mercoledì 6 dicembre 2017

M42


Russian diplomatic station heard some weeks ago on HF.


Fsk modulation with a symbol rate of 100 Bd and 500 Hz shift.


The bitstream after demod shows a typical 7-bit structure (5 bit + 1 bit START and 1 STOP bit).


By removing the start and end bits, we obtain sequences of 10 groups of 5 letters each as shown in the figure.


Fsk transmission followed by op chat in morse code.

venerdì 24 novembre 2017

Inmarsat D+ / Inmarsat's satellite paging system

Inmarsat D+ paging system received yesterday night on L-Band. This is a signal downlink from satellite.


The symbol rate is 4 symbols/sec and 5 bits / symbol ( 20 bps ).


Modulation is a 32-MFSK


"The main use of this technology nowadays is in tracking trucks and buoys and SCADA applications".





lunedì 20 novembre 2017

MIL188-110A transporting FED-1052 protocol


MIL188-110A waveform ( acf 200ms ) sending encrypted email data.


Output bitstream.


FED-1052 protocol.


CFB encryption.



Source about CFB

mercoledì 8 novembre 2017

802.15.4 IoT - Internet of Things...


"IEEE 802.15.4 is a technical standard which defines the operation of low-rate wireless personal area networks (LR-WPANs)". This signal and many other signal like this are easily recevible in our house with a simple antenna. Probably this is a ZigBee device working on 868 MHz ( european standard frequency ).


Modulation and symbol rate.


Burst sequence.


Packet frame: 199 bits: "32 bits synchronization + 8 bits packet delimiter + 7 bits PSDU lenght + 1 bit reserved service" followed by PSDU ( variable lenght from 0 to 127 bytes )


in the next post a more in-depth analysis.

martedì 7 novembre 2017

Nokia Adaptive Message Terminal

Another interesting signal heard some days ago.


Looks like an FSK modulation....


Symbol rate: 301 Bd


Shift ~ 755 Hz Yes ! it's a Fsk modulation...



Bitstream after demod.


Bandwidth: ~950 Hz

...yes, it's a Nokia Adaptive Message Terminal...

More technical info:

- Antonio Anselmi's blog
- radioscanner
- SigidWiki.com

S4538, FLSU Asynch Request


Short burst, a BW5 waveform ( STANAG 4538 ).



FLSU Asynch Request.

Short encrypted data


A short FSK transmission transporting encrypted data.


Looking the bitstream is visible a KG84 encryption.