SUMMARY of SPECIFICATION (Not definitive Standard)

Weighting curve specification (Weighted measurement)

The weighting curve is specified by both a circuit diagram of a weighting network and a table of amplitude responses.

The ITU-R 468 Weighting Filter Circuit Diagram. The source and sink impedances are both 600 Ohms (resistive), as shown in the diagram. Values taken directly from the ITU-R 468 specification. Note that since this circuit is purely passive, it cannot create the ~10dB gain required. You must correct any results by a factor of 8.1333 or +18.2dB.

Table of amplitude responses:

Frequency (Hz)	Response (dB)
31.5	-29.9
63	-23.9
100	-19.8
200	-13.8
400	-7.8
800	-1.9
1,000	0.0
2,000	+5.6
3,150	+9.0
4,000	+10.5
5,000	+11.7
6,300	+12.2
7,100	+12.0
8,000	+11.4
9,000	+10.1
10,000	+8.1
12,500	0.0
14,000	-5.3
16,000	-11.7
20,000	-22.2
31,500	-42.7

The values of the amplitude response table slightly differ from those resulting from the circuit diagram, e.g. because of the finite resolution of the numerical values. In the standard it is said that the 33.06 nF capacitor may be adjusted or an active filter may be used.

Tone-burst response requirements

5 kHz single bursts:

Burst Duration (ms)	Steady Signal Reading (dB)
200	-1.9
100	-3.3
50	-4.6
20	-5.7
10	-6.4
5	-8.0
2	-11.5
1	-15.4

Repetitive tone-burst response

5 ms, 5 kHz bursts at repetition rate:

Number Of Bursts per Second (s−1)	Steady Signal Reading (dB)
2	-6.40
10	-2.30
100	-0.25

Unweighted measurement

Uses 22Hz HPF and 22 kHz LPF 18dB/octave or greater (Tables to be added)