4G (LTE) Home Repeater With LimeSDR

with reference https://www.instructables.com/id/4G-LTE-Home-Repeater-With-LimeSDR/ . unfortunately 4G_repeater.ini file is missing . Kindly share 4G_repeater.ini file with me if any respectable member from the forum has available . It will be a good start point for me .

I don’t think it was ever public. I have checked the Wayback and the link was broken back when that article was new.
I will try to recreate it as one of my next projects. @TegwynTwmfatt has an almost working version here somewhere. It needs a few tweaks. I did have it seemingly working but I was just fiddling around and didn’t take notes or anything so I have to approach it as new again. But I remember what I was doing and know the next step is to try it on some instruments with a test signal.

@FRkhan you need to check out this project: https://hackaday.io/projects/hacker/184263
… and you will be able to see .ini files etc that you need.

I did some tests on @TegwynTwmfatt 's ini. I does repeat a modulated signal. The gain settings are VERY picky. Using LimeSuiteGUI I was able to find settings that allowed a voice FM modulation tho go through. I was using a low powered transmitter at 500mW, cross polarized, that was still too strong. The FFT display showed a strong peak even when nothing was transmitting or being received. My SpecAn shows a peak at center frequency with large sidebands when nothing is transmitting. This changes into a large peak with low sidebands when repeating. Something is still not right with this. I had changed the frequencies to something close to 70cm that my radio could Tx.
I can do a more precise test once I set up an attenuator so I can do a track and read. Then I can see what the gain vs bandwidth is. I can directly inject a -60db signal on the Rx and see what the Tx is sending out over a range of frequencies around center. I can use the desired frequency that way. No knocks on the door from the phone police.

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Nice work @Axeman. Have you any ideas on how to improve it?

I didn’t need the attenuator as long as the output is below 0.5mW.
This is the same pattern I see if it is just amplifying noise. The peak with the two plateaus. The 50uV signal being swept into the LNAL input equates to -73dBm, the lowest dotted horiz. line on the display. The peak is about -16dBm, The sides are about -24 to -28.
I used the TRX gain tab to adjust the gains. I would like to know why this is not just a flat-ish line.
I guess the only way to upload the ini file is as text.
The next step is to get both UL and DL channels going. This is only channel A.

Single channel INI file.

@Axeman I think you can reduce that central peak using the dc correction sliders in lime suite although one of the latest versions the sliders were not working :(.
The dc calibration register in the ini file was set for my LimeSDR so yours will be different.

@TegwynTwmfatt It worked using the auto correction in LimeSuiteGui. It still gets a dip in the middle at lower inputs but that goes away as the level increases. There is a lot of ripple in the response at the edged that goes away at higher levels too.
Making the jump between DL and UL. I tried two different ways. I put the LO at the center between the two bands and used the NCO to go down on A and up on B. I did not like the response of that. Then I tried setting the LO to the higher band and downconvert on A for the lower band. That looked OK.
INI file: You can only get 30MHz separation this way. I will go back and experiment more with other means.
The signal starts to saturate at around 1mV. it looks best at between 75uV and 300uV. To be good on a weak signal I have to get that down a lot, like /10.

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@Axeman what amplifier are you planning to use for transmit to the base station?
I’d strongly recommend the TQM879028 which is available as an evaluation board at a very reasonable price. I’ve got Arduino code to control it if you go down that route and my offer for a free populated repeater pcb is still open!

You sourced from producer or from some of distributors like Mouser?
At what cost?

@9a4db yes it’s on mouser at $160 which is good value compared to most other similar boards:


Most importantly, Quorvo supply really useful information on the data sheets and go a few steps further in this regard to the competition. I’ve also got hackable PCBs coming this week that use 2 of these chips and need testing on band 13 somehow. Can the lime SDR be used as a signal generator.?

Thank you for information.
Here in EU cost bit more 172,80 € (euro) cca $204
Yes Lime can be used like signal generator,
just question of accurate calibration and signal purity…
Here have one Agilent E7495B GSM test set up to 2,7 GHz and ordered ERASynth+ on Crowd

@9a4db I guess I would set it up in gnu radio?

yes, why not…
or SDRAngel now is usable with Lime

I will most likely build my own. The LNAs cost less than $5 And the other components are cheaper. I am going to make a board with switching that will have various filters and amps for all of the inputs and outputs. Use an SBC like an Arduino or something else to control it. One of the hats I wear is that of of a PLC/HMI programmer. Like for your still.:wink: Paying projects come first, though.

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I found out something important. Tx and Rx upload/download must be set opposite on the same channel at the same frequency. There must be some logical reason for this but it escapes me.
I have updated the Band_13 (VZ) INI file. The old one didn’t work. The new one is probably a good replacement for the missing INI from the OP’s question. The band parameters, ie frequency, offset, maybe bandwidth, will have to be set.

@Axeman that sounds good! I think I’ll have a go at using switched filters in a month or two once I’ve got the main concept sorted.

I have been doing some fine tuning to my Band13LTE_2x.ini file. I update it every time I find an improvement to it.
For some reason, if I have a certain setting to repeat a signal to the left of the LO center, in this case 766.5Mhz, those same settings do not yield the same results when they are used to the right of center. I also find that not all of the settings I have made return when I restore the INI file. I think LimeSuiteGUI allows you to make setting that do not make sense when restored.
I am dealing with some cable issues that are vexing me now, if I move some cabling the signal changes a lot, and will get back to this later.

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So you set up convert and down convert to a ‘middle’ frequency? If so, this is supposed to be more ‘efficient’.

Are you planning to use an antenuator on input to rx on the channel transmitting to base station?