DMR Hotspot from SharkRF

Amateur adoption of Digital Mobile Radio (DMR) continues to increase, with a number of new innovations playing out. It was way back in 2012 when I wrote this article about DMR for CQ VHF Magazine: TRBO Hits the Amateur Bands. 

A few years ago, I picked up some used MOTOTRBO gear to use on our local DMR repeater system (MOTOTRBO is Motorola’s version of DMR). Here in Colorado, the Rocky Mountain Ham Radio group has been instrumental in establishing a great network of DMR repeaters, a real asset for Colorado radio amateurs. See Rocky Mountain Ham Radio TRBO/DMR Network.  Worldwide, the DMR-MARC organization has created a robust network of MOTOTRBO repeaters in over 60 countries.

A more recent development is the establishment of the BrandMeister Network, which promotes more of a homebrew approach to DMR. This evening, the BrandMeister dashboard shows 634 industrial repeaters (commercial equipment), 263 homebrew repeaters and over 1300 hotspots of various types.  A variety of DMR hotspots are available, including the DV4mini. I’m not going try to list all of the hotspots available as I’m sure I’ll miss something.  The SharkRF openSPOT caught my attention because of this excellent review by John ‘Miklor’ K3NXU. Because of its popularity, the openSPOT is on backorder (price: 182.5 Euro).

This HamRadioConcepts video walks through the setup and basic operation.

I thought the openSPOT would be a good widget to have around the shack. It is a standalone hotspot, so I don’t have to dedicate a computer to it. Also, it is very turnkey…no assembly required…but some configuration to work out. Its user interface is a web page that you access via your local network…nicely done. I got it working in less than one hour and have been fiddling around with it ever since.

Hotspots are a funny item. They have very limited RF range, so their main purpose is to provide local RF access into the network (just like your Wi-Fi hotspot). One role they play is to provide fill-in coverage when no repeater is available. Another role they fill is being a personal device that can be connected to your favorite reflector or talk group.

I should point out that the openSPOT also operates as a D-STAR and Yaesu Fusion (YSF) hotspot. You just change the configuration of the modem and it starts speaking the selected modulation. More surprising is that I was able to use a YSF handheld radio to talk to the openSPOT which routed me to a DMR talkgroup. Yes, a Yaesu YSF radio talking on DMR.

The first thing I noticed when listening to some of the more active talk groups is that it seems like every person getting on the system said “I just got this Tytera MD-380 radio and you are my first DMR contact.” OK, sometimes it was a Connect Systems or Motorola radio but the MD-380 at around $100 is having a big impact. I picked up an MD-380 and while its not quite as nice as my Motorola, I really do like the radio. (Note that there are other low cost DMR radios that have serious technical issues.) There will be other radios on the market…the technology will keep improving and improved models will hit the market. Right now, everyone is wondering who will create a good dualband 2m / 70cm transceiver for DMR.

I see some very strong technology and market trends in play here that are going to impact the ham radio world. First off, DMR is a true industry standard (ETSI),  well designed and documented. Second, we are seeing multiple radio vendors offering competitive, low cost transceivers. Third, there is high quality commercial repeater gear available from land mobile providers such as Motorola and Hytera. But there’s one more thing that really tops this off: the number of ham-built products emerging that are focused on DMR. This is classic ham radio adaptation and innovation that leverages commercial gear for ham radio use.

Stay tuned…this is going to be interesting!

73, Bob K0NR

6 Replies to “DMR Hotspot from SharkRF”

  1. Thanks for the review, Bob!

    Another radio that may be of interest to hams is the CS750. I just picked up a CS-750 UHF DMR radio and I am very impressed with the build quality, programming tools, signal quality and usability. Connect Systems is aiming these radios at the ham market, so there are lots of features you can program. The 2000 channel capacity and 65,000+ contact capacity means I can program frequencies in for other areas without having to overwrite my local favorites. These are more expensive at $239 for the CS750 and the new CS760 with the big color screen is $299. I picked mine up on the QRZ swapmeet forum for quite a bit less than that.

    Living on the west side of Pikes Peak, there are Colorado RMHAM repeaters I can hit, but no Brandmeister repeaters, so I am looking at getting a hotspot. I am studying both the DV4Mini and the OpenSPOT and your review is giving me some valuable info.

    One option I want to explore is sticking an inexpensive amp on the hotspot and boosting the output to a watt or two. That would give enough range, especially with a decent antenna to cover an incident command or even serve as an emergency team hotspot on a hilltop. Do you know if the OpenSPOT will handle multiple HTs?

    • Thanks for mentioning the CS750 and CS760. I don’t have any experience with them but they do get used by hams.

      The memory capacity of the MD380 is definitely an issue as the number of radio IDs keeps increasing. I am a little less worried about storing enough frequencies but that is also a factor.

      I would proceed with caution on adding an amplifier to a hotspot. The amp will need to turn on fast enough to handle the TDMA timing.

      I am not sure about handling multiple HTs on the openSPOT but I think that will work. However, there is only one radio ID programmed into the openSPOT, so that seems to imply that all user radios will show up with that ID on the network.

      73, Bob K0NR

      • I just updated the firmware in the openSPOT to v 101, lots of new features including voice status messages.

        Bob K0NR

  2. The SharkRF OpenSpot does not have a Wi-Fi connection on board, only wired Ethernet. For most of my use, this does not matter. However, I need to do a demo of the device at a radio club meeting which will need to use Wi-Fi.

    I purchased the most awesome device for translating Ethernet to Wi-Fi: TP-Link N300. It works great and I’ll use it for other applications.

    Check it out at Amazon:

    TP-Link N300 Wireless Wi-Fi Mini Router with Range Extender/Access Point/Client/Bridge Modes (TL-WR810N)

  3. While I have not used the TP-N300, I have other TP networking gear and it is solid stuff.
    That is a good point about the switching speed of the amp – with 30 msec time windows, the amp is going to need to be able to turn on and off within a 100 microseconds or so, I think. I saw these cheap UHF amps on eBay that putt out a watt or so and my mind started to wander 🙂 I check the specs and see. Or maybe just buy one of the little things and try it out.
    In the meantime, I read the OpenSPOT docs more closely. I conclude it is an access point into the DMR/D-STAR/YSF network of your choice, linking into a network “bridge” or “server” via the internet. At least on DMR, it uses a fixed ID. No matter what radio talks to it, it will use that ID on the network. I will put it into my research log to see if anyone has tried using multiple radios with different ids (and maybe attempting to use different talk groups) to communicate via the openSPOT

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