HD Voice from Moscow Operators
A few years, slips messages from operators about the launch of HD Voice technology. This technology significantly increases the quality of sound transmission during a conversation, bringing it closer to office and digital city PBXs (without taking into account the fallout, of course) - it was more detailed in HD-Voice for cellular communication ... from Beeline in 2014.
Nevertheless, I never found relevant information on the operation of the service in Moscow and decided to figure out for myself how common this technology is.
The tests revealed that as of February 2016 between Moscow subscribers in Moscow, HD Voice works for all 4 operators (MTS, Beeline, Megafon, Tele2) and only for on-net calls in 3G / LTE networks, provided that both devices support the technology de facto.
Note: about LTE, I believe that it works in the case of voice transmission over 3G.
')
Due to the large number of options, the main testing was performed “by ear” through a test signal:
This screenshot shows (horizontal - seconds, vertical - Hertz) that the test signal consists of the following components:
The test signal was transmitted to the network using ordinary large headphones. it took longer to build the cable, but for the purposes of the test it was not necessary.
Sony xPeria S and HTC One (m7) became the main test devices in cellular networks; other devices were also connected; control support device was carried out through on-net calls (which immediately give HD Voice). From MGTS spoke DECT-phone texet.
Testing of interconnection connections was carried out taking into account the verification of the law of symmetry - that is, both MTS-> Megaphone and Megafon-> MTS calls were tried, as well as signal passing in both directions. Symmetry was confirmed in all cases of inter-operator connection tests, therefore I will omit further mention of this fact and I will say “MTS <-> Megaphone”, implying symmetrical operation.
For the sake of a clearer explanation, I recorded some calls on the HTC One (m7) and attached them further as examples.
For the creation of tests and visual presentation used the old program CoolEdit Pro, the recording on the phone - through CallRerorder .
MP3 files of the test signal and examples are uploaded to disk: cloud.mail.ru/public/EJPB/NArqZHyNU
Those who want to expand the knowledge base on regions / roaming / redirects and anything else - well!
In the case of HD Voice, frequencies up to ~ 6.5 kHz pass, an example for a Mega-Mega call:
(remember, horizontal - seconds, vertical - Hertz)
In the case of the usual type of communication pass frequencies up to ~ 4 kHz, an example for a Mega-Bi call:
At the same time, MTS-Bi, MTS-Mega, MTS-Tele2 calls give some defect:
In the region of 5 kHz, a signal is transmitted to the network just below 4 kHz. Perhaps this is due to the lack of frequency suppression above half the sampling rate from the MTS (for example, if the MTS gives the HD Voice signal and other operators incorrectly convert it into normal) - I do not know. In any case, this was observed only during inter-operator calls from / to the MTS.
* with defect
Also, for the sake of interest, I slightly “swung” on intranet roaming and forwarding.
In roaming, found a symmetry violation:
Call from Tele2-Tula -> on Tele2-Moscow (both phones in Moscow) - HD Voice.
From Tele2-Moscow -> on Tele2-Tula (both phones in Moscow) - normal.
This is most likely due to the call routing: in the first case, the call remains in Moscow, in the second it travels to the Tula switchboard and loses HD Voice.
Forwarded tested unconditional inside Megaphone, in the call Mega -> Mega-Forward-> Mega preserved HD Voice.
All relatively modern devices that came to hand earned in HD Voice:
At the same time, HTC Sensation did not want to work with HD Voice on different firmware: ViperS (Android 4.1.2), CyanogenMod12 (Android 5.1.1) and some older CyanogenMod - although it is indicated in all compatibility lists, in t h in the aforementioned Beeline publication.
Also expectedly, “did not take off” on a friend’s HD Voice iPhone 4 or 4s.
I made a conclusion for myself that HD Voice is, of course, good, but so far it works only within the operator. It is strange that MTS did not make it with MGTS, all the same it is one structure - that would be a serious advantage, I think.
Nevertheless, I never found relevant information on the operation of the service in Moscow and decided to figure out for myself how common this technology is.
The tests revealed that as of February 2016 between Moscow subscribers in Moscow, HD Voice works for all 4 operators (MTS, Beeline, Megafon, Tele2) and only for on-net calls in 3G / LTE networks, provided that both devices support the technology de facto.
Note: about LTE, I believe that it works in the case of voice transmission over 3G.
')
Testing method
Due to the large number of options, the main testing was performed “by ear” through a test signal:
This screenshot shows (horizontal - seconds, vertical - Hertz) that the test signal consists of the following components:
- control component - 1 kHz sine wave, in order to distinguish a simple dropout from the cutoff frequency
- test component - a sinusoid with a linearly increasing frequency from 3 kHz to 9 kHz
- reference component - a series of pulses with a frequency of 400 Hz for counting the frequency of the test component by ear (1/2/3 pulse when the test component reaches 4/6 / 7.5 kHz, respectively; where the test component disappears in the region of a single pulse - a normal communication, after 2 impulses - HD Voice)
The test signal was transmitted to the network using ordinary large headphones. it took longer to build the cable, but for the purposes of the test it was not necessary.
Sony xPeria S and HTC One (m7) became the main test devices in cellular networks; other devices were also connected; control support device was carried out through on-net calls (which immediately give HD Voice). From MGTS spoke DECT-phone texet.
Testing of interconnection connections was carried out taking into account the verification of the law of symmetry - that is, both MTS-> Megaphone and Megafon-> MTS calls were tried, as well as signal passing in both directions. Symmetry was confirmed in all cases of inter-operator connection tests, therefore I will omit further mention of this fact and I will say “MTS <-> Megaphone”, implying symmetrical operation.
For the sake of a clearer explanation, I recorded some calls on the HTC One (m7) and attached them further as examples.
For the creation of tests and visual presentation used the old program CoolEdit Pro, the recording on the phone - through CallRerorder .
MP3 files of the test signal and examples are uploaded to disk: cloud.mail.ru/public/EJPB/NArqZHyNU
Those who want to expand the knowledge base on regions / roaming / redirects and anything else - well!
Testing and results
In the case of HD Voice, frequencies up to ~ 6.5 kHz pass, an example for a Mega-Mega call:
(remember, horizontal - seconds, vertical - Hertz)
In the case of the usual type of communication pass frequencies up to ~ 4 kHz, an example for a Mega-Bi call:
At the same time, MTS-Bi, MTS-Mega, MTS-Tele2 calls give some defect:
In the region of 5 kHz, a signal is transmitted to the network just below 4 kHz. Perhaps this is due to the lack of frequency suppression above half the sampling rate from the MTS (for example, if the MTS gives the HD Voice signal and other operators incorrectly convert it into normal) - I do not know. In any case, this was observed only during inter-operator calls from / to the MTS.
| Mega <-> Mega | HD voice |
| Mega <-> Beeline | usual |
| Mega <-> MTS | usual* |
| Mega <-> Tele2 | usual |
| Mega <-> MGTS | usual |
| Beeline <-> Beeline | HD voice |
| Beeline <-> MTS | usual* |
| Beeline <-> Tele2 | usual |
| Beeline <-> MGTS | usual |
| MTS <-> MTS | HD voice |
| MTS <-> Tele2 | usual* |
| MTS <-> MGTS | usual |
| Tele2 <-> Tele2 | HD voice |
| Tele2 <-> MGTS | HD voice |
Also, for the sake of interest, I slightly “swung” on intranet roaming and forwarding.
In roaming, found a symmetry violation:
Call from Tele2-Tula -> on Tele2-Moscow (both phones in Moscow) - HD Voice.
From Tele2-Moscow -> on Tele2-Tula (both phones in Moscow) - normal.
This is most likely due to the call routing: in the first case, the call remains in Moscow, in the second it travels to the Tula switchboard and loses HD Voice.
Forwarded tested unconditional inside Megaphone, in the call Mega -> Mega-Forward-> Mega preserved HD Voice.
Devices and reflections
All relatively modern devices that came to hand earned in HD Voice:
- HTC One m7 (not official firmware on 4.4.3 - MaximusHD
- Sony xPeria S (not official firmware on 4.2.2 - CyanogenMod10
- Pristigio Multipad 4 tablet (official firmware 4.2.2 - MaximusHD
At the same time, HTC Sensation did not want to work with HD Voice on different firmware: ViperS (Android 4.1.2), CyanogenMod12 (Android 5.1.1) and some older CyanogenMod - although it is indicated in all compatibility lists, in t h in the aforementioned Beeline publication.
Also expectedly, “did not take off” on a friend’s HD Voice iPhone 4 or 4s.
I made a conclusion for myself that HD Voice is, of course, good, but so far it works only within the operator. It is strange that MTS did not make it with MGTS, all the same it is one structure - that would be a serious advantage, I think.
Source: https://habr.com/ru/post/391031/
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