 |
| |||
| voice-frequency telegraphy | |||
| frequency telegraphy; VF telegraphy (voice-frequency telegraphy) | |||
| carrier telegraphy; harmonic telegraphy; tone telegraphy | |||
| тональная телеграфия: 7 phrases in 5 subjects |
| Electronics | 3 |
| Mass media | 1 |
| Military | 1 |
| Technology | 1 |
| Telecommunications | 1 |