More on 82Hz Radio Comms ZEVS

It is a year alnost to the day since the Russian ZEVS Transmitter was as good a signal at my location.
Interestingly the 82Hz Idle / Start / End carrier has been constant between transmissions.
Also there have been much longer messages and I have identified what is to me a new frequency 83.2Hz labelled by me as ZEVS 13, for now I am calling it P, Page. This addition in fact balances the code making it symmetrical. As 82.0Hz, ZEVS 7 was the observed centre frequency, adding ZEVS 13 gives 6 frequencies either side.

2011 messages had a 3 figure repeated code e.g. S 10,6,11 R 10,6,11 E
easy on the eye to interpret.

S=Start, R=Repeat, E=End, P=Page.

2012 long message e.g. S 10,12,6 R 10,12,6 E 10,9,6 R 10,9,6 E 9,4,3, R 9,4,3 E 5,12,6, R 5,12,6 E 3,12,5 R 3,12,5 E —-S 8,8,3 R 8,8,3 E

2012 new message with 13 frequencies used e.g. S 12,3,11 R 12,3,11 P
2,8,11 X X,X,X E The X’s were wiped out by noise at this end but I can guess, (I hope the Submarines never do) at R 2,8,11. This brings in a whole new block of possible messages above the 2011 estimated 1,000.

It seems odd that I have not seen ZEVS in the UK for a year. Unfortunately I normally switch off my Grabber in the summer, my last note of ZEVS presence was in June so I have no idea of when it disappeared. Maybe the Transmitter been off or is it Propagation, does the noise level at 82Hz rise and obliterate the signal in the winter months.

My Grabber is showing an excellent signal 10dB above the noise peaks at this time, the first message seen today was at 13:00 UTC

My Grabber will be on air as much as possible with live signal capture.

As a reminder the transmission comes from Northern Russia is able to communicate to Submarines under the Polar Ice. The antenna is quite long, long enough to stretch from Italy to The Netherlands plus some.

The other carrier at 80Hz is always present, very stable and 5dB above the noise peaks, I don’t know the origin of this signal, I have seen it in Grabs from the Netherlands also.

Opera, Panto, Drama Radio Data Mode

It is quite exciting to receive Amateur experimental carriers on 8.97kHz identifiable as the station on frequency from 1000km distant. Once QRSS Morse on off or FSK is sent the results become pretty poor for DX.

I like to experiment with Data modes, others do not, vive le difference.

Opera with a time frame of 10 days is a stretching it a bit. Panto has been suggested as a name for a development, I have had some thoughts and would like to announce Drama. Dreamers Radio Audio Mode Automated or Digital Radio Audio Mode Automated.

There are very few stations that transmit on 8.9kHz at any one time. To cut complexity I suggest a system with a narrow bandwidth (424uHz), single frequency 8970.05 so that is is in Grabber range, filtered and sound card locked with 1 Hour per dot. Not sending a call sign, just a single character country identification code. For instance. UK = G, PA = P, DL = D, OK = O, OE = E, W = W, Other = X. A 3 unit code would cover these 7 possibilities, (I think 000 may be invalid for 8) although when coded it could possibly be used.
The level of activity does not warrant an automated reporting system on the web, there are groups which can handle all reporting. Automated timed sending is all that is required so that each station can find a time slot to TX in.

Once coded I am not sure long would it take to send the single ident, a lot shorter than a full call sign for sure. Users would announce, as they do now, that they are sending today at XX:XX:xx Hours. I really can’t envisage lots of stations fighting over the right to send a G or D at a particular time.

I can’t code it, will Jose take up the baton or is there a coder out there who would like to be first to produce an Automated Data Mode for 8.97kHz.

It is the Dreamers Band after all.

Opera Radio Mode for 8.9kHz

Using the WSPR software it is possible to set the audio output to frequencies other than 1.5kHz this has been used for tests at 8.9kHz with not a lot of success as far as I know.

Naturally the thought crossed my mind with ROS Opera software, it is a much easier mode than WSPR to key a carrier with. Problem, you can’t shift the Opera output frequency.

I put together a specification for a separate 8.9kHz Opera terminal. You would need a narrow FFT bandwidth say 424uHz, Software filtering, Noise Filters and Sound Card Locking to a stable signal source just like we can use in Spectrum Lab. The data should be based on 1Hour per dot QRSS 3600 at least, 10days for a de-code using the current format. A new format sending just 2 letters for a unique identification would be better. At this point I considered it was too much of an ask and shelved the idea.

Great minds often think alike and later I was asked what I thought of direct Opera at 8.9kHz. What evolved was Opera with an 8.0kHz Op4H mode, somewhat different to my Op240H spec. Also OP4H uses the normal 2.5kHz bandwidth and no filters as far as I can see.

We discussed this and I considered this to be at least 20dB short of what would be needed to de-code Amateur 8.9kHz signals.

My first test in March decoded at -46dB, sounds good but the signal level required for this was 20dB/N in 4.5mHz. No Amateur station has produced signals of this level at my QTH, G3XIZ at 46km does not achieve these signal levels despite my reception of signals from North Germany and the Czech Republic.

Further tests at the moment by PA1SDB and myself have confirmed these results. Note these are not contacts between our stations they are local tests down our own plots from Computer Sound Card to RX Antenna, my best DX being 15m:D

Final, as far as I am concerned, refined tests at this time of the mode, with the current configuration, use separate Computers dedicated to Transmit and Receive. here are my latest decodes.

06:06 8 G3ZJO de G3ZJO Op4H 0 km -44 dB in Northampton with 0.5w + 4element at 5.5m
01:44 8 G3ZJO de G3ZJO Op4H 0 km -46 dB in Northampton with 0.5w + 4element at 5.5m
*********** 08/05/2012 ***********
*********** 07/05/2012 ***********

Please ignore the equipment details.
Again the signal level required to produce these results is 20dB/Noise in 4.5mHz FFT.

The concept is interesting and the next quantum leap to make the mode useful I think will be to produce a stand alone Op 8.9kHz program. Unfortunately no experienced TX stations have taken the move to test what we all ready have so the work involved may be not worthwhile.

My Op4H signal can be seen on my Grabber When test are running.

Today

Previous

Signal at 424uHz shows that the normal Computer Sound Card output is not stable enough for use as a generator for 8.9kHz.

Edit January 2018 Opera has not been used on VLF, I still consider it to be 20dB short of a picnic. Whereas Ebnaut text messages have crossed the Atlantic.