Clifton Laboratories 7236 Clifton Road  Clifton VA 20124 tel: (703) 830 0368 fax: (703) 830 0711

E-mail: Jack.Smith@cliftonlaboratories.com
 

I've added a page covering data capture and instrument control via the GPIB (HPIB or IEEE-488) interface at EZGPIB and Prologix GPIB Adapter,

The page summarizes the equipment and software I've found useful and is not intended to be an exhaustive or comprehensive survey of GPIB hardware and software.

I thought visitors might find statistics of operating system and browser usage for visitors to my web site. The data below is for the month of September, 2008. Windows is still the predominant operating system, but Firefox (my web browser of choice) is clearly making inroads into Microsoft's IE market share.

Operating System Statistics:

Web browser statistics:

I've added two spectrum analyzer images to the Signal Level page. One shows a -2.2 dBm signal at 9.6 MHz and the other is an expanded view of the 40 meter band, zoomed to show 6.0 - 8.0 MHz.
 

I've added a page with spectrum analyzer captures showing the peak signal levels receiver over the 0-20 MHz range in Clifton VA. You may view the page by clicking here, or via the Signal Level link in the navigation bar at the right side of this page. The strongest signal seen is around -5 dBm.

I've added a short page with the Norton Amplifier results, available by clicking here or through the navigation table at the right side of this page under "Norton Amplifier."

As I mentioned, I'm considering making a kit available and anyone interested in one should drop me an E-mail for status reports.

The last two weeks have been busy with a low noise, broadband Norton transformer "noiseless feedback" amplifier and looking at another audio transformer. I plan to add a page on the Norton amplifier in the next couple days. It's quite an impressive performer and I may offer it as a kit if there's sufficient interest.

I've added a new page describing an easy and inexpensive broadband RF isolation transformer, with loss loss, usable over the frequency  range 10 KHz - 85 MHz (3 dB response limits.) It's at Easy Broadband Transformer.

As usual, I've moved the September 2008 updates page to an archive, available by clicking here or through the archive link table at the top of this page.

I've been working on a couple of projects over the last few days. One of them is collecting signal strength data using the HP 3586B selective voltmeter.

The plot below shows five days data for two stations, WWVB at 60 KHz and NML4 at 25.2 KHz.

WWVB is a standard time and frequency station operated by the National Institute of Standards and Technology from a site in northern Colorado. It operates with an ERP of 50 kw.

NML4, operated by the US Navy from LaMoure, North Dakota, is part of the Navy's worldwide submarine communications system. It operates with an ERP of 500 kw.

There's quite a difference in propagation modes shown in the two signals. NML4 is relatively stable, with a day/night difference of a couple dB, and  the sunrise/sunset dips are at most 4 to 5 dB. WWVB, in contrast, shows nearly 10 dB day/night signal difference and sharp, deep sunrise/sunset effects.

Although only 35 KHz apart in frequency, it's more useful to look at the ratio of frequencies; WWVB operates at a frequency more than twice that of NML4. This difference is enough to cause different propagation mechanisms. I hope to address this subject in more detail after collecting additional data.