Unknown Data Type

[KC2CQD]

While fooling around with my RTL-SDR I found a signal at 159.329.755 MHz. It looks a lot like an ACARS burst but is a lot longer. I’ve tried PDW and MULTIPSK Pro modes with no luck. Any ideas? The audio isn’t as pitchy as ACARS. I even tried and MDT decoder. I’m in Erie County New York.

 

[bob550]

ACARS frequencies are not in this range. Frequencies in this band are generally assigned to conservation, so maybe ENCON. Or, you're dealing with an image or harmonic of another frequency.

 

[k2hz]

159.330 WNFR431 County of Erie - Division Sewerage Management 11K0F2D FXO (digital telemetry - operational fixed).
It is a SCADA system for the County sewers.

 

[N2YQT]

159.330 WNFR431 County of Erie - Division Sewerage Management 11K0F2D FXO (digital telemetry - operational fixed).
It is a SCADA system for the County sewers.

Crappy modulation?

 

[KC2CQD]

ACARS frequencies are not in this range. Frequencies in this band are generally assigned to conservation, so maybe ENCON. Or, you're dealing with an image or harmonic of another frequency.

I'm aware that ACARS is in VHF Air band, it's also in AM. This burst is FM, well above Air band. I don't believe it to be a harmonic as I've received it on my dual band handy as well as my mobile.

 

[KC2CQD]

159.330 WNFR431 County of Erie - Division Sewerage Management 11K0F2D FXO (digital telemetry - operational fixed).
It is a SCADA system for the County sewers.

Got it! Thanks! Any idea where I can DL a decoder?

 

[KC2CQD]

Crappy modulation?

I see what ya did there ;-)

 

[nd5y]

Got it! Thanks! Any idea where I can DL a decoder?

There are a lot of different SCADA formats. You need to find out what kind of SCADA control software and radio modems the sewer plant is using to determine how to decode it. If you were able to decode it you probably would not see anything meaningful. If they are smart they encrypted it.

Back in the 80's the city water deptartment here was using AX.25 packet radio on their SCADA channel. Since it was the same thing as ham packet radio I could decode it with a MFJ-1270 TNC.

 

[k2hz]

As nd5y said - Most SCADA system manufacturers use proprietary modulation schemes. Even if you had the proper modem, you would only get unintelligible raw data. Decoding would depend on the control system software used and the message format is usually unique to the particular system.

And, the tendency now is to use sophisticated encryption to prevent hacking, especially on control commands.

 

[N2YQT]

As nd5y said - Most SCADA system manufacturers use proprietary modulation schemes. Even if you had the proper modem, you would only get unintelligible raw data. Decoding would depend on the control system software used and the message format is usually unique to the particular system.

And, the tendency now is to use sophisticated encryption to prevent hacking, especially on control commands.

Imagine if it was just ASCII art of Cousin Eddy dumping his RV tank in the storm sewer?