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wildbill442
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Periodic Calibration

Fri Nov 10, 2006 1:15 am

I've searched the forums for an explanation for this settings and didn't find anything definitive.

What I learned from the search is that it sometimes helps with connections that timeout due to "extensive data loss". And it helps in areas where the climate changes frequently..

Here's the description from the manual:

periodic-calibration (default | disabled | enabled; default: default) - to ensure performance of chipset over temperature and environmental changes, the software performs periodic calibration

What exactly does it calibrate? And when this calibration takes effect do clients lose connection?

Thanks
 
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acim
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Fri Nov 10, 2006 3:40 am

Yes, this is good questions. I've also tried to find some good explanation, but there is nothing. Please someone from MT explain this.
 
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chvdr
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Re: Periodic Calibration

Sun Nov 12, 2006 11:32 am

I've searched the forums for an explanation for this settings and didn't find anything definitive.

What I learned from the search is that it sometimes helps with connections that timeout due to "extensive data loss". And it helps in areas where the climate changes frequently..

Here's the description from the manual:

periodic-calibration (default | disabled | enabled; default: default) - to ensure performance of chipset over temperature and environmental changes, the software performs periodic calibration

What exactly does it calibrate? And when this calibration takes effect do clients lose connection?

Thanks
yeah, i found that link usually works better with "periodic-calibration enabled". but what really happends, who knows...

regards,
C. G.
 
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djape
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Mon Nov 13, 2006 1:16 pm

I have some issues on many APs when atheros radio will stop working (no packet/s - no bandwidth).
Simple disable then enable solve this problem.
I thought that periodic calibration do something similar, but unfortunately I never figure what is calibration doing or does do anything at all.

Off topic question but regarding this subject: What could cause a problem with radio (no traffic at all, even though signals are good)?

I understand that there are frequency/noise issues, but can't understand that there is not even one packet passing through......

Checked with prism and no hanging issues at all.
So I'm thinking....it must be some problem with atheros chip...or drivers.....

Cheers...
I drink like a pirate and smoke like a hippie...
 
npero
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Mon Nov 13, 2006 3:45 pm

On some older version of Mikrotik 2.9.x I have problem some time signal streight going crazy client disconect after scan work ok some time, but after enabling periodic calibration everething work ok. On all wireless interface now always enable period calbiration and I don't have that problem. Possibly is problem disaper after upgrade to new version I don't know.
 
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acim
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Wed Nov 15, 2006 8:55 pm

A method and apparatus for determining transmit and receive gain of a wireless transceiver as well as the path loss between multiple (e.g., two or more) transceivers. The technique described herein allows the transmitter gain, receiver gain, and path loss to be determined in real-time in a closed-loop control scheme with each transmitter in the wireless system adjusting its output power level to a predetermined power level. In one embodiment, the real-time gain and path loss calibration scheme can determine the gain and path loss of a wireless system during network establishment and at periodic intervals during regular operation.
This is from http://www.freepatentsonline.com/6272322.html

If you register at this site, you will be able to see more specific data about periodic calibration.

Obviously, periodic calibration is a feature of Atheros chipset (and patent owned by Atheros) and Mikrotik probably just use this feature. Same applies to madwifi Atheros driver for Linux. Maybe we should see ast_per_cal function of madwifi driver to figure out what is going on, but as I said, it seems this is hidden inside Atheros hardware and firmware. We should just use it and don't worry :)
 
music
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Thu Nov 16, 2006 10:14 am

I have some issues on many APs when atheros radio will stop working (no packet/s - no bandwidth).
Simple disable then enable solve this problem.
I thought that periodic calibration do something similar, but unfortunately I never figure what is calibration doing or does do anything at all.

Off topic question but regarding this subject: What could cause a problem with radio (no traffic at all, even though signals are good)?

I understand that there are frequency/noise issues, but can't understand that there is not even one packet passing through......

Checked with prism and no hanging issues at all.
So I'm thinking....it must be some problem with atheros chip...or drivers.....

Cheers...
Changing from 802.11g to 802.11b solved my problem.
 
titius
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Thu Nov 16, 2006 9:30 pm

well a friend told me that periodic calibration is option that enables communication between two mikrotiks ( from time to time ) for ACK calibration.
 
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GWISA
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Tue Nov 21, 2006 1:28 am

well a friend told me that periodic calibration is option that enables communication between two mikrotiks ( from time to time ) for ACK calibration.
Sounds more like N-stream to me...
 
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bjohns
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Tue Nov 21, 2006 5:14 am

I'm pretty sure there's a thread kicking around here that explains it. If I remember correctly it was a method where the radio can 'recalibrate' itself to adjust for extreme temperature changes and other environmental effects.

http://www.freepatentsonline.com/6272322.html turned up in a google search. Not sure if its referring to the same technology. However for this kind of calibration wouldn't the radio have to be full duplex??
 
jo2jo
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Tue Nov 21, 2006 6:50 am

what about the DFS radar function? anyone have a good explination on that? tks
 
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GWISA
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Tue Nov 21, 2006 10:28 am

what about the DFS radar function? anyone have a good explination on that? tks
DFS will change to a frequency specified in scan-list if excessive noise is detected on the current operating frequency.
 
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sten
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Tue Nov 21, 2006 7:55 pm

metal and silicone changes performance under different temperatures.
Periodic calibration is called from host system at intervals the host wants to sample the current performance characteristics of the radio. The radio will then reconfigure to use different parameters when transmitting to compensate for the difference in performance caused by temperature. The reason it's not done automatically by the radio, i assume to be;
#1 it would require an extra timer (expensive in terms of production) and
#2 the process itself uses up a tiny bit of potential air time (a few microseconds).

These are mere assumptions as i do not work for Atheros.
Move along. Nothing to see here.

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