On 13 Aug 2004 07:43:23 -0700,
(E-Mail Removed) (Rick)
wrote:
>I'm currently receiving internet access via wireless. I'm in a rural
>area and the distance between my home and the tower is right at 19
>miles. I'm not sure what they have at the tower but my setup is a
>Hyperlink Antenna 24db 8 degree beam width connected through a Wincomm
>1 watt amp to a Linksys Wireless-B Ethernet Bridge.
Wincomm resells several models of 1 watt amplfifiers. Some have AGC
(automatic gain control) while others do not. The fixed gain variety
comes in various amplifier gains to compensate for corresponding
amounts of coax cable loss. Any idea which Wincomm amplifier?
Also, your Linksys Wireless-B ethernet Bridge has a model number and
hardware revision level. What is it? That will determine how much
power you have to start with.
>And yes I did say
>19 miles.
Impressive.
>My coax run from the antenna to my cabinet is about 70 feet.
What type of coax? My guess is that it would be LMR-400 or LMR-600.
That's quite a long coax cable run.
>I recently moved the ampifer inside instead of at the antenna. I
>didn't see any noticable difference.
That could mean that your ISP is throttling your bandwidth or that you
have some kind of interference problem that causing lost packets. I
would suggest that both are equally probable. Do you have any way to
obtain packet loss statistics?
>There are times when my
>transmission rate is, compared to a modem, great. Typically between
>18-26 kbytes/sec to download. When things are good my times for pings
>run 200ms to 600ms.
Ok, you have 256Kbit service. The long latency is a problem. It
could be due to delayed ACK's in your ISP's bandwidth management
system, packet loss, or interference. Dunno.
>The problem is that I need to upload data frequently. The transmission
>rate is typically below modem speed. I get around 1.2 to 2 kbytes/sec.
That's about 16Kbits/sec. 56K modems will do 33.6 on upload. Not
good. What service level is your unspecified ISP selling? (What are
you paying for?)
>I have a second ampifier (100mw) and was wondering if I can hook it in
>the line in reverse?
I wouldn't. Hopefully, the WISP installed an amplifier that is
matched to the 70ft coax cable length and your Linksys. If you
over-drive the amplifier, and it does NOT have AGC, you will probably
belch garbage instead of a clean signal.
My guess(tm) is you have one of these:
http://www.hyperlinktech.com/web/amplifiers_2400.php
http://www.hyperlinktech.com/web/ha2401g.php
They have AGC and can handle 100mw on the input. So, your 2nd amp is
not going to overload the 1watt amp, even with no coax in the line.
Well, if that's your amplifier, it's safe to try. If not, kindly
disclose the exact model number. (Yeah, I know you don't wanna climb
the tower. Use a telescope.) No clue if it will help.
>I hate to blow my 1watt amp by doing this so I
>though I would get some advise. The Linksys puts out about 15dbm
>(approx. 32mw).
Well, in order to calculate this mess, I would need to know quite a
few numbers, including the EIRP and sensitivity of your WISP's system.
If you will supply the models, numbers, and details, I can calculate
the fade margin and reliability of your link. Or, you could do it
thyself:
http://www.ydi.com/calculation/som.php
You want to have at least a 10dB fade margin.
At this point, we don't know exactly where the weak link is in your
system. It could easily be your receiver picking up 2.4Ghz junk
(interference). It could also be a timing issue:
http://peertech.org/LongShotWiFiTiming
or your WISP's tower is picking up junk. Methinks you should work
with them on a solution.
Incidentally, how tall is your tower (and your ISP's tower)? If your
WISP is on a tall mountain, this is not an issue, but if his tower is
on the ground, you need about 115ft high towers on both ends to go 20
miles without hitting the ground. (The earth is not flat). Perhaps
you also have a line of sight problem?
--
Jeff Liebermann
(E-Mail Removed)
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 AE6KS 831-336-2558
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