Warning

 

Close

Confirm Action

Are you sure you wish to do this?

Confirm Cancel
Member Login
Site Notices
11/22/2017 10:05:29 PM
Posted: 8/27/2004 9:38:08 PM EST
update (via the computer) is slow?

Basically, how is it that one radio wave (800 megahertz) is so slow to carry info (like 30K baud), but the W-LAN (unknown freq) is screaming?
Link Posted: 8/27/2004 9:39:56 PM EST

Originally Posted By AZ-K9:
update (via the computer) is slow?

Basically, how is it that one radio wave (800 megahertz) is so slow to carry info (like 30K baud), but the W-LAN (unknown freq) is screaming?


Isnt 802.11 shorter?
Not sure about radio waves dont know jolly shit about them
Link Posted: 8/27/2004 9:51:10 PM EST
800 megahertz= noisey band (cellphones,some car alarm remotes,cordless phones)

W-lan=not as much noise
Link Posted: 8/27/2004 9:52:28 PM EST
higher frequencies can carry higher bandwidth

a wireless lan operates at 2.4GHz which is three times the frequency of your dispatch at 800MHz (.8 GHz)
Link Posted: 8/27/2004 9:54:17 PM EST
I don't understand. How does one radio wave carry more information than another?

Link Posted: 8/27/2004 9:56:50 PM EST
Link Posted: 8/27/2004 9:57:21 PM EST

Originally Posted By Samstead:
higher frequencies can carry higher bandwidth

a wireless lan operates at 2.4GHz which is three times the frequency of your dispatch at 800MHz (.8 GHz)



+1
802.11b and g opperate at 2.4ghz
Link Posted: 8/27/2004 9:57:51 PM EST
Simple, the protocol and bandwidth for your car computer is likely much different than the standard used for wireless internet.
Link Posted: 8/27/2004 10:03:45 PM EST
The 800 MHZ system will successfully send data when you are running 120 mph, the WiFi system pretty much needs you parked to work well. The 800 MHz system also will have much longer range (tower to car) in the area of 15-20 miles or more depending on the system, where the WiFi system has a range of a few hundred feet.

Different technologies for different purposes.
Link Posted: 8/27/2004 10:11:46 PM EST

Originally Posted By AZ-K9:
I don't understand. How does one radio wave carry more information than another?



The speed of the internet connection is proportional to how much of the radio spectrum it takes up. A high-speed connection will occupy a wider slice of the spectrum than a lower-speed connection - this is an inescapable fact of physics. For example, a low-speed connection might require only a 10 MHz slice of the spectrum (e.g., 800 to 810 MHz), while a high-speed connection might require 5 times that amount (e.g., 800 to 850 MHz).

Every slice of the radio spectrum that the FCC assigns for wireless data communication is only so wide, and can only accommodate so many connections at the same time. However, the slices that the FCC assigns on the higher frequencies tend to be wider than on the lower ones, and thus can accommodate either faster connections, or a greater number of low-speed connections.
Link Posted: 8/28/2004 6:11:41 AM EST
[Last Edit: 8/28/2004 6:13:03 AM EST by Garand_Shooter]

Originally Posted By Skibane:

Originally Posted By AZ-K9:
I don't understand. How does one radio wave carry more information than another?



The speed of the internet connection is proportional to how much of the radio spectrum it takes up. A high-speed connection will occupy a wider slice of the spectrum than a lower-speed connection - this is an inescapable fact of physics. For example, a low-speed connection might require only a 10 MHz slice of the spectrum (e.g., 800 to 810 MHz), while a high-speed connection might require 5 times that amount (e.g., 800 to 850 MHz).

Every slice of the radio spectrum that the FCC assigns for wireless data communication is only so wide, and can only accommodate so many connections at the same time. However, the slices that the FCC assigns on the higher frequencies tend to be wider than on the lower ones, and thus can accommodate either faster connections, or a greater number of low-speed connections.



Exactly. You MTD setup is using the exact same bandwidth that you dispatch radio uses for voice, IE one narrow voice channel at 12.5 KHZ. I havent messed with 802.11b but i imgaine its using 10mhz or better of the 2.4ghz freqs assigned it..

Imagine the data is water, your MDT gets it through a straw, 802.11b through a 1 1/2 fire hose, 802.11g through a 2 1/2 inch hose.

Then remember that every car in your fleet is sharing that one straw.
Link Posted: 8/28/2004 6:35:59 AM EST
[Last Edit: 8/28/2004 6:37:03 AM EST by Paul]
Link Posted: 8/28/2004 6:45:12 AM EST
[Last Edit: 8/28/2004 6:46:47 AM EST by Garand_Shooter]
Paul, most MDTS and computers in publicb safety vehicles are even more handicapped than that when it comes to bandwidth... they essentially use one single voice "channel" on the agencies radio system to put the data through. Even if they are using different areas of spectrum they are still pretty much limited to that narrow 12.5 khz channel.

Not unlike how us hams use packet. Not exactly the same, but very similar.
Link Posted: 8/28/2004 7:09:58 AM EST
Top Top