Opera Digital Data Mode Performance

Due to the effects propagation it is difficult to evaluate the parameters of a mode, particularly with detectability around the noise level.
PA0A has done Lab Tests on the ROS OPERA digtal radio data mode and found the following results.

Op1 decode @ -24dB Average from many test
Op2 decode @ -27dB Average from many test
Op4 decode @ -30dB Average from many test
Op8 decode @ -33dB Average from many test
Op32 decode @ -37dB Average from many test

This is nice to know as it agrees closely with the expected theoretical values. Odd readings are obviously the result of propagation.

Loss of Data in the signal will give abnormal S/N results. I tried removing 1/3 of the bits throughout the message, the act of doing this looks like sabotage of the correct message coding, it is, the result was just one decode from many tests of a bogus call with a marginal S/N ratio.

13:35 500 8N3CSZ de G3ZJO Op4 -30 dB in Northampton

Removing the complete mid 1/3 of the Data in the message does degrade the S/N as does removing the first 1/3, anyone can try removing the last 1/3 by stopping the transmission.

Readings with complete Data:-

14:21 500 G3ZJO de G8HUH Op4 181 km -26 dB in Somerset.
14:21 500 G3ZJO de M0BMU Op4 -15 dB in nr Hatfield
14:21 500 G3ZJO de G3ZJO Op4 0 km +6 dB in Northampton

Readings with 1/3 blocks of Data loss.

14:47 500 G3ZJO de M0BMU Op4 76 km -17 dB in nr Hatfield
14:47 500 G3ZJO de G3ZJO Op4 0 km +3 dB in Northampton

Next 1/3 of the Data was removed in blocks of 8 bits in a random fashion throughout the message again OPERA decodes successfully:-

14:53 500 G3ZJO de G8HUH Op4 181 km -28 dB in Somerset. test4
14:53 500 G3ZJO de M0BMU Op4 76 km -17 dB in nr Hatfield
14:52 500 G3ZJO de G3ZJO Op4 +0 dB in Northampton

In further tests I may try removing 50% of Data bits.

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O P E R A is (should be) a Beacon only Mode

ROS OPERA digital radio data mode at 200uW ERP is still performing well here, G1OPS at 135km distant received me earlier today.
I often hear Chris G3XIZ on the Key when I am testing OPERA, I thought that it would be possible to work cross mode. With my PIC system I can input anything I like all be it a bit of a task and it must not be rejected by Jose as a non call sign.

I put the idea to Chris and he downloaded OPERA, within minutes I spotted that he had seen me, OPERA chat is useful, In exactly 30 minutes we had completed a QSO. A but irregular for the mode, a bit like M/S and good fun.

This was my transmission with a 13WPM Morse ident before each.

17:02 500 RR5RRR Op4 +7 dB
16:57 500 G3XIZ Op4 +6 dB 46 km @ 120
16:49 500 R5SIG Op4 +5 dB
16:43 500 G3XIZ Op4 +7 dB 46 km @ 120
16:38 500 G3ZJO Op4 +7 dB 0 km @ 000
16:32 500 G3ZJO Op4 -16 dB 0 km @ 000

Chris’ Morse transmission was more verbose but his hand is so good I could type my comments on how it was going and the next proposed step in OPERA Chat and read him at the same time. A bit of a 3 way even, via the web although it was not internet assisted we knew the procedure we were going to use. Chris did not know what form the reporting messages were going to take.

An evening at the OPERA (OPERA Radio Mode)

I have waited for the TX experience of ROS OPERA digital radio data mode until I had my QRPp home built PIC controlled TX running. Yesterday evening I ran OP4 on 500kHz, the TX produces less than 200uW ERP from my antenna which is now a simple inverted L 5m up 5m out.

The TX was built for QRSS FSK so I had to modify it to run A1A on off keying although I have proved that OPERA does not mind being sent as FSK. The TX had been running on QRS3 and QRS10 on 500kHz with zero reports. I therefore was not expecting much in the way of results.

But results we got, very impressive.

opera_500k

My PIC Code sends selectable OPERA Speeds/Modes followed by 12WPM Morse ident, it is simplistic and like my WSPR PIC Code, written only for my call sign so please don’t ask for a copy. G4JNT has produced a sophisticated multi user code for both OPERA and WSPR which are available for download.

The ROS/Opera software is still in its Beta versions, the CPU load is very high which tends to put me off. No problem for me if I don’t want to receive too, everyone else uses oodles of computer power to receive me.

OPERA New Data Mode 7 Days on

ROS OPERA digital radio data mode was launched at the beginning of the year (2012). Using single frequency on/off keying it is about as basic as a Digi Mode can get. Resembling Morse Code which was designed for manual de coding, OPERA is designed for computer de coding. It was particularly developed and is suited for LF propagation and communication using slow data rates. Initially it is a Beacon mode sending Call Sign only. The Data is sent at different speeds giving rise to Op2 Op8 etc, these are not different modes, Op2 sends in 2 minute time frame Op8 takes 8 minutes.
There is data repetition on TX and FEC in the decoding I believe, which enables performance well down into the noise level.

I tried it on the first day and had good results, I have held fire on commenting mainly due to the Soap Opera which followed the release of ROS from the same software author. Could this have had an influence on the choice of name for the new mode.

OPERA has not been immune to the same sort of problems and criticisms. One source of dismay for some is the amount of web connection that installs with the software. Well learn to live with it, the facilities it provides are useful and suited to the mode which is from EA5HVK, Jose Alberto Nieto Ros so what did you expect.

If you don’t like being connected to the web facilities, turn off your modem and you will never be bothered by spammers, or rude people on forums either. However you will be left a bit in the dark.

Processor and memory use is high. Even to the extent that AVG warns of excessive memory use by Firefox when running OPERA. In my world the best software is elegant and puts the least load on the system. Does this simple mode really need more processor power than running 3 simultaneous versions of SpectrumLab. When writing software I always remember Neville G4CPY and his standard line “WHAT your program resides in more than 1K of memory, your code is not very efficient”. He was always right too.

Another problem is frequency choice and clarity of operation. OPERA does not want to be among the CW stations, well only if you want bile from them. Some operators need to be told where to set the dial too which has caused problems.
My main improvement would be related this, already many users including me have moved today to Dial 503kHz on 600m to avoid the CW region. If only the drop down frequency box said Dial XXXHz Transmit XXXHz to XXXHz instead of leaving operators to do the complex maths of Dial = mean(frTX High,frTX Low)- 1500Hz, surely we don’t expect operators to know what they are doing, or to be able to count.

It would be very good to have at least the parameters of the TX data released once all is settled (there have been several changes since release) so that a simple computer-less beacon can be programmed like we do with WSPR. Many Hams are avidly against secret coding.

EDIT :- Next day our wish has come true, apparently the new version will output the TX Code.
However frustration, the download link doesn’t work, maybe more mods in the pipeline.

Finally how can we be sure that this single keyed carrier (yet agile) frequency is not spread spectrum and furthermore what ever is the bandwidth of this new mode :DD

In this capture of a couple of nights ago on 500kHz my stations received on a very poor antenna are shown on the left other reports via the web are on the right.

operaPA3ABK

Note:- 1) I don’t use the Waterfall on my XP SP3 machine to save processor load as I run SpectrumLab to my LF Grabber.

ROS Modem Update

I have not commented on ROS for a while, looking back in my blog I don’t think I even commented on its last swing in the US. When the mode was launched it was considered ‘legal’ by all, then it was ‘illegal’ in the US, then it was ‘legal’, then ‘illegal’ again which is how it remains until today.

For me it has reached the stage of another mode, to use when I wish, that is still developing, with new baud rates and band widths added which is a good thing. I know of no active developer who would code a new version of a mode in request from a few users like Jose did for the 500kHz case.

I am a member of the ROS Yahoo group. Recently the US issue has reared its ugly head again. Ugly? Yes the posts soon get ugly, the constant bickering nearly got a comment from me but I resisted. I almost directed all the messages to the big Yahoo mail bin where I go and look, occasionally only, at group posts in which I have a passing interest.

I want to keep an eye on ROS development but I don’t want constant posts with character assassinations and yah booh shucks your mother smells stuff. Its a long time since I was a schoolboy.

Just in time we have ROSmodemusa Yahoo Group

Lets hope this stops the junk, it does no good for amateur Radio.

ROS arguments go on and on

I will not join in in this war of posts to groups. I will just sit and smile, as usual.

Why are hams so capable of causing constant aggro and ill feeling, with continual bitching posts to every radio group on earth, and in their blogs, about ROS but not capable of grasping the metal and making a decision for them selves.

A quote:-
“The FCC expects you too determine if you are legal are not…Thats why we have a license process.”

ROS and QRM

Today on 14MHz 1 baud I was called by a series of stations, some quite low signal strength. Sometimes 2 stations called at once, ROS sync’d on the strongest signal the data stayed intact, due to the slight frequency difference I think, even when calls overlapped for a time. The weaker station waited and called after the first caller had completed, all in all the mode did well and the operators were good too.

There were tuners, whistlers and aaaaaloooas present on the frequency and also some Olivia signals which I have not heard for some time. ROS was not troubled by any of them.

It is time that people calmed down and just let time and the mode just take its course. I am sure some of the controversy has been caused by cunning tricks by the anti brigade.
Not since WSPR jumped on top of the 10MHz QRPp QRSS frequency slot has there been such high tension among the gentlemen who usually agree and live in peace.

Careful boys you may be being used. We don’t suddenly need to be regulated by anyone just because there is a new mode and a few folk wanting to try it.