Hemisphere S321+ Smart Antenna

(16 customer reviews)



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The S321+ is Hemisphere’s newest smart antenna. The S321+ delivers amazing precision and performance in a durable and compact enclosure. The S321+™ is Hemisphere GNSS newest survey product that provides the quality one can expect from a North American manufacturer, without the shocking sticker price.


  • GPS, GLONASS and BeiDou
  • SMS Communication from Base to Rover & Cell Phone
  • L-Band DGPS Support
  • Internal UHF Radio & Cellular Modem
  • Surveyor Tough Magnesium Housing
  • SureFix & aRTK Intelligence for RTK
  • 4GB Internal Memory, with Expandable SD Memory Slot
  • Dual Bluetooth
  • Long Life Batteries


  • S321+ Smart Antenna with 400MHz radio
  • S321+ Battery (2)
  • S321+ Battery Charger
  • Eclipse L-Band Activation
  • Eclipse 10 Hz Activation
  • Raw Data Activation
  • 400 MHz Radio Antenna
  • External Power Cable w/ Alligator Clip
  • I/O Cable w/ USB Host, USB Device, DB9
  • Free Bench-Mark Approved Technical Support
  • Best Hemisphere Pricing Guarantee


The Hemisphere S321+

The Hemisphere S321+ was Bench-Mark’s top-selling surveying receiver until the release of the S631, a consistent favourite of surveyors. At the time of its release it was one of the most versatile and powerful RTK receivers on the market, and encompassed all the cutting-edge features found in high-end GNSS technology, all at a price that makes sense. With the S321+, there’s no need to deplete your budget; this receiver offers a rapid return on investment and longevity that ensures it remains your trusted companion for years to come, keeping you consistently ahead of the competition.

Multi-Constallation GNSS and Triple Frequency: The S321+ is Hemisphere’s multi-GNSS, multi-frequency smart antenna, providing access to GPS, GLONASS, Galileo, BeiDou, and SBAS constellations, all included as standard. No need to activate extra satellite constellations. Furthermore, it’s a triple-frequency receiver, unlocking the power of the L5 signal, which empowers you to achieve performance levels previously unattainable with traditional signals, even in challenging canopy-covered positions. The L5 signal’s strength allows it to penetrate tree canopies, enabling you to capture data from otherwise inaccessible locations.

Built Tough for Surveyors: The S321+ is built to thrive in harsh conditions, encased in a robust aluminum body that can withstand accidental drops of up to 2 meters. It’s designed with accidents in mind and primed to endure. Its IP67 environmental rating ensures it can tackle any field conditions, making it a long-lasting investment that can stand the test of time.

Athena RTK Engine: Powered by Athena RTK technology, the S321+ offers state-of-the-art RTK performance, whether receiving corrections from a static base station or network RTK correction system. With multiple connectivity options, including radio, cell modem, Wi-Fi, Bluetooth, or serial connection, the S321+ delivers centimeter-level accuracy with near-instantaneous initialization and robustness, even in challenging environments.

The S321+ also boasts SureFix technology, ensuring that you consistently obtain the right solution. It runs parallel solutions on the board level, guaranteeing the correctness of your solution with a remarkable 99.999% accuracy. This is the reliable data you can count on every time

Global Corrections with Atlas: The S321+ opens the door to Hemisphere’s Atlas correction service. Atlas provides worldwide centimeter-level correction data via L-band communication satellites. With Atlas, S321+ users can achieve sub-decimeter positioning performance anywhere on Earth, without the need for GNSS or communication infrastructure nearby.

Powerful Communication: The S321+ is equipped with the ability to send and receive corrections via both cell and UHF modems. Its internal 1 W Satel radio is among the best in the industry, boasting an optimal range of 10 km, reducing the need for an external base radio. This internal radio excels in challenging conditions and ensures corrections are received and positions are fixed even in non-line-of-sight situations. It’s the ultimate internal radio.

The internal 4G cell modem expands communication options, enabling corrections to be sent and received via cellular networks. The S321+ is a preferred choice for our StormCaster internet RTK service, allowing for unlimited-range surveys as long as you have cell service. With an internal cellular modem, multiple rovers can operate from a single base at various job sites, making it exceptionally versatile.

In addition to the communication options mentioned, the S321+ broadcasts a Wi-Fi signal for easy setup and updates. With the user-friendly Web-UI, configuring static data, a base, or a rover becomes hassle-free. The S321+ accommodates the way you prefer to work.

Key S321+ Features

  • Multi-Frequency, Multi-GNSS Base Station/Rover
  • GPS, GLONASS, BeiDou, Galileo, and QZSS
  • Athena™ RTK, Atlas® L-Band, and SBAS-Capable
  • Hot Swappable Batteries with 12 Hours of Combined Life
  • Wifi, UHF, Cellular, and Bluetooth Communication
  • 8 GB of Internal Memory for Data Logging, Downloading, and Uploading
  • 572 Channels
  • 1, 2, 4, 5, or 10 Hz Update Rate (20 Hz Optional)
  • Internal Radio (410 – 470 MHz)

The Hemisphere S321+ GNSS Receiver is more than a device; it’s your partner for precision surveying, designed to tackle the most demanding environments and consistently deliver exceptional results. With the S321+, you’re always a step ahead.

16 reviews for Hemisphere S321+ Smart Antenna

  1. John Lohnes, ALS – Vista Geomatics LTD.

    Brian and I took the system out on Sunday and we got radio at 10km. I was really surprised. Brian really likes the system. I will have no problem recommending this to people.

  2. Osama Saadeldin – Bosys Technologies

    Just wanted to thank you for the great support we got from both of you. S321 is working out pretty good. We went out to the site and the equipment performed nicely. We had a SureFix and it stuck throughout the whole survey, and even after dumping it, it picked it up so quickly. It was a beautiful thing…

  3. Andrew Tool – Don-More Surveys

    It works well and I am happy with it. Topcon can be “tricked” by having a good fix then going into a very high multipath area. Hemisphere S321 will recognize the bad solution much faster and dump the fix. Hemisphere is also better at not giving a “bad” fix in an area like woods where there is high blockage and multipath. Topcon will give the fix but as soon as you start to move it will dump the fix. Hemisphere will hold off on giving the fix until it is actually good. There are some physical features that are much better on the s321. Price-point of Hemisphere is also very attractive. Overall I am happy with purchase and would recommend to others.

  4. Erin Miller -Terramatic Technologies Inc

    Just quick note to commend you on the s321 RTK system we just purchased. It works great under tree canopy, it held a SureFIX in thick tree cover and saved me a bunch of time hiking with my total station. The ties I’ve been getting have been extremely good when checking with my total station.

  5. Blair Slater – Clunie Consulting Engineers Ltd.

    We love the new S321 GPS set that we recently received. I would like a quote on a second full GPS set just like the last one.

  6. Benoit B. – Tree Ninja

    The S321 is a great unit.

  7. Daniel E. Garber, RLS, Garber Surveying Service

    My guys seem quite happy. Thank you very much. This will be a lifesaver. Thanks again for your great service. We’ll keep you in mind for future needs.

  8. David M. Brubacher O.L.S. – Strata Surveys

    I really like the S321. Battery life is great, positioning is very repeatable and I’m liking Carlson SurvCE more and more. I’m very happy with it. Performance in and around trees is excellent.

  9. Kevin Fitzpatrick, P.Eng.- Silver Standard Resources Inc.

    The unit is working well, no problems at all. Thanks for getting it to us so promptly.

  10. Peter Llewellyn- DGH Engineering Ltd.

    A great unit. Did even better near trees compared to other GNSS Equipment I’ve used in the past. I will definitely recommend it to others.

  11. Lenny Guyett P.L.S. – GGI

    Everything seems to be going good and rock solid.

  12. Todd Kuntz – City of Saskatoon

    The guys that are using the S321 are very happy with them. They fix quickly and seem to be very accurate.

  13. James Kenny – Pasquini & Associates Consulting

    Just an update, well Rene it’s the best built GPS I’ve ever used, I’m completely impressed with the design, the radio is way better now, and since the S321 firmware update it’s repeatability and accuracy has been dead on!

    Also this Mesa2 works awesome in every aspect daylight, it’s viewability is like nothing else on the market and in wet conditions the screen works flawlessly.

  14. David Sawatzky

    I can tell you everything works flawlessly and we would be in a very tight spot if you hasn’t been able to ship the gear that you did in such short notice ! Thanks a ton!! I love the s321 and I like the 15 min aRTK drift option on the 321, it helps us in a lot of situations.

  15. Shawn Tyler PLS – Dirigo Surveying, Maine

    I just purchased a S631 base and rover system with the field genius software. The equipment and software were very easy to setup and install. Everyone at Benchmark has been very helpful and answered all my questions quickly. They are very knowledgeable about the products they sell. Everything was shipped quickly and all accessories were included to get up and running. I can’t wait to test out my new equipment next week. I would highly recommend anyone to consider using Benchmark for their next purchase. Their prices and support has far exceeded what I get from my local dealers.

  16. Rob Camirand – RC Drone Services

    For the past few years, I have been utilizing the S.321+ unit, transitioning from a different model. My primary application of this device has been in establishing ground control for UAV-based photogrammetry and LiDAR operations. Throughout this period, the S.321+ has demonstrated exceptional performance and reliability. Additionally, the support and assistance provided by the staff at Benchmark have been commendable. Based on my experience, I confidently recommend the S.321+ for professionals in similar fields seeking a dependable and efficient solution.

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