Wireless: More Ch 4

Jerry's been yakkin quite a bit.  Showed us some different types of antennas in class.

Reviewed pictures/graphs showing filters and what is blocked. 

Wavelength (meters)( λ) = 300/F MHz - remember this, it'll be on the test and used.  

Extra Credit ops-              Ham Fest in Severville 9/29 50points

                                        LOPSA meeting 10/2 30points

Digressions links, unsure where they fit in, but looks important.
Dipole Antennas

Cell Phone Booster

Notes from class (such as it is) after the break.

Wireless: Ch 4 cont.

Short one today, as we had a test and Jerry talked quite a bit on unrelated stuff.  Also, sorry about the format, the keyboard I had was sticky and I could not type well, I had to copy/paste from the powerpoint slides. 

Antenna Characteristics

Types, sizes and shapes

Passive antennas

–The most common type

–Constructed of a piece of metal, wire, or similar conductive material

–Does not amplify the signal in any way

–Directional gain

•Passive antennas radiate the RF energy supplied by the transmitter in one direction

•Exhibits an effective gain that is similar to amplification of the signal

Wireless: Start of Ch 4

Supplemental notes for the review of Ch 3. 

High pass aka low cut

Low pass aka high cut

The spike or raised area on any graph shows the BLOCKED frequencies.

Chapter 4 start

Gain and Loss

Understanding RF signal transmission involves the strength or power with which the transmitter is sending out the signal, the amount of reduction in signal strength caused by cables, connectors, and other components, the transmission medium and the minimum strength of the signal required by the receiver to be able to properl recover the data sent by the transmitter. 

An amplifier boosts the power of a signal, called a gain.  Cables and connectors offer a resistance to the flow of electricity and tend to decrease the power of a signal (loss).  Signal power changes logarithmically and gains and loss are relative concepts.  You need to know the power level of the signal at two different points. 

Wireless Ch 3 cont

Signal Strength cont.

 

Directional Antenna is used to minimize multipath distortion and radiates electromagnetic waves in one direction only.

There are other methods to reduce multipath distortion; using an amplifier in front of receiver to increase SNR and transmitting the same signal on separate frequencies.

Wireless: Chapter 3, Radio Communications

Filters removes unwanted F signals.  RF filter either passes or rejects a signal based on frequency.  There are three basic types of filters; low-pass, high-pass and bandpass filters.  Low pass blocks the high, lets the low through, high blocks low and keeps high.  The bandpass sets a range called a passband, which has a min and max threshold.  

R/S: Cisco Router IOS Start

9/17 notes- Cisco Routing

Cisco Router IOS

How do I access my router?

Physical – hooking up a wire and logging into the device

Remote- using SSH or TelNet to log in remotely

How do I configure my router?

Console Port

            Designated by a light blue color and label

            Console cable has one RJ45 port and one Serial port.  The RJ45 goes into the router, serial into the computer. 

Via modem using an aux port – only found on older routers

Virtual terminal

Tftp server

Playing Catchup

I'll get everything that I have missed posted in the next few days.  Life kinda crashed into me all at once, so little time has been had to sit and organize notes to make them play well with the blog.

R/S: Troubleshooting

Don’t do things in random order, but a set of steps.

First step is to define the problem.  Try to isolate the problem. 

Four step troubleshooting:

1 Ping loopback address- trying to isolate the problem Ping 127.0.0.1 When you ping the loopback, you are checking if the TCP/IP software is on the computer, available and working correctly.  There is always a file on the computer that has the loopback address, and if that folder is deleted, the network connections will not work correctly.

2 ping ip address of the local system (192.168.40.10)  When pinging the local system, you are checking if the NIC is working or not.  If these two steps are successful, you know that the user’s machine is ok. 

3 Ping the default gateway ex: ping 192.168.40.1.  A default gateway is the router, which is your translator between the inside network and your outside network. 

4 ping a system outside your local network- google, yahoo, ect.  At this point, we know that the local system is ok, now we are looking to the outside network for the issue.

***These are the specific order that has to be done on the tests and the CCENT test***

More After the Break

Wireless: End of Chapter 2

Went over audio stuff, sample size and rate.  Not sure what this has to do with chapter 2….

Digital Modulation Cont.

-Binary signals are digital data transmissions are typically sent in bursts of bits.  There are three types of binary signaling techniques that can be used:

Return-to-zero (RZ) calls for the signal to rise to represent 1 bit.  It must return to zero in its allotted time.

Non-return-to-zero (NRZ) the voltage signal remains positive, or high, for the entire length of the bit period.

Polar non-return-to-zero (polar NRZ) raises the signal to represent a 1 bit, but drops to a negative amount to represent a 0 bit.  Works well with light by using different colors.

A variation on a non-return-to-zero-level is a non-return-to-zero, invert-on-ones (NRZ-I).  A change in voltage level represents a 1 bit, whereas no change in voltage level indicates that the next bit is a 0. 

 The rising edge is on the left of the pulse, the falling edge is on the right.  The top is the level edge of the pulse.  

More After the Break

Wireless: More Chapter 2

Analog and Digital 

-Analog signal intensity (voltage or amplitude) varies and is broadcast (occurs) continuously.  Examples are audio, video, voice and light.
-You turn it on, ramps up like a lightbulb, when the power is cut, it powers down and the signal ramps down.

-How do you get a negative voltage with a battery?  Turn it around ;)

-LED cannot use a backward battery.  The way they are built, it only conducts in one direction, so if the flow is reversed, it is blocked, sometimes catastrophically.

-The flow of energy in a battery is out the negative side (gtfo!) and in the positive.

-DC (direct current) Resistance causes electrons to lose their energy over time. 

-AC The highest points are called peaks, the lowest is also called a peak.  P-P (peak to peak) voltage is calculated by the distance between the two.   

-Digital signal consists of discrete or separate pulses.  It has numerous starts and stops throughout the signal stream, for example; Morse code.  Computers operate using digital signals.  The analog signal must be converted into a digital format before it can be stored and processed or interpreted by a computer. 

-A Modem (modulator/DEModulator) is a piece of equipment that converts the distinct digital signals from a computer and encodes them into a continuous analog signal for transmission over analog phone lines.  Modulation is the process of encoding the digital signals (bits) onto an analog wave.

More After the Break

R/S Subnetting Videos

Subnetting Made Easy pt 1

Subnetting Made Easy pt 2

Wireless: Data Transmission

We are using Wireless# Guide to Wireless Communications by Jorge Olenwa and Mark Ciampa.  The pictures on here are screen clippings from either the book or the power points that my instructor is using. 

This first post is two classes combined. 

Chapter 2- Wireless Data Transmission

Notes and stuff after the break

Routing/Switching: Review Notes

**All notes with the CSIT 2750 Routing/Switching tag and labeled R/S are derived from Nathawat Laxman's classes.  If you wish to use any of these notes, you must give credit to him, as this is his work, not mine, not something out of a textbook** 

Most of this is going to be a review of my notes from the Network Fundamentals class.  Over time, I may add links to videos on subnetting as well.

Segments of Original Notes

More after the break