If you follow me on Twitter you’ll see that in the last month or so I’ve been sending out images of classification and decoder software go2MONITOR working with a number of my SDR’s.

go2MONITOR is part of the go2SIGNALS range of software solutions created by PROCITEC GmbH operating from Pforzheim in Germany, themselves part of the PLATH group. PLATH Group is the leading European-based solution provider for communication intelligence and electronic warfare (EW) with worldwide government customers. The group covers all aspects of signal interception and analysis split between a number of companies such as PROCITEC. EW, COMINT/SIGINT, Jamming and Decoding are just a small part of what the group specialises in.

go2MONITOR is advanced high-performance, automatic HF, VHF and UHF monitoring software capable of recording, SDR control, wideband and narrowband classification and multichannel signal decoding.

It isn’t for the faint hearted, but once you get used to using it, it really does make gathering information on networks extremely easy. And it decodes many modes other software can’t.

In a series of blogs I’m going to show you the capabilities of this amazing software, though I must stress now, it is aimed at Professional SIGINT gathering and it comes with a Professional price tag.

Saying that, it doesn’t mean it isn’t available to the non-professional. It is open to all and to cover this it comes in various versions starting with the Standard package progressing to a full Military package – which gives you the full range of HF, VHF and UHF classification and modem recognition decoders available, including PMR and SAT (Inmarsat AERO). The Standard version isn’t to be sniffed at, it still gives you an amazing range of decoders, though you could easily argue that many of these are available in other free – or near to free – decoding software like MultiPSK or Sorcerer. A full list of decoders available can be found here. Note, this list is broken down into the various packages and not all are available with the Standard option. Confirm what belongs to what if you’re thinking of purchasing.

Various signals within the Satellite L-band using an AirSpy R2 and SDR#

So what’s the difference in what go2MONITOR can do with other software available? That’s the idea of these blogs, to answer just that question. It will take quite a few blogs – mainly because there isn’t just one answer.

Here then, is a brief overview of what can be done, what SDR’s it works with – in fact, not just SDR’s but all receivers that can produce a recording – and any other things I can think of.

As, I’ve said then, it can decode pretty much any data signal out there. Obviously, some signals are encrypted so it wouldn’t fully decode unless you had the key, but you can get the encrypted messages. It can also classify voice signals, not just data. So, if you wanted to hunt out various voice networks, go2MONITOR can assist you in doing this.

Here is where it excels. Classification – and doing it very quickly.

Imagine being on your SDR (SDR1) and you can see a whole load of data signals on the waterfall/spectrum and you quickly want to know what they all are. With go2MONITOR operating another SDR (SDR2) you can dial in the centre frequency of the bandwidth shown on SDR1 into the go2MONITOR/SDR2 combo, click one button – Find Emissions – and within seconds the whole bandwidth has been analysed and every signal classified.

I’ll go back a step though here. You don’t need two SDR’s. One will do. SDR1 – as long as it is a compatible SDR – can be controlled through a GUI by go2MONITOR. The software includes a waterfall/spectrum display. Like all SDR software, these displays are fully adaptable to how you like to see the signals.

The previous L-band bandwidth but his time using go2MONITOR and the AirSpy R2 GUI, decoding INMARSAT 3-F2

Either way, you now have a list of every emission that go2MONITOR has received within that bandwidth. This list includes Modulation type, Frequency, Bandwidth, Symbol (Baud) rate and SNR. It also shows which SDR you have used for interception (useful if you’re using go2MONITOR with more than SDR at the same time, but also with other advanced features such as network control), and it also shows if the frequency is already stored within the frequency database – yes, you can create this too; or import ready made databases in a CSV format.

All the emissions within the bandwidth have been analysed and types ascertained.

Already then, you have built up a picture of what these signals are. One thing to note. If the signal type is not one of those included within the package you have, it will be classed as unknown. Example – a STANAG 4285 will show as unknown in the Standard and PMR/SAT package, but will be classified correctly in the MIL package.

OK, those of us that are looking at SDR’s all the time can pretty much tell what the signals are just by looking at them, so there’s no great advantage here is there? Except, now go2MONITOR has logged these in its database which can be searched through at a later date – handy if you’re looking for potential schedules for example.

However, the next step is where things get interesting. By putting one of these emissions into a “Channel” you can carry out an advanced classification, recognition and decode. You have multiple choices here, but I generally start off with a Classification. Whilst the software has already decided what the emission type is, by doing this it double checks just this one channel and produces a choice of decoders that it is likely to be.

go2MONITOR in Classification mode. Here it has calculated that the FSK emission received has a 50 Bd symbol rate with two tones with 859 Hz spacing. From this it has deduced it is likely to be one of four modems – one of which is ALE-400.

By using STANAG 4285 as an example, it will put this into the list of choices, but it may put other PSK signals there too. By clicking on another button, this puts the channel into Recognition mode and it reduces the hundreds of decoders down to just those in the classification list produced. The software then calculates which is the best decoder and starts to decode the signal.

If you think about STANAG 4285 in other software, you generally have to try all the various potential Baud rates – is it Long Interleaving? is it Short? etc etc. Well go2MONITOR does this automatically. It checks the alphabet and protocol and will decode it if known. More often than not it can’t calculate the alphabet, but every now and again it does and it will produce encrypted data – don’t forget, if it’s encrypted it won’t decrypt it without the correct key.

By continuing on the process from the Classification mode into the Recognition & Decode mode, here from another emission go2MONITOR has selected the CIS-50-50 modem and started to decode the message.

This further Recognition and Decoding is also stored in the database for later analysis, along with a recorded wav file for playback and deeper signal analysis.

Seriously, it is harder describing it in text than it is doing it so I’ve created a video that’s at the end of this blog.

I mentioned previously that the software works with receivers that aren’t SDR’s. That’s because, as long as you can create a wav file recording – Narrowband as it’s known in go2MONITOR – it can be analysed. There are things missing, the actual frequency for instance (though this can be typed into a text box so that you can then have the right information – this i’ll show in a later blog). Time stamps aren’t naturally there but again you can add these by telling the software to use the time the recording was started.

I’ve used recordings made on my Icom IC-R8500 as an example of this but it is literally the bandwidth of the mode used by the receiver that is shown on the go2MONITOR spectrogram.

You don’t actually need to own a receiver of your own. Use an online SDR such as a KiwiSDR, record the IQ as a wav file and play it back through go2MONITOR for analysis. I’m doing just that for a Jane’s Intelligence Review magazine article.

If you use SDRConsole, then you may have also tried the File Analyser function that I blogged about in August last year. The File Analyser in SDRC is excellent, there’s no doubt about it, but it has one drawback. Once you’ve carried out your recording you have to create a run through of the recording, making an XML file that effectively joins all the wav files up. If you’ve made a wide and long IQ recording this can take quite some time. With most of my overnight recordings – normally 7 hours long, with a 768 kHz bandwidth – this takes around 45 minutes to complete.

With go2MONITOR you can also record the bandwidth IQ data. With this you can do two things. Firstly you can run it through as a normal playback, classifying and decoding as you go. Secondly though, you can open the Results window which gives you a time based view of the whole recording allowing you to immediately see any transmissions. Unlike SDRC Analyser, the signals have already been classified, and more importantly, this is done straight away without any need to create an XML file first. The Results window will be covered in greater detail in a blog of its own.

Analysing a Wav file made using the IQ recording capabilities with go2MONITOR
Further analysis of a STANAG 4285 emission within the recording.

However, there are no decodings here. With just an IQ recording you need to play it back and run an emission search etc. There are some basic automation tasks available, such as setting up an emissions search every 10 seconds.

But, if you have the Automated Monitoring and Tasking package, you can also have the software automatically record, recognise and decode a single emission type – or all emissions types within the bandwidth, a set frequency, between two frequencies or any other parameters you may wish to set up.

The go2MONITOR results window of a IQ recording that has been set up to automatically run an emissions search every 10 seconds. The blue rectangles are every emission found. By running the mouse of them you can get basic information on each emission. Clicking on them brings further details that can be viewed in the tabbed area to the right.
The red rectangles are emissions that have also been Recognised and Decoded. By clicking on them the decoded data is shown in the tabbed area.

The list of SDR’s that can be used with go2MONITOR is pretty good, though due to the target audience, many of them are high end, “government/military” receivers. But, it does work with Perseus, SDRplay RSP1 & RSP2, RFSpace NetSDR and SDR-14, and of course AirSpy R2 – and now the AirSpy HF+ and AirSpy HF+ Discovery.

Supported receiver list:

ReceiverMax. Rx bandwidthSpectrum overviewScanRemark
AirSpy2 MHz  Experimental support
CommsAudit CA78515 MHz  VITA 49
Grintek GRX Lan1 MHz   
IZT R3xxx series20 MHzXXUp to 3 channels  spectrum
IZT R4000 (SignalSuite)1 MHz  1 channel only
Microtelecom PERSEUS800 kHz  Limited USB 3.0 compatibility
narda® NRA-3000 RX320 kHz   
narda® NRA-6000 RX320 kHz   
narda® IDA 2320 kHz   
narda® SignalShark®331020 MHz  VITA 49 support. Only 1 MHz and no receiver control at LINUX
PLATH SIR 211020 MHz  LINUX recommended. External receiver control only
PLATH SIR 21154×20 MHz  External receiver control only
PLATH SIR 511012 MHz  16×768 kHz subbands External receiver control only
PLATH SIR 5115Full HF  40×768 kHz subbands External receiver control only
R&S EB5005 MHzX No gain control available
R&S EM100 / PR100500 kHzXX 
R&S ESMD15 MHz  External receiver control only
RFSPACE SDR-14190 kHz   
RTLSDR/Noxon USB-sticks3.2 MHz  Experimental support. Continuous signal up to 2.4 MHz
SDRplay RSP1 & RSP26 MHz  Experimental support
ThinkRF R5500-4086.25 MHz  VITA 49
ThinkRF R5500-4276.25 MHz  VITA 49
ThinkRF WSA5000-408780 kHz  VITA 49
ThinkRF WSA5000-427780 kHz  VITA 49
WiNRADiO G31DDC800 kHz   
WiNRADiO G39DDC4 MHzX Up to 2 channels + spectrum
Generic VITA 49 receiver supportMax. receiver bandwidth  Can be configured in a wide range for different receiver types
Other generic “Winrad ExtIO” supported receiversMax. receiver bandwidth  Experimental support

As you can see, there is a huge difference in bandwidth capabilities for each receiver. I use my WinRadio G31DDC quite often with go2MONITOR, but the AirSpy HF+ Discovery (not listed as i’ve only just got it working) isn’t much worse with it’s full 610 kHz bandwidth.

When you think that the G31 has a much better operational bandwidth than 800 kHz when you use it on its own, it’s obvious which is better value if you were buying an SDR solely for using it with go2MONITOR. It is this kind of thing that many Government agencies are looking at when it comes to funding operations aimed at large scale monitoring.

That then is a very basic overview of go2MONITOR. The quick video and images have hopefully shown you a little of what is possible.

Outside of a Professional SIGINT operation, why would an amateur radio monitor need something like go2MONITOR? And would they pay the price?

I think they would. After all, most of us have spent a fair amount on radio monitoring over the years, so why not on software that would make their monitoring not only quicker and easier, but potentially open up new areas of monitoring.

Many of us specialise in certain monitoring areas – Russian military, particular the Navy and Strategic aviation for me for example. With go2MONITOR I have already used it to hunt out potential Russian Northern Fleet frequencies by running an automated 10 second CW emission scan overnight within a bandwidth block. By doing this, and then analysing data found in the results window, I was able to target certain frequencies to see what activity there was on subsequent nights.

Whilst there are other decoders available – some of which are plugins in software such as SDR#; some of which are free – it is the quickness and ease with which it can be done that makes go2MONITOR attractive. The big question is, would you pay for this?