S17a
| Enigma ID | S17a |
| Name | Czech Lady "Control" |
| Frequencies | |
| Status | Inactive |
| Voice | Female, automated |
| Emission mode | AM |
| Location |
Czechoslovakia
|
| Activity pages |
S17a was run by the Czech military intelligence. It was a "control" variant of S10d that did not convey actual messages.
Transmission format:
| 313 | 313 | 313 | 99032 | 99032 | 99032 | Konec, Konec |
| 5-figure group, middle digit always "0" | ||||||
| Repeated for 5 minutes | ||||||
"313" was the only ID ever used on S17a.