Caratteristiche principali : 2 gruppi di 4 canali spaziati di 300 Hz, spaziatura tra i due gruppi è di 400 Hz. Alcuni "Utility Listeners" ritengono si tratti di un sistema Cinese Frequenze in kHz : 6874, 7628, 7755, 7840, 7845, 7855, 7888, 8060, 9060, 11160, 10806.5, 14835, 16270, 17430, 18320. Canalizzazione e frequenza centrale
ch 1 2 3 4 5 6 7 8 CF Hz 615 915 1215 1515 1965 2265 2565 2865
4 + 4
This is an 8 tone MFSK signal with a unique tone
arrangement. It is a Chinese Diplo system with most
traffic originating from Peking. Its real name and
base modulation mode (FSK/PSK) are unknown although
analysis suggests that each of the 8 channels is 150bd
or 75bd synchronous FSK. No estimation of total baud
rate. The tones are grouped in sets of 4 spaced 300Hz
apart with a 450Hz intergroup gap, 4 tones w/300Hz
spacing, 450Hz gap, 4 tones w/300Hz spacing. Most 4+4
signals seem to be centered on .74. For an example try
the signal centered on 8321.74:
Il sistema 4 + 4 in ciclo di IDLE
Il sistema 4 + 4 in trasmissione