1. Centre frequency = (High Frequency - Low frequency)/2 + Low Frequency
Centre frequency = (880000 - 76000)/2 + 76000= 478000Hz
Frequency spacing = Centre Frequency x MOR tolerance
478000 x 0.00025 = 119.5Hz
Which agrees with your calculation.
When I put those values into the Spectrum Sweep calculator and save that program, the section highlighted doesn't change.
2. Just for your info :
+ / - 119.5 Hz is MOR tolerance range (0.025 %) . It's not Frequency spacing which Spectrum will produce ( 4187.5 Hz ).
MOR tolerance range ( 477,880.5 to 478,119.5 Hz ) shows a range of frequencies that will be effective in destroying/disabling a pathogen ( according to Dr. R. Rife ). Each frequency produced by the Spectrum Sweep will be effective in this range ( freq + / - 119.5 Hz ).
To increase effectiveness you may increase " Frequency Hits Per Sweep " from 1 to e.g. 2 or 4. This will also increase the total running time.
You may adjust the value for the " Wave Cycle Multiplier " to get different Frequency Spacing. This will also affect Spectrum Amplitude.
3. Many people make this mistake. The spectrum waveform contains both positive and negative asymptotes, each with different spectral contents. It is not an evenly-repeating waveform, where the negative asymptotes can be ignored. You can only do that if they are phase-angle related to the positive asymptotes. The frequency spacing is therefore (spectrum high frequency - spectrum low frequency) / (2 * WCM). This can be confirmed using a spectrum analyzer.
With a low-frequency of 76000, high-frequency of 880000 and WCM of 32, 64 frequency spikes will be observed in a spectrum analyzer; 32 above and 32 below fundamental / 32.
The spacing between each frequency spike is (880000 - 76000) / 64
= 804000 / 64
= 12562.5 Hz
SweepStartFreq = CentreFreq - (0.5 * HitsPerSweep * FreqSpacing) - (CentreFreq * FreqTolerance / 100)
SweepStopFreq = CentreFreq + (0.5 * HitsPerSweep * FreqSpacing) + (CentreFreq * FreqTolerance / 100)
A retentive spectral-analysis of an entire sweep will confirm an almost-even blanket coverage of the desired target frequencies using these values.
For more details, please check the link: