Hacker News Reader

Comment by samstave | Hacker News Reader

>2) Shitty hardware Antenna design is black magic and only a few firms in the US do it well. It took us almost 10 months to fully design and test our antenna assembly(s) with a very capable third party firm.

I think that you are remiss if you don't actually name the companies/produucts/devices which are designed well then....

There was a company in Aptos/Santa Cruz who was designing the antennas for a lot of Lockheed stuff back in about 2006/2007 or so who we went to for antenna designs for our active RFID devices - but I cant recall for the life of me the name of the company now...

View on HN

As a rule of thumb, the notable product manufacturers like Apple, Samsung, Nokia, Microsoft, Amazon, etc, have extremely capable RF design teams.

Your run of the mill bluetooth headset, mouse, or keyboard likely does not spend the time on the RF design beyond "does it work".

"Run of the mill bluetooth headset, mouse, or keyboard" manufactures don't make Bluetooth chips, they buy them. What part of the bt stack do you work on? You're saying nonsensical things, wifi does not do AFH. I didn't know apple made bluetooth chips? You don't even mention Nordic or TI, also not all big bt companies are in America.

> You're saying nonsensical things, wifi does not do AFH.

Many, many Wi-Fi implementations are capable of frequency hop, including my own at home.

That is not possible, it's not part of the spec. Maybe what you're thinking of is the wifi hotspot selecting the channel automatically when setting up a network based on the neighbours it can see. Nothing to do with frequency hopping. AFH happens between packets and maps out bad channels. Wifi does not do that, never has and never will because it's governed by different rules.

Nope, I’m thinking of when I transparently switch channels when my neighbor comes home and starts blowing up his own network. I’m aware it’s not part of the specification, which I’m sure you’re aware doesn’t mean anything except that it’s not part of the specification.

I don't know what you're thinking of but no, you can't have that because if you had this magical hotspot your network card in your iThing would not know what to do because wifi does not do frequency hopping. Every time your hotspot changes channels it disconnects all your devices.

You're forgetting devices with two bands, and assuming a lot about my devices (and competence). I know my network and its behavior, and I'm not just spewing hot air here.

You are arguing with me about something that is easy to verify in 10 seconds by looking at the wiki page: https://en.wikipedia.org/wiki/IEEE_802.11

(it does mention a frequency hopping physical layer but that was part of the obsolete predecessor from 1997, the modern spec uses OFDM so unless all your equipment is from the last century you're not using frequency hopping)

Paul_S, could you be a bit more civil to jsmthrowaway so as to elicit what he does know and how he knows it?

jsmthrowaway can you give more information about your setup and what the devices do?

No need for a heated argument. This whole thread is quite instructive!

Why was this downvoted?

(No I'm not complaining about being downvoted - this isn't even my comment - just trying to learn.

Based on my frequent lurking, I would guess it was due to the personal (and off topic) nature of the comment. Addressing users specifically in this way seems to be looked down upon here.

not really. people aren't allowed to be rude and uncivil with each other here, as it shuts down constructive discussion. this is in the guidelines.

I think there is a misunderstanding related to the terms here:

1. IIRC my router is supposed to switch channel (i.e. frequency) automatically unless I explicitly set it to a fixed channel.

I don't know how but my devices figures out and continues working.

2. I think the misunderstanding is related to the word frequency hopping or whatever was used further up in the discussion.

I normally take "frequency hopping" to mean changing frequncy multiple times a minute or even faster while I doubt my wireless access point will switch channels more than a few times in 24 hours.

Disclaimer: I never really sat down and verified if it ever changed.

Also agree with logicalle that I wish for a bit more civility.

I can't speak for jsmthrowaway but I think that he's referring to Band Steering (please correct me if I'm wrong). It's not in the spec but my Unifi gear definitely has a checkbox to enable it if I opt-in to see "advanced settings".

As far as I know it's not dynamic, though. It just happens when a device connects to a base station and only "steers" the client to connect using one of the 2.4 or 5 GHz bands, and that doesn't interfere with channel selection.

The AP also has a function to scan bands to find the "best" channel to use but that disconnects all devices while the scan is in progress. I think some APs might be doing this automatically (?). My other AP (a Mikrotik) has an "auto" channel selector but I don't know what it does or when.

Correct. I’m on Unifi gear with two bands. When it has opportunities to do so, it moves around the SSIDs themselves, too, which seems to happen after every client gets steered to one of them (it’ll reconfigure the other). I might have enabled this feature at some point without realizing it.

My neighbor moves around his channels, too. That’s what’s making me comment that it’s likely more common than we think. I’m not at home to prove this and I’m getting downvoted for sharing, but I’ve watched him move between 36, 40, and 44 at a frequency that suggests it is happening automatically, probably when all of his sessions go idle or something. I have observed this with multiple tools.

My 5 GHz was on 44 this morning, because I happened to look for unrelated reasons. I just SSH’d home and it’s now on 36 without interaction from me. Specifications are not implementations. I’m almost positive this is a common feature which I’ve seen in many APs over the years, even though it’s not per-packet like Bluetooth (which I was also aware of, given that I'm experimenting with a Bluetooth 5 mesh system for IIoT).

Right, and that's band steering, not frequency hopping.

Just because a spec doesn't have it doesn't mean it can't be done. At the same time, implementing something that makes you out-of-spec (like Zero Handoff with a virtual floating BSSID between multiple orchestrated AP's -- totally unsupported and not in the spec) and designing it the right way can sometimes mean that a function you thought could not be there is there anyway.

What he is probably referring to isn't frequency hopping, because what it sounds like and that it actually refers to means different things to different people. For someone who is not a RF engineer, hopping might simply mean "an AP that has multiple radios that uses one to scan the 802.11 2.4Ghz space to see what channels have the least utilization, and then restarts the other radios on a that channel, possibly forcing all clients to lose their connection as if out-of-range and reconnecting again on the new channel as they find it".

This, of course, has nothing to do with RF frequency hopping, but if you don't actually know anything about RF, you won't know what hopping means either, and just imagine that what your router with built in AP is doing must therefore be that 'hopping'.

> For someone who is not a RF engineer, hopping might simply mean "an AP that has multiple radios that uses one to scan the 802.11 2.4Ghz space to see what channels have the least utilization, and then restarts the other radios on a that channel, possibly forcing all clients to lose their connection as if out-of-range and reconnecting again on the new channel as they find it".

Bingo, except add 5 GHz (and soon, 900 MHz), too.

I never said the chip manufacturers were device manufacturers, perhaps you read that incorrectly?

The companies that deploy a TI, Nordic, Broadcom chipset are subject to the scrutiny I just mentioned. The chipset manufacturers offer reference designs but generally you need a custom matching circuit and a complex RF design to do it correctly. That's where most manufacturers skimp out because its generally "good enough"

As for WiFi, it does not frequency hop but is capable of "auto" selecting a channel on boot (generally).

Yes, I clearly misread that.

I didn't know apple made bluetooth chips?

https://9to5mac.com/guides/w1/

Anecdotally, I have a Microsoft Surface Pro 4 and a Microsoft Surface Keyboard (Bluetooth), and it is incredibly unreliable. Pressing a key after a period of inactivity will select an action from:

1. Do absolutely nothing.

2. Completely lock up the computer so it needs a hard reset.

3. Completely lock up the computer for a few seconds, then work.

4. Start working, but ignore ~40% of the key presses.

5. Swallow the first keypress or two, then work.

6. Actually function like a keyboard.

If Microsoft has a good RF team, I'd hate to see what worse teams do.

I wish there was a USB version of this keyboard, or at least a wireless dongle version (like Microsoft's cheaper keyboards).

Those sound like software/firmware problems, not RF problems. I think it's pretty well-known that Microsoft has an absolutely dreadful software team.

Reply on news.ycombinator.com