Finding the best external antenna direction - Advice Please

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rolexboy

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Please forgive me if these questions sound some what dumb :o , Ive recently bought a USB 3G modem , and have it connected to my external roof antenna , with the antenna disconnected there is One bar shown on the onscreen signal meter , with the external antenna connected the bars move up to Two . I am trying to align the roof external antenna to the best physical direction to receive the best signal, I have downloaded and installed a copy of MDMA , and with the help of members here I finally got it working, there are Two things I'm not too sure on,


1. Now ive got MDMA working , if I physically turn my external roof antenna , what am I looking for in MDMA that will tell me when the antenna is actually pointing in the best direction to receive the best signal.


2. Am I right in thinking that the more signal bars shown on the signal meter , directly relates to receiving the over all best signal .


Thanks
 
rolexboy said:
Please forgive me if these questions sound some what dumb :o , Ive recently bought a USB 3G modem , and have it connected to my external roof antenna , with the antenna disconnected there is One bar shown on the onscreen signal meter , with the external antenna connected the bars move up to Two . I am trying to align the roof external antenna to the best physical direction to receive the best signal, I have downloaded and installed a copy of MDMA , and with the help of members here I finally got it working, there are Two things I'm not too sure on,


1. Now ive got MDMA working , if I physically turn my external roof antenna , what am I looking for in MDMA that will tell me when the antenna is actually pointing in the best direction to receive the best signal.


2. Am I right in thinking that the more signal bars shown on the signal meter , directly relates to receiving the over all best signal .


Thanks
Click to expand...

MDMA is bad for you (j/j).:)

What antenna are you using? A directional or omni antenna?

With any wireless signal you want to improve the SNR.

The noise level should be in the range of -100 and your signal to the tower would be any figure less than -100.

The further away these two figures are the better.

Example.
Noise floor: -100

Tx/Rx: -72

SNR: 28
 
1. RSSI - the less negative that is, the better the signal. A good signal will start at about -86 dBm

2. Yes (I think the signal bar is just a graphical depiction of the RSSI)
 
In general, turn the antenna 10 to 20 degrees, wait 20 seconds, observe RSSI. Repeat. The SNR is important but you'd generally do ok by just minimizing the absolute value of RSSI.

Some pitfalls to the above:
If your area serves both UMTS 900 and UMTS 2100, you may find the signal suddenly jump up or down by easily 10 dB or more as the modem switches bands, and possibly towers. So best to make a note of the tower ID's as you are turning the antenna.

You could actually use the band config in MDMA and enable only one of UMTS 900 and UMTS 2100 bands at a time and turn the antenna through 360 degrees.

The whole exercise would be futile if the modem doesn't report the signal of the external antenna, like the E1820 and K4505 and some others, unless you use an inductive coupler.
 
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Read @ajax, read... You can't use your K4505 with pigtail connector. You can use inductive coupler with this modem for this job, or - better - chose different modem.
 
KeezA said:
MDMA is bad for you (j/j).:)

What antenna are you using? A directional or omni antenna?

With any wireless signal you want to improve the SNR.

The noise level should be in the range of -100 and your signal to the tower would be any figure less than -100.

The further away these two figures are the better.

Example.
Noise floor: -100

Tx/Rx: -72

SNR: 28
Click to expand...


Hi and thanks for the advice , its just what I'm looking for :)
 
ajax said:
In general, turn the antenna 10 to 20 degrees, wait 20 seconds, observe RSSI. Repeat. The SNR is important but you'd generally do ok by just minimizing the absolute value of RSSI.

Some pitfalls to the above:
If your area serves both UMTS 900 and UMTS 2100, you may find the signal suddenly jump up or down by easily 10 dB or more as the modem switches bands, and possibly towers. So best to make a note of the tower ID's as you are turning the antenna.

You could actually use the band config in MDMA and enable only one of UMTS 900 and UMTS 2100 bands at a time and turn the antenna through 360 degrees.

The whole exercise would be futile if the modem doesn't report the signal of the external antenna, like the E1820 and K4505 and some others, unless you use an inductive coupler.
Click to expand...



Thanks again for your time and advice, the thing I can't get my head around is this ..


with out my external Yagi antenna connected to the USB modem the signal bars only show 1 , but when I plug in the external antenna the signal jumps up to 2 bars , and the download speeds increase a lot , so could the modem actually be reporting the signal of the plugged in antenna ? , if its not reporting then why does the signal bars increase and the download speeds improve ?



Thanks
 
rolexboy said:
with out my external Yagi antenna connected to the USB modem the signal bars only show 1 , but when I plug in the external antenna the signal jumps up to 2 bars , and the download speeds increase a lot , so could the modem actually be reporting the signal of the plugged in antenna ? , if its not reporting then why does the signal bars increase and the download speeds improve ?

Thanks
Click to expand...
There is long thread in this matter:
http://mybroadband.co.za/vb/showthread.php/276198
As per @ajax, K4505 is a version of the same modem, sorry I didn't pickup this from the start. Any more doubts, post it in above thread.
 
I gave up on this climbing up and down the ladder to move the aerial about a little. Thanks to a post by a friendly member who lives about 200 metres from me, he sent me a map and the locations of the towers. Using Google Maps distance calculator, I was able to measure the angle relative to my house with a protractor. After aligning the aerial thus, the download jumped from 0.4mb to 2.8.

The aerial is connected to the E1820 modem with an inductive coupler. I also tried a pigtail which plugs into the socket, but the inductive coupler, when positioned right at the end of the modem works the best.

Most cell operators are very reticent to divulge the location of their towers. Of course some are obvious, like the one near the Total Service Station in Main Road, Diep River (CellC) and on top of the Bergvliet telephone exchange (8ta) but some are hidden away, on the corners of blocks of flats (Main Road, Plumstead/Wynberg), at the Home Affairs offices in Wynberg, on top of the Sheraton Building, corner DeWaal Road and Princess Vlei Road.

But you are in Thailand... Tricky to advise there, since I only visited as a tourist
 
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... and it seems to be IMPOSSIBLE to get the 8ta tower info...:cry:
 
Bundu said:
... and it seems to be IMPOSSIBLE to get the 8ta tower info...:cry:
Click to expand...

In Cape Town, most of them are on top of telephone exchanges. You can figure this out from the coverage map. For instance, the coverage area from the Bergvliet telephone exchange is more or less a circle around this spot. The same with the Claremont exchange. It seems that the newer exchanges have the 8ta transmitters on top. Check out your area from the coverage map. If you have lived in the area for some time, you should know where the telephone exchanges are located. They are usually large buildings without any windows (Bergvliet) or behind the Post Office (Claremont). The one in Wynberg was built before WWII and is 90% empty space now. When I was at school in the 60's I went there one day and saw these diallers chattering away from subscribers turning the dials on their steam phones. Thank god that era is over. A friend who retired from Telkom in 1980 was a dial cleaner (maintenance engineer), he had to take these gadgets apart, renew any worn components and re-assemble it, all without turning off the power.
 
Hey Guys! Need some help please?


edit - thanks sorted
 
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