of HF

3) Most Maritime Mobile stations only have SSB telephony capabilities on HF, which is untenable for the volume of commercial traffic that is routinely passed.

To fix this problem, at a minimum:

1) Incorporate GMDSS drills onboard as part of STCW.  We have periodic drills on things like loss of gyro compass and grounding, but not any sort of radio drills.

2) Incorporate a high speed data protocol in the Maritime Mobile radio service.  To make it workable, you'd need at least a 2.4 kHz bandwidth which would need a change in ITU channels.

I doubt any of this will happen, so if we lose satellite communications, the ship's will generally be on their own with both communication and navigation since terrestrial electronic shore support has generally gone the way of the dodo bird.

73

Jeremy Allen

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[Michel Bougard]

Hello Dave and to all,

In Belgium, they need also to up-to-date the MRCC Ostend radiostation, in order to provide again TOR facilities in addition to radiotelephone facilities.

Again 73’s,

Michel.

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[D.J.J. Ring, Jr.]

In addition to SiTOR (Simplex Teletype Over Radio), what high speed data protocol would you suggest,  Captain Allen? 

[Note: Captain Allen holds Master Unlimited, Radio Officer and Chief Engineer licenses from the United States Coast Guard - so we could call him "Captain Chief Sparks Allen", but only a precious few would understand what in blazes we were talking about. ;-(

73

DR

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[Bougard Michel (Gmail)]

Good evening Captain Allen,

High speed data protocol need direct stable radio communication, such like VHF , MF or IF radio frequencies

Propagation variation of HF radio long distance communications seems not possible for high speed data communication protocols.

It is back to only on-board maritime navigation, including again scriptural charts corrections !

Best greetings,

Michel.

+

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[Jeremy C Allen]

Hello Michel,

I agree that "high speed" is a relative term for sure.  My point is that 110 BAUDOT code offered by the current GMDSS TOR isn't going to be sufficient for a modern ship's communication needs.

Modern HF digital protocols using multiple carrier QAM and similar modulation schemes are approaching the Shannon Limit and speed is primarily dependent on bandwidth and SNR.  For a standard SSB bandwidth of 2.4 kHz, the net data rate with an excellent SNR (<15 dB) is about 5400 bps which can be increased with compression, but would decrease with encryption.  With modern transceivers and the appropriate regulatory framework, you could use wider signals and increase bandwidth.  Doing so would probably require higher transmitter power than the normal 125-150 Watts we see on most GMDSS consoles, but this is certainly technically feasible.

Sailmail is available for email service for maritime mobile stations with their relatively minimal shore stations, and provide a reasonable service for the small boat crowd.  However those stations would be quickly saturated if commercial traffic started using them, and they are not as well equipped as a traditional CW station equipped with Rhombic arrays and run QRO.  

Sadly, I don't see a market for these stations, and without a regulatory requirement, we won't see ship owners outfitting their ships with QRO stations and/or advanced modems on the off chance that we lose all satellite communications.

I do hope that the maritime mobile service does start to add higher speed systems on VHF which could start with increase navigational aid information and be expanded to regular data services at greater range than current mobile phone coverage.

73

Jeremy

[Jeremy Allen]

Hello David,

This ended up in my SPAM folder for some reason.

I am sure there are some protocols I don't know too much about, but the two QAM schemes that seem to do quite well with speed in good conditions, and tenacity in poor ones, are VARA and PACTOR 4.  They manage to do well under varying conditions by using various modulation schemes and varying the number of carriers depending on real-time data exchanged between stations.  

Here is a link for Pactor 4

Here is a link for VARA.

I am sure there are some exotic military modes out there, but I don't know too much about them.  I would love to include CLOVER 2500 and CLOVER 3000 on the list, but my experience with these modes is that they require significant SNR  (> 0 dB) to maintain links and pass traffic, while the other two work down to -20 dB.

SITOR dates from the 1960's and there have been great strides made in HF digital protocols since then.  It's just too bad the Maritime service hasn't kept pace.  Unfortunately, they seem to be putting all of their eggs in the basket of satellite communications at this point.

73

Jeremy

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[D.J.J. Ring, Jr.]

Impressive, Captain-Chief-Sparks, I  thought your VQ9ZZ blog was very interesting, however I didn't see any  information about CLOVER 3000. I was very impressed with the throughput of Pactor 4 and VARA. Also I was confused given fair signal strengths SNR 10 dB or greater which of the three, PACTOR 4, VARA or CLOVER 2500 has the best throughput?

I've had the chance to use PACTOR 3 and was very impressed, and I knew nothing about the introduction of PACTOR 4 and until your post, I had never heard of VARA.

Your post was quite a revelation.

Members with knowledge of these modes are requested to share additional knowledge with this group.

73
DR

To view this discussion visit https://groups.google.com/d/msgid/radio-officers/1886331961.2098010.1743879181019%40mail.yahoo.com.

[D.J.J. Ring, Jr.]

The VQ9ZZ blog is located here:

https://vq9zz.blogspot.com/2014/04/operating-clover.html

73

DR

[Jeremy Allen]

Hello David,

A few things to note about VARA.  It's a "sound card" modem.  This means that the computer generates the modulated tones which are generated via either the internal or an external soundcard and audio is then fed into the SSB transceiver.  This is a bit different than the FSK found in RTTY and SITOR where the radio itself makes the tones.  VARA comes in two HF  variations.  The first is a full SSB bandwidth of about 2.4 kHz and the second is a restricted 500 Hz signal.  The 500 Hz signal is slower of course, but fits very nicely in a standard CW filter and allows for more signals and is fast enough for most person to person QSO work.  The top speed for VARA 500 is about 1100 bps.  VARA is available as a free download, although the unlicensed version is speed restricted.  The license is under $100 and when compared to Pactor, incredibly inexpensive for essentially the same speed.

Of course the modem is only half of the equation.  You need effective software to make full ues of it.  The main two programs using VARA are Winlink Express, which is strictly an email exchange program, and VARAC which does pretty much everything you might want to do with the modem.  There is also a commercial version of VARAC called Safecom.

One of the big differences between VARA and Pactor is that VARA works quite well in FEC mode to send beacons, and telemetry.  I have always found Pactor to fall a bit short in this regard.

Since you've used Pactor III, you are at least familiar with how Pactor 4 works.  Basically it's a ARQ mode that uses a stand-alone modem to generate and decode the tones.  The computer merely reads and writes the serial data to the modem.  Pactor 4 uses a different modulation than Pactor III and is faster at the high end, and slower, but more robust on the lower end.  Pactor 4 is limited to the newest modems due to the intense DSP that occurs that is beyond the 25 MHz chips of the older modems.  Pactor 4 modems also offer ALE and AES encryption as well as onboard compression which is why they are still used in commercial service.  You do pay for the hardware and a fully equipped Pactor modem with the ALE and encryption firmware is running close to $3000 now.

Clover is a different animal and was originally offered on the HAL Communications modems.  It started out with Clover 500 and a marine version called Clover 400 that fit in the narrow Maritime Mobile bands.  These versions have four tones at a low base baud rate.  To increase speed for Clover 2000, they increased the number of tones to eight and increased the baud rate as well.  Clover 2500 maintains the 8 tones, but managed a bit more speed by again increasing the baud rate.  Clover 3000 was introduced after Barrett bought out HAL a number of years ago.  Barrett was in turn bought out by Motorola a few years ago.  Clover 3000 is a bit of a mystery to me.  It is available as a modem firmware upgrade in the Barrett 4050 radio with internal modem.  I am not sure if it works on the older Barrett 2050 radios which can be fitted with Clover 2500 modems.  I haven't seen any specifications, but surmise that it's a bit faster and wider than Clover 2500 due to increased baud rate.  Since the mode probably exceeds the 2.8 kHz limit on Amateur radio and I don't know of a commercial service that uses it, I have not experimented with it. The main weakness of Clover is that the number of tones is fixed so it really needs a good SNR to work well.  The high end Clover protocols aren't used much, but when the are, it's generally for message transfers using a program called Barrett Mail, which is a radio email to commercial email bridging program.  You can also use it for chat and file transfers.

Now as to your question, I find that with a SNR of +10 dB you are going to get pretty good speed on all three waveforms.  VARA and Pactor 4 will run at about the same speed with Clover 2500 bringing up the rear.  

I ran VARAC extensively on my last trip, especially on my run between the US East Coast and Germany.  A number of people kept tabs on me and dropped messages to my mailbox and I had a number of long text chats with people.  It was a really fun mode that I could use when I had free time, and also allowed me to beacon and do mail exchanges when I was busy.  This type of system could also be useful in commercial services as it allows to unattended traffic to be exchanged over HF, AIS like beacons, and allow for robust QSO's when required.  It would work significantly better than SSB, and probably as good as CW, but without needing the skilled operator needed for CW.

Anyhow, those are my thoughts.

73

Jeremy