John Griffiths discovers a whole new world of listening out there with his Grundig Satellit 800 HF radio. He has kindly wrote the following article to share has findings with the readers of Transmission1. He is happy to receive your comments and has provided his email address at the end of this article. Read on and find out about easily receiveable data modes on HF….
Apart from its use as a mid range receiver for short wave listening, the venerable Grundig Sat800 has just proven its worth in an area that I am happy to admit I was aware of but knew very little about; It all seemed too technical for me! Data modes – or to put it another way, the mysterious world of RTTY, FAX, WEFAX and NAVTEX.
If those abbreviations means little to you, then let me explain in an easy enough way to maybe whet your appetite, how this whole new aspect of short wave listening works. Not whole new as in it is something that has just been opened up – whole new to me!Firstly, data modes never really got my attention until I was bored one night by crashing static and very little HF activity. I was looking at marine sites on the ?net when I came across an AIS site showing ship movements when the small ad for a free Navtex, Fax and RTTY decoder caught my eye. Free? Well, a trial version – but enough to get my interest going! Having just erected a long wire at the QTH, I thought I?d see how stable to Sat800 was for this form of receiving – and I was not disappointed!
So what exactly is NAVTEX, WeFAX and RTTY? Basically, they are marine based weather and navigational information systems aimed at mariners – both professional and leisure. As an introduction to data modes receiving, it is probably the best place to cut your teeth and see whether this is for you before you splash out big bucks on a programme you realise you have lost interest on!
As for the radio. the Grundig Satellit 800, whilst looking like an over technical household radio, is actually an excellent bit of kit – see my earlier review of it on here. Whilst looking like something the missus wouldn?t object to in the living area, it is in reality a high spec short wave radio in a class of its own. It is not too technical to operate and is my personal radio of choice after many years using sets such as the Yaesu FRG7700 and other lower priced radios for HF listening. It is a solid, somewhat chunky, set that is both aesthetically pleasing – it really doesn?t look out of place in the main room of the house – as well as being constructed with the dedicated SWL in mind.
For data modes, the set is stable enough to make copy very readable -Grundig claim figures of 10ppm for frequency with an accuracy of 100Hz whilst in practice, the set coped well in decoding a Weather Fax broadcast that ran for over 40 minutes with miniscule deterioration of copy. I would like to test it further with other data modes but, at the moment, am focusing on maritime signals. Maybe later, when I get the hang of it, I?ll start looking for the other signals that are out there. Stability in these modes is critical for good signal reproduction and I am not certain that less expensive radios would cope – but I could be wrong!
My plan has always been to add an ATU to the set up, to make signal discrimination a bit better, and the next project will be around getting my hands on one to add to the radio itself. I?d like to have a more dedicated antenna as well, but this is not possible with a small garden unless I splash out on a highly expensive ?do it all? antenna system, so I went back to my roots and rigged up a very basic long wire that does exactly what I want it to do, albeit in a slightly rougher way than a dedicated antenna. Hopefully the addition of an ATU will allow me to peak the wire to enable better reception but for now I am very happy with what I have got..
So, back to rudimentary decoding. I use SeaTTY, which is a free trial programme available on http://www.dxsoft.com. For other modes – WEFAX, FAX and RTTY, I would suggest looking at http://www.hffax.de/index.html which, again, provides a good starting point to explain more about the various modes and also provides reception tips, freqs, scheds and the like. From there it is hoped you will ?graduate? to the WUN site http://www.wunclub.com/index.htm which together with the other site mentioned, are probably the best available on the net for really looking at what is available on short wave.
So. how simple is it? Well, if you have RCA jacks to the back of your receiver – and an RCA cable that ends with a jack for the mic in socket of your PC – you are halfway there. Downloading the programme was easy, as was the set up, and simply connecting the cable between the RX and the PC and starting the programme had me up and running in less than five minutes. Once I?d messed about with it and tried to receive something, I decided to focus on the NAVTEX side of things as these are broadcast on LW and thus travel well – up to about 300 miles in good conditions from the transmitting site. I live in Kidlington in rural Oxfordshire and I was able to receive European signals day and night at excellent strength. An example of copied NAVTEX follows:
NAVIGATIONAL WARNING NR. 82 131459 UTC APR
3 OVERSIZED 40FT CONTAINERS ON SEABED
A. 51-44.7N 003-30.0E B. 51-45.1N 003-30.5E
C. 51-56.2N 003-38.5E
POSSIBLY DANGEROUS FOR SHIPPING AND FISHERY
My long wire extends in a rough east – west direction, is 30? in length, and is made up of very thin copper wire ( 30 SWG) fed by RG58 50ohm coaxial (about five metres in length) via an unsoldered PL259 to the Sat800. The cable is not earthed and is very rudimentary, never being designed as a long term antenna – more of an experimental effort at seeing what I could pick up.
As you can see from the attached images, I was able – with little more than half a day playing around with the programme – to clearly receive NAVTEX as an excellent signal and also to receive WEFAX at, again, an excellent reproduction. Radio TelyTYpe (RTTY) was copied as follows:
FQEN71 EDZW 152000
WEATHERREPORT FOR GERMAN COAST ISSUED BY MARINE WEATHER SERVICE HAMBURG 15.04.2006, 21 UTC:
GENERAL SYNOPTIC SITUATION:
LOW 994 WESTRUSSIA, MOVING NORTH. LOW 983 NORWEGIAN SEA,
WEAKENING A LITTLE, MOVING EAST A LITTLE. SECONDARY DEPRESSION 993 CENTRAL SWEDEN, MOVING EAST. TROUGH 1000
LITHUANIA, MOVING SOUTHEAST. HIGH 1017 CENTRAL FRANCE WIH
RIDGE 1015 SOUTHWESTGERMANY, MOVING EAST, SATURDAY NOON
1020 CZECH WITH RIDGE 1015 HOLSTEIN. LOW 1007 23’5 9! PORTUGAP, MOVING NORTHEAST, SATURDAY NOON 1008 BRITTANY.
How do you start? Firstly, it is important that your receiver has the necessary RCA jacks to its rear panel and that you have a line in socket on your PC plus the cable to connect both. This is the essential interface to enable the programme to work. The Line In socket is basically the one you use for the PC?s microphone and you?ll know if you are in the right place as it will kill the speakers – if you can hear audio from your PC?s speakers, you are not in the right place. Once you have connected it up and have the decode programme started, it is then a case of reading the instructions and trying it out.
One hint I quickly picked up was that whilst the main NAVTEX broadcasts are on 518kHz, tuning 1.7kHz less (to 516.3kHz) gave a stronger signal. Similarly for WEFAX, it is best to tune off about 1.9kHz for better picture quality. An xample being Hamburg Meto on 7880kHz – tuned in on 7878.6kHz produced the better quality picture you can see here. Modes are USB for both and whilst the Sat800 has auto filter settings (which you can override), I found the narrowest filter used (2.3) produced the best results. I played about with the AGC as well, but it seemed to have little effect on the signal.
The programme has an AFC (Automatic Frequency Control) radio button which I find helps, although manual tuning to ensure the twin red needles on the display match the twin peaks of the carrier also works. These are mouse click and drag so you can set the signal to decode extremely easily.
From this small beginning I am now hoping to set something with more tech-spec bells and whistles up and have my eye on Radio Raft, which is a multi platform decode system that requires a demodulator but which promises far greater ability to decode the signals out there. Having said that, there are still stand alone units that offer the world of data decode – it is really a question of wait and see.
Meanwhile SeaTTY is perhaps the very best of programmes on offer for its ease of set up, understanding and quality. I heartily recommend this small introductory bit of software to anyone contemplating squeezing a little bit more out of their radio. They also have another trial programme – trueTTY – which I am planning to look at a bit later, once I feel I have fully mastered seaTTY.
Shortwave radio is not yet dead, despite the looming prominence of DAB and DSM, both of which are aimed squarely at the BCL enthusiast. For those of us who like our radio raw, having to wok to get the weak signals out from the ether, there is still life in the old dog yet! Data modes is not an new aspect to the hobby – but, thanks to the internet, it has just taken on one more convert!
Any comments to: [email protected]
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