Provides no distortions of the input voice signals, operating in wide gain range — up to 42 dB.

Ideal as a preprocessor before parametric vocoder, especially in conjunction with Noise Canceller.

For Digital HF Radio, Digital Mobile Radio (DMR) and other markets of voice communication.

Technology Features. The DSPINI's AGC is based on unique proprietary technology developed by DSPINI experts. 

This technology differs from any other AGC in:

  • very low level of non-linear distortions
  • very low time of the gain decreasing to avoid the signal clipping - just 1-2 samples
  • smooth increasing of the gain in any of three modes: FAST, MEDIATE, SLOW
  • wide dynamic range of gains, can be set to any of eight modes:  0 dB, 6 dB, 12 dB, 18 dB, 24 dB, 30 dB, 36 dB, 42 dB
  • high quality noise cancelling preprocessing

Thanks to these unique features, DSPINI's AGC technology provides much better speech quality in comparison with any well-known AGC, especially when is used as a preprocessor before speech coding with parametric vocoders, sensitive to non-linear distorsions.

Superiority In Speech Quality. Here is the comparison with MELPe and GSM AMR vocoders in noiseless channel. TWELP 2400 bps vocoder, MELPe 2400 bps vocoder and GSM AMR 4.75 kbps vocoder were tested, using ITU-T P.50 speech base for 20 different languages. ITU-T P.862 utility was used for estimation of the speech quality in PESQ terms:

A diagram demonstrates a huge superiority of the TWELP 2400 bps over MELPe 2400 bps and a closeness (and even superiority for a few languages) to GSM AMR 4750 bps vocoder of the speech quality in clear channel. Exact numbers are presented in the table below.
LanguageAMR 4750TWELP 2400MELPe 2400
American 3.351 3.330 3.077
Arabic 3.277 3.253 3.053
British 3.272 3.181 3.019
Chinese 3.267 3.307 2.970
Danish 3.311 3.275 3.022
Dutch 3.089 3.114 2.830
Finnich 3.166 3.049 2.791
French 3.277 3.325 3.106
German 3.321 3.183 2.998
Greek 3.206 3.275 3.004
Hindi 3.286 3.246 3.089
Hungarian 3.305 3.279 3.086
Italian 3.462 3.363 3.226
Japanese 3.369 3.407 3.188
Norwegian 3.267 3.286 3.032
Polish 3.263 3.267 3.029
Portuguese 3.377 3.350 3.146
Russian 3.186 3.165 2.952
Spanish 3.343 3.294 3.048
Swedish 3.391 3.269 3.147

Superiority of the TWELP 2400 bps vocoder over MELPe 2400 bps is on average 0.220 PESQ and just -0.028 PESQ in comparison with AMR 4750 bps

Speech Samples (WAV-files). A few independent experts listened TWELP 2400 bps vocoder in comparison with MELPe 2400 bps vocoder and GSM AMR 4750 bps vocoder, using method of preferences. All experts preferred TWELP to the MELPe, having noted much more natural human-sounding of voice in the TWELP vocoder. A majority of experts haven't given preferences to GSM AMR or TWELP, but a majority of the remained prefered TWELP, having noted more clear sounding of speech in TWELP vocoder.
You can play and listen short samples of the source speech as well as the speech processed by these vocoders for any of 20 languages, using links in the table below.
Also, you can download full set of the P.50 samples as zip-files for all languages simultaneously, using the links in the "Downloads" para in a bottom of the page.

LanguageSource speechAMR 4750 bpsMELPe 2400 bpsTWELP 2400 bps


Technical Characteristics And Resource Requirements:

Technical characteristics
ModuleFrame size
Sampling rate
Signal format
AGC 20 8 Linear

Resources for ARM Cortex-M4 platform
Memory (KBytes)
AGC 0.3 56 0.03 0.01 0.05

Resources for TI's C64+ DSP platform
Memory (KBytes)
AGC 0.3 56 0.03 0.01 0.05

Resources (estimated) for TI's C55 DSP platform
Memory (KBytes)
AGC 0.3 56 0.03 0.01 0.05

* DSPINI continues optimization of the AGC algorithm and code in order to minimize computational complexity. Please contact with us for updating.

Vulnerability / Security. DSPINI guarantees ABSOLUTE cleanliness of the software from any undocumented features, undeclared capabilities, etc. All our customers can be sure that any our software/ code doesn't contain any secret functions and features hidden from user. We are ready to provide source codes of our software products for an appropriate certification if need.

Guarantee And Support.  DSPINI guarantees a quality and accordance of all technical characteristics of the product to requirement of current specifications. Testing and other method of quality control are used for guarantee support.

Any Platforms.  DSPINI can port this AGC software into any other DSP, RISC or general- purposes platform inshort time: a few days.

Licensing Terms.  To use the software, customer should obtain a license from DSPINI only.

Customization.  The AGC can be customized under any specific requirements- other dynamic range, frame size, other temporal characteristics, etc. Please contact with us for details.

Prospects.  DSPINI is impoving and developing continuously own technologies. Please contact with us for updating.

Related Software.  This AGC may be effectively used in a bundle with other DSPINI's products:

  • Vocoders and speech codecs
  • Noise Cancellers / Speech Enhancers
  • Linear and acoustic echo cancellers,
  • Multichannel noise cancellers (including two-microphone adaptive array),
  • Wired or radiomodems for any types of channels and bitrates,
  • Other products.