"Why do people use KiwiSDRs to listen to the HFGCS? Why don't they just use the UTwente WebSDR?"
I’ve been monitoring the HFGCS for a few years now using KiwiSDRs across the continental US. I’ve noticed that some KiwiSDR owners either kick users off when they tune to these frequencies or mask those frequencies entirely. (For those unfamiliar; the HFGCS is the US military’s HF communications system, using 4724, 8992, 11175, and 15016 kHz as its primary frequencies at this time.)
Of course, SDR owners are free to manage their systems however they wish, and it’s understandable that you might be annoyed by HFGCS listeners that can tie up slots for long periods, unlike those monitoring for scheduled shows or even numbers stations which have known, limited timeframes.
However, I want to address a suggestion I’ve seen in some kick messages and other communications with SDR owners: that HFGCS monitors should just use the UTwente WebSDR instead, as it doesn't make sense that users tie up KiwiSDR slots to monitor the HFGCS instead of using UTwente. There are, in fact, good reasons why serious HFGCS hobbyists will prefer US-based KiwiSDRs over UTwente. (Of course, you might decide you don't want people using your KiwiSDR to monitor the HFGCS anyways and that is your right. I've nonetheless taken the time to make this write-up, as knowing the "why" of it may minimize some of the frustration for anyone curious.)
Here are a few examples of things broadcast on the HFGCS that, despite the G in the HFGCS, will not be heard globally, and of which SDRs in other parts of the world will pick it up and UTwente will not;
Regular E6 Broadcasts
In addition to ground station simulcasts, Mercury E6s also broadcast EAMs (search: Strategic Communications Wing 1), separate from the ground station simulcasts. They typically broadcast in locations near the US coasts, and UTwente does not pick most of these up. (I've seen UTwente chatbox users accuse others of exaggerating/lying about a total number of EAMs heard a day, apparently unaware they are missing these E6 broadcasts and unable to reconcile the fact they themselves are essentially 'underreporting'.)
- UTwente is, once in a blue moon, able to hear E6 EAM transmissions if they are broadcasting from the eastern seaboard of the US...
- but almost never hears EAM broadcasts from E6s located over the Gulf of Mexico or Pacific.
Non-Simulcast Individual Station Tests
Not all ground station traffic is globally simulcast – and relying on UTwente can cause confusion for something as apparently unremarkable as per-station test counts. I have seen monitors speculating that the Hickam (Hawaii) or Elmendorf (Alaska) have been decommissioned because they haven't heard their callsigns used for test counts in years. I can only conclude they must be exclusively relying on UTwente, because if they used a continental US SDR to monitor the HFGCS they would still hear these stations often enough.
- UTwente picks up Europe-based stations fine (e.g., RAF Croughton, NAS Sigonella, Lajes Air Field)...
- but not necessarily the rest of the network.
CONUS US Phone Patches
US military aircraft can call HFGCS ground stations to request phone connections. Aircraft over the CONtinental US won’t be heard on UTwente; their transmitters aren't strong enough to reach Europe, and ground stations facilitating these phone patch requests don’t globally simulcast their end of it.
- Anyone monitoring the HFGCS only with UTwente will miss these conversations altogether.
Barksdale AFB transmissions
There is an apparently emergent phenomenon of "non-HFGCS stations acting like HFGCS stations". RED RIVER [Barksdale AFB, Louisiana] and WOLFHOUND [Ramstein AB, Germany] aren't known as 'HFGCS stations', but are now being heard in communications with airborne assets, coordinating things hobbyists might have previously expected the HFGCS ground stations to do. Neither RED RIVER or WOLFHOUND simulcast their transmissions.
- So yes, UTwente will be good for receiving transmissions from Ramstein AB...
- but it will not be good for receiving transmissions from Barksdale AFB.
Major CONUS STRATCOM Exercises
Most remarkably, a few times a year major STRATCOM drills will flood the HFGCS with unique, diverse traffic across all four frequencies — E6s, bombers, tankers, missile cruisers, etc. For these exercises, the HFGCS can end up absolutely flooded with a diversity of activity on all four frequencies, with message traffic completely different from each other coming from E6s, bombers, tankers, missile cruisers, etc. For these exercises. These exercises are as busy as the HFGCS gets. And yet, there are a number of self-professed long-time monitors who assert they are much rarer than they are, and insist on this. Why might this be the case?
Of 8 major exercises I identified as such in the 2024 calendar year;
- 1 exercise involved an E6 in Europe and a majority of relevant communications were better heard using the UTwente rather than any SDR in the US...
- But for the other 7 exercises, while UTwente would have heard ground station simulcasts, it picked up NONE of the transmissions from the additional assets. Someone only using UTwente would miss these exercises and end up with a mistaken impression that the HFGCS was only used for one major STRATCOM exercise in the 2024 calendar year, rather than at least 8.
There are more examples, but they are all variations on the same theme – yes, the HFGCS is a global communications system, but it is not EXCLUSIVELY global. The presence of KiwiSDRs in different parts of the world (particularly the continental US) are a valuable asset to hobbyists. And so, redirecting users to UTwente on the impression it's the same traffic anyways is incorrect. (And as I've insinuated, many of the 'regulars' in the UTwente chatbox significantly overestimate their knowledge of the HFGCS. Redirecting people to UTwente is to redirect them to a point of contact where misinformation about the network is disseminated as 'common knowledge'.)
Again, my goal here is not to chastise anyone for blocking or managing users using their SDRs at their discretion. Even with this information you may decide it is still an undesirable user case for your KiwiSDR, and that is very much your right. But some of you may be less aggrieved now that you know why users might prefer monitoring the HFGCS using your KiwiSDRs rather than UTwente.
My own experience is almost entirely positive, I think you all voluntarily provide a wonderful 'service' as it were and I've gotten a fair amount of enjoyment and fascination thanks to your efforts.
I'm happy to answer any questions anyone might have.
Comments
I think your question is more about the ethics of fair use of a free* but limited resource.
Unlike Twente which can support hundreds of simultaneous users, a KiWi will typically only support four. This usually not a problem when used for short periods of time to listen to amateur nets, or for casual utility monitoring.
However there are some folks who will monitor certain frequencies almost continuously and tie up multiple receiver slots, denying everyone else the opportunity to listen to other signals. Worse still they just leave their browser running, even when not actively monitoring.
I have had to kick or block persistent offenders, who seem to have no regard for other users, so I can understand why other KiWi owners have taken even more drastic action to avoid similar problems.
In addition there may be some sensitivity in certain countries about the legal aspects of allowing various frequencies to be monitored. In other countries, such as the UK, it is technically illegal to monitor anything other than broadcast or amateur stations, but the law is hardly ever enforced, unless there is some other associated crime.
I'm sorry you are disappointed, but a few years ago, such monitoring would not have been possible, so accept that you can now do what you are able to, albeit with some restrictions.
Regards,
Martin
*apart from the owner who has facilitated it
I'm sorry you are disappointed, but a few years ago, such monitoring would not have been possible, so accept that you can now do what you are able to, albeit with some restrictions.
I'm not disappointed at all and my write-up does not even hint towards that. I think you've misread me! As I said towards the end, I have had an almost entirely positive experience with the use of KiwiSDRs to monitor the HFGCS. Any KiwiSDR owner I've individually reached out to and answered back has been positive about the usage. My write-up is meant for the benefit any other owners who might be confused, curious, or frustrated, of which I know there are at least a few.
However there are some folks who will monitor certain frequencies almost continuously and tie up multiple receiver slots, denying everyone else the opportunity to listen to other signals. Worse still they just leave their browser running, even when not actively monitoring.
Of course, which (except for the matter of a single person taking up multiple slots) I discussed and acknowledged at the top! KiwiSDRs can have timeout limits set in place. From my experience, most do, and those should be sufficient. Nowhere in my writeup did I ask anyone to remove their KiwiSDR's timeout limits. (The only request in my post is an implicit suggestion for some to stop automatically redirecting anyone interested in the HFGCS to UTwente WebSDR.)
In addition there may be some sensitivity in certain countries about the legal aspects of allowing various frequencies to be monitored.
You haven't phrased this as a question, but I'm happy to answer it as one anyways. 😀 I'm aware of no US law forbidding listening to the US HFGCS. There seems to be a myth regarding this, one that may come from a very old issue of Monitoring Times (a SWL hobbyist magazine). That a correction was published a few issues later does not seem to have helped anything. In modernity, some people have occasionally cited the US Espionage Act. When pressed for details the statutes they cite are irrelevant. I have not seen any case law that would support a superstition that listening to the HFGCS would be illegal.
My response was intended to be complementary to your original posting, but from a KiWi operator's perspective.
The majority of my users are responsible, some do occasionally take the time to provide feedback and encouragement, most just use my KiWi's without comment, but a small minority believe they are entitled to a 24/7 service, and start complaining if there is a slight problem (for them), such as the internet link failing, the site power being off, or the wind has blown the antenna down in the middle of winter. All of these present major problems for me, and despite their various protestations, I'm not going to climb a mast on an exposed ridge during a gale, just so that they can have uninterrupted reception. This is why I don't ask for donations towards my running costs, as it only further enhances their false sense of entitlement, that I'm running a "commercial" grade service.
I think the suggestion, to redirect to Twente, is a sensible one. It's not so much about area coverage or propagation aspects, but simply that Twente is (to my knowledge) the only web sdr that can support hundreds of simultaneous users, without any time constraints. Goodness knows what will happen when their proprietary hardware eventually fails.
The legal aspects are not so much about who is listening, or where they are located, but more about the laws in the country of whoever is facilitating it. China and Russia are maybe the most obvious examples, where a KiWi operator could very easily find themselves on the wrong side of the authorities, by allowing people from outside the country to have remote access to a receiver located within the country. You only have to have a look at the world map of KiWi receivers to spot the countries that are most restrictive. America and Europe are very well represented, but other countries, with comparable levels of income and population, are not.
I just wish that more of the 800+ active KiWi's had decent noise free reception, especially in North America, where there is a better prospect of being able to erect a decent antenna, in the wide open spaces and rural locations, as opposed to the rather crowded urban environments that are common in Europe. Because only about 10% of the KiWi's that are available provide decent reception, they get a lot of use, and this is generally why the operators have to be more restrictive.
I understand your viewpoint, reasons for posting, and that you are a responsible user. However, many are not, and I guess my response has been tainted by this.
To quote John, "This is why we can't have nice things"
Some days I feel like completely removing public access, because a self entitled user has made unrealistic demands, despite receiving a totally free service. It has cost me many thousands of pounds to establish my chain of KiWi's, and the monthly running cost is substantial for me as a retired person. But I don't see why a few "bad eggs" should be allowed to taint things for others.
My toys, my rules.
The key takeaway is that, like society in general, there are always a few people who don't play by the rules, and this forces others to take action, that ideally shouldn't be necessary, in order to minimise the impact on the majority of folks who do act responsibly.
Regards,
Martin
You're speaking to almost an existential or philosophical question. I mean, why would anyone make their KiwiSDR publicly accessible at all, since UTwente is up? It is, as you say, the only SDR able to support hundreds of simultaneous users without time restraints. The second-order issues – which I've actually considered myself – are valid but the HFGCS isn't actually some special case in the context of your concerns.
I think some users maybe recognize the HFGCS as some point of compromise between these two. It's actually your statement that "I think the suggestion, to redirect to Twente, is a sensible one." I take issue with. It's too simple and actively ignores what I've taken the time to discuss. Think of it like this;
If you have an KiwiSDR in California and I use it to listen to a station broadcasting from California, and you immediately kick me off of your SDR with a kick notification using UTwente to listen to the station since it has more slots and no timeout, is this sensible? If the UTwente SDR cannot pick that Kansas station's signal up, I don't see how this is sensible.
If you have an KiwiSDR in California and I use it to listen to a station broadcasting from California, but I am regularly taking up one or more slots to do so, or clearly using VPNs to regularly override your pre-set daily usage limits, etc. and you kick me for violating 'best use practices', is this sensible? Of course.
In the first example, the existence of the UTwente SDR is not relevant because it can't be used to listen to the desired transmission anyways. In the second example, the existence of the UTwente SDR isn't relevant because it's not the point of the problem. The HFGCS, as I've illustrated, isn't actually any different from a 'station broadcasting from California' or anywhere else.
It's like those Kiwi owners who block out the entire AM/MW band. They decided they want their Kiwi to be used for amateur radio purposes only. You can probably thank users who repeatedly park on a frequency or set of frequencies for long periods of time. When I attempt to use a distant Kiwi for content matching while DXing on AM, I'll normally put "DXing for WXYZ" in the callsign box as to give a hint that I'm not just sitting there listening to some commercial broadcast that may also be available on the station's online stream.
I take the point you are making, and your understanding of the responsibilities and trades to be made, but unfortunately, I suspect you are in a minority among typical web sdr users.
There are some people who simply sit on a channel, or channels, all day long, waiting for some activity, especially HFGCS. They hear about a specific "interesting" frequency, which in many cases has been hyped up by social media ("Buzzer" frequencies are other common ones), and just sit there hoping to catch something sensational, but they will most likely be disappointed, and wouldn't know what it was if they ever did hear something that was different. These are the folks who I believe would be adequately served by Twente.
My comments don't just apply to HFGCS, but also to folks listening to Pirate music stations, or in some cases amateur nets, but these tend to be at particular times and are relatively short-lived events, so they don't tend to have a long term impact.
I don't object to folks, who know what they are doing, and utilising my KiWi's to monitor a specific frequency, in a specific coverage area, and generally act responsibly.
You wished to explain some specific points about the vagaries of HFGCS monitoring, which you have done in great detail, and I totally understand.
But it doesn't really change anything, as your considered behaviour, is unfortunately a very rare thing, and we frequently have to take action to mitigate against the worst offenders.
Regards,
Martin