1.1 Necessary bandwidth If the frequency shift, or the difference between mark and space frequencies is 2 and if is the D m modulation index, 2 the necessary bandwidth is given by one of the following formulae, the D/B, choice depending on the value of m: 2.6 0.55 within 10% for 1.5 5.5 D  B  m  2.1 1.9 within 2% for 5.5 20   D B m 1.2 Shape of the spectrum envelope The of the RF spectrum for class of emission F1B is described in § 1.2.1 to 1.2.3 below for various shapes of the telegraph signal. 1.2.1 Telegraph signal consisting of reversals with zero build-up time The amplitude of the spectrum envelope relative to the amplitude of the continuous emission, A(n), is shown in Fig. 12 (solid lines) as a function of the order of the sideband component for a telegraph signal consisting of reversals with zero buildup time and equal mark and space durations. The linear or asymptotic parts of the solid curves shown in Fig. 12 may be approximated with the aid of the formula: (8) where: : of the sideband component n = 2 /B n f : frequency separation from the centre of the spectrum (Hz) f : modulation rate (Bd) B : modulation m 2  m D/B : peak frequency deviation or half the frequency shift (Hz). D 1.2.2 Periodic telegraph signals with finite build-up time The amplitude, of the envelope of the spectrum produced by a telegraph signal consisting of A(x) reversals with a finite build-up time and equal mark and space durations is given by the following empirical formula: (9) where: /D  x f : amplitude of the continuous emission E  u
1.1 Necessary bandwidth If the frequency shift, or the difference between mark and space frequencies is 2 D and if m is the modulation index, 2 D/B, the necessary bandwidth is given by one of the following formulae, the choice depending on the value of m: 2.6 D  0.55 B within 10% for 1.5  m  5.5 2.1 D  1.9 B within 2% for 5.5  m 20 1.2 Shape of the spectrum envelope The of the RF spectrum for class of emission F1B is described in § 1.2.1 to 1.2.3 below for various shapes of the telegraph signal. 1.2.1 Telegraph signal consisting of reversals with zero build-up time The amplitude of the spectrum envelope relative to the amplitude of the continuous emission, A(n), is shown in Fig. 12 (solid lines) as a function of the order of the sideband component for a telegraph signal consisting of reversals with zero buildup time and equal mark and space durations. The linear or asymptotic parts of the solid curves shown in Fig. 12 may be approximated with the aid of the formula: (8) where: n : of the sideband component n = 2 f /B f : frequency separation from the centre of the spectrum (Hz) B : modulation rate (Bd) m : modulation m  2 D/B D : peak frequency deviation or half the frequency shift (Hz). 1.2.2 Periodic telegraph signals with finite build-up time The amplitude, A(x) of the envelope of the spectrum produced by a telegraph signal consisting of reversals with a finite build-up time and equal mark and space durations is given by the following empirical formula: (9) where: x  f /D E : amplitude of the continuous emission u 
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