Voice Keyer ISD1760 |
During SHF skeeds, a voice keyer "parrot' is useful for antenna alignment and rain scatter testing. Of course it can be used also during SSB contests. The functionality of next project is inspired from BX-184 but with additional features and simplified operation.
As recording device i was used ISD1760 designed by Novotek. To be sure about item's quality, it was ordered directly from manufacture (Taiwan). As usually, let's see the main requirements:
- built-in electret microphone used for recording and radio normal operation (bypass mode)
- Voice Keyer recording function, maximum 60 sec. / 8KHz sampling rate
- only one key to select the operation mode: BYPASS / PLAY LOOP / BEACON / RECORDING
- integrated "beep" tail, adjustable lenght 50...500msec, "beep" function enabled/disabled by jumper
- tone frequency 800Hz / 1000Hz by jumper selection
- beacon mode, continously transmission of CW lines (1 sec. lenght, 0.5sec. pause), useful more microwave testing, antenna alignment, etc
- fixed delay time during PLAY LOOP mode (3 sec. receiving period) .
- open colector output to control radio's PTT.
- Arduino IDE compatible software
HOW TO USE
SELECTION "PB2" push button function:
PLAY LOOP (pressed 0.75sec...3sec) / BEACON (pressed 3sec...6sec) / RECORDING (pressed >6sec)
1. BYPASS MODE
After power-on, the voice keyer goes to BYPASS MODE, the integrated microphone will be routed directly to radio MIC input. Audio signal quality is not affected by ISD IC. In this mode only the "beep" tail can be active.
2. RECORDING MODE
To record your first voice message, hold more than 6 sec. SELECTION (to be installed on microphone body or to reuse other key). The holding time to reach RECORDING MODE is quite long, to avoid accidentaly erasing of ISD content (in case of necessity, release and press again SELECTION to cancel recording mode).
Press PTT key (ISD content will be erased) and speak your message. Release PTT key to save it. Maximum track lenght is 60 seconds. During recording mode, the PTT_OUT is not enabled, radio's TX will not be activated.
*
The lenght of message will be automaticaly stored inside Attiny84 EEPROM as reference for PLAY LOOP MODE.
3. PLAY LOOP MODE
To play the recorded message, briefly press SELECTION for more than 0.75sec, up to 3 sec. PLAY routine will be activated. PTT_OUT line will be enabled and radio's TX activated. When the message period elapse, the radio goes back to RX mode for 3 seconds (enought time to check the band activity), then the cycle is repeated. Press PTT key or SELECTION to stop PLAY LOOP MODE.
4. BEACON MODE
Hold SELECTION more than 3 sec., up to 6 sec. to activate BEACON MODE. One (1) second lenght CW lines will be generated in loop with 0.5sec spacing period. PTT_OUT will be enabled continousy during BEACON MODE. Press PTT key or SELECTION to stop BEACON MODE.
"Beep" tail will be generated everytime when PTT key is released. Beep function is enabled by default but can be disabled if J1 is closed.
Default tone frequency is 800Hz. Close J2 to change it on 1000Hz. The lenght is adjustable by "AUX" trimmer between 50...500msec. PTT_OUT line will be delayed accordingly.
Schematic
PCB files
Hex Firmware vers.1