ROS is MSFK just like I said

Sorry folks gotta say it, no one else will admit it will they.

I made the Video and posted on this blog what was obvious to me 6 days ago. ROS is an MFSK Mode. What a pity the whole brotherhood of US Hams and the FCC got it wrong. How long now before they sort it all out. You gotta laugh when a world power makes an ass of itself. Me I can do it regularly and get away with it.

The Technical Description by Jose is just published.

ROS is a easy interface chat mode for real-time amateur contacts. It is a half-duplex non-Automatic Repeat ReQuest (ARQ) forward-error-correcting (FEC) mode. It performs well on long-path fading conditions and in the presence of interference.
The transmission is based on M-FSK (sequential single tone FSK), with continuous phase (CPSK) tones. There is no delay between tones, and no shaping of the tones (rectangular window).
The ROS transmission system is divided by frames of tones. A Frame is formed by 144 tones: 128 tones for data (with 7 bits Gray Code), and 16 tones for synchronization.

From Zero Me to Zero dB

The local Hams have been very good regarding looking for my 500kHz signal. I asked three operators initially to take a look thinking that I must be strong with them. All three initially reported nothing seen.
This story of from Zero me to 0dB should encourage everyone who hasn’t tried 500kHz on ‘a bit of wire’ to have a go.

The first station is just 5km across town, we chat on 433MHz often, we were both astounded that there was nothing apparently, to be seen of my signal. The WX was bad for me to go out portable for tests and for antenna improvements at the other end. His antenna is actually down and sometimes some parts buried in snow, but hey that is still a ‘bit of wire’.

I suggested a series coil tuned with ferrite to peak the antenna. This brought reports on WSPR of -27dB which peaked at times and faded away at others. I suggested making a loop but another project was already on the plans.

Once I had been Spotted I asked for another try from other stations who tried other antennas and also removed all ATU’s (this is very necessary I know). Around -20dB reports resulted.
Using prediction software I worked out what my signal strength should be at various stations using a standard rig and normal HF antenna and e-mailed them asking to “please take a look on 50okHz, you should see my WSPR signal at -26dB”, etc. It worked, the station I predicted -26dB for, switched on and immediately reported -25dB.

So can these -20dB reports be improved upon? The other project, ‘on the plans’ was a Top Band Z Match, ready for when the WX allowed getting the wire back up. The design (GQRP) uses a Ferrite Ring Core, he added more turns than quoted for 1.8MHz, filling the ring and added fixed capacitance across the tuning. As this was optimised reports crept up, finally there have been 0dB reports from WSPR. This Spectran screen shot is when my signal was at -3dB.

Of course with the improvement in my signal comes Spots of the G4JNT signal seen above mine also G7NKS has been Spotted. When that wire goes up there should be some superb signals.
I have not tried an ATU for 500kHz, some stations use them for TX, clearly it is something well worth a try.

ROS Digital Mode

I spent several hours yesterday e-mailing the author, Jose, of ROS mode who apart from his name is a mystery. I think is not a Licensed Ham (if you are declare your Call please) and has little background in Ham Radio. He has taken on a big project here and needs support re the terminology he uses for the mode and the frequencies chosen for use or testing.
The mode is having some success, it was used via the moon within a couple of days. It will be interesting to see how the regular Moon Bounce operators find it compares with WSJT modes.

Several 10MHz frequencies are quoted, one of them 10.140000 is the QRSS QRPP frequency and of course the WSPR slot for the band. BTW the frequency range of ROS is stated as 400 – 2650Hz or 400 – 2600Hz the exact figure is not clear. 400 – 2600Hz was quoted to me, which gives a centre frequency of 1700Hz which keeps ROS clear of the narrow modes.

However in most of the world it is agreed that the 10MHz band is limited to Narrow Band Data modes only. ROS is Wide Band Data, just because you can produce a copy of IARU Region2 Band Plan that says 2.7KHz wide modes can be used on the band does not mean that it is the thing to advocate worldwide. Jose saw my point and promised to remove 10MHz frequencies from the list, I see that this morning they are still there.

It would be a good idea for everyone to check that the frequencies for other narrow band activity is not being recommended, like 7.0400 another frequency which I discussed with him, again with the 1.7kHz centre frequency and shifts it is clear of WSPR. I am in favour of new modes and experimentation, in the right place on the bands as long as it is not to the detriment of other activities.
Check the frequency list. HERE

In a classic bit of incompetent fumbling the USA stations have got them selves banned from using the mode. They will be back when they and the FCC learn a bit about radio :-
It is the RF and the Modulation that does the communicating, not the words written in a description, ROS is a Multi Tone Data Mode, not Spread Spectrum in the proper sense, that is not authorised.

500kHz / 136kHz Windowsill Loop Completed

Well almost completed I want add a switch for // 3000pF with the tuning capacitor. At the moment I am soldering it in.

Picture shows the details of the ferrite ring coupling and tuning capacitor.

On test, results were pleasing G4JNT at -13dB, tuning very sharp. The test was in daylight and once I switched off my TX to test the loop only JNT was left on air. 136kHz also tuned very sharply, unfortunately no signal were on apart from a carrier that goes barrr— barrr—- barrr which was strong and clean. Not knowing the allocation I don’t know if this is a good or bad sign. The “Monster that Panasonic set loose in my neighbours house” (in quotes because that is what I told Panasonic UK they did to me) was off for the complete test. Of course in the evening when there will be Amateur stations on, the Plasma Beast interference will swamp the bands.

I haven’t optimised the turns on the ferrite coupling yet, this loop is a much higher impedance so I quickly tried 1 turn, it was useless. Using 6 turns the signal produced from my signal was 5dB down on my larger loop, that is only a rough test.

Window Sill Table Top Portable Loop

My 750mm Loop for 500kHz an 136kHz is good but a bit big, I want a Loop to take portable and one that can be placed in the main bedroom and not decapitate the XYL when it falls over.
So I have started a Window Sill Loop 440mm square, only 18mm wide and light weight, it has 16 turns of 40 strand Litz. I shall ferrite ring couple it again the centre tap is provided for that. It will tune on 500kHz with a 500pF capacitor 136kHz will need 3500pF or more, a twin gang 500pF and some fixed polystyrene capacitance.

 

I am pleased with the outcome of my chippy work and design. I wanted to prevent the turns taking a sharp 90 degree at the corners and also stop them slipping off. I carefully rounded the corners once the frame was complete and left horns at each side. Being close grain Ramin the wood behaved and didn’t split off at any of the 8 horns.

New Mode ROS Tested

ROS is a new Digital mode by Jose Alberto Nieto Ros, still in Beta test, using Spread Spectrum techniques and low baud rates of 1 or 16.

It is actually a Mulititone FSK system that spreads in an SSB bandwidth. The step sequence is set and synchronised by a start signal sequence.

An interesting feature is the Automated e-mail Report which is sent to the TX’ing station via the RX station if the details are included in the Transmission. I made use of my g3zjo@aim.com mail address, it is short and snappy and the reason I have it. I use it on PSK31 at times.
At one baud john.theobald-saintamillion-loudenblaster364@clearpurpleyonder.com would be a bit stupid.

I had my first 40m contact at 16baud with ON followed by PA on 16 and 1 baud. I heard LA and DL and W stations. What is more I had e-mail reports from listeners in G, DL, EA, ON. PA, and W.

Antenna Icing – Coupling for Loops

Both the UK Rail System and the Euro Tunnel trains have been brought to a standstill by “the wrong sort of snow” in the past. The term ‘wrong sort’ gets ridiculed at times, yet there are many different sorts of snow.
We have had lots of snow this year, 10 years worth at least, none has been the sort that fell last night. It settled 5cm deep on the windward side of lamp posts, (vertical snow). Even fishing line grew to 15mm diameter. My antenna wires grew to 2cm diameter and sagged alarmingly under the weight.
It settled on the Top Hat Load for my 500kHz antenna despite the wind, and the vertical wire, causing a huge sag and a 10dB drop in signal at 76km. I shook off what I could by yanking the support cord. Overnight frost produced icicles and a tilt to one side.

 

Thankfully it is not a ‘big freeze’ and all is back to normal now.

I tried something which has been raising questions regarding the best coupling method for Multi-turn MF Loops. Now I have the answers.

Standard designs normally show a 1 turn coupling loop. This will not often be 50 Ohms. I tried a 1 turn loop on my Meatball Special, the impedance mismatch seemed to make no difference and the signal level coupled in was the same as with my Ferrite Ring coupling.

I found previously that it is best to use the correct number of turns with a Ferrite Ring Coupling, also the coupling efficiency can be reduced if the ferrite material is not suited to the frequency of use. It would seem then that a way to test the goodness of your Ferrite Ring coupling is to compare it with a 1 turn link, they should perform identically.

Using a simple Closed Loop Faraday Loop coupling I found to be very inefficient. The type of Faraday Loop that has two open points, at the start and at half way round, was more efficient, although some 15dB down on the 1 Turn Loop and the Ferrite Ring.

Panasonic Plasma TV Video

Well every so often in the last year I have really frustrated by the Panasonic Plasma TV that my neighbour was foolish enough to buy. Just lately I am having a hate session, so I have written to Panasonic to let them know that I will never deal with them again, despite my existing Panasonic Technics household here.

Whilst searching for their contact details I came across this:-

Its well worth a watch right through, its funny too.

500kHz – 136kHz Loop Improved and Tested

Today I have added a 15pF twin gang tuning capacitor and knob to the Litz Loop. It gives me a final tweak of the tuning peak of the loop without hand capacitance problems. Does it work? yes, if the main tuning capacitor is adjusted with the fine tune set at half mesh swinging the fine tune either way can give a drop/peak of 5dB. Incidentally 5dB is a bit of a round number for me, well it is one segment light on my S meter.

On test in another room away from the shack results were much more promising than previously, G4JNT was a constant -9dB no other stations were active. On 136kHz a good clean background peaked sharply, no signals were present. At 17:04 the Evil Panasonic Plasma Television junk was switched on and polluted the the complete spectrum covered by the loop.

Here is the action area of the loop, where it all comes together. Top to bottom, 10000pF fixed Capacitor and switch mounted on the tension plate, 500pF 3 gang main tuning capacitor, Toroid coupling, SO239 socket, 15pf 2 gang, fine tune.

15pF twin gang variables can be obtained by dismantling an Icom IC700 Communications Receiver saving it, the VFO Capacitor and the 500pf twin Gang Pre Selector Capacitor and throwing the rest in the bin.

Some times rash decisions have to be made, this RX was in an awful state old technology and well butchered about. The 9MHz Xtal Filter had been taken apart and even the associated nearly 9MHz HC6U Crystal had been un-hermetically sealed and soldered back together with an air gap at the base.

I don’t know its full history just that an old friend G3HWE used to enjoy sorting out its problems. He gave it to me when he moved QTH due to advancing years (his not the radios).

Ray G3HWE was a fine fellow, he served in the Royal Navy. He was one of the last Sailors to serve on Nelson’s Flagship HMS Victory when she was still at sea. He hoisted the signal flags on Her and slept in a hammock slung under the deck.

He died at the age of 103. At 80 years old he was happy to climb antenna masts and on his own house roof. At 90 years he crawled under his floor to install antenna cables. Later after moving to York he ensured he had an antenna system installed for 2m capable of working DX and back down to me.

Cats Whiskers on 500kHz

Some strong traces observed on the PA9QV Grabber reminded me of some I have seen on the M0GWT Grabber. The PA ones were single sided others were more parallel than other real cats whiskers.

This has put us in head scratching mode again. First job was to find the classic Capture of some fine whiskers.

So on the face of it some side band energy collapses to zero then is generated again from zero point. Could a mixer hit with a strong harmonic / sub harmonic signal produce this.

Is it ringing, there are two possible sources, the Sound Card and the Receiver. I think the Sound Card is ruled out by the fact that the phenomena is observed only on 500kHz as far as I know.

One difficult thing to explain if it were an external signal source is the anticipation involved (required to display the collapsing waveform).

I have a thought:-
(a) Ringing is taking place in the receiver.
(b) It changes due to the influence of the known, displayed signal.
(c) The ringing is at a high frequency out of passband so not observed until the known signal changes.

The receiver types most affected seem to me to be SDR types, there may be a big clue there.

Having worked with Regenerative Braking DC Motor Control Systems I have gone along with theories pertaining to these. They chop DC at LF and apply the power back to the 3 Phase Mains Supply when braking. The Supply Cables could make a good MF antenna. I know we did some ‘naughty’ things. Somehow though this does not fit.