trimble app and bad elf GPS booster on iPhone screen with coffee on wooden table

Trimble Catalyst — No Receiver Required*

*A groundbreaking new service turns your smartphone into a high-precision, software-defined GNSS receiver.

The new Trimble Catalyst is a little hard to describe in terms we’re used to regarding high-precision GNSS. Is it a receiver? Is it a service? Do we really need only an external antenna, a subscription, and a smartphone? 

The answer is yes to each, and while there are nuances to consider, my conclusion is that this is a very big deal, not only as a specific solution but also as a harbinger of things to come.

Announced at Trimble Dimensions in November 2016, the Catalyst drew a lot of reactions. Some folks were excited at the prospect that the much-anticipated era of commercially available software-defined-receivers (SDRs) had finally arrived (I am in that camp). Others looked at a simple external antenna plugged into a smartphone and wondered out loud, “Could this thing really work?” Shown above, the antenna is about the diameter of a large cup of coffee.

SDRs have been talked (and talked, and talked) about in the GNSS development community for more than a decade, but with little in the way of actual working examples. I had been skeptical of commercial viability any time soon—until now.

Catalyst is still in the early phases of distribution, but I hounded the development team for a quick demo. Fortunately, someone from their team was passing through town with time for a quick afternoon of testing—and there was enough time to establish that it does work and it works well. It’s not marketed as a replacement for a survey-grade solution, rather more for GIS, mapping and asset work. As far as my testing went, however, it did yield high-precision results nearly on par with a survey rover (at the same locations, time, and conditions).


The DA1 antenna is threaded to fit on standard poles and connects via USB-micro to compatible smartphones (in this test, a Galaxy 7). The antenna can get its power from the phone, but there is an auxiliary battery pack for extended use (so as not to drain the phone’s battery).


To understand why Catalyst is a significant step in the development of GNSS solutions, we must look at the subject of SDRs. They are a departure from the architecture of the standard, stand-alone GNSS receivers (rovers) we’ve been using for the past two decades.

A standard receiver is a collection of dedicated hardware, the core of which is an Application Specific Integrated Circuit (ASIC): often a very large chip on the GNSS boards at the heart of standard rovers. These boards typically host several other dedicated hardware components. Each manufacturer has one or more flagship GNSS boards (e.g., for Trimble there are popular boards like the BD970 with a large ASIC on it running their Maxwell technology). Or, an increasing number of third-party rover manufacturers use OEM boards produced by firms like Trimble.

The promise of a future of SDRs is the reduced need for dedicated hardware due to being able to load software onto a wider variety of “generic” processors—like those on your smartphone—and turning those processors into GNSS receivers.

Other advantages over the legacy dedicated hardware units, especially in flexibility, are that new constellations, signals, and advances in GNSS algorithms can be added with a simple software upgrade. This makes the jockeying over how many gazillion channels a receiver can boast a bit moot.

The only limitation is processing power, and it’s likely that smartphone processing capabilities will advance fast enough (or even faster) than changes in GNSS technology. An Achilles heel in GNSS solutions can be an antenna: there are physical limitations. If you are receiving garbage, rife with multipath, you will process garbage. The GPS antenna in your smartphone is (and I think this is the technical term) terrible. A ground plane to mitigate multipath is essential, and size is also a function of the nature of the signals.

There are also Chu limits to consider (i.e., thresholds on how much signal certain sized elements can receive). It can be heartbreaking to see a GNSS receiver hosting great innovation but paired with a tiny or poorly engineered antenna. It was encouraging to see that the Catalyst team put a lot of effort into a decent antenna.


The idea of SDRs is not completely new; software-defined-radios for telecommunications have been in development for decades, and a lot of great work has been done in GNSS SDRs in academia by entities such as the University of Texas and the Universität der Bundeswehr München in Munich, Germany, as well as in the open-source community and by commercial manufacturers.

But this may be the first (mainstream) commercial GNSS SDR. About three years ago, Trimble formed a team to explore SDRs lead by their Westminster, Colorado office, with expertise tapped from team members in New Zealand, Germany, Sunnyvale, and Moscow.

Jason Rossback, Trimble’s marketing director of geospatial field software and mobile computing (who brought the Catalyst for the tests), explained that the team was aiming to build a “receiver-as-a-service” (RaaS). A Catalyst user would subscribe to the software and load it on a smartphone and the only physical piece of hardware they would need to buy would be the external antenna.

A further goal was to keep the antenna under a specific price point because a user would not need to make a major investment to begin working with higher precisions. Rossback  said, “There are so many markets that are underserved, such as developing countries, that could benefit greatly from increased precision but cannot afford the upfront investments, especially for short duration or one-off mapping projects.”


How do the subscriptions work? If you have a smartphone with enough processing horsepower, all you need to do is buy the Trimble DA1 antenna (about $350) and plug it into the micro-USB port of the phone. Presently, Android OS phones are supported, with other OS in the works. We used a Galaxy 7; Rossback said they have successfully tested on Galaxy 6 and 5 models, as well.

You have four levels of software subscription to choose from, depending on what kind of work you are doing. The subscription prices go up with the levels of precision (prices are online at:

  • Meter provides code-processing using the correction data from Trimble’s RTX service. It tries to get code data from the RTX online service first, but if there is no internet connection it can get the data from the geostationary L-Band satellites that transmit RTX corrections. It can also use an SBAS solution if the others sources are not available.
  • Sub-meter uses the same RTX code correction sources and in the same manner as the meter option, but the higher subscription rate unlocks the precision. With online code data, it tends to get 30cm-60cm, and with sat-based code data it is only slightly less precise: 40cm-60cm
  • Decimeter uses RTK and/or Network RTK sources. If a user is in an area serviced by Trimble’s VRS Now networks (parts of the U.S. south and midwest, most of western Europe, parts of Australia, etc.), corrections are delivered via internet connection and are included in the subscription. If you are in a non-VRS Now area, you can connect to local, regional, or state real-time networks (some are free and others charge) or get RTK corrections from an I.P.-enabled base (some people set up their own). This level of subscription unlocks the processing capability for only decimeter precision.
  • Precision level unlocks the processing of full-on RTK/Network RTK, in the range of 2cm. It can use non-proprietary RTK formats, like RTCM-3. It also supports RTCM-3 MSM (Multi-Service Message) for multiple constellations.

Okay, how well does it work? Typically, when I test GNSS solutions I visit a National Geodetic Survey (NGS) calibration baseline, and I compare inverses from sets of pairs of observations to the published values. I test at least one mark under moderate canopy, introduce multipath hazards, plus take some static observations with a high-end receiver and antenna as a check.

Catalyst DA1 antenna has an insert for a standard 5/8”-11 threaded pole mount. I attached the antenna to a standard 2m pole w/bipod and wound the antenna cable around the pole to connect to the Galaxy 7. It might be a good idea to take a hardened case for the phone and Velcro that to the pole, but it was simple to just hold the phone and leave enough cable slack.

The antenna needs a little bit of power, and it gets that from the phone, but for extended periods there is a port on the DA1 for a battery pack you can attach to the pole.

We took several dozen observations each on marks about 300m apart. The test app for Catalyst, used mainly for settings and status, displayed a latitude and longitude (WGS84) plus an expected precision (in one sigma). I could immediately see that the values matched my previously derived values (from a lot of testing on that baseline) within a few centimeters.


Checking position and status in a development app (left). Position shown in TerraFlex (right).

Later, putting the results into a spreadsheet I compared 3D values to the published “mark-to-mark” distances. Inverses checked out to under a centimeter (in the Precision mode). Of course, I would want to do more rigorous testing under more varied conditions, but this was quite encouraging right out of the gate. We connected via NTRIP to a nearby base, using standard RTCM corrections, then switched to RTCM-3 MSM to use additional constellations.

Results were consistent with more rigorous tests the development team had done on their own test courses. Despite the great results, Rossback said they are careful not to oversell the precision capabilitiesas results can vary depending on conditions.

The DA1 antenna is a patch antenna with a ground plane, much like most typical survey rover antennas. There are additional hardware elements in the antenna housing; the analog-to-digital conversion is done in the antenna, and there are hardware filter elements. The DA1 is roughly the same size as the Zephyr antenna, or the diameter of the R10 antenna. The DA1 appeared to perform (in the moderate canopy and nearby multipath hazards at the same site) as well as a similar-sized survey rover antenna.

The big question is about multiple constellations. We processed GPS and Galileo, but at the time of testing GLONASS was not being processed. Rossback says that supporting other constellations is a top priority and is expected to happen in 2017. He explained that there are a lot of trade-offs in adding processing for other constellations (such as GLONASS), and these are still being evaluated. GLONASS is a worthy goal as few of the other constellations are in play at this time—though they seem to be launching them at a rapid rate.

What mapping apps are supported? Right now, Catalyst can feed live positions directly to the Trimble TerraFlex asset/mapping app (which we used during the tests). They also offer a software development kit (SDK), which is freely available, and supports Catalyst; the GNSS Direct SDK (same as for their R1 and R2 receivers) is available for third parties to use to integrate their software solutions with Catalyst.

Rossback says they are encouraging new partners to develop function-specific apps, like the Korec Group in the UK is doing for their own mapping app and Precision Concrete Cutting for an inspection app. There is no surveying software at this time.


On the day of the tests I tweeted out a photo of the Catalyst and mentioned we were working on an article about this new SDR. I soon got swamped with inquiries from folks wanting to know more about it (Okay! Here’s the article!☺) It is unique, and likely a first, in many ways: a commercially viable SDR and receiver-as-a-service model, and it performs admirably.

The bigger deal is that the era of SDR has truly arrived, and I can only speculate what possibilities that era might hold.

Trimble Catalyst — No Receiver Required*” Comments

  1. Goodio article Gavin. The magic is not SDR as much as it is the geostationary PPP correction you get…

    Take care my friend.

    • Gavin Schrock

      Thank you Mr. Desjardins,

      The fact that it is (most likely) the first mainstream commercial SDR was what caught our interest. After all, real-time PPP capabilities are not unique to the Catalyst; there are many other receivers that can utilize PPP data from geostationary satellites; Trimble and (to be fair) others. The fast-fix centimeter capabilities (at this point in time) do not really kick in unless tapping network RTK style corrections, like from VRS Now et al. Rapid improvements in PPP are greatly anticipated and will be a truly significant development in its own right – I think the folks that brought this SDR development to fruition deserve their day in the spotlight.

  2. This is great.

    Thanks for sharing this test.

    I just thought if the IF data is processed in the processor of the smartphone, it probably could not support full constellations and full frequency bands.

    What frequency bands does it support? thanks a lot.

    • Gavin Schrock

      At the time I tried it (Dec 15, 2016) it is L1/L2, GPS + GAL. GLN is supposed to be enabled sometime this year, and then (I am told) BDS and QZSS would be worked on after that. I can imagine there are a lot of trade-offs in balancing processing load and adding all constellations. I was told that GLN is of course a high priority.
      I have been following SDR dev for many years, have tinkered with open-source, but had not imagined that we’d see smart-phone-based SDR for a few more years. This is just the first step and we are in for a fun ride….

  3. Hi Gavin, Thanks for that amazing trial ! I thought the SDR was on the Cloud, not on the SmartPhone ? So what would be the difference in term of operation to use on the pole a low cost good quality GNSS receiver such the u-Blox ? Actually many companies are releasing such low cost RTK (for drone, UAV applications) and one talk about “RTK Revolution”. Thanks for your feedback ! Greetings from Belgium. Joël

    • Gavin Schrock

      Hi Joel,

      I agree, there is a wealth of innovation and development in the low-cost, high precision GNSS segment. I really had a lot of fun trying out some of the peripheral devices (as you mentioned); like the various ones from Bad Elf: (one model has u-Blox inside per your example). Some great stuff from Arrow, Emlid, SwiftNav, SXBlue, and many more. The subject of the impending, and greatly anticipated, era of low-cost peripheral “pucks” had been a running conversation for many years. I even did a humor piece on the subject of GNSS “pucks” a few years ago:{“page”:48,”issue_id”:258636}

      So what would be the difference in field operations n the pole between a phone-based SDR and a phone w/peripheral GNSS “puck”? Not much, but then again there would not be much between either of these and a dedicated (legacy style) GNSS rover. Costs go down, flexibility goes up, and with SDR one of the touted gains is being able to modernize without being tied to dedicated hardware. I do not think I am alone in being a bit excited to actually see a phone-based SDR (on the device and not in the cloud) finally come to fruition (after hearing a decade of talk about such thins at ION). SDR and peripheral pucks…. I’m kinda liking the idea that we’ve got so many new options. Cheers, G

      btw: Would love to publish some of your insights on the state of GNSS development sometime 🙂

  4. Hey Gavin:

    I’m not really well versed in GNSS technology, but our company recently demoed the Trimble R1 Receiver.

    From what I’m reading this seems like a really similar device in terms of functionality (connect to smartphone and use that as the processor) but it lacks the Bluetooth capability, limits the operating system (currently) to Android, and lacks the internal battery.

    I’m sure I’m missing something as everyone seems really excited about the potential of Catalyst, but could you explain a bit more what the benefits of this platform are over the existing receivers such as the R1/R2?

    • Gavin Schrock

      Hi Hunter,

      The significance is that this represents a first big step. We had to put people into orbit before w could send them to the moon 🙂
      The developers indicated that they will enable this for other OS – this example is just the beginning.

      That someone finally developed a software defined receiver (SDR) into a mainstream commercial solution is, in its own way, quite the big deal. Of course there are advantages and disadvantages to different makes and models of GNSS gear (and we are not going to get into a detailed comparisons as some are better suited for certain types of work than others).

      You mentioned dedicated peripheral units like the R1 and R2; there are instances were those (and many like them) would be the best choice (at this time). We ran a review of the R1 when it came out: and more recently one on another family of peripherals: All great, lots of options, and so many of such peripherals being developed all the time..

      Ok; when would something like the SDR be a good choice? Say a mapping outfit, that only does field work a few months of the year; they can do that now without a huge up front hardware investment. Another potential plus for SDR’s (as a general feature, and not necessarily this first example) is that as they would not be locked or limited to dedicated hardware – future SDR’s could have the latest and greatest in signals, constellations, and algorithms loaded into them just like an app update. Sure, there are great low cost peripherals like the R1 (but with only sub-meter capabilities) and to go to cm grade, receivers like the R2 or others are a substantial investment. That is great for outfits that need those capabilities daily and all year around.

      My posit, and the reason I wanted to try one out (and see if it could actually get cm precision) was the potential that SDR could, and very likely will have a big impact on the development of GNSS solutions moving forward. If I could offer an analogy: every time I see news about SpaceX landing one of their new rockets, vertically, on a floating barge, I guess I could conclude that because it did not goe to Mars that it wasn’t really big news 😉 You’ll have to pardon me for getting excited about the potential for SDR’s…

  5. Hi,Gavin
    You did a great job.
    I want to know if we can acquire the raw GNSS measurements from the software or they are processed in the software and do not provide to us.
    Looking for your reply!
    Best regards!
    Qiang Wen

    • Gavin Schrock

      Hi Qiang,

      At the time I tested there was no accommodation for external processing; I will do a followup if/when that is available.
      I would suggest contacting the manufacturer about an SDK. I see you are with Wuhan University; please extend my regards to Professor Hui Liu 🙂

  6. […] released a new innovative antennae, the Catalyst (you can read more about the technology in this post) that enhances the Android’s position […]

  7. Hi Gavin,

    Thanks for the article.
    I’ve bought a Trimble Catalyst and Decimeter Subscription and tested and works fine but I only need for simple works of data collecting on finished works.

    I’ve tried Terraflex and Arcgis but they are cloud services and also subscription based, do you know any software that works with Catalyst, collects points in several Gps formats (In Germany they use Gauss Kruger for example) and stores the point with the coordenates/Description (name)/precision recorded that is free form subscription or one time only buy.

    Thanks once again

    • Gavin Schrock

      Hi Luis,

      Our test was over a year ago and since then I am sure that third party developers have figured out how to use the location output from the catalyst in other mapping apps; but I do not know any offhand yet. One option is to use Catalyst with ESRI Collector:
      You could try using an NMEA output and find a 3rd party app to accept that… there are probably developers doing that, so a good web search might yield some ideas.

  8. Hi, Gavin.

    Thank you very much for the article. I have some questions that I’d really appreciate if you take the time to answer. It is possible use the DA1 antenna as the primary antenna of the android device, and then use another app like Geo++ to get the raw GNSS measurements?.

    Best regards!
    Temo Escudero.

    • Gavin Schrock

      Hi Temo,

      For that depth of question it would be best to contact the manufacturer or one of their dealers. The antenna is purpose built – it does the analog-to-digital conversions and low noise amplifications on the antenna (hence the power needed for the antenna. Phone antennas are wholly inadequate to achieve any high precision. The receiver is actually a software defined receiver (SDR) that is n a way “rented” from the manufacturer and run in the processors of your phone. It comes with an NTRIP client so there is no need to add a different one. With that “subscription” (at the top tier) you get access to their L-Band corrections service and VRSNow corrections (if available in your area) service. The resultant positions can take the place of the phone’s location outputs to augment nearly any app on the phone that uses location. It is a complete system with internal dependencies to make the SDR component work correctly, and as far as I know you cannot simply take the antenna and hack to try to use it for some other method; it is designed to work with an SDR and this one in particular.
      As I noted, such technical question would be best answered by the manufacturer.

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