Radio troubles of a sailor and the promises of software defined radio (SDR)

[conachair]

But I never tried to configure a Pi for SDR. I've one Raspberry Pi 3B but just to listen [/FONT][/COLOR]Spotify and my ripped Cds at home (HiFiBerry DAC+, Volumio).


Good luck and keep me updated!


Fair winds,
Jorge

Similar onboard, I've a hifiberry amp on a Pi3B+ which is the boat music/podcast/radio system. Good fun having a radio receiver to look from near DC to 2GHz over the speakers without having to get out of bed
Also gets used for streaming web radio using MPC. with node red making a control interface. Works great

sudo apt-get install mpc
mpc stop
mpc clear
mpc add http://www.djamradio.com/sound
mpc play

[ejs]

I use a Pi and a cheap dongle (NESDR Smart) running 24/7 to do backup AIS receive and Low earth orbit weather satellite download. I receive the three NOAA weather satellites and the two Russian Meteor ones. It is very useful for local weather informationas it is realtime data and not a prediction. I use the same antenna as the frequencies are close enough. it is tuned for satellite at 137 MHz but works fine for close in AIS at 162 MHz. The pi just switches frequency when a satellite is overhead.



I've tried an early SDRPLAY with a tuned whip antenna for HF wefax reception, but it was no where near as good as my dedicated HF radio on the backstay.


Cheers, Eric

[Harry99]

Hi Eric, can you tell us which Software you use on raspberry pi?

[conachair]

Originally Posted by Harry99

Hi Eric, can you tell us which Software you use on raspberry pi?

[ejs]

Hi,
Not really a satisfying answer, I cobbled a bunch of python programs together, teaching myself a bit of python at the same time. For example, no one else expects your station to move around so I use the GPS to set the location.


I got the base for the NOAA weather part from:
https://github.com/cyber-atomus/autowx


the Meteor part from:
https://github.com/dbdexter-dev


and the AIS part (easy) from:
https://github.com/dgiardini/rtl-ais


I also run OpenCPN on the PI. The system runs well but is rather fiddly to set up, I have a script that does most of it, but I've never had it run through without something I forgot or had to tweak. I'm an engineer but hardly a programmer.


Cheers, Eric

[conachair]

Originally Posted by JSantos

But I never tried to configure a Pi for SDR. I've one Raspberry Pi 3B but just to listen Spotify and my ripped Cds at home (HiFiBerry DAC+, Volumio).


Good luck and keep me updated!


Fair winds,
Jorge

A reinstalled pulseaudio and GQRX works again on a Pi3b+ running raspbian buster

[JSantos]

Hi,


For those interested in details of my radio reception rope antenna here is an update with numbers ... (also updated in the blog).


MF/HF, SSB
Voice, data as Navtex, DSC-RTTY, WeatherFax ….

A DIY Rope Antenna of around 9 meters, fits well in a sailing boat from a 28 feet monohull to big catamarans. Hanging from the mast to a rail in the stern as far as possible of the backstay(s) but without interfering with the boom and main sail.

- wire of the appropriate length (not a random one even, use online ham calculators, mine= 8,38 m) --> coax cable (mine= 5,56 m) --> connector to SDR
- embedded in a 12 strands single braided polyester rope with two eye splices (total length = 9,16 m , total weight including wire/rope/coax = 0,54 Kg)


Fair winds,
Jorge

[JSantos]

Hi Eric,


[QUOTE=

I've tried an early SDRPLAY with a tuned whip antenna for HF wefax reception, but it was no where near as good as my dedicated HF radio on the backstay.


Cheers, Eric[/QUOTE]


Just curious, and did you try a SdrPlay connected (just for reception of course) to your backstay/HF antenna?


FW
Jorge

[ejs]

Hi,
Most of the testing was with the receive whip for the emergency DSC on my M802, but I did try it using the main antenna as well. It was through the tuner but in thru mode not tuned mode. The SDRplay still was not as good as the reception through the M802/Pactor modem combination for weatherfax. It was a bit better than the whip, but still not really usable for our weather needs.

These tests were all using the New Zealand wefax broadcast which does seem to use finer detail than the US broadcasts.



Cheers, Eric

[JSantos]

HI Eric,


Thank you for the clarification.




Fair winds and season's greetings!


Jorge







T

Originally Posted by ejs

Hi,
Most of the testing was with the receive whip for the emergency DSC on my M802, but I did try it using the main antenna as well. It was through the tuner but in thru mode not tuned mode. The SDRplay still was not as good as the reception through the M802/Pactor modem combination for weatherfax. It was a bit better than the whip, but still not really usable for our weather needs.

These tests were all using the New Zealand wefax broadcast which does seem to use finer detail than the US broadcasts.



Cheers, Eric

[JSantos]

Samples of Voice Warnings/Notice to Mariners.

Sample1 VHF16_11.wav link:

https://www.dropbox.com/s/n914nc6vyi...16_11.wav?dl=0

Sample2 VHF16_11.wav link:

https://www.dropbox.com/s/63a1fsgg1j...16_11.wav?dl=0

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.


Longer version of this message in "https://radioforcruisers.blogspot.com/"


Fair winds
Jorge

[JSantos]

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=1ao...ingDhGm9DyJwI5

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.


bw
Jorge

[JSantos]

Hi,

Note1_PiR

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

As someone said (maybe here 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. Much like Software Defined Radios, SBC are small, cheap but nevertheless serious pieces of technology. Even in leisure boats SBC have been used hidden in **commercial products.

The Sea does not forgive. 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.



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.



But 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 this forum thread. 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 fidelity 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.



(check radioforcruisers.blogspot.com for an extended version of this message).

Fair winds,
Jorge

[ohgary]

There seems to be a lot of interweaving of SDR radios and digital modes. SDR radios have nothing to do with modes of operations. SDR radios are simply the way the RF energy is processed. Via a digital signal processor. Using the DSP you can via digital methods create filters and amps to improve a signal.

What you do with that signal is secondary. Then you would apply the various modes, voice(SSB), or various digial modes, but those are secondary to the DSP.

It does get somewhat confusing when you have a DSR module and feed that into your computer then run programs on your compute to decode digital signals but they are truely two seperate functions.

Most true DSR radios, NOT DSR modules look just like a normal SSB radio, just the inerts are digial vs analog.

[JSantos]

Originally Posted by ohgary

There seems to be a lot of interweaving of SDR radios and digital modes. SDR radios have nothing to do with modes of operations. ...
It does get somewhat confusing when you have a DSR module and feed that into your computer then run programs on your compute to decode digital signals but they are truely two seperate functions.
... just like a normal SSB radio, just the inerts are digial vs analog.

Hi Gary,


Thanks for your reply.


Of course you are right (as in your previous message of 18-12-2019). At least for almost all the situations to transmitting/receiving or just to receive radio signals.


But there are notable exceptions or near exceptions. Most of only theoretical interest for us. At least one of practical interest for cruisers.



- In the spatial domain /bandwith, very wide spread "messages" across several frequencies; mainly used by the military, forbidden for the rest of us, if I'm not wrong.



- In the time domain , very timely sparse "messages", weak signals below noise floor; mainly scientific applications at first, but increasing popular for amateurs - ex. Weak Signal Propagation Reporter (WSPR) the called "whisper" mode.



This one maybe useful for modern sailors lost as Robinson Crusoe.


- Real panadapters for continuous monitoring of frequencies from VLF to UHF. Or in human language, from dealing with time signals or submarine communications up to listen satellite conversations. A small SDR headless black box, a computer with SDR software and that´s it.


- for cruisers interested in practical, portable, and reliable solutions to receive SOLAS/GMDSS or just useful information, from Navtex to the SafetyNet, with all the voice and data modes in between.


You might want to read the extended version of posts at "radioforcruisers.blogspot.com" to better understand the rationale of my approach.


Fair winds and thanks again for your message,


Jorge