My original system for a Multi Mode Beacon with WSPR is achieved in the simplest manner possible i.e.. the addition of just one more tone to MEPT_JT coding.
This give the possibility of S/MT Hellschreiber in a very narrow bandwidth. The Hell has a squashed appearance for sure and could be improved.
QRSS3 Morse takes some time to send, Dashes being 3 times longer than a Dot, have 3 times longer to be effected by QSB, broken up and their information wasted.
There is another system, using equal length characters for both, Castle Mode, this can require up to 12 Tones. Hence I gave thought to perhaps re using the tones in the same character. My new system, Step Mode does this. Using luck my call sign can be represented with 5 tones. I have implemented this. There are plans afoot for a full Morse Character system using 7 tones.
Fine tweaking of the software timing has reduced any long term timing drift to well within MEPT_JT parameters. In reality its stability outstrips my shack computer when it is free running, (no time sync from the Web).
I have changed the name of my coding to avoid confusion. Whilst I am happy to have bits of binary code and bits of chewing gum in the same sentence, I can see that it could cause problems. Equally the system is 5 tone, I have gone for RTTY terminology of units.
It is now 5 Unit Multiomde + WSPR
All of the coding is based on MEPT_JT elements 682.66mS long. A QRSS3 Dot in theory 3 Seconds long is in fact 4*0.68266 Seconds = 2.73064 Seconds a QRSS3 Dash, 9 seconds in theory is 13*0.68266 = 8.87458 Seconds.
S/MT Hell Characters are produced by elements of MEPT_JT code. A 5th element is produce by an extra 3rd Binary bit.
All spaces are multiples of 0.68266 seconds apart from one filler, for accurate 2 Minute slot timing, just prior to the start of the MEPT_JT data and after the 2 step waveforms. The Steps are produced by the 5 element tones spaced precisely 😉 1.46484375Hz apart and 4 elements long. Originally I had a 5-4-3-2-1 countdown with 5 of these. Now just 2-1, as they convey no real information. The top of step 1 is twice the length of step 2.
My WSPR Data starts at 1.36532 Seconds past the even minute, 2*682.66mS, as near to 2 seconds as the elements allow, although the 2 Minute filler can place this where ever it likes.
Paolo IZ1KXQ produces some fine screen shots of my signal.
Don’t worry, be happy.
Precision timing is in the eye of the beholder. This is a MANNED Experimental Propagation Transmitter after all.
The dirty finger is deliberate,it was actually dirtier in real life.
My 40mW 5unit Home Built Computerless Transceiverless Multimode Solar Powered MEPT crossed the pond Last night.
Signals into Italy were good too.
I still have critical adjustments to make to the PIC Microprocessor Oscillator to get the timing precise. Over night the timing does get out of synch. It does not help if you make an adjustment in the wrong direction like I did last night just before retiring.
Oh well start again.
Now a report from Denmark OZ1PIF and we are on the WSPR Spots site and the map.
Just wait until I get this thing set up precisely.
We have results despite still being ‘work in progress’ Paolo IZ1KXQ has sent a report.
The complete MEPT beacon including PIC processor takes just 50mA at 12 Volts.
This is the PIC controller section.
And the Micro PA stage, my smallest yet, it runs 40mW RF Output.
MEPT_JT set the world on fire. MEPT was a term little known among Radio Amateurs, a little group of enthusiasts world wide, we built our own gear and studied propagation using very low power signals (QRPP).
MEPT_JT soon became WSPR, Weak Signal Reporting System, Whisper, a great name which encompasses the concept and keeps it in the WSJT camp.
A GUI version was soon released making it easier to use and soon a Web Site was set up to list reports and plot results on a world map. This overloaded the servers and the ISP closed it down. No problem, it moved almost seamlessly and goes from strength to strength.
Right from the first day I thought it would be good to have MEPT_JT as an ident on a true Multimode Beacon. A few Hams world wide are working on a computer less system, I needed a further spark from Johan SM6LKM who said yes it can be done.
Yesterday I completed the Multimode concept with a PIC processor controller and a QRPP VCXO transmitter.
Still work in progress I have introduced a 5th bit giving a Manual Time Sync signal and Multimode capability. I have produced a Helschreiber ‘font’, QRSS3 is programmed in and WSPR is de-coding locally.