If you surf on "fax answer tone" you find a lot of wav files that are
continuous tones.

If I call a real fax I hear that tone, BUT it seems to be strobed on
and off at about a 0.5Hz rate.

Anyone know the actual spec rate and on/off dutycycle?

Thanks!

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

"Jim Thompson" wrote
in message ...
If you surf on "fax answer tone" you find a lot of wav files that are
continuous tones.

If I call a real fax I hear that tone, BUT it seems to be strobed on
and off at about a 0.5Hz rate.

Anyone know the actual spec rate and on/off dutycycle?

Thanks!


ITU communication standards
V.27 V.29 V.17V.34 V.34bis

You can fin the specs here http://www.3amsystems.com/wireline/hmo.htm

from V.34...
10.1.2.1A
Tone A is a 2400 Hz tone transmitted by the answer modem. Transitions
between A and A, and similarly between A and
A, are 180 degree phase reversals in the 2400 Hz tone. During the
transmission of A and A, the answer modem sends a
1800 Hz guard tone without any phase reversals. Tone A is transmitted at
1 dB below the nominal transmit power while
the guard tone is transmitted at the nominal transmit power.
NOTE – The bandwidth of a tone with phase reversals should not be
constrained in a way that appreciably affects the accuracy of
round trip delay measurements.
10.1.2.2B
Tone B is a 1200 Hz tone transmitted by the call modem. Transitions
between B and B, and similarly between B and B,
are 180 degree phase reversals in the 1200 Hz tone.
NOTE – The bandwidth of a tone with phase reversals should not be
constrained in a way that appreciably affects the accuracy of
round trip delay measurements.

Cheers

On Sun, 24 Apr 2011 15:59:20 -0400, "Martin Riddle"
wrote:



"Jim Thompson" wrote
in message ...
If you surf on "fax answer tone" you find a lot of wav files that are
continuous tones.

If I call a real fax I hear that tone, BUT it seems to be strobed on
and off at about a 0.5Hz rate.

Anyone know the actual spec rate and on/off dutycycle?

Thanks!


ITU communication standards
V.27 V.29 V.17V.34 V.34bis

You can fin the specs here http://www.3amsystems.com/wireline/hmo.htm

from V.34...
10.1.2.1A
Tone A is a 2400 Hz tone transmitted by the answer modem. Transitions
between A and A, and similarly between A and
A, are 180 degree phase reversals in the 2400 Hz tone. During the
transmission of A and A, the answer modem sends a
1800 Hz guard tone without any phase reversals. Tone A is transmitted at
1 dB below the nominal transmit power while
the guard tone is transmitted at the nominal transmit power.
NOTE – The bandwidth of a tone with phase reversals should not be
constrained in a way that appreciably affects the accuracy of
round trip delay measurements.
10.1.2.2B
Tone B is a 1200 Hz tone transmitted by the call modem. Transitions
between B and B, and similarly between B and B,
are 180 degree phase reversals in the 1200 Hz tone.
NOTE – The bandwidth of a tone with phase reversals should not be
constrained in a way that appreciably affects the accuracy of
round trip delay measurements.

Cheers


Thanks, Martin! So the "click"/strobing I'm hearing is actually a
phase reversal?

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

Remember: Once you go over the hill, you pick up speed

"Jim Thompson" wrote
in message news
On Sun, 24 Apr 2011 15:59:20 -0400, "Martin Riddle"
wrote:



"Jim Thompson"
wrote
in message ...
If you surf on "fax answer tone" you find a lot of wav files that
are
continuous tones.

If I call a real fax I hear that tone, BUT it seems to be strobed on
and off at about a 0.5Hz rate.

Anyone know the actual spec rate and on/off dutycycle?

Thanks!


ITU communication standards
V.27 V.29 V.17V.34 V.34bis

You can fin the specs here
http://www.3amsystems.com/wireline/hmo.htm

from V.34...
10.1.2.1A
Tone A is a 2400 Hz tone transmitted by the answer modem. Transitions
between A and A, and similarly between A and
A, are 180 degree phase reversals in the 2400 Hz tone. During the
transmission of A and A, the answer modem sends a
1800 Hz guard tone without any phase reversals. Tone A is transmitted
at
1 dB below the nominal transmit power while
the guard tone is transmitted at the nominal transmit power.
NOTE – The bandwidth of a tone with phase reversals should not be
constrained in a way that appreciably affects the accuracy of
round trip delay measurements.
10.1.2.2B
Tone B is a 1200 Hz tone transmitted by the call modem. Transitions
between B and B, and similarly between B and B,
are 180 degree phase reversals in the 1200 Hz tone.
NOTE – The bandwidth of a tone with phase reversals should not be
constrained in a way that appreciably affects the accuracy of
round trip delay measurements.

Cheers


Thanks, Martin! So the "click"/strobing I'm hearing is actually a
phase reversal?


I think so, if you read into the v.34 document they explain the answer
negotiation.
TONE A and TONE B are defined early on in the document.

Cheers

Jim Thompson wrote:
If you surf on "fax answer tone" you find a lot of wav files that are
continuous tones.

If I call a real fax I hear that tone, BUT it seems to be strobed on
and off at about a 0.5Hz rate.

Anyone know the actual spec rate and on/off dutycycle?

Thanks!

...Jim Thompson
I do not know about the standards, but that "strobe" is from the fact
that a FAX machine identifies itself on pickup.

Martin Riddle wrote:
"Jim Thompson" wrote
in message news
On Sun, 24 Apr 2011 15:59:20 -0400, "Martin Riddle"
wrote:


"Jim Thompson"
wrote
in message ...
If you surf on "fax answer tone" you find a lot of wav files that
are
continuous tones.

If I call a real fax I hear that tone, BUT it seems to be strobed on
and off at about a 0.5Hz rate.

Anyone know the actual spec rate and on/off dutycycle?

Thanks!

ITU communication standards
V.27 V.29 V.17V.34 V.34bis

You can fin the specs here
http://www.3amsystems.com/wireline/hmo.htm

from V.34...
10.1.2.1A
Tone A is a 2400 Hz tone transmitted by the answer modem. Transitions
between A and A, and similarly between A and
A, are 180 degree phase reversals in the 2400 Hz tone. During the
transmission of A and A, the answer modem sends a
1800 Hz guard tone without any phase reversals. Tone A is transmitted
at
1 dB below the nominal transmit power while
the guard tone is transmitted at the nominal transmit power.
NOTE – The bandwidth of a tone with phase reversals should not be
constrained in a way that appreciably affects the accuracy of
round trip delay measurements.
10.1.2.2B
Tone B is a 1200 Hz tone transmitted by the call modem. Transitions
between B and B, and similarly between B and B,
are 180 degree phase reversals in the 1200 Hz tone.
NOTE – The bandwidth of a tone with phase reversals should not be
constrained in a way that appreciably affects the accuracy of
round trip delay measurements.

Cheers

Thanks, Martin! So the "click"/strobing I'm hearing is actually a
phase reversal?


I think so, if you read into the v.34 document they explain the answer
negotiation.
TONE A and TONE B are defined early on in the document.

Cheers




Well, if one uses a telephone to call a FAX, there cannot be any
negotiation, yet one hears that (what i call) "tweedle".