moving to: theviewfmarmchair.blogspot.com

moving to: theviewfmarmchair.blogspot.com

Note1_PiR_ Side note on the interest of using Single Board Computers in a leisure boat

Note1_PiR

Side note on the interest of using Single Board Computers in a leisure boat

As someone said (maybe in the Cruisers.forum.com, quoting from memory):

                        “ in a boat the equipment is in one of 3 states:  broked, 

                         breaking or about to break”.

Single Board Computers (SBC) are nowadays credit-card sized or even smaller. But with performances close to average consumer computers of just a few years ago. They are everywhere, even in the houses of the more anti-technological persons. And, with the Internet of Things (IoT) they will became even more ubiquitous. Raspberry Pi SBC started by 2012 to be targeted only to promote the computer literacy in schools and poor countries; then they were adopted almost as pet toys by the geeks and nerds; and also more and more used to accomplish very demanding tasks even in industrial contexts. So SBC are small, cheap (just a few dozen of euros) but nevertheless serious pieces of technology. Even in leisure boats SBC have been used hidden in ­­commercial products.

The Sea does not forgive. With irregular and stressing motion paths in all axis. Also, even in the cabin of a cruising boat, large variations of temperature and humidity and the accompanying condensation. Always with salt in the air, more than enough to corrode even the best and protected piece of equipment. A problem in particular for electronics, regardless of  being dedicated “marinized” and thus insanely expensive commercial items or just the consumer gadgets brought aboard by the cruisers.

So, what can we do?

Try to use as much as possible devices with no moving parts, with the least holes/connectors as possible, enclosed in air-sealed cases whenever possible with passive thermal cooling, etc. It might have been  difficult in the past, but nowadays is becoming more and more easily achieved even with consumer appliances.

-       idevices – with no moving parts by default and with less and less “holes” and buttons, thanks to Steve Jobs. Plus, there are plenty of waterproof and shockproof cases around.

-       Computers – the “mechanical” hard drives are now almost completely replaced by SSD (solid-state drives, with no moving components). Moreover it is now quit easy to find computers with no moving parts at all and very few “holes”. Notable example: a few  models of MackBooks.

Right, and what about SBC as the Raspberry Pi series? SBC could certainly find its place in a cruising boat, installed by a geek crew member or by a contracted professional. A few years ago, a few wealthy/tech oriented sailors even installed several hidden MiniMacs to control and manage  on-board commercial pieces of equipment as  autopilots, weather sensors, electronic navigation tools, radio transceivers, etc.

The Ham land based enthusiasts seems to appreciate SBC both as standalone SDR computers to operate in the field, to simplify their home rigs and to run panadapter displays for exploring large samples of the RF spectrum. There seems to be also some interesting applications in remote operation for both reception of raw IQ data and pre-processed audible streams. In a similar way, in a leisure boat, instead of installing an antenna and run a long coaxial cable, subject to all sorts of RF interferences, up to the sdr/computer in the chart table – it might be possible to use a very short coax feeding a waterproof box with a SDR and SBC inside, with just a USB or UTP net cable (digital signals note so prone to RFI) running up to the chart table. Or just feed electricity to the “distant” SDR/SBC through Power over Ethernet (POE).  With a Wifi connection between the SBC and the main computer on the chart table.

Now how often and how many sailors do use such setups in the real Sea world? I have no idea.

Nevertheless my curiosity was piqued by the messages from Conachair and Eric in the cruisers.forum’s thread, “Radio troubles of a sailor and the promises of software defined radio (SDR)”. Therefore, I decided to make some trials at my armchair with a Single Board Computer. So at home I have now two Raspberry Pi units, one 3B with a DAC hat to stream high quality music and one Pi 4B, a brand new candidate to become a sailor.

Setup

            - general setup -  see previous messages, tech2 and tech3

            - Raspberry Pi 4 Model B 2GB running SDRPlay RPi image V0.6

I will post a first review shortly.

Tech5_VHFwav_Samples of Warnings VHF Ch16 or the armchair radio-sailor

Tech5_VHFwav

Samples of Warnings VHF Ch16 or the armchair radio-sailor


Samples of Warnings/Notice to Mariners. North Atlantic Coast of Portugal. Voice VHF, after short call "all ships, all ships" in Ch16 directing to Ch11.

Sample1 VHF16_11.wav link:

https://drive.google.com/file/d/1zRUGJ4iH_NQ5HffqdpAaTsTdms1g_l1A/view?usp=sharing

Sample2 VHF16_11.wav link:

https://drive.google.com/open?id=1BE4UrNyV6KKRxaH3CuFiR_8TAGhikHeO

Lots of RFI noise, operator not a native English speaker. Hard to understand, right? A common experience while sailing well known by seafarers.

From an armchair radio-sailor and with all the technical jargon, trying to find a portable and reliable solution to a real cruisers problem: the very low quality of User Interfaces(UI)/Human Machine Interfaces (HMI) for voice and data of commercial systems installed in leisure vessels.  Poor quality of audio, data truncated and/or presented in very small displays, limited (if any) possibility of recording voice messages and re-listen it or to read later the data messages in a really readable display. A concern with all the radio sources and fixed systems in leisure boats: L/M/HF frequencies, usually SSB, VHF, UHF (SafetyNet-Inmarsat and other satellite services).

A recommended good practice in big vessels (sorry, do not have the authoritative source at hand) is to have reception-only systems with clear sound alarms to  alert the officer on watch that a new message was received and recorded. The new  message could then be read, in a big and good enough display. Not sure if such good practice for big vessels addresses also VHF/SSB/Satellite verbal warnings. But this is/would be certainly a must for all types of ships.  Particularly, for our leisure vessels with limited radio equipment and with no 24h designated officer on watch at all.

In short,

In the real world of leisure sailing

(1) voice warnings and notice to mariners (regardless of the media, VHF/SSB/Satellite) are very often poorly heard and understood by the cruiser crew

(2) text messages are usually presented in very small, near to unreadable displays (see VHF-DSC “displays” even in the recent models high-end certified models)

Therefore,  having a way to automatically record and listen/read, as many times as necessary, both audio and text messages with a independent setup of the fixed in-board equipment, with a good audio/image output (i.e. at least our own portable computer …) should be a must. These issues were the primary motivation for my interest in Software Defined Radio with mid-range equipment as the SDRPlay models.

Setup

See previous messages on general setup of antennas and SDR hardware

Sampled recorded from a flat, 4^th floor. In a very busy city area.

Antenna in the inside face of a large window facing NW with a field of view from 20 to 210 degrees (magnetic), thus,  in a anticlockwise direction,  from NNE to SSW.

About 10 Km/5,4 NM in a straight line from the nearest broadcasting VHF radio marine authority.

A very hard setup for receiving marine VHF but:

-       not as a far experience from those I and most seafarers have when navigating near to shore of large European urban areas

-       a good test-bed to stress the SDR setup, i.e., if it works here it should work while really sailing

-       meteo forecasts of winds up to 40 NM/h, rough seas with waves of 5-6 meters and peeks of 14-15 meters, so much safer and cosy to stay at home.

Meth2_WhyaSDR_Why a SDR approach to radio reception for cruisers

Meth2_WhyaSDR

Why a SDR approach to radio reception for cruisers?

Or, given the goals and the available radio sources (check my previous post about the background and motivation ) what are the feasible options  for a cruiser?

Goals: to have a portable, yet easy to deploy, reliable and easy to use system

What radio sources of timely safety warnings, notices to marines and other useful information?

(From my experience mainly by the Iberian Atlantic Coast and the Mediterranean)

And listing such sources, from the lower to the upper radio spectrum, in a language simple to understand for cruisers even if not the most accurate for experts:

Navtex

Similar to verbal warnings and notices through VHF channels but in text format, thus the messages could be checked in a display and/or printed. General architecture of the system is fine. Unfortunately the radio frequencies used (around 500 KHz) are very prone to be impaired by obstacles and all sort of radio and electromagnetic interferences. Up now, I knew only two skippers happy with their Navtex; for myself as for the majority of  skippers I talked to this source, at least through the available commercial systems, is unreliable  and completely useless. It seems navtex is also available, in a few areas, around 2800 KHz, but I had no experience with it.

RTTY-DWD

Warnings and useful information in text format. Not part of the safety, mandatory, SOLAS network but nevertheless regarded by both professional and leisure sailors as a good source. Broadcasted by the German DWD through several medium/high frequencies. A maritime or Ham SSB transceiver coupled with a data/digital system could be used to receive RTTY, but it is an overkilling approach. In fact, it is very easy to receive readable messages even with a dated small receiver connected to an iDevice or a computer running digital modes software.  For example, a Sony ICF-SW7600G. You would receive messages and warnings about all the covered regions, regardless of your actual area of navigation. Quiet funny, to read ice warnings while enjoying a Sun bath in the Baleares.

WeatherFax

Meteo Charts. Very useful. Broadcasted by several USA, UK and German radio stations. Much of the previous comments on RTTY do  apply here.

VHF

Coastal safety, meteo and other useful information broadcasted by national maritime authorities. Voice messages through Very High Frequencies, VHF in short, hundreds of MHz. Usually the first call is issued in channel 16 both in the local language and in English. Easy to receive with almost any fixed or portable transceiver/receiver. Main problems: we just do not listen the messages, radio noise, hard to understand the local language, the proficiency of the radio operator trying to speak in English is not  the best … so recording the messages would be a must.

SafetyNet/EGC

Several types of safety and other useful messages available through the satellites of the Inmersat network. Mandatory for certain vessels. UHF, GHz frequencies. There are dedicated receivers used in large vessels and very expensive offshore leisure or racing boats. For the rest of us a portable satellite phone coupled with a data reader/display is  the most common approach. Nevertheless, even the cheaper satellite phones and communication fares are considered still quite expensive by most cruisers and its use is almost restricted to offshore navigation.

Wifi/3-4-5 G

Yes, lots of useful maritime and meteo sources, web pages and apps. Readily available for coastal navigation, at least in the developed countries. Easy to receive by ordinary mobile phones, idevices and computers. Not part of the mandatory maritime safety networks. Always staying close enough to the coast to receive such “terrestrial”  GHz radio frequencies might not be wise nor safe.  Not the scope of this blog anyway.

So,  repeating the initial question of this post,  why a SDR approach to portable radio reception for cruisers?

First, let us face it, even the “fixed” systems often found in leisure vessels are not satisfactory. Navtex commercial receivers are useless. SSB maritime transceivers and related modems to transmit/receive text and images are expensive, difficult to install and power hungry; and surely overkilling if used  to “just” receiving information. It seems even that nowadays it is impossible to get a new SSB transceiver compliant with the European legislation. Satellite fixed systems are regarded as too expensive for must of us.

Second, there is no such thing as a conventional piece of hardware, a portable classic radio receiver able to cover the entire spectrum for the sources listed above.  My Sony ICF-SW7600G, and similar radios used by sailors, are honorable pieces of technology. Only for SW/MW/LW or FM. As many old school sailors I almost always travel with mine. But for a similar price tag of these old radios we can now buy a far better SDR.

Therefore a SDR, mid range unit with a price tag of 100-300 Euros, seems the best option. Several models in this range are able to cover all the spectrum from the low/medium to the ultra high frequencies. Furthermore, for each radio broadcast frequency we could select the best, built in filter/amplifier. No need to play with several small pieces of hardware, connectors and cables as with those so called “cheap dongles”. Finally, paired with the proper antennas such SDRs could receive all the voice and data messages of interest for cruisers. With a quality that matches higher-end transceivers (check Ham forums, the Akos blog radioforeveryone.com and other commendable reviews).

For example, SDRplay RSP 1A (for single antenna coupling) or the 2 or Dx models, that might be paired with up to three antennas simultaneously, thus really covering all the spectrum of interest for us. Ie., (1) a simple wire antenna for navtex, rtty, weatherfax and M/L frequencies in general, (2) a VHF one for well … receiving/recording vhf channels and (3) a patched or equivalent antenna for receiving data from satellites.

 (more on technical specs, examples and tests of SDRs, antennas  and software in future posts).

Meth1_Background_Background or why a blog of a sailor on radio, why SDR, why starting now

Meth1_Background

Background or why a blog of a sailor on radio, why SDR, why starting now?

My firm belief : the best sailing boats are those of friends and charter companies. 

However, as a skipper or co-skipper, by 2006, I had become more and more concerned with safety and reliability issues of the navigation tools. Of course, I put questions in advance on the availability of official updated charts, both in paper and electronic, availability and specifications of plotters, AIS and Radar receivers, radios, safety equipment, etc. The usual answers were always quiet assuring on each and all topics of enquiry. Nevertheless, the reality in the first day in the boat was always frightening. Both, the paper and electronic charts were outdated and/or just fancy commercial ones with no traceability. Yes, the boat had even an AIS transponder but just for sniffing your coordinates and sending the data to the charter staff; not for your own use. If you want to be proficient with the plotters, radios and all the essential navigation gear in the boat you would need to spent days reading the manuals, testing, asking for help … instead of enjoying your sailing holidays with your friends or family.

So,  I decided to build my one portable pack of navigation tools with two maincriteria:

• safety, reliability, ease of deploying and using in any sailing boat I intended to skippering;
• compact enough to be carried in a cabin case.

By 2007 I was very happy with almost all of my own set of navigation tools. The notable exception: radio hardware and software to receive timely safety warnings, notices to marines and other useful information. So I continued following the usual path as most cruisers: (1) just before leaving the marina I rushed to find a WiFi spot to check and download the relevant information (2) praying during the coastal or offshore trip for stable meteo conditions and no bad surprises of any kind. And what about the VHF messages issued by the local marine authorities? Let us also admit it: we did not get it because we were very busy changing sails (or just relaxing), messages were  scramble by lots of noise, the radio operator had a weird accent, etc.

Therefore, I decided to start a systematic search and test of possible solutions. First decision: the best approach would be to experiment with mid range SDRs. Not those cheap dongles (but see my previous post on AIS) nor the high-end systems used for military, scientific and ham communications. Instead, the ones which are serious pieces of radio hardware/software (check radio ham reviews) in spite of its funny names. For example, HackRF, AirSpy or SDRplay with tag prices in the range of 100-300 Euros. (more on this option in a future post). Unfortunately by 2008,  I started facing severe personal problems. And both, my sailing holidays and radio equipment tests have been postponed.

So, in short, the motivation for starting this blog and post maybe a half dozen of messages, is quite simple: to share the results of my past research on portable radio solutions for skippers. No, I did not reach a “definitive solution” but at least my test results might be useful for other skippers and maritime radio hardware and software developers. And hopefully, I’ll be able to post further and new tests in a foreseeable future.

Tech4_SDRBookmarks_Marine MF-HF-VHF bookmarks for CubicSDR

 Tech4_SDRBookmarks

Marine MF-HF-VHF bookmarks for CubicSDR

Update:
Here is a direct  link to open and download  my marine MF/HF (Navtex, RTTY_DWD, WeatherFax_DWD_Northwood_Boston)  and VHF bookmarks for CubicSDR 

https://drive.google.com/open?id=1aoV0rCXgapQdkG6p4TingDhGm9DyJwI5

Not fully tested; to be used at your one risk. Keep in mind common sense, etiquette rules and regulations when listening to marine radio channels.

 

Some time ago I (1) collected information on MF/HF and VHF UK and PT marine frequencies ( relevants for my navigation goals) and (2) made a few preliminary tests with the VHF bookmarks ready to be used under CubicSDR. Screen shoots below.

These bookmarks can be used to

-       a fast scanning of radio channels with information on the expected content (instead of the “blind” experience with a marine VHF or Ham radio)

-       to record at scheduled times the notices to mariners, safety or other useful information (channel 16 …)

-       to use in conjunction with data/digital modes software (Fldigi, other free or paid digi mode apps) to see/record navtex, weather fax, etc.

Tech1_ais_A long over-due report on the feasebility for skippers of a AIS/RTL-SDR receiver

 Tech1_ais

A long over-due report on the feasibility for skippers of a AIS/RTL-SDR receiver

Portable setup: commercial AIS antenna -> coaxial cable -> LNA, linear amplifier -> USB RTL-SDR v3 dongle -> USB cable -> portable computer | AIS decoder, rtl_ais / OpenCPN v4x| -> WiFi hotspot of the portable computer -> iPad |SEAiq

Tested during a charter of 15 days.  each morning,  just needed a couple of minutes to had everything up and running. Fast, reliable data for ais tragets up to 20 miles. The linear amplifier, by providing a stronger signal,  seemed to reduce the load and heating of the dongle.  RTL-SDR v3 dongle  far better than an older v2 dongle, not sure why.

Bottom line: it worked even better than I expected. Good  as a portable solution for ais receiving when chartering and other occasional situations. Could be made a more permanent/clean setup in any cruising boat. Of course , not a replacement for a good AIS transponder.