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?? RF SPECTRA of the THOR speeds on HF SSB

There is a new (alpha) THOR mode with the designation? THOR 25

We tried THOR25 after the PA NBEMS net? (Sunday 0730 hr on 3583.0 kHz) and it worked well as a traffic mode, compared

to THOR32 which we have been using (as well as MFSK32).

I wanted to compare the RF SPECTUM of each of the THOR speeds, so I used a SDR? (RSP play hardware) and RSP Spectrum Analyzer (software)

and set it on 3585.5 kHz center frequency with a very high resolution bandwidth.

Transmitter was an Icom 7610 (built in sound card) with VFO set to 3585.0 kHz

Here are the results, showing the? "peak" bandwidth of the THOR speeds, as well as the BW at ? 30dB below the peak.

I think the present definition of "bandwidth" is? that width at? -26dB below the peak, so? -30dB is close to that standard and easy to see.

I think the other definition of BW is that signal containing 99% (or was it 99.9%) of the energy.

THOR25 is still in testing (alpha) and does not yet have an assigned TXID/RXID? identifier.

But you can manually go to OP MODE on top menu and select? THOR25.

The goal of the 80m and 40m NBEMS nets is to use one mode for taking check-ins (usually THOR22) and to send the call sign twice,

then the name, location (county if in Pa) and traffic/no traffic or? QTC/QRU, and many send a?? S/N? of the net control.

THOR vs. MFSK

THOR modes are far easier to tune in on SSB compared to MFSK modes.

I find if I mistune a MFSK32 signal by about 15 Hz? then I lose all copy.

THOR can be badly mistuned and still get full print.

THOR also uses the "difference in pitch" from one tone to the next tone as the character, not the absolute pitch.

There are other reasons I prefer THOR on HF NBEMS nets.

So take a look at the RF? spectra? (not the audio spectra) and see for yourself the pros/cons of each speed.

As FLDIGI develops the THOR 25 mode, we will have more data to report back to W1HKJ.

de k3eui? Barry

Kennett Square PA? (near Phila)

Dec 08 2024