How About a Receive Squelch???

[tkerns]

I've been wanting to ask this, and recently heard it on another list. With the abundance of consumer AP's and other WISP out there, can a Squelch be added to the radio config? Set the min. signal strength and ignore the rest. Like in my area, listen to all signals less than (-80), but ignore all those above. Possible ? Others want / need?

Thanks,

Tim Kerns

[soulmata]

What's your goal? Your AP will still be receiving the noise, so in the grand scheme of things it probably wouldn't boost capacity or performance all that much.

[tkerns]

The goal is to block or ignore unwanted noise and improve performance.... the radio also receives signals from all the the channels, but is able to ignore or filter them, can this be extended to signals on the same channels, setting a "filter" or "threshold" for the required signal strength. It may not be possible through software and may only be possible in the firmware

Note: Tony or Lonnie, this should be in the "Feature wanted" area, I incorrectly started it in the Doc. Please move if you can. --- Thanks

[David L. Vrablic]

I think this was one of those "If you can't Fix it, Feature it" settings back when the sens levels were -85 dbi.

I always got into more trouble than it was worth trying to make it work right.
The problem lies with the variable nature of the received signals.
Bursting signals can drive the threshold selector nuts trying to keep up.
The new cards are down to -105 for sensitivity I think you will find the tools are built in now.
If a system is that bad It is most likely time to revisit antenna selection or add better radios.
I have also heard amazing results using bandpass filtering for this type f problem

Just my 2C

[rebel2234]

what cards are you speaking of that have a -105 for ears?

[David L. Vrablic]

I read an article that there are chipsets coming that reached way down for their signals and they made reference to -105.
(I wonder how big the supercooler is.)
They also wrote a lot about the new magic they are adding to automatically enhance the packet path on it way through the network.
I'll see if I can find it as it was like reading a science book.

[rebel2234]

I did a google on it and from what I can tell it is thet XR (eXtended Range) technology provided by atheros chips. From what I gather it is rates that go below 1mb/s eg. 0.5mb/s and .25mb/s.

[tkerns]

From what I have heard, MT has announced this on their product. You can set the senstivity to -82 (as an example) and it ignores all signals above this, reducing interference from unwanted signals (noise). With as much RF noise that we have in our area. something like this is needed to continue to offer service. Smaller channels help, but that requires a replacement of many CPE's and is not financially possible.

[lonnie]

So you're saying you have two identical ESSID's but you want to ignore one of them because it is too low?

I'm not sure I understand the benefit of this when applied to digital modulation. There is no analog component except RSSI and I really see no point to ignoring low signals since they are most likely ignored anyway, based on the ESSID.

Educate me if I have it wrong. Explain how it is supposed to work, and not simply that MT has it.

Also, how will this feature benefit all of those CPE's that cannot do Cloaking. They would also not be able to do the squelch, so how does this feature save your business? Sorry, but I'm confused.

[tog]

I think the general idea is to somehow set the radio ignore any signal of any type from anywhere where its signal strength is below -82 (for example) ?

Theoretically this would cut down on the impact that the -85 signal wifi devices would have on your AP or your client with this feature.

Sounds good in theory...

[lonnie]

It would also eliminate side lobes in the normal spectrum. Also once the squelch was opened all weak and strong signals would get through and have to be processed.

I fail to see the benefit of ignoring weak signals since the ESSID mechanism already does that. If you add a receive attenuation to eliminate -85 dB signals then that would drop you desired signal as well, which would cut your rate.

There must be some other mechanism at work here which I do not see and which you guys are not aware of. A simple RF squelch would not accomplish anything useful (in my opinion). The whole point of DSSS modulation is to ignore signals of no interest and recover the bits of interest. The digital processing the radio already can separate a weak background signal from the stronger foreground and it also handles multiple out of phase signals (from reflections). In part this is why Cloaking is more effective. There is less RF to process so it has more processing power to recover the good from the bad.

[jeff]

Squelch is an analog feature that uses a comparator to turn off the output whenever the received signal is below a given threshold. This keeps you from hearing the static and random noise from weak signals. There is no real comparable feature in spread spectrum receivers. I suppose you could put a front end filter but it would certainly degrade performance for any signal that was near the cut off and any additional elements will reduce the signal strength in some way.

I am guessing that any vendor advertising this "feature" is simply using a marketing term to describe some form of digital processing that they are doing. Odds are whatever it is is already being done by Star-os they just don't use a bogus name to describe it and don't make it a specific "feature".

[go.fast]

It would be better if cloaking was more versatile.
IE:
A) Having variable widths aside from the standard 5MHz such as 1 MHz
B) the ability to move the center channel over by 1MHz increments

[ninedd]

I'm don't know how/what MT is doing, but they might simply be ignoring signals below a certain threshold in the Site Survey display, plus not have the radio associate with anything below that threshold. I'm not sure how you actually get the radio not to hear the signals, but you easily could get it not to display those stations.

Personally, I'd love this - at least in the site survey display. I'd love to be able to...
a) Choose how to sort the stations (by Signal Stength or by channel for example), and
b) Not display stations past a certain threshold, and
c) Have fewer lines on each station, so that the display was better organized and more compact.

[lonnie]

We have figured it out and the advanced Atheros RF frontend allows us to do a low signal threshold (ignore anything below a certain value) AND a high signal threshold (ignore anything above a certain threshold).

The high threshold is great for your multiple install on a tower where the signals from other radios will be blasting your antenna on the same tower.

Check in the new release area for the link to the download.