Low signal: will an antena help?

[DavidS]

I'm considering subscribing to MyWireless. Signal tests at my house, however, show that whereas the signal is strong outside, it is very low inside the house. Sentech suggest I try it out, using the 7-day approval period. I'm loathe to go to all that effort and expense if it's not going to work. Someone suggested an antenna. Do any members have any advice?

Thanks

DavidS

I live in Cape Town above the Main Rd in Kenilworth

 

[daysleeper]

Save your money!

If you are even in doubt, then don't. Reason being, firstly with the most fancy and expense external cable, there is still a loss along the cable which would not show when you did the test.

Another problem with wireless is signal fluctuation. So if you signal is strong and it fluctuates as it naturally does, due to environmental conditions, then the service is still usable.

If the signal is borderline to start with, the fluctuations will cause connectivity problems.

Setting up an arial "just to test" is a waste of money, unless you can lend one or take it as the expense of education.

 

[ProAsm]

What is the distance to the Tower you are receiving from ?
What is the signal strength and SNL outside compared to inside ?

 

[Peterkb]

Talking of signal strength - What is the strongest signal theoretically possible?

I'm getting a delta of between 12 and 14 from Brixton (116). Seems good to me but maybe I can improve it by moving the modem.

Can someone recommend software that will give me an accurate indication of my true download speed.

Thanks

Peter

 

[bdt]

Talking of signal strength -

1. What is the strongest signal theoretically possible?
2. I'm getting a delta of between 12 and 14 from Brixton (116). Seems good to me but maybe I can improve it by moving the modem.
3. Can someone recommend software that will give me an accurate indication of my true download speed.

Thanks
Peter

G'day, to answer you:

1. I've heard that the "signal strength", as seen in the ProAsm MySignal app, max is in the mid 50's or so, but I've yet to see it; the highest I seem to have on record is 44%, at -61dBm. But (IMO) a more meaningful strength indicator to watch for is the RSCP number, in -xx dBm, that's not some arbitrary, non referenceable number like a signal percentage (no fault of ProAsm here, it's how Sentech have set it up).
2. Heh, you can *definitely* do better: I've got a site that feeds of Brixton- from Northcliff, which is around 5km away. He sits at mid 40's%/early -60's dBm signal strength. FTR, the screenshot I have here shows 44%/-62dBm (note that the higher, as in closer to 100 the number is, the weaker. Also -64dBm is HALF the strength of -61dBm). If moving the modem is a viable option for you: sure, go for it. But if that turns out to be a hassle, instead of moving the modem, your other option is to bring more signal strength to the modem- enter the HGA (high gain antenna).
3. I use NetLimiter- see www.netlimiter.com. I've found it to be *excellent* for the task of just watching, 'cos it shows what each and every app that's using bandwidth wants, not just an overall usage that leaves you with no way of knowing who's using what.

HTH
-bdt

 

[bdt]

DavidS: an HGA is almost guaranteed to help. For a start; seeing as your signal *is* strong outside, it suggests that you're in range- with a good signal right off the bat . That it falls inside says that your building is killing the signal- maybe you've got a metal roof?

The other benefit to you is that, seeing as you're starting from a strong signal, your HGA requirement would be low- and cheap with it. IOW, you are probably going to be able to get away with a 12dBi Yagi or flat panel on a few metres of thin (and easy to use and cheap(er)) cable.


daysleeper: you appear to be nurturing some rather off-base misconceptions, to clarify:

- *all* co-axial cables have losses. We know this going in and factor it into our calculations. In the context of MyWi, I've typically used LMR195 @ 0.6dB/m loss or LMR400 at 0.2dB/m loss -but that's just a starting point: typically I won't use LMR195 beyond 4m, but have done so out to TEN metres- 'cos I had so much signal strengh coming in I could *write off* the loss as not being a problem. On the other hand, I've used LMR400 on short runs 'cos of such a weak signal off the antenna. And THEN I've just done a job where someone used RG11- *SO* not specified for this work, that I "knew" of, but when I'd finished moving his HGA to his new flat, I left the job with 38%/-67dBm signal -and that off the base station I usually detest, 'cos I usually have to fight to get anything useful off it!

- if your signal is fluctuating above the 100% signal *quality*, i.e. above 21%/71% ber- it simply doesn't matter- you've always GOT your 100% signal quality anyway. But more than that, a properly done HGA job results in minimal fluctuation anyway, regardless of environmental conditions short of a major (rain) storm, rendering the point moot.

- true, this one you actually got right: it's the opposite end of my point above. If you're fluctuating at or around the cut-off level, you should expect to lose connection!

- heh, I'd love to see an "arial" (sic) on a roof- what letter of that font do you propose would to the best job? But to put up an aerial/antenna might well be a (financial) gamble ..if things were borderline, which it seems isn't the case here. This is where using (and yes, paying for) someone who does this for a living makes sense- unless you DO happen to be lucky enough to know someone to _borrow_ from.

..thus endeth the lesson
-bdt

 

[DavidS]

Signal strength

Thanks to bdt for that very helpful message. You write "this is where using (and yes, paying for) someone who does this for a living makes sense". Does any one have any suggestions about a reliable and not too expensive perosn in Cape Town?

DavidS

 

[bdt]

Thanks to bdt for that very helpful message. You write "this is where using (and yes, paying for) someone who does this for a living makes sense". Does any one have any suggestions about a reliable and not too expensive perosn in Cape Town?

DavidS

Glad *some* use came of my input! ..as to your request, I don't know anyone personally down that way, but I can put in a call for you up the foodchain (you may gather I'm an HGA installer) and get a recommendation from above: that's about all I can volunteer from my side.

-bdt

 

[Peterkb]

Signal Strength

FTR, the screenshot I have here shows 44%/-62dBm (note that the higher, as in closer to 100 the number is, the weaker. Also -64dBm is HALF the strength of -61dBm).
3. I use NetLimiter- see www.netlimiter.com. I've found it to be *excellent* for the task of just watching, 'cos it shows what each and every app that's using bandwidth wants, not just an overall usage that leaves you with no way of knowing who's using what.

HTH
-bdt

How does one convert -xxdBm to a percentage? Is there a formula? I'm getting anything from -90dBm to - 68dBm from Brixton. Seems to vary considerable day to day. I'm in direct line of sight - I can see the top of the tower from my window! From another window I can also see Northcliff, perhaps I should try that.

I tried NetLimiter - seems like a great program with good info but it freezes on my Win XP machine after a few minutes. No error messages just stops responding.

 

[bdt]

How does one convert -xxdBm to a percentage? Is there a formula? I'm getting anything from -90dBm to - 68dBm from Brixton. Seems to vary considerable day to day. I'm in direct line of sight - I can see the top of the tower from my window! From another window I can also see Northcliff, perhaps I should try that.

I tried NetLimiter - seems like a great program with good info but it freezes on my Win XP machine after a few minutes. No error messages just stops responding.

As far as -x dBm to MyWi signal % goes, I'd suggest you ask ProAsm- he wrote it, I figure he'll be able to answer that a whole lot better than me!

So you can see the tower eh? Could you be more specific about that? IOW, are you in Brixton where you can see it, or in another suburb (like Northcliff) where you can also see it, but is a very different thing! Then, that kind of dBm range is *huge*: that's a 22dBm range, round about a five fold difference in signal strength. My gutfeel (entirely subjective, and quite open to being shot down ) is that if you're in a place where you get -68dBm, that you're going all the way down to -90dBm suggests something is sorely wrong. But my experience HAS shown that the tower with the clearer line, pretty much independent of range, is the one the modem will prefer- at least at 1st.

On NetLimiter: you try the 1.3 version, or the new 2.x beta series? I've seen it on a few machines, of *wildly* varying specs, and not had a problem..

-bdt

 

[Peterkb]

bdt

I'm in Emmarentia close to Barry Hertzog and have a south facing window that has a view of the Brixton tower although there are a few thin (1cm thick) tree branches a metre or so from the window. My west facing window can see Aasvoelskop (Northcliff) but I'm not sure where or which way Sentech's transmitter faces. I would need to lengthen some cable to use Northcliff so haven't tried for the best signal from there yet.

When I'm not connected the bar graphs both show maximum. I have added a patch antenna so will see if the signal stays a bit more stable now.

I tried NetLimiter 1.3 but I'll download a newer version and see if that works.

Thanks
Peter

 

[ProAsm]

As far as -x dBm to MyWi signal % goes, I'd suggest you ask ProAsm- he wrote it, I figure he'll be able to answer that a whole lot better than me!

LOL, this is a nobrainer here
The modem sends me all the information I need including the signal strength which it gets from the NodeB.
If you put MySignal into command mode:
Go offline, and un-check "Hide Commands" in the config menu, you will now see a area at the bottom of the Network Tab where you can type in commands directly to the Modem, or just click the pulldown list and they are all there for you.
Select the AT+CSQ and click on Send.
You will see the a display similar to the following:

+CSQ: 16,99,-90,-99,4

Where 16 is the % signal.
Cannot remember the 99 anymore, but the -90 is the RSCP in dBm, the -99 is the ISCP in dBm and the 4 is the BER (Bit Error Rate) which goes from 1 to 7 and this MySignal displays as a percentage as I used to get a zillion emails when it displayed 1 - 7 about what, why, where etc

Oh, btw, the best ever recorded signal strength was from a staff member in Radiokop of 74% directly off the modem.
The second best was a customer in Pretoria with 64% and I get 54% at my home in Durban with a 21dB gain panel antenna.
However at 54% my SNL is only 13 so I angled it for the best SNL of 17 and then my signal dropped to 46% where it is now.

Oh, btw2, my antenna system is nothing fancy.
I use 14 meters of plain good ol RG214 cable which is flexible and the N type connectors are 1/10 the price of those for LMR whatever and my pigtail is a homebrew job made from an old minature NCX as seen on my site.
My total loss from the antenna to the modem measure on a HP spectrum analyzer is only 2 dB.
The antenna is an old 2.4 gig Vodacom backhaul job.
The whole lot cost me less than 100 bucks.

 

[Peterkb]

LOL, this is a nobrainer here
Oh, btw, the best ever recorded signal strength was from a staff member in Radiokop of 74% directly off the modem.
The second best was a customer in Pretoria with 64% and I get 54% at my home in Durban with a 21dB gain panel antenna.
However at 54% my SNL is only 13 so I angled it for the best SNL of 17 and then my signal dropped to 46% where it is now.
QUOTE]

Is the SNL the (or related to) "Delta" figure shown by the software supplied with the new (no external antenna) modems? If so then I'm at 15 on most days.

 

[ProAsm]

The only time I saw one of the new modems was when I went to the IPWireless course and to be honest i dont remember.
I will however try and get hold of one.