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Left is a pix of my data logger & signal generator which connects to a radio at the far end of a data link. This unit will monitor the received signal level and, upon command, return that reading to the terminal connected at the near end. The pix to the right is of the near end hand-held terminal | 
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| Most digital radio links are half-duplex meaning that the transmit RTS control must be raised to send and dropped to receive. The logger's RS/EIA232C standard specifies RTS,CTS, etc for control applications and supports these functions as well as providing the necessary delay before sending the data. |
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These units can be used for bench
testing or in the field. The module to the left will monitor an analog
level and send it in a data format. When external transmit keying is required,
the "key on data"device to the right raises RTS and delays data for proper
radio control and transmission. |
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| When testing a data radio system, it
is necessary to know that data are being generated and the interface
signals at the data source and the receiving terminal are functioning properly.
Below are two small units which plug into a data port for testing and will
easily fit in a tool box. |
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Left is a "Quick Fox" generator. It
raises RTS and sends a continuing "quick red fox" message at a selected Baud
rate. Right is a 9 pin data port tester using red and green
LEDs to tell the level of an active signal on the interface pins. Red for
(+), green (-), yellow pulsing. |
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| For my Ham Radio ATV project, I needed a small video pattern generator with an easy way to change the image for testing and generating an ID. I remembered that in the early days of commercial TV, some repair shops had a "flying spot scanner" with multiple pattern inserts for CRT alignment. Using that idea, I built my version of the "flying spot scanner" with simple technology. |
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My "scanner" consists of a small board
camera, two LEDs for illumination, a 5V regulator, a video output buffer,
and an "L" shaped chassis with plastic binders to hold the artwork.
The left view shows the camera and LEDs. To the right, the
artwork on card stock held in place by plastic holders. |
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| In the early 1970s I became interested in designing a DTMF system so the hearing impaired and the hearing world could easily communicate using a standard telephone. At that time, and now, a call required special equipment and an expensive operator relay system. The "Tone Writer", as I call my system, didn't catch on then but now a similar method is in widespread useage (sadly, not to my credit). In developing "Tone Writer", I needed simple testing and accessing devices. Below are some examples. |
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Left is a battery powered "blackbox"
with a keypad and a DTMF I-C to generate the tones. A coupling network allows
connecting inductively to a "POTS" line or to a unit under test. Right is
a simpler device using an inexpensive telephone, a coupling transformer and
a battery connection to power the phone. The transformer coupling and matching
is for either test bench or phone line use. |
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| To do a test over the phone line, I needed a means of connecting a dialed number and receiving a returned tone message. The autopatch and "Tone Writer" transceiver shown below helped a great deal. |
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Left is the autopatch. It answers
the ring on a dialed line and, when command, will return
a recorded tone message. To the right is a "Tone Writer" tranceiver that
can transmit single or double DTMF characters. A single to dial a number
and issue a command, the double to send and receive a
message. |
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| The above units have been adapted for other than their intended uses and have found several Ham Radio applications. I realized great satisfaction and pleasure in designing and building these and other projects. |
email: w6ooc@earthlink.net