Here's one for the digital experts: I do a lot of interviews in which
the other party is on a cell phone, and I think I've noticed a
difference over time in how they work.
If the call is conducted at a busy time of day, and there are clear
signs of bandwidth becoming limited, it used to be that there would be
a corresponding number of dropouts in the conversation. Lately (and I
call mostly the Chicago and Los Angeles areas) I've detected something
different: it sounds like they're just reducing the audio bitrate. It
starts to sound like it's coming from a cheap microphone.
Does anyone know?
Yeah, well, the cruddy audio is something I've just noticed over the
past year. The dropouts have been going on for years.
Chicago, particularly, seems to have bandwidth problems on both
landlines and cell systems. I try to time my calls for early morning.
If I do, the audio is perfectly clear.
It's gotten to be a problem for my transcribing service. Not knowing
our jargon, they have a really hard time with it when it gets muddy.
In the beginning cellphones were all analogue. The sound quality can
vary due to distance between the cellphone and the cellphone tower.
Today cellphones have almost all gone digital. You cannot buy an
analogue cellphone anymore and even if you still have an analogue
cellphone you might not be able to find a service provide which still
runs the old analogue cellphone systems.
Digital cellphone system is almost like digital TV. You either get it
100% or you don't get it at all, because the signals are all in ones and
The difference in sound quality is most likely due use of "Voice over
IP" (people dialing you using Skype or other WiFi connection Apps to
avoid airtime charges), or use of low quality Bluetooth headset when
talking to you (most cellphones have built-in Bluetooth technology).
On Fri, 15 Jul 2016 13:17:48 -0400, BPVeW???????? ? ?????????fZSSO
VoIP is a frequent problem in recording for articles. That's why I
still have a conventional landline at my end, recording directly into
the computer. But I also use my cell phone with an earbud microphone
into my Sony digital recorder -- the difference is almost
undetectable.I don't bother with the in-line adapter on a cell phone
Having played with different bit rates over the years, it really does
sound like a bit-rate reduction to me. I don't think my interviewees
are using Bluetooth. I never use it for anything that has to be
Ah, well, it's not something that seriously bothers me because it only
happens once in a while. I was thinking about it today because I had
to transcribe a half-hour conversation myself (which I hate to do),
because my transcribing service couldn't make it out. They have a good
collection of audio filters, but they couldn't do it. I could, because
I know what the other guy was saying.
You are obviously a top notch investigator! Thank God we have people
like you devoted to exposing these things. Here is one I will be
talking about soon. https://www.youtube.com/watch?v=sYikArdbDto And we
all know it's true because he has endorsed me and because it's on the
How many alarms go on the fritz - they use cell phone connections for
instant help and reporting. They know when an alarm is set and rings -
they are the ones who calls the cops. But when cut off - we go back
to self protection. 24/7.
On 7/15/2016 1:56 PM, Donald J. Trump wrote:
That ain't right---you can see how it really works with progressive GIFs.
Basically, you send the crude approximation of your signal (image in this
case) first, and then if you have bandwidth/time/money/patience you show
more detail. A good example is here:
You could think of this as using very low bandwidth aka low bitrate
connection in the beginning (sending just few 'bits' of the image), and
then increasing the number of sent bits per unit time to get more detail.
Ed was talking about the phone companies using adaptive audio bitrate,
which is how the phone company manages their limited aggregate cell tower
bandwidth. They basically can serve small number of customers at high
bitrate that gives very good sound quality. If, however, they get a lot
of cellphones trying to use an oversubscribed tower, they run out of
bandwidth. They COULD drop the call (drop from 100% to nothing at all, as
you say), but the customers tend to complain loudly about that.
Instead, the phone company came up with a brilliant idea: they switch
everyone to a low, crappy bitrate, so they can handle a lot of cellphones
at lower quality. It's much harder for the customers to quantify their
complaints now ("maybe momma is just mumbling"). Geniuses.
You are talking about "digitizing" voice or video.
I am talking about the "transmission mode" of analogue cellphone and
digital cellphone, and the equivalent technology of digital TV and
Canada has phased out analogue TV broadcast a few years ago. All TV
broadcast over the airwaves are now digital in Canada.
It is true that when you are transmitting in digital form, the signals
are in ones and zeros, so that you either get it clearly or you don't
get it at all.
Analog Versus Digital TV: What's the Difference?
How Digital Television Works
DTV is more advanced than the older analog technology. Unlike analog
television, which uses a continuously variable signal, a digital
broadcast converts the programming into a stream of binary on/off
bits?sequences of 0s and 1s. This is the same way that computers store
information in data files; each bit represents a small part of the
picture, and all the bits combine to reproduce the original picture.
The primary advantage of digital broadcasting is that these binary bits
recombine to reproduce an exact copy of the original material. The
picture and sound received from a digital transmission are always
identical to the original source.
Even better, over-the-air digital signals don?t weaken over distance, as
analog signals do. As long as the signal can be received, the picture is
perfect, with no degradation or ghosting. Because digital signals are
composed of binary bits, a 1 is always a 1, and a 0 is always a 0. There
is no fuzziness or snow in the picture, no ghosts caused by interference.
In addition, digital is a more efficient technology. A digital
transmission requires less bandwidth than does a similar analog
broadcast; this lets local television stations broadcast two, three, or
even four digital channels in the space of a single analog channel. This
?multicasting? technology means you?ll receive more variety in
programming from your local stations?all delivered with superior digital
I love HD TV myself. If a storm comes I can start seeing digital
blocks start to drop out and screen freezes... It comes back or not.
Martin - been HD since the first time they tried to push it. It was
720x720. Old tech now. But still HD.
On 7/17/2016 9:00 PM, ZwMLx???????? ? ?????????MRRfv wrote:
I studied voice and data communications in 1970 and took a refresher
class in the phone system in the 1990's when an interest in
infrastructure didn't brand one a potential terrorist. I haven't
looked into it since and don't intend to now.
My cellular internet modem drops out completely when the system hits
voice call capacity. There are a number of ways they could reduce the
audio data rate when that happens such as duplicating frames or
dropping the least significant bit, which they do anyway to some
extent to transmit the on/off hook signal. That's why the dialup
maximum is 56K instead of 64K.
Digital TV drops a lot of data intentionally to stuff 20MB of HD video
into 6MB of TV channel. They send a full "key" frame and then only the
changes to it, until the next full frame. It works fine when the
background is static or changes slowly. It isn't quite fast enough for
football play closeups so the TV may display larger solid blocks
Speech can be similarly trimmed down to taking and sending one sample
every 50 milliseconds or so and just repeating it until the next
sample, because most of us can't change the shape of our vocal tracts
any faster than that. The intelligibility is still tolerable although
JFK demanded and got a higher sound quality digital phone that needed
special dedicated lines.
The underlying tech of digital phones dates from a secure channel
between Roosevelt and Churchill.
"The voice encoding used the fact that speech varies fairly slowly as
the components of the throat move. The system extracts information
about the voice signal around 25 times a second."
Interesting. If you've played with recording systems, computer or
otherwise, that record digitally and that allow you to select from a
menu of bitrates, you've encountered what I'm talking about. Any
decent digital recorder today has optional record-time settings, which
actually are different bit rates.
AFAIK the landline phone system is locked into the bit rates of G.711
Mu- and A-Law encoding.
A cell phone has to be compatible with a landline, or even an old
rotary dial phone.
I don't know exactly how they might compress it, or interpolate
dropped samples. The military gear I mentioned transmitted a
simplified spectrum analysis of the speech instead of the sequential
Aha! Maybe this is the clue. I should have looked it up but I was lazy
and thought one of you guys should know:
"For example, engineers at Nokia found that when they compressed voice
data to 5.15 kilobits per second, which cellphones do automatically
"Standard compression rates vary from 12.2 kb/s to 4.75 kb/s,
depending on the volume of voice traffic and the strength of the
wireless signal. Calls compressed to speeds as low as 7.95 kb/s can
still sound almost as good as a landline connection. But beyond that,
and distortions such as ringing or warbling..."
Where this leads...
"...one proposal would require all TV stations, including LPTV, to
give up all spectrum, with subsidized multichannel services replacing
over-the-air TV, even after viewers spent a great deal of money on the
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