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Equis
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what is reasonable to expect? (Speed)

Wed Jun 18, 2008 4:10 pm

Hi Guys

With a 5 mile link -60 at each end running an rb333, what speed would you expect to get?

would 20Mbps be about right?
 
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Re: what is reasonable to expect? (Speed)

Wed Jun 18, 2008 6:22 pm

I've got a 6.6 mile shot, 5GHz, 10MHz channel, I get about 10Mbps. Signal is -68 to -75.

Using standard channel bandwidth, yea, you can get 20Mbps.
 
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Re: what is reasonable to expect? (Speed)

Wed Jun 18, 2008 8:01 pm

I've got a 6.6 mile shot, 5GHz, 10MHz channel, I get about 10Mbps. Signal is -68 to -75.

Using standard channel bandwidth, yea, you can get 20Mbps.
Does anybody know why the 10mhz and 20mhz spectrum gives less bandwidth? Where standard 802.11a with standard channels gives a faster connection? Just curious. -Jordan
~Agricultural WISP "ZONE"~ Beware of oncoming cattle and dont hit the farmer!!! I need to ask him about using his silo for an AP first"~

*Automated Billing Installer* http://wiki.mikrotik.com/wiki/AutomatedBilling Built by Krige ;-)
 
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tgrand
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Re: what is reasonable to expect? (Speed)

Thu Jun 19, 2008 4:50 pm

A hose that pushes 2 Gallons Per minute delivers twice as much as a hose that can push 1 Gallon per minute.

20MHz is used to produce a air rate of 54 Meg Bits per second.. (Frequency versus data rate)
It just normal that if you reduce the amount of bandwidth available to the carrier, that the data rate would also drop in half (or more).

The advantage to 10MHz versus 20MHz is that with half the width the total power although the same is higher.
If a 1 Gallon Pail is 1 Foot tall, but you need the water level to go to 2 feet using the same 1 Gallon of water, then you would use a pail which was half the diameter.
 
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Equis
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Re: what is reasonable to expect? (Speed)

Fri Jun 20, 2008 1:07 am

Does that mean to be legal we have to drop the power with 5 & 5mhz channels?

Does Mikrotik power setting allow for this (so when set t 10 or so will only push 10) or we need to set to 5?
 
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tgrand
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Re: what is reasonable to expect? (Speed)

Mon Jun 23, 2008 6:08 am

No the power is the power, regardless of how much bandwidth you use.
If you only use 20kHz (ie Audio) then you can go extremely far in comparison to data.
 
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Equis
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Re: what is reasonable to expect? (Speed)

Mon Jun 23, 2008 6:30 am

OK, Thank for the reply.

I am not so smart in this area, do you knwo why 5mhz seems to give a better signal than 10mhz etc?

eg
a sample could be
20mhz -70
10mhz - 67
5mhz -64

Thanks :-)
 
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jordantrx
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Re: what is reasonable to expect? (Speed)

Mon Jun 23, 2008 4:06 pm

OK, Thank for the reply.

I am not so smart in this area, do you knwo why 5mhz seems to give a better signal than 10mhz etc?

eg
a sample could be
20mhz -70
10mhz - 67
5mhz -64

Thanks :-)
I get the same results as you equis. However I do notice even with the good signal Bandwidth is degraded compared to the regular frequency. -Jordan
~Agricultural WISP "ZONE"~ Beware of oncoming cattle and dont hit the farmer!!! I need to ask him about using his silo for an AP first"~

*Automated Billing Installer* http://wiki.mikrotik.com/wiki/AutomatedBilling Built by Krige ;-)
 
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tgrand
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Re: what is reasonable to expect? (Speed)

Tue Jun 24, 2008 9:56 am

If you draw a sine wave or a half oval, the power is the AREA within the sine or half oval.
If you narrow out the sine or oval to maintain the same AREA you gain Peak power or relative power, but the actual power remains the same.
 
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Re: what is reasonable to expect? (Speed)

Tue Jun 24, 2008 7:19 pm

In simple terms, if you take the same amount of power and put it in half the space, the density increases. Every time you cut the channel size in half, you double the power density. When you use turbo (40MHz) you get half the power density, and lose about 3dB, but double the total available bandwidth, if the signal is reliable.
 
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Re: what is reasonable to expect? (Speed)

Wed Jun 25, 2008 2:36 pm

Good way to put it Oldman.

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