Friday, October 23, 2009

LDG DTS-4 VB Switching App

A quick test of a VB switching application. 

Please forgive the REALLY crude video.  Just a quick demo.  I cycle through the radio buttons selecting each of the antennas.

LDG DTS-4 Commands

Page 9 of the LDG DTS-4 documentation states

"Under PC control, the PC program you write would take the place of the remote (DTS-4R).  Simply open the port, send the appropriate two-byte command, receive and process the two-byte reply as desired.  Note there is no space between the letter prefix (M or R) and the code.

"Example: to select antenna 1, your program would send the characters "R2" to the switch via the serial connection."

Unfortunately this is not exactly right.

The command stream is two-bytes long.  The first byte is an ASCII "R" which has a hex value of 52.  The second byte is sent not as an ASCII "2" (hex 32).  The second byte to select antenna 1 would be a hex 02.  This makes the two-byte command hex 52 02 not hex 52 32 as given in the documentation.

The following command table will work:

Antenna     Two-Byte Command
      1                   hex 52 02
      2                   hex 52 03
      3                   hex 52 04
      4                   hex 52 05

Virtual Com Ports

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Thursday, October 22, 2009

Can we retransmit an HF QSO?

Retransmitting Signals of Other Stations

Q: May my station retransmit the signals emanating from other amateur stations?

Yes, generally. Section 97.113, however, requires that the control operator of your station manually cause the retransmission because the radio signals of other amateur stations must not be automatically retransmitted.

Q: What do the words "manually" and "automatically" imply?

"Manually" means the retransmission is caused by some immediate physical action, e.g.,activating a push-to-talk key, voice-actuated-switch or similar action, by the control operator. "Automatically" means the retransmission is accomplished by some other means, such as a device which determines that a specific reaction is called for and then causes it to occur.

Q: Are there exceptions where my amateur station may automatically retransmit the radio signals of other amateur stations?

Yes. The Rules provide such accommodation for three types of operation. Section 97.201 accommodates auxiliary stations, Section 97.205 accommodates repeater stations and Section 97.207 accommodates space stations.

Q: May my station retransmit the programs or signals emanating from any other type of radio station?

Section 97.113 provides two exceptions for retransmissions that are for the exclusive use of amateur operators. Your amateur station may retransmit occasionally as an incident of normal amateur radio communications, but not on a regular basis:

Propagation and weather forecast information intended for use by the general public and originated from United States Government stations; and

Communications, including incidental music, originating on United States Government frequencies between a space shuttle and its associated Earth stations. You must, however, obtain prior approval for shuttle retransmissions from the National Aeronautics and Space Administration.

See FCC site.

Thursday, October 15, 2009

Tuesday, October 13, 2009

Monday, October 12, 2009

The First Tube


De Forest Audion from 1906.De Forest had an interest in wireless telegraphy and he invented the Audion in 1906. He then developed an improved wireless telegraph receiver. At that time, he was a member of the faculty at the Armour Institute of Technology, now part of the Illinois Institute of Technology.

In January 1907, De Forest filed a patent for a two-electrode device for detecting electromagnetic waves, a variant of the Fleming valve invented two years earlier, a.k.a. the diode vacuum tube detector. It was granted US Patent 879,532 in February 1908. It was a three-electrode device (plate, cathode, control grid), was a vacuum tube. It was also called the De Forest valve, and since 1919 has been known as the triode. De Forest's innovation was the insertion of a third electrode, the grid, in between the cathode (filament) and the anode (plate) of the previously invented diode. The resulting triode or three-electrode vacuum tube could be used as an amplifier for electrical signals, notably for radio reception. The Audion could also act as a fast (for its time) electronic switching element, later applicable in digital electronics (such as computers). The triode was vital in the development of long-distance (e.g. transcontinental) telephone communications, radio, and radar. The triode was an important innovation in electronics in the first half of the 20th century, between Nikola Tesla's and Guglielmo Marconi's progress in radio in the 1890s, and the 1948 invention of the transistor.

De Forest had, in effect, stumbled onto this invention via tinkering and did not completely understand how it worked. De Forest had initially claimed that the operation was based on ions created within the gas in the tube when, in fact, it was shown by others to operate with a vacuum in the tube. The American inventor Irving Langmuir of General Electric Corp. was the first to correctly explain the theory of operation of the device, and also to significantly improve it.

First broadcastIn 1904, a De Forest transmitter and receiver were set up aboard the steamboat Haimun operated on behalf of The Times, the first of its kind. [3] On July 18, 1907, De Forest broadcast the first ship-to-shore message from the steam yacht Thelma. The communication provided quick, accurate race results of the Annual Inter-Lakes Yachting Association (I-LYA) Regatta. The message was received by his assistant, Frank E. Butler of Monroeville, Ohio, in the Pavilion at Fox's Dock located on South Bass Island on Lake Erie. DeForest disliked the term "wireless", and chose a new moniker, "radio". De Forest is credited with the birth of public radio broadcasting when on January 12, 1910, he conducted experimental broadcast of part of the live performance of Tosca and, the next day, a performance with the participation of the Italian tenor Enrico Caruso from the stage of Metropolitan Opera House in New York City.[4] [5].

Friday, October 2, 2009