The Huawei B593 LTE discussion thread

[sajunky]

However, when tested on the "diode test" range included on some multi-meters - which uses a higher test voltage - you will see about a 0.6V volt-drop when measured in either direction. This would be considered a DC short.
(On an even more technical note, this might indicate that the "DC short" on the B593s-601's flat whip antennas is provided by means of some anti-parallel (back-to-back) diodes connected between shell and centre pin).

View attachment 195306

Whether your B593 modem/router cares about it or not, a DC short on an outdoor external antenna is desirable for ESD and surge protection reasons.

I agree to the indication for presence of anti-parallel diodes and a reasoning for surge protection. Technically it is not DC-short antenna.
However if you are still trying to suggest that router would use diodes for detection, read on... I think it doesn't make sense, as it is easier to test connection with the tower than build extra detection hardware. But if you still insist to prove DC-short theory, I tell you how to do it.

All you have to do is to measure voltage on the router's SMA connector. If you see 0.6V or more, there is a possibility of DC sensing by the router. If you don't, then accept the fact that diodes are used solely for surge protection.

 

[jcheek]

The B593 and antennas which have DC shorts (or not)

However if you are still trying to suggest that router would use diodes for detection ...

I'm not. I've only been talking about their possible significance for ESD/surge protection.

But if you still insist to prove DC-short theory, I tell you how to do it.

That's a very kind offer, but I'm good, thanks.

 

[sajunky]

That's a very kind offer, but I'm good, thanks.

Embarrassing, I know. At least we will stop talking about DC-short from now, I hope.

 

[Conrads]

Hi Guys

Ok just to answer some or give some input....
The SP100 firmware is the best you will get now at the moment for the B593u-91. I got it from Huawei SA.
I have searched high and low for the V100R001C82SP150 firmware (had this on before my firmware crash)with no luck.
If I load the SP054 or the SP100, there is no real difference so I just kept the SP100 on the router for now.
Here is the link for it: http://consumer.huawei.com/za/support/search/index.htm?keywords=B593
Sp54 is a customized software version for Telkom, might have added features and Telkom settings.
Sp100 is just the general version.


Regarding the aerial situation:- Same problem here.
I got the (Otto) Mimo OA-0727 Omni which has 2 aerial connectors for the 2 ports (apparently if you only connect one connector, it also just stays on internal setting) but for the life of me stays on "Internal" only.
I reloaded various firmware and same results, internal. SP053, SP054, SP100.
Signal stays the same, same rubbish download and upload, 1 to 2 signal bars.
I am now going to try another aerial and will post if this works or not, if not, I am going to buy the -601 as I am on the verge of giving up with the -91.
The answer I got from Otto is this:- Yes correct but some of these models do not have a built in DC short shunt that activates the external antenna, your model is unfortunately one of those.

Maybe someone can help me to find a cell tower? I keep connecting to Cell ID: 191 and would like to find out where this tower might be.
How can I go about it please, I do have a android phone if someone can suggest an app to try and locate it if I have to? I am in Constantia, Roodepoort.

Hope this helps

 

[Azimuth]

Oh boy. You mentioned "DC short".

 

[sajunky]

Oh boy. You mentioned "DC short".

Nope, it is from Otto. It looks like they also read all DC-short crap posted on MyBB.

 

[jeaninek]

Nope, it is from Otto. It looks like they also read all DC-short crap posted on MyBB.

Wasn't going to mention that "dc" word again....

But couldn't resist.......
http://www.lte-anbieter.info/lte-fo...antenna-coupling?p=11869&viewfull=1#post11869

and

http://onwireless.com.au/service-pr...s-huawei-b593-4g-wifi-router-antenna-kit.html

 

[jcheek]

... There was talk of an V100...SP150 release, but no-one seems to have been able to get it. (Conrads, feel free to chip in here if you have new info ...)

... The SP100 firmware is the best you will get now at the moment for the B593u-91. I got it from Huawei SA.
I have searched high and low for the V100R001C82SP150 firmware (had this on before my firmware crash)with no luck.
If I load the SP054 or the SP100, there is no real difference so I just kept the SP100 on the router for now.

Good feedback, thanks.

Here is the link for it: http://consumer.huawei.com/za/support/search/index.htm?keywords=B593
Sp54 is a customized software version for Telkom, might have added features and Telkom settings.
Sp100 is just the general version.
...
<snip>
...
Hope this helps

I remember Jaco saying that Huawei SA were planning to make the firmware and docs available on a support page. Good to see they've done it now, even though the version descriptions are a bit cryptic and it seems the device itself still doesn't have it's own dedicated page :-(

And yes - it really does help - well spotted!

 

[jcheek]

Wasn't going to mention that "dc" word again....

But couldn't resist.......
http://www.lte-anbieter.info/lte-fo...antenna-coupling?p=11869&viewfull=1#post11869

and

http://onwireless.com.au/service-pr...s-huawei-b593-4g-wifi-router-antenna-kit.html

Good find! At least you know you "u-91 guys" are (still) not alone with this issue !
Disappointing that the antenna selection difficulty is still an issue on the u-91, even 2.5 years and one or two firmware releases later.

PS: The fact that one of the sites where this dialogue/cr*p is hosted is called "dc-unlocker" just adds to the fun ...

 

[sajunky]

Wasn't going to mention that "dc" word again....

But couldn't resist.......
http://www.lte-anbieter.info/lte-fo...antenna-coupling?p=11869&viewfull=1#post11869

and

http://onwireless.com.au/service-pr...s-huawei-b593-4g-wifi-router-antenna-kit.html

No jokes, it is a good find. It makes me think that B593 has a real design fault in the input pre-amp circuit. I suspect there is extensive noise with high input resistance. Thermal noise typically gets lower with lower resistance, so problem is reduced but not eradicated, as B593 is still picky on the external source even with DC-short antennas (external antenna - as reported - is not such effective as with other devices). Huawei saved few cents on the input transformer, some guys tried to make fortune on the non-inductive resistor. Seriously I think it was rather a separating transformer. Various firmware updates could not help, as problem is in the hardware.

Huawei knew about the problem, it is why they removed manual selection of the antenna in early version of the firmware. They restored it under pressure, but kept silent allowing DC-short urban legend to spread out, so our specialists from Poynting could pick it up.

 

[Conrads]

Morning everybody

Ok, I have managed to get my hands on the V100..........SP103 firmware for the B593u-91.
I will update tonight and give some feedback tomorrow.
It does seem like that this firmware does support an antenna tab for you to choose between external and internal (fingers crossed).
Screenshot does show this....: http://translate.googleusercontent....page=2&usg=ALkJrhiSjfC7uI0M6e9eFx_cliaQ1gw4Sw
I got the firmware from an Arabian forum and loaded it into the upgrader and it does show SP103, so looks legit.

Found it here: http://translate.google.com/transla...www.adslgate.com/dsl/showthread.php?t=2018599

Will keep you posted....

 

[viveiros]

Hi there,

I am one of the (3) owners of Otto Wireless Solutions. We take a lot of pride in ensuring that the products we provide are properly tested, and we would be happy to test and address any product which has been purchased from us.

I am not sure about this need for as dc shunt in the B593 router, but I will look into it. One thing we have noticed recently is that some B593-601 routers supplied by our competitors, although they support all our bands, have recently been coming out with what appears to be a new firmware challenge. It appears that there is a limit to signal strength. When one connects a powerful external antenna, the router then automatically reverts back to using the internal antenna. We can only surmise that when high signal strength is detected, which will then translate to fast download speeds, the router has been set to use the internal, less capable antenna instead. We are not sure if anyone else has seen this, but it is definitely a challenge we have seen when customers use our antennas with B593 routers purchased from competitors. Our B593 routers do not have this limitation at all. We make sure that the routers we provide allow the user to choose internal or external antenna, and do not only support "auto" mode which appears to have some background limitations of late.

In short, the problem you describe might very well be solved by using an antenna which is not providing as high gain as the one you purchased from us, because then you are not passing that signal strength cutoff threshold.

As far as the "DC-Short" goes, I will look into this but I cannot see why an antenna would need to have a DC short. There are 2 connection points - signal and ground. If you short the signal to ground, the RF signal will be shorted straight to ground and will not function correctly, in the case of a passive antenna. The exception may come where one uses an antenna which has gain circuitry, in which case, measuring a short to ground becomes irrelevant because then all you are measuring is the input impedance of the internal amplifier.

Here is a link to an article I was asked to write for EngineerIT. Please keep in mind that our antennas are well priced because we sell high volumes, not because they are inferior performance. We have, for many years, been a corporate supplier to many major companies, who would certainly not purchase inferior products. http://www.ee.co.za/article/qa-look-gsm-hspa-lte-antenna.html

www.otto.co.za
https://www.facebook.com/pages/Otto-Wireless-Solutions/224306037655071?ref=aymt_homepage_panel

Chris Viveiros

 

[jcheek]

Hi there,

I am one of the (3) owners of Otto Wireless Solutions. We take a lot of pride in ensuring that the products we provide are properly tested, and we would be happy to test and address any product which has been purchased from us.

Hey Chris - welcome to the forum. Nice to see an agent representing themselves and their products directly here.

One thing we have noticed recently is that B593-601 routers supplied by our competitors, although they support all our bands, have recently been coming out with what appears to be a new firmware challenge. It appears that there is a limit to signal strength. When one connects a powerful external antenna, the router then automatically reverts back to using the internal antenna.

Interesting observation.
Firmware version V200R001B270D00SP00C00 - the latest version for the B593s-601, as far as this forum is aware - does not seem to exhibit that characteristic. In fact, that version of firmware allows one to explicitly override the automatic antenna detection and force the use of external antenna(s), even in the presence of external antenna signals that are inferior to those provided by the built-in patch antennas.
Can you identify which firmware version(s) on the B593s-601 exhibit this new behaviour ?

The antenna-related difficulties reported by several forum users at present are being experienced with various versions of firmware for the B593u-series devices.

As far as the "DC-Short" goes, I will look into this but I cannot see why an antenna would need to have a DC short. There are 2 connection points - signal and ground. If you short the signal to ground, the RF signal will be shorted straight to ground and will not function correctly, in the case of a passive antenna.

Your reasoning around the action of the DC short is correct for DC, but not for AC at RF frequencies.


A specific concern with the Chang-Hong dual-element patch antenna (as described in and around this post) is that it appears - if one reads the specs clinically - to contain two vertically-polarised elements in close proximity. Whilst such an arrangement can work for LTE in certain circumstances, it does not of itself provide a pair of signals that are de-correlated either through (a) different polarisation, or (b) adequate spatial separation, to provide signal diversity.
Looking at pictures and specifications for the Chang-Hong antennas offered by Otto Wireless for use with LTE, it would seem that more than one of these antennas is configured in this way.

Can you comment ?

 

[viveiros]

Hi jcheek

I know this "DC Short" is becoming a swear word here, but I have just met with the client who was having difficulties (and resolved her issue), and I did some measurements which I would like to share.

Firstly I took her Hauwei-provided blade antennas, and when I measured with a multimeter, there was no dc short. When I used a proper continuity tester which we fortunately also have available, there was a short.

The router being used had old firmware. It relied on auto-detect for the antennas, there was no way of "forcing" it to use external antennas. For any antennas which did not have the "dc short" present, the router will not detect an external antenna. When we used other antennas from stock which have this "dc short", the router detected the external antennas.

I then tested with the new B593-601, and when one sets the antenna to "auto", it too will not detect an external antenna, unless that antenna has "dc short".

Very interesting. I am going to read more about this.

As far as the firmware goes, where there appears to be a "signal strength cap", I saw this on only one occasion, last week, and it was also a customer's router, and I was stupid enough not to get the firmware version, so I cannot answer you. I must add, having learnt something new today, that I did not test for "dc short" of the antennas that client purchased, and this could very well have been a similar case to what we experienced today, as I honestly cannot recall if that client's router allowed one to select an external antenna, or if it was stuck on "auto".

As far as our client goes, we provided her with 2 extremely powerful 12dB omnidirectional LTE antennas which have just arrived and are not even being advertised yet.... One was invoiced at the same price as the original (now credited) antenna she purchased (which is about R400 cheaper than we will actually be selling this antenna), and the other was provided to her free of charge, as a token of our thanks for taking the time to allow us to thoroughly test and better understand this "DC Short" issue, and to take a close look at the firmware which was present on her router. We consider it school fees.

As far as the question regarding Chang Hong Antennas goes - I have not opened one and checked. I will do so. Personally I am not a huge fan of any MIMO antennas, and it would not surprise me if your concerns are perfectly valid not only for Chang Hong, but for all similar products from comparable suppliers. I will make a note that we test products locally before adding to our portfolio, so we never simply "go with the supplier's spec". We have been supporting Chang Hong as one of our suppliers for many years, and have always found their products extremely reliable. As far as MIMO antennas in general goes, I use the B593-601 at home, with two directional antennas which I have put out of phase of one another, and also separated with enough distance. I "fortunately" have terrible signal at my home, providing a lovely practical test environment for all our products.

Otto Wireless prides itself on exceptional standards of customer service. As GM and partner, I take pride in personally involving myself in matters like this and leading by example, in the hopes that the rest of our team follows suit.

Thanks for all the comments on this forum. It is always good to see and read what our valued customers are experiencing in the field. It helps us a lot in choosing what items we streamline into our product portfolio.

Like us on Facebook.... I sometimes do crazy things like dressing up as Father Christmas and giving stuff away to our FB community....

Chris

 

[Darook]

Hi Viveiros

I just purchased a 3G antenna (1 cable) from your premises today. I am also having the internal antenna issue. Must I patch the firmware first? Where do I get the firmware? I have an MTN B593 u-12

 

[jcheek]

I know this "DC Short" is becoming a swear word here ...

Nah, not really.
We have one participant who seems to have been on the design team for the B593 and may be exasperated by such discussion, but speaking for the rest of us, I think we are here to share our experiences with real-world equipment that we actually use, and in that way learn from one another and optimise the way our equipment is set up. So any discussion that sheds light on the antenna-detection issue is welcome, and it helps the "u-series folks" in particular.

I have just met with the client who was having difficulties (and resolved her issue)

I guess we will hear in due course how she fares!

... Firstly I took her Huawei-provided blade antennas, and when I measured with a multimeter, there was no dc short. When I used a proper continuity tester which we fortunately also have available, there was a short.

Possibly you were seeing the same "anti-parallel diode symptom" described earlier in the thread ?
Edit: Subsequently I re-tested with other meters and I'm now 95% sure that what's inside the flat whips included with the B593s-601 is just a plain 1.2kΩ resistor. So, no diodes, I don't think.

The router being used had old firmware. It relied on auto-detect for the antennas, there was no way of "forcing" it to use external antennas. For any antennas which did not have the "dc short" present, the router will not detect an external antenna. When we used other antennas from stock which have this "dc short", the router detected the external antennas.

I then tested with the new B593-601, and when one sets the antenna to "auto", it too will not detect an external antenna, unless that antenna has "dc short".

I think this is case of "where there's smoke, there's fire". Personally, I am prepared to accept that DC resistance could form part of Huawei's antenna detection methods, but I think there's more to it than that. Specifically, I believe that actual, measured signal strength/quality also plays a role - possibly the major role - in how the B593 makes its antenna-selection decision. If that is true it would make the kind of "benchtop" test you describe a bit more difficult to control.

As far as our client goes, we provided her with 2 extremely powerful 12dB omnidirectional LTE antennas ...

12dBi, wow. That's an almost incredible spec for a multi-band omni, unless it's active. We look forward to seeing technical details in due course.
In her case, having two separate omni LTE antennas (with the same polarisation) where you can vary the separation, should work fine. That is unlike the Chang-Hong patch antenna where the two antenna elements have the same polarisation (apparently), but the separation is fixed.

As far as the question regarding Chang Hong Antennas goes - I have not opened one and checked.

Great. Might also be good to get comment from the manufacturer on specific compatibility with SA LTE operators. The "question mark" applies to both this antenna and this one.

Personally I am not a huge fan of any MIMO antennas ...

Interesting - why ??

... and it would not surprise me if your concerns are perfectly valid .... for all similar products from comparable suppliers

Not so, I'm afraid. The comparable "one piece" LTE products are generally configured to achieve signal diversity through having two orthogonally-polarised elements.

 

[jeaninek]

Just thought i would quickly pop in...

Had a nice visit with Chris today... came home with 2 new omni antennas...

Haven't been able to test properly yet, since I'm NOT climbing on the roof till the weekend! But just by sticking them out the door, my speedtest went from our avg 23Mbps to 38Mbps

Will give more feedback once I've done proper tests.

 

[Azimuth]

Some great updates in this thread. Thanks for all the feedback to our newcomers.

And to Chris, welcome to the forums. It's a nice change to have a product representative on board.

 

[jcheek]

What is this antenna ?

Tonight I was looking over some old posts in Azimuth's Antenna Installation and Alignment thread, where a Chang-Hong dual patch antenna first made an appearance.

Specifically in this post, where suel09 was having similar problems with a B593s-82, the following picture appears :

Now the antenna in this particular photo only goes up to 2170MHz (a 3G band), but if the dual patch antenna that jeaninek has been trying to use is labelled in a similar way, then the problem may have been staring us in the face all along.

Without having the antenna in front of me, it's hard to say for sure, but ... it may be that this is in fact not a dual-element wideband antenna; rather, it is two separate antennas (covering different frequency bands) packaged in the same housing. If that's the case, then the problem is pretty obvious ...

Food for thought ... ?

 

[Azimuth]

That would be quite the revelation. Keen to hear from current product owners. Like you said, staring us in the face (back then) but I too never noticed the antenna cable labels.