3.9 Distortion (handset and headset MS)

03.503GPPTransmission planning aspects of the speech service in the GSM Public Land Mobile Network (PLMN) systemTS

3.9.1 Sending

The sending part shall meet the following distortion requirements.

NOTE: Digital signal processing other than the transcoder itself is included in this requirement (e.g. echo cancelling).

Distortion shall be measured either between MRP and the UPCMI or between MRP and the SS audio output (digital output of the reference speech decoder of the SS). The ratio of signal‑to‑total distortion power measured with the proper noise weighting (see table 3 of ITU‑T Recommendation G.223) shall be above the limits given in table 5 unless the sound pressure at MRP exceeds +10 dBPa.

Table 5: Limits for signal‑to‑total distortion ratio

Sending level dB relative to ARL

Sending Ratio (dB)

‑35

17,5

‑30

22,5

‑20

30,7

‑10

33,3

0

33,7

+7

31,7

+10

25,5

Limits for intermediate levels are found by drawing straight lines between the breaking points in the table on a linear (dB signal level) – linear (dB ratio) scale.

Compliance of the sending distortion shall be checked by the test described in annex C, clause C.4.1.

The gain variation relative to the gain for ARL shall remain within the limits given in table 6. For intermediate levels, the same limits for gain variation apply.

Table 6: Variation of gain with input level, sending

Sending level dB relative to ARL

Upper limit (dB)

Lower limit (dB)

13

0,5

‑0,5

0

0,5

‑0,5

‑20

0,5

‑0,5

‑20

0,5

‑2

‑30

0,5

‑2

‑30

1

‑40

1

‑40

2

‑45

2

Compliance of the gain variation in the sending direction shall be checked by the test described in annex C, clause C.5.1.

3.9.2 Receiving

The receiving part between the UPCMI and ERP shall meet the requirements in this clause at the nominal setting of the volume control.

The ratio of signal‑to‑total distortion power measured with the proper noise weighting (see table 4 of CCITT Recommendation G.223) shall be above the limits given in table 7 when the sound pressure at ERP is up to +10 dBPa. For sound pressures exceeding +10 dBPa at the ERP there is no distortion requirement.

Table 7: Limits for signal‑to‑total distortion ratio

Receiving level at the digital interface (dBm0)

Receiving Ratio (dB)

‑45

17,5

‑40

22,5

‑30

30,5

‑20

33,0

‑10

33,5

‑3

31,2

0

25,5

Limits for intermediate levels are found by drawing straight lines between the breaking points in the table on a linear (dB signal level) – linear (dB ratio) scale.

Compliance of the receiving distortion shall be checked by the test described in annex C, clause C.4.2.

The gain variation relative to the gain at an input level of –10 dBm0, shall be within the limits given in table 8. For intermediate levels, the same limits for gain variation apply. The requirement is valid for sound pressures up to +10 dBPa. For sound pressures exceeding +10 dBPa at the ERP there is no lower limit requirement.

Table 8: Variation of gain with input level, receiving

Receiving level at the digital interface (dBm0)

Upper limit (dB)

Lower limit (dB)

+3

0,5

‑0,5

‑10

0,5

‑0,5

‑40

0,5

‑0,5

‑40

1

‑1

‑50

1

‑1

‑50

2

‑2

Compliance of the gain variation in the receiving direction shall be checked by the test described in annex C, clause C.5.2.