A customer was upgrading their communication system but did not want to give up the legacy handsets with the long frame dual plug that existed with the Zetron equipment. The most common part numbers are PJ7, WE425, and W.E. 425A
LMC Systems was tasked with a custom engineering project of adapting the legacy handset to a computer via USB.
This was a two part process. The first part was matching the transmit and receive of the handset with the levels of the USB audio CODEC. This was a simple case of analog electronics on both the transmit and receive sides of the handset matching the levels required of the USB audio CODEC.
The more difficult part was to turn the handset PTT (Push to Talk) into something the computer’s voice software would understand. The customer agreed that a keyboard keystroke could be accepted by the host software as a shortcut or hotkey for PTT. LMC Systems engineering staff designed a single keystroke to be sent, which would be activated by the contact closure on the handset. This “hotkey” would not interfere with other applications on the computer because the combination was so unusual in nature. It was mutually agreed that the key configuration would be Ctrl-Alt-Shift-a. This proved to be a successful key combination.
The end result was a functioning legacy PTT handset that communicated with VoIP software on a computer via USB. Customer response was extremely positive. LMC Systems had met all of the customer’s needs for adapting PJ-7 handsets to USB and utilizing new technology.
The Slim™ speaker/microphone station is a new introduction for LMC Systems. Just introduced and already on backorder at the time of this writing we at LMC Systems are very pleased with the initial response of a game port, transmit / receive station.
The Slim™ speaker/microphone station comes with game port PTT (Push to Talk) capabilities and speaker volume control. Unlike other stations on the market the Slim™ station uses game port commands for PTT rather than keyboard commands.
If hotkey PTT commands are performed using the keyboard or a second keyboard accessory, then the keyboard interrupt is busy and no other programs can use a keyboard function during PTT. By using a game port command this allows the operator to utilize their computer for other functions that use the keyboard.
Game port PTT has become a very popular method of PTT because many applications of hardware are now multi-function. Rare is the computer that is a VoIP specific device.
To meet with the changing needs of desk top stations LMC Systems is pleased to introduce this new model of transmit / receive station.
The shortcomings of keyboard PTT on a multi-function computer
For many years LMC Systems, along with other industry leaders, has used keyboard keystrokes as hotkeys for activating PTT (Push to Talk) in many well known VoIP (Voice over Internet Protocol) applications. This use continues today for certain computer specific VoIP applications.
As computer usage and performance has increased, there has been a move away from task specific VoIP computers. With increasing regularity desk top computers are being called to perform as multi-function machines. This causes a conflict with keyboard based PTT with other non-voice applications. When a user is in a VoIP application and any PTT is active, this causes the keyboard interrupt to be active or in use. Put simply, no other application using a keyboard is able to function.
Our solution to this problem is to utilize a different internal interrupt. The game port was a likely candidate. By using a game port command for PTT, this leaves the keyboard functions free to be used in other simultaneous applications.
Now a multi-use computer can have full keyboard function while still having a PTT command working with the users’ VoIP applications.
The practical application of the FTT-200 keyboard command programmable foot pedal.
The FTT-200 foot pedal is a unique device. It has three programming modes for sending keyboard keystrokes. The modes are sequential, immediate, and keyboard.
An example of the use of sequential mode would be printing a document. A document can be printed by keystroke using ctrl-p and <enter>. Ctrl-p is a hotkey that calls up the printer window. Windows defaults to the “OK” button, so pressing “OK” or <enter> after the print window opens would execute a print command and close the window. In Sequential mode the first press of the foot pedal would send a ctrl-p. The next press of the foot pedal would send an <enter>. Pressing the pedal again would start back at the beginning of the sequence with a ctrl-p.
Immediate mode sends a string of characters in one press. For example, d-o-g would be sent as “dog” with a single press of the foot pedal. Up to 30 characters can be sent in the immediate mode.
Keyboard mode behaves just like a keyboard. If shift-g is used (which is actually capital g or “G”) for example, the foot pedal behaves exactly like a keyboard would. A single press yields a single “G”. A prolonged press, and the foot pedal goes into repeat mode just like the keyboard would (GGGGGGGGGGGGGG).
The applications for such a foot pedal device are as varied as the imagination.
- The sequential ctrl-p & <enter> example has been used in the health care industry for printing documents.
- Another sequential example would be toggling in and out of a certain mode in a CAD program. Ctrl-F4 and ctrl-F5 toggles a layout mode on and off in a CAD application.
- The Immediate mode has been used to replace a serial foot pedal in an industrial control upgrade application. The string “down” is sent to a machine control computer to execute a cutting function.
- The keyboard mode has been used in both the financial industry and emergency call center applications for PTT (Push to Talk) in voice communication applications.
- Forms have been more efficiently filled out by using key in keyboard mode.