LimeSDR Mini Transmits TV over 35 km

Applications Amateur Radio
1

I set a challenge to members of the British Amateur Television Club (BATC) to transmit TV pictures using a LimeSDR Mini barefoot - without any amplifiers (just an output filter and an aerial). Dave, G4FRE reports that he has now achieved a distance of 35 km on 1255 MHz (the 23cm Amateur band).

On transmit, he used the BATC Portsdown system (a Raspberry Pi driving a LimeSDR Mini), and on receive he used a preamp, Analog Devices Pluto and a PC running SDRAngel. Very impressive for 5 mw output power!

Full details of the Portsdown system here: BATC Portsdown Wiki.

Dave, G8GKQ

limesdr23cm
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4 Likes
2

Awesome. Just wondering, why not use Mini for receiving?

3

No reason why not, but I think that Dave only had one LimeSDR Mini and one Pluto to use for the test.

4

Correct, I only have one mini, and until it is boxed and in a screened case it is too delicate to take portable

Dave

5

Very impressive! I have to wonder how long that transmission took; certainly there’s no way one could transmit more than a few hundred bytes per second with that amount of attenuation.

6

Under 15 seconds before seeing a picture

7

Last weekend the same 35km path was also covered on 2.4GHz with the barefoot Limesdr mini. The receiver did have to be improved by changing from the adalm pluto to the BATC Minituner. Also bigger antennas were needed to cope with the lower limesdr mini output power…transmitter used an 25 element Yagi, the receive antenna was a 40 element yagi

8

Nice going! My LimeSDR mini took me a month to start to be able to do anything with it. First I had to buy a new computer that had Windows 10, then I had to load several peices of software, then correspond with forum members as to why this or that didn’t work. (It comes with zero written anything.) When I finally got the software up and running it would not reset, would not load and was unable to be reprogrammed. I had to return it and I’m not getting another until they come up with a solid set of instructions on how to use it!

9

There is documentation on the wiki for setting up the drivers etc. and beyond this, how to use it depends on what you want to do with it.

10

@Deane if you were to build an SD Card image using the simple instructions here: BATC Portsdown Github, and put the card into a Raspberry Pi 3B, plug in the LimeSDR Mini and log in via ssh, you can have the LimeSDR Mini generating Digital TV signals within an hour (the automated card build takes 45 minutes).

A specialised application I know, but it shows what can be done if you steer clear of the Windows GUI.

Dave, G8GKQ

11

I’m just pointing out it would have been nice if there was just one bit of paper that came with it with the URL to the Wiki. Yes, the wiki is very helpful.

12

lime_mini_boxed
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The lime SDR mini is now ruggedised and ready for road trips

13

cooling?

14

Cooling not been needed so far in its month of intermittent service. Would probably need it if it was continually transmitting

Dave

15

OK,
but in case you decide to measure real temps inside
this may help -> Heat Sinks on Limesdr-mini
put just few layers bellow PCB and whole case is your cooler.