Very low consumption and radiation softphones.
Very low consumption and radiation softphones, with the support of the frequency shifts and the ultrasonic communications.
Mobile phone apps to promote an audio codec (audio compression and decompression method) characterized by its simplicity, its low bitrate and its low audio frame emission frequency.
is an app based on PJSIP and Open Source products, whose goal is to promote, in the future versions, a new codec (compression and decompression method) for the audio and the ultrasounds.
This codec is based on FFT (Fast Fourier Transform), the greatest points and the most energetic bands. It can also use only the local peaks.
This codec is characterized by its efficiency, its simplicity and its robustness.
It will allow low battery consumption (VLC, Very Low Consumption, yellow button) and emissions of audio frames limited to the strict minimum, so the electro-magnetic radiations will be minimized (VLR, Very Low Radiation, green button).
It will allow, in real-time, the frequency shifts, the pitch shifts and the equalization for the correction of hearing losses.
It will allow also to do local or near-field ultrasonic communications, so with no electro-magnetic radiation, with or without frequency shifts.
If the codec is not implemented, the app behaves as a normal softphone.
If the correspondent does not use vlrPhone, the app behaves as a normal softphone.
For more information:
- Frequency Shifting
- Pitch Shifting
- Audio Equalization
The VLC and VLR codecs and the Ultrasounds
The ultrasounds are commonly used in many areas, including in the medical imaging, the motion or presence detection, the leak detection and the distance measurements (the ultrasonic radars).
In recent years, their importance has become growing in the field of the local or near field communications, in particular, thanks to the development of the Internet of Things (IoT).
VlrPhone uses a codec (or rather a family of codecs) compatible with the ultrasounds.
These codecs can take the ultrasounds into account in three ways:
- By increasing the useful audio band. Beyond 20 kHz, the sounds become inaudible for the human ears and are called ultrasounds.
- By taking into account only the areas in the ultrasound.
- By performing frequency shifts towards the ultrasounds.
The examples cited below are of increasing interest:
- The uXDT protocol (Ultrasonic Cross-Device Tracking).
For more information on this protocol, see:
With this protocol, one can for example take advantage of a television program to send non-audio messages (uBeacons) to smartphones, via the ultrasounds.
It should be noted that this protocol raises questions because it may compromise the anonymity or the integrity of the data.
- The gesture recognition, without contact, using the ultrasounds, instead of the infrared.
- The contactless payment using the ultrasounds.
- The indoor positioning system (IPS) or the indoor location service, using the ultrasounds.
- The chargement of the batteries, without contact, using the ultrasounds (at the research stage).
It should be noted that the detection and recognition systems are characterized by a low cost and above all by a very low energy consumption, compared to systems that do not use the ultrasounds.
It should be also noted that the frames of the audio codecs used by vlrPhone can carry audio messages (additional or not) by putting them in the ultrasonic areas. Simple frequency shifts are sufficient to put them in the audible areas.
Ultrasonic Receivers (linear, 360 degrees, spherical)
Broadband ultrasonic receivers, composed of a linear array of 8 microphones.
With the vlrphone project, we will propose receivers for the surveillance and the detection, using the ultrasounds, for use alone or with a classic video camera.
These receivers will record the ultrasounds using the VLC and VLR codecs algorithms, including:
- The basic algorithms (the greatest points and the most energetic bands, or the local peaks).
These algorithms are currently implemented in the Windows version with the PJSIP library. One can get an idea of the quality by visiting the listening page:
- Listen Page
- Optionally, the algorithms used by the VLR codec, notably the possibility of not transmitting or recording successive similar frames up to a certain point.
Since all non-similar or forced frames are numbered, the notion of exact time of recording is preserved. These algorithms are particularly powerful if the frames are identical most of the time.
- Optionally, later, one will be able to use the algorithms used with the codebook version of the codecs. This involves generating a database with the most frequent vectors of magnitudes and positions.
One will be able to replace dozens of bytes of a compressed frame by one or two integers. For more information, see at the following address:
- Codebook Version
There will be up to ten (10) receivers in the general case, and up to thirty two (32) receivers in option.
We will consider the sampling rates of 48 and 96 kHz in the general case, 192 and 384 kHz in option.
The receivers will be compatible with the projects using the Doppler effect (frequency changes when the distance between the transmitter and the receiver varies over the time).
The obtained bitrates will be compatible with certain low bitrate networks for connected objects, such as the LoRa network (Low Range).
These networks, which are also low consumption networks, are called LPWAN (Low Power Wide Area Network).
Broadband ultrasonic receivers, composed of a 360 degree array of 8 microphones.
Broadband ultrasonic receivers, composed of a spherical array of 10 microphones.
He developed the WhMic software (running on Windows, http://www.whmsoft.com program) in which there is a codec called WHM Voice that will be used for VLC.
He maintains the following web sites:
The objectives are:
- Programming of the codec (VLC and VLR versions) for Windows with an Open Source softphone (GreenJ).
- Programming of the codec (VLC and VLR versions) for Android with an Open Source softphone (GreenJ or CSipSimple).
- Programming of the codec (VLC and VLR versions) for iOS (iPhone / iPad) with an Open Source softphone (GreenJ or Siphon).
- Promotion of the codec in order to be used the most widely possible.
The sources will be available for the developers.
The project is divided into four distinct parts:
1) Program VLC and VLR for Windows.
2) Program VLC and VLR for Android.
3) Program VLC and VLR for iOS.
4) Promotion of the codec.
This fundraising is for the three first parts (programming).
The contributors will have obviously free access to all apps as they become available.
A portion of raised funds will be used to buy and send the counterparties promised to contributors.
Address of the web page of the apps:
On can find onhttp://www.whmsoft.com/m_voip_apps.php this page additional information, including more details on the algorithms to be used.
The possible Android app with the final user interface is available on Google Play at the following address:
This app does not yet contain the codec but can be used as a normal softphone.
The project has a very significant impact in everyday life:
- It will help to greatly reduce the battery consumption during the voice communications, if the two correspondents use the codec.
- It will help to reduce the audio frames emissions, so the electro-magnetic emissions.
Discussions are currently taking place between experts to know if the effects of these waves are carcinogenic in the long term or in case of intensive uses of mobile phones.
You can also support the project:
- By downloading and using the apps.
- By signaling the project around yourself.
- By sharing your observations and reporting the problems.
See on the crowdfunding website.