[Asterisk-Dev] Re: How to measure delay in meetme?

[Steve Edwards]

On Sat, 3 Sep 2005, Clive Nicolson wrote:

> And the delay is?

Setup 1 - TE410p in a Supermicro p4 2.8gHz 1u. Dialplan dial's the
conference server (Compaq 2x xeon 3.06 gHz 2u) using IAX.

Delay is 0.111 seconds.

Setup 2 - TE410p in the conference server.

Delay is 0.027 seconds.

It appears that IAX/network latency adds about 0.084 seconds of delay.

And the customer is still complaining !!!

Their existing system consisting of an Excel switch talking to an IVR
based on Dialogic 240's and Vendetta 128's.

The delay through the existing system is 0.012 seconds.

> On Wed, 31 Aug 2005, Steve Edwards wrote:
>
>> Thanks for the reply. I thought about a solution similar to yours, but
>> rejected it because of a lack of resources -- primarily access to an
>> oscilloscope.
>
> What I described can all be done (by analogy) with audio software on a pc.
>
>>
>> I came up with a cheaper and easier solution.
>>
>> Radio Shack/Tandy sells a "Telephone Recording Control" (P/N 43-22BA,
>> US$25.99).
>>
>> This little black box has an RJ11 jack, an RJ11 plug, an 1/8" mono plug,
>> and some sort of plug to control a tape recorder.
>>
>> I connected the "TRCs" to 2 POTS phones and plugged the mono plugs into a
>> "mono to stereo adapter" (P/N 274-375, US$4.99). I plugged the adapter
>> into the line in jack on my laptop.
>>
>> Using Audacity (http://audacity.sourceforge.net), I can record both phones
>> as left and right.
>>
>> I muted 1 phone to make sure I wasn't recording sound from its mic.
>>
>> By tapping the other handset on the table, Audacity can measure the
>> interval between the 2 "pips."
>
> =================
> And the delay is?
> =================
>
>>
>> On Thu, 1 Sep 2005, Clive Nicolson wrote:
>>
>>> On Mon, 29 Aug 2005, Steve Edwards wrote:
>>>
>>>> On Mon, 29 Aug 2005, Tony Mountifield wrote:
>>>>
>>>>> I've never found problems with delay when only Zap channels are involved;
>>>>
>>>> Personally, I don't think anybody would notice in a real conversation, but
>>>> you can notice it if you have a separate phone to each ear or if you
>>>> listen on one handset and tap the table with the other.
>>>
>>> Get a dual channel oscilloscope, a audio signal generator, a small speaker
>>> and a microphone. Set the generator to a frequency lower that the delay you
>>> think you are hearing. Feed the signal to the speaker and one channel of
>>> the scope (trigger of this signal), adjust the level so you can hear it.
>>> Connect the microphone to the other scope's other channel and place the
>>> microphone near the speaker. Adjust the gain on that channel so that you
>>> can compare the 2 undelayed signals.
>>>
>>> Now place the speaker near the mouth piece of one phone and the microphone
>>> near the ear piece of other phone. Establish a call between these phones.
>>>
>>> You should be able to measure the delay over that path on the scope!
>>>
>>> Borrow the scope and signal generator and get the speaker and microphone
>>> from Tandies (your local electronics store).
>>>
>>> Clive
>>>
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>>
>> Thanks in advance,
>> ------------------------------------------------------------------------
>> Steve Edwards      sedwards at sedwards.com      Voice: +1-760-468-3867 PST
>> Newline           pagesteve at sedwards.com            Fax: +1-760-731-3000
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>
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Thanks in advance,
------------------------------------------------------------------------
Steve Edwards      sedwards at sedwards.com      Voice: +1-760-468-3867 PST
Newline           pagesteve at sedwards.com            Fax: +1-760-731-3000