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Tuesday, April 17, 2018

What is it? Lime SDR Mini First Look

The excitement about the LimeSDR Mini was very high and I could not wait to get my hands-on mine as part of the early backer program through Crowdsupply.  Compared to the original Lime SDR, the level of frustration has been a bit higher though, so I have waited in sharing my experiences as to not add further “internet reader confusion”.

What is a Lime SDR?

Lime Microsystems is a semiconductor and single board software defined radio (SDR) vendor headquartered in the United Kingdom.  The LMS7002M field programmable SDR (FPRF) chip is the heart of the Lime SDR and Lime SDR MINI. This chip is essentially a radio on a chip that enables wide band frequency applications. The Lime SDR transceivers are primarily marketed to the professional RF design and integration ecosystem.  

Ham radio operators are not the intended core market of Lime Micro, but there are many boards currently in use by those in the amateur radio hobby since both devices are open source architecture which appeals to both those interested in hardware and software aspects of software defined radio. 

The Lime SDR MINI is a nice step up from the inexpensive  $20 RTL SDR dongles that are limited to a maximum of 3 MHz wide bandwidth since the Lime SDR MINI can show 30 MHz wide at one time.

(RTL SDR dongle shown using SDR Console software to decode a FM broadcast
station and its sub carrier and RDS information)
The Lime SDR MINI is the latest product offering by Lime Micro and provides a nominal 15 mW transmit power output and receive sensitivity like that of common VHF/UHF hand held radios. The transceiver can operate anywhere from 10 MHz to 3800 MHz at full duplex and up to almost 31 MHz bandwidth.

Some Curated Material

Here are some helpful links to ensure yoy did not end up with a defective piece of equipment since documentation and support is not well defined which leads to early adopters blaming Lime Micro for a "busted unit" when its more a case of "user issues".

My goal was to utilize the Lime SDR MINI under a Windows environment compared to my preferred Linux distribution, Ubuntu for a variety of applications which will be further reviewed here on in future articles.

Helpful LimeSD Mini Files

The correct USB device driver for the Lime SDR MINI - The Lime SDR and the Lime SDR MINI use different USB drivers. My installation of Windows 10 64-bit version was able to find the right USB 3.0 driver right away, but I changed it to the version offered by FTDI, so it appears in my device manager more accurately. The original Lime SDR used a driver provided by Cypress Semiconductors which made it slightly more compatible with popular SDR software applications such as SDR# and SDRangel.

Here is where you can download the correct USB 3.0 drivers for Windows for the Lime SDR Mini

Latest Firmware (Gateware) - My LimeSDR MINI came loaded with version 1.18 in late January 2018. I upgraded to 1.22 and then to 1.24. Here is where to find the latest firmware, which is really called gateware (new term to me)

Under the Limesuite 18.04 folder is where to find the 1.24 version files. Future new versions should be found here as well.

How to upgrade the LimeSDR MINI gateware - Before doing this, you should use the LimeSuite to verify your Lime SDR Mini works. There has been a lot of confusion the past few months as early adopters got frustrated in trying to get the Lime SDR MINI under Windows. Linux did not have as much an issue.

At the time of this article, version released on April 6th, 2018 was used.

After installing Limesuite and ensuring your USB driver is correct, go to “Options” and select “Connection Options”.  Your serialized Lime SDR MINI should appear like below.  Click the “Connect” button.

Now, let’s run a basic test to read the internal operating temperature of the Lime SDR Mini.

Quick Lime SDR MINI Test - A helpful application which automates the myriad test parameters in the Lime Suite can be found here and is pretty easy to run.

Upgrading the Lime SDR MINI Gateware - It is simple to upgrade the gateware. Here is where you go to check which version you currently have installed

Receiving your first transmission with the Lime SDR MINI under a Windows environment -The easiest software to get working with the Lime SDR MINI is the SDR Console Ver. 3 provided here:

Next Steps

Receiving signals in the next article in the Lime SDR MINI series here on HVDN.

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