AT&T U-verse Observations

I got AT&T U-verse installed on 12/3/09, with 2 TVs and 2 PCs connected. Because of an older analog modem in my monitored home alarm system, I declined the U-voice VoIP portion of the service bundle, keeping the voice phone service on its existing arrangement. The alarm company's solution for using VoIP is to avoid it by using a cellular data connection. This would have involved an equipment upgrade of about $150 plus an $8 increase in the monthly alarm monitoring fee.

Click here to access a captioned photo set showing the U-verse equipment and a few selected (standard definition) TV screen photos.


I captured some connection data from the 2Wire 3800HGV-B which serves as a residential gateway for the three U-verse services. Here is a portion of the DSL Connection Detail screen:

A speed test from one of the PCs gave the results shown below. Since I ordered the same Internet speed bracket that I was previously using on ADSL, the download speed is limited to 3 Mb/s max. The upload speed is significantly better than what I had on ADSL.

This morning I tested for VDSL noise impacts on amateur radio reception. I noted a high level of white noise near the top of the 75 m band, but nothing noticeable on 40 m. I powered off the gateway and observed that the noise on 75 m disappeared. Next I unplugged all devices that connected to the LAN side of the gateway and powered it up. The white noise returned on 75 m at the following levels:

• 3.9 - 4.0 MHz -- S9
• 3.85 to about 3.9 MHz -- S6
• 3.80 to about 3.85 MHz -- S4
• 3.75 MHz -- below S2

Since no LAN cables were connected, I concluded that the noise pickup is via the 75 m leg of my fan dipole that crosses about 6' above the aerial drop wire at about a 30º angle. The 40 m leg of the dipole does not pass near the aerial drop. Rearranging the 75 m leg would probably reduce the interference.

Update 12/9/09: This morning I see only S2 noise floor on 75 m. I'll need to check this on multiple days, cycling power to the gateway, to be sure about the noise origin.

Update 12/11/09: Additional testing on multiple days failed to confirm a correlation between presence of white noise on 75 m and the state of my gateway. Generally the white noise is very low or absent in early morning and late afternoon or night, but seems to rise mid-morning thru mid-afternoon.

In the past I experienced occasional interference to my ADSL connection when transmitting on 75 m. This was later resolved when the drop wire and inside wiring connections were cleaned and reterminated at the network interface. There was no recurrence of this problem to ADSL, or to VDSL while transmitting around 3.74 MHz. However, transmitting on 3.97 MHz caused the VDSL gateway to loose sync. This condition is probably related to the proximity of antenna and aerial drop as discussed above.

I need to do more (online) reading as I explore the service performance and impacts further. Some resources are:

• U-talk Peer-to-Peer Forums
• DSL Reports U-verse Forum 
• eHam.net forum
• QRZ.COM forum 
• ARRL TIS - Possible Impact of VDSL on Stations Operating in the Amateur Radio Service
  

JK

Frequency Analysis of W4BXI Keying

Here are two views of the audio recording of W4BXI's keying. (Click on the image to magnify.) The first shows amplitude vs frequency for a portion of the initial dit. A fairly sharp peak is seen near 622 Hz. The amplitude above the peak rolls off more slowly than I expected, and this shape is also seen when I analyze just the noise waveform between CW characters. It might relate to the audio filter mode or some other noise entering the recording.



The second figure shows the amplitude and frequency content vs time as in the previous post for the recording of keying from KB4XX. Except for some brief additional high-frequency content near the beginning and end of each CW character, the tone is steady for the duration of each character.

Many, many other views can be obtained by choosing the time portion of a waveform to be analyzed.

-- John

Key chirp -- another view

I selected another view in the Cool Edit 2000 program to help illustrate what the ear easily tells us about chirp in the CW sample from KB4XX. Above is a spectral view showing the initial dah and the following dit sent in the semi-break-in mode. Click on the image to magnify.

This graph plots frequency on the vertical axis, in a limited set of discrete bands, and time on the horizontal axis. Intensity is represented by color, with light colors on the high end of the range, and dark colors on the low end. A steady tone is seen by the solid horizontal bar in the 700 - 1000 Hz range for most of the dah and the dit. The early part of the initial dah shows instability represented by the bright spots above and below the 700 - 1000 Hz band.

Next I'll post corresponding views of the keying sample from W4BXI. All analysis views are based on the audio waveforms recorded from W4UOA's receiver.

-- John

Frequency Analysis of Key Chirp

During a discussion of key chirp on Phil's transceiver, I offered to do a spectrum analysis of the recordings made by Carl. While listening to selected slices of the audio I concluded that the chirp is most noticeable on the initial character sent on semi break-in and on the first character of a letter sent on full break-in.

I used Cool Edit 2000 to analyze the following slices of the audio waveforms:

• First 30 msec of the first character sent on semi break-in
• Third 30 msec of the first character sent on semi break-in. This allowed some time for the pitch to stabilize.
• First 30 msec of the initial dah sent in full break-in
• Third 30 msec of the initial dah sent in full break-in

The same analysis can be done with the Audacity program.

The annotated screen shots are shown below. Click on any one for an expanded view. All have background noise showing in the upper part of the spectrum. The area of interest is the tone peak around 690 Hz.

Web log-in storage by Intenet Explorer

Most if not all web browsers provide the convenience of storing usernames and passwords for logging into web sites that require them. While I do not recommend using a web browser to store log-in data for very important or sensitive web accounts, the service can be convenient for other web accounts. For your most important log-in data I recommend a program such as Password Safe. This program saves your data in an encrypted file that you can easily save on back-up media, too.

Some web browsers let you access stored log-in data easily, and provide the option of password protecting the stored data. However, this 'master password' feature is not as secure as a dedicated password program.

Log-in data (usernames and passwords) stored by Internet Explorer (IE) are not accessible within IE. When you access a web site log-in page that uses the stored data, your username will be visible, but the password will be obscured. If you have stored such data while browsing with IE and later need to view it, because you don't have it saved elsewhere, you will need to use a third-party software tool or an obscure procedure.

This web page discusses the protected storage used by IE and provides links to several tools for accessing the stored data. Most of the tools listed are priced at $39. One is offered free of charge. Another page features such a tool for $10. I cannot advise about the effectiveness or trustworthiness of such tools.

In summary, be cautious about where you store web account log-in data so that it is secure but also accessible when needed.

4 years after Hurricane Katrina

Here are two reports I found interesting from the weekend news:

New Orleans four years after Katrina
Profiles a couple who built a new home to replace their flooded home next to the London Ave Canal.
This page includes a link to a nice narrated slide show from 2008 that includes a view of the family's house plans -- exterior views.

La. Family Finishes Rebuilding, But Struggles Go On
This is the 13th interview of the Bordelon family, who rebuilt their home in St. Bernard Parish. The web page has links to their 12 earlier interviews.
Sadly, the 1/25/2010 program reported the passing of Donald Bordelon.

John

Laptop Online with Puppy Linux

After installing a 64 M memory module donated by KE4ID (thanks, Jack!), I powered up the Dell Inspiron 3000 and booted up with Puppy Linux. The resulting 233% increase in available RAM provided a nice boost to the laptop PC's performance -- much less frequent hard disk access. Puppy Linux is happy to run with the current total of 112 M of RAM.

I resumed efforts to get the PC Card (aka PCMCIA) Ethernet interface configured to enable LAN / WAN access. With some guidance from online forums about configuring Linux on older hardware, I got the Ethernet card working (as it did under Windows ME that I inherited with the PC). Here is a photo of the screen showing the Bell Ringers home page displayed by the SeaMonkey browser that is part of the Puppy Linux distribution.

I've now verified the PC's ability to access the Internet via Linux, for web browsing and email access. Next I will work on achieving Java applet operation.

Puppy Linux on Old Laptop PC

Various light-weight distributions of Linux are promoted as options for extending the usefulness of older PC hardware that cannot be used easily or economically with today's Windows software and applications. I'm in the process of testing this concept on a 14-year old Dell Inspiron 3000 laptop that came with Windows Millennium Edition. This PC has 48 M of RAM and a 4 GB hard drive partitioned into two drives of about 2 GB each. I left Windows on the C: drive for now, and used the nearly empty D: drive (partition) to install Puppy Linux, a popular distribution for older hardware with limited memory.

The PC is now set up as a dual-boot Windows / Linux machine with the Puppy Linux branded GRUB boot menu as shown in the screen photo below (click on image to expand).


The Puppy Linux desktop is shown in the next photo that includes a part of the PC keyboard.



The next photo shows the main menu list and the top submenu expanded.

Additional work is needed to get the PCMCIA network card recognized and working in Linux. Three of the many available drivers were loaded, but a connection was not established. Also not yet working is the PC's USB interface. Both of these interfaces work correctly under Windows.

During the Linux exploration I also tried out the very slim Damn Small Linux, which works very well running from its (pocket sized) boot CD. This provided some good opportunities to review Linux / Unix filesystem concepts and commands, and to see the usefulness of this very compact distribution as a maintenance tool for any PC that can boot from a CD.

Other Linux presence in my household includes Ubuntu installed on two desktop PCs.

Comparison of background noise

Here is my attempt to better illustrate the difference in signal-to-noise of the two recorded signals.

First I performed a high-pass filter operation on the waveforms of the first two transmissions. This was to focus a little more on the noise and less on the complex voice waveform. Analyzing the resulting waveform did not reveal a visually significant difference between the two operators' signals.

Next I selected a segment of the waveform between words and performed an FFT operation. The resulting displays show the levels vs frequency. The top graph is from the recording of WA5MLF's transmission, and the bottom is from KB4PYR.

The sharp peak around 6 to 7 kHz is from aliasing and should be ignored. Looking at the graphs in the 1200 to 2400 Hz range reveals a higher level on the recording of WA5MLF's signal, which I think represents its higher noise level relative to the voice peaks. Click on the figure to expand it for better viewing. I believe the noise is higher for WA5MLF due to the receiver's AGC allowing more gain on average during the voice transmission, allowing greater amplification of the background noise.

The FFT graphs shown here were produced by the Cool Edit 2000 program which was acquired by Adobe and is now part of their Audition product offering. An equivalent FFT graph can be produced with the free Audacity program, which also provides a text export of the data to be plotted with the software of your choice.

Analysis of received audio

KB4PYR audio

In reference to Carl's audio recording, here are histograms of each station's initial transmission, as analyzed by Cool Edit 2000 software.


WA5MLF audio

KB4PYR's audio sounded like it had better signal-noise ratio, but it is hard to draw conclusions from the analysis since voice is a complex waveform and the stations have different hardware and different operator's voices. The presence of more lower-level content in WA5MLF's audio suggests that it may have more noise or maybe that it is not as strong, but the AGC action of the Tuscaloosa receiver may obscure the comparison.

FFT analysis shows some differences, but mostly in the low-frequency end of the spectrum. A better frequency analysis should be obtained by first doing a high-pass filter operation on the recorded audio file. I'll report on that later.

Carl's antenna comparisons

Carl's posting provided a recording of HF receiver audio while switching every 10 seconds between two different antennas. Since the audio level on the first antenna was a bit lower than the second, I thought it might be helpful to make the two cases approximately equal for a better listening comparison. Below is my software's view of the edited recording, with the 1st, 3rd, and 5th segments boosted by 40%. A copy of the edited recording is available here.

My impression while listening to this copy of the audio is that the 2nd segment has slightly stronger voice audio but with background noise that has more of a power line noise character.



Using my copy of the Cool Edit software I ran some Fast Fourier Transform analyses on the edited copy of the recording as well as the original. A transform of the complete audio recording, based on 8192 points, is displayed in the graph below.



Transforms of the 1st segment of audio (antenna 1) and the 2nd segment (antenna 2) looked fairly similar. Let me know if you'd like to see those graphs.

Due to the varying frequencies and levels of the voice, it was not possible to pick out its characteristics easily from the broadband background noise. A better test would be to transmit one or more steady audio tones and record the received results on the different antennas for comparison using the FFT analysis.

John