#### EMF Calculator

G4UDU Phil

New RSGB EMF Calculator nor online

Phil G4UDU

M0XYF Berni

It's much better than the spreadsheet version.

What exactly is 'Processed SSB' as opposed to just SSB? What is the purpose, how is it implemented and why does it have such a marked effect on the Mode Factor (an increase from 20% to 50%)? That's significantly more than a full duty-cycle data mode!

I can sort of guess that it's full-fat speech processing, but I don't really understand, and I can't get any sense out of the internet.

Thanks,

Berni M0XYF

On 07/12/2021 07:48, G4UDU Phil wrote:

New RSGB EMF Calculator nor online

Phil G4UDU

G8JBJ John

If it’s useful, here’s my twopennnyworth.

The heating effect of the radiation (and hence the danger to humans) will be a function of the energy in the signal.

The energy is the area under the curve when viewed as bins in the occupied bandwidth from 300Hz to 2.5kHz. With non-processed SSB the energy in each bin dances up and down in line with the speech. Quiet and loud speech is reflected in low and high energy with time and frequency.

Speech processing amplifies all frequencies across the audio band such that there are no low and high energy pieces. All speech from 300Hz to 2.5kHz is then at maximum modulation. As a result, the energy is considerably higher.

And data modes are transmitted in a narrow RF bandwidth.  So a 50Hz bandwidth data mode will have a very low energy. In theory 50/2000 of that of processed SSB but corrected to account for pseudo-momentary SSB versus continuous PSK.

Hope I got that somewhere about right!

I shall have to grapple with the spreadsheet now myself.

John GM8JBJ

On Tue, 7 Dec 2021 at 09:47, M0XYF Berni <msars@...> wrote:

It's much better than the spreadsheet version.

What exactly is 'Processed SSB' as opposed to just SSB? What is the purpose, how is it implemented and why does it have such a marked effect on the Mode Factor (an increase from 20% to 50%)? That's significantly more than a full duty-cycle data mode!

I can sort of guess that it's full-fat speech processing, but I don't really understand, and I can't get any sense out of the internet.

Thanks,

Berni M0XYF

On 07/12/2021 07:48, G4UDU Phil wrote:
New RSGB EMF Calculator nor online

Phil G4UDU

--
John Berry
TimelessTime Ltd
Tel: 07553 250 919
Tel: 01450 372 274

Sent from my Gmail Mobile.

M0XYF Berni

OK, brilliant. Yes, that makes a lot of sense.

I was having trouble reconciling the difference between processed SSB and data, but I wasn't factoring in the bandwidth. Then I thought I was misunderstanding how SSB processing was actually implemented, but viewing it in terms of total energy really helps.

Berni M0XYF

On 07/12/2021 10:49, G8JBJ John wrote:

If it’s useful, here’s my twopennnyworth.

The heating effect of the radiation (and hence the danger to humans) will be a function of the energy in the signal.

The energy is the area under the curve when viewed as bins in the occupied bandwidth from 300Hz to 2.5kHz. With non-processed SSB the energy in each bin dances up and down in line with the speech. Quiet and loud speech is reflected in low and high energy with time and frequency.

Speech processing amplifies all frequencies across the audio band such that there are no low and high energy pieces. All speech from 300Hz to 2.5kHz is then at maximum modulation. As a result, the energy is considerably higher.

And data modes are transmitted in a narrow RF bandwidth.  So a 50Hz bandwidth data mode will have a very low energy. In theory 50/2000 of that of processed SSB but corrected to account for pseudo-momentary SSB versus continuous PSK.

Hope I got that somewhere about right!

I shall have to grapple with the spreadsheet now myself.

John GM8JBJ

On Tue, 7 Dec 2021 at 09:47, M0XYF Berni <msars@...> wrote:

It's much better than the spreadsheet version.

What exactly is 'Processed SSB' as opposed to just SSB? What is the purpose, how is it implemented and why does it have such a marked effect on the Mode Factor (an increase from 20% to 50%)? That's significantly more than a full duty-cycle data mode!

I can sort of guess that it's full-fat speech processing, but I don't really understand, and I can't get any sense out of the internet.

Thanks,

Berni M0XYF

On 07/12/2021 07:48, G4UDU Phil wrote:
New RSGB EMF Calculator nor online

Phil G4UDU

--
John Berry
TimelessTime Ltd
Tel: 07553 250 919
Tel: 01450 372 274

Sent from my Gmail Mobile.

 1 - 4 of 4