# Max gain - LimeSDR Mini

**URL:** <https://discourse.myriadrf.org/t/max-gain-limesdr-mini/6079>\
**Category:** LimeSDR\
**Created:** [10 May 2020 18:46 UTC](https://discourse.myriadrf.org/t/max-gain-limesdr-mini/6079 "2020-05-10T18:46:08Z")\
**Posts on this page:** 12\
**Page:** 1

<div class="post-metadata">

**Author:** ![BlackF](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/blackf/32/3251_2.png) [@BlackF](https://discourse.myriadrf.org/u/BlackF)\
**Post date:** [10 May 2020 18:46 UTC](https://discourse.myriadrf.org/t/max-gain-limesdr-mini/6079/1 "2020-05-10T18:46:08Z")

</div>

Hello, trying to set the max gain on my LimeSDR mini but can’t go over 0.8421052631578947. Is that normal?  
I’m using the native library.

```
print(cyLimeLib.set_normalized_gain(1))
print(cyLimeLib.get_normalized_gain())

0.8421052631578947

```

(This is for TX)

Changing centre frequency or LPF band wont bring different results

This is the code:  
import cyLimeLib

```
cyLimeLib.open()
cyLimeLib.init()

cyLimeLib.set_normalized_gain(1)
cyLimeLib.disable_all_channels()
cyLimeLib.set_center_frequency(2000e6)
cyLimeLib.set_lpf_bandwidth(20e6)

print("LPF Band", cyLimeLib.get_lpf_bandwidth())
print("Centre Freq", cyLimeLib.get_center_frequency())
print(cyLimeLib.get_normalized_gain())

cyLimeLib.close()

```

Output:  
Reference clock 40.00 MHz  
Filter calibrated. Filter order-4th, filter bandwidth set to 20 MHz.Real pole 1st order filter set to 2.5 MHz. Preemphasis filter not active  
TX LPF configured  
LPF Band 20000000.0  
Centre Freq 2000000000.0  
0.8421052631578947

---

<div class="post-metadata">

**Author:** ![Zack](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/zack/32/89_2.png) [@Zack](https://discourse.myriadrf.org/u/Zack)\
**Post date:** [18 May 2020 07:28 UTC](https://discourse.myriadrf.org/t/max-gain-limesdr-mini/6079/2 "2020-05-18T07:28:31Z")

</div>

Hi @BlackF,

Let us check.

---

<div class="post-metadata">

**Author:** ![Garmus](https://avatars.discourse-cdn.com/v4/letter/g/a183cd/32.png) [@Garmus](https://discourse.myriadrf.org/u/Garmus)\
**Post date:** [19 May 2020 08:21 UTC](https://discourse.myriadrf.org/t/max-gain-limesdr-mini/6079/3 "2020-05-19T08:21:55Z")

</div>

Hey @BlackF,

I don’t see the result of the return value from the set\_normalized\_gain(1) function which could and, I assume, in your case actually failed. Getting normalized gain value of ~0.84 would mean TRFPAD gain was set to 52(max value) and TBBIAMP gain failed.

Can you post results of [LimeQuickTest](https://wiki.myriadrf.org/LimeQuickTest) ?

---

<div class="post-metadata">

**Author:** ![yt7pwr](https://avatars.discourse-cdn.com/v4/letter/y/ecd19e/32.png) [@yt7pwr](https://discourse.myriadrf.org/u/yt7pwr)\
**Post date:** [21 May 2020 09:00 UTC](https://discourse.myriadrf.org/t/max-gain-limesdr-mini/6079/4 "2020-05-21T09:00:09Z")

</div>

Sometime between 19.04 and 20.01 releses TX functions are changed. I had fully working TX code with 19.04 dll but after 20.01 output signal level is lower. Also TX NCO settings have no effect and TX LPF bandwidth is broken (increased BW decreases output level!). Positive side is reduced CPU usage.  
My OS is Win10, hw LimeSDR-USB and frequency is 144MHz. I did not notice any change in function definitions. Any idea?

---

<div class="post-metadata">

**Author:** ![andrewback](https://avatars.discourse-cdn.com/v4/letter/a/22d042/32.png) [@andrewback](https://discourse.myriadrf.org/u/andrewback)\
**Post date:** [21 May 2020 15:28 UTC](https://discourse.myriadrf.org/t/max-gain-limesdr-mini/6079/5 "2020-05-21T15:28:07Z")

</div>

@Garmus may be able to advise.

---

<div class="post-metadata">

**Author:** ![BlackF](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/blackf/32/3251_2.png) [@BlackF](https://discourse.myriadrf.org/u/BlackF)\
**Post date:** [28 May 2020 23:10 UTC](https://discourse.myriadrf.org/t/max-gain-limesdr-mini/6079/6 "2020-05-28T23:10:54Z")

</div>

Hello,

This is the output of my script

**Python script**

> ```
> import cyLimeLib
> cyLimeLib.open()
> cyLimeLib.init()
> 
> print(cyLimeLib.set_normalized_gain(1))
> cyLimeLib.disable_all_channels()
> cyLimeLib.set_center_frequency(2000e6)
> cyLimeLib.set_lpf_bandwidth(20e6)
> print("LPF Band", cyLimeLib.get_lpf_bandwidth())
> print("Centre Freq", cyLimeLib.get_center_frequency())
> print(cyLimeLib.get_normalized_gain())
> 
> cyLimeLib.close()
> 
> ```

**Output**

> Reference clock 40.00 MHz  
> 0  
> Filter calibrated. Filter order-4th, filter bandwidth set to 20 MHz.Real pole 1st order filter set to 2.5 MHz. Preemphasis filter not active  
> TX LPF configured  
> LPF Band 20000000.0  
> Centre Freq 2000000000.0  
> 0.8421052631578947

**The set\_normalized\_gain definition**

> ```
> cpdef int set_normalized_gain(float_type gain):
> return LMS_SetNormalizedGain(_c_device, IS_TX, CHANNEL, gain)
> 
> ```

**LimeQuickTest**

> ```
> [TESTING STARTED]
> ->Start time: Fri May 29 02:10:19 2020
> 
> ->Device: LimeSDR Mini, media=USB 3.0, module=FT601, addr=24607:1027, serial=1D588F01B6A2F2
> Serial Number: 1D588F01B6A2F2
> 
> [Clock Network Test]
> ->REF clock test
> Test results: 49150; 62347; 10008 - PASSED
> ->VCTCXO test
> Results : 6711054 (min); 6711215 (max) - PASSED
> ->Clock Network Test PASSED
> 
> [FPGA EEPROM Test]
> ->Read EEPROM
> ->Read data: 13 0A 16 13 0A 16 02
> ->FPGA EEPROM Test PASSED
> 
> [LMS7002M Test]
> ->Perform Registers Test
> ->External Reset line test
> Reg 0x20: Write value 0xFFFD, Read value 0xFFFD
> Reg 0x20: value after reset 0x0FFFF
> ->LMS7002M Test PASSED
> 
> [RF Loopback Test]
> ->Configure LMS
> ->Run Tests (TX_2 -> LNA_W):
> CH0 (SXR=1000.0MHz, SXT=1005.0MHz): Result:(-12.8 dBFS, 5.00 MHz) - PASSED
> ->Run Tests (TX_1 -> LNA_H):
> CH0 (SXR=2100.0MHz, SXT=2105.0MHz): Result:(-13.7 dBFS, 5.00 MHz) - PASSED
> ->RF Loopback Test PASSED
> 
> => Board tests PASSED <=
> 
> Elapsed time: 2.47 seconds
> 
> ```

---

<div class="post-metadata">

**Author:** ![andrewback](https://avatars.discourse-cdn.com/v4/letter/a/22d042/32.png) [@andrewback](https://discourse.myriadrf.org/u/andrewback)\
**Post date:** [5 August 2020 07:57 UTC](https://discourse.myriadrf.org/t/max-gain-limesdr-mini/6079/7 "2020-08-05T07:57:27Z")

</div>

> [@yt7pwr](#):
>
> Sometime between 19.04 and 20.01 releses TX functions are changed. I had fully working TX code with 19.04 dll but after 20.01 output signal level is lower. Also TX NCO settings have no effect and TX LPF bandwidth is broken (increased BW decreases output level!).

Could you please test with the new 20.07.1 release and let me know if you still encounter these issues.

---

<div class="post-metadata">

**Author:** ![BlackF](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/blackf/32/3251_2.png) [@BlackF](https://discourse.myriadrf.org/u/BlackF)\
**Post date:** [13 August 2020 12:05 UTC](https://discourse.myriadrf.org/t/max-gain-limesdr-mini/6079/8 "2020-08-13T12:05:08Z")

</div>

Hello,  
The new 20.07.2 version does help with the intermittent, temperature sensitive LimeQuickTests.

As for my initial post, I still get  
0.8421052631578947

set\_normalized\_gain(1) returns “0” as per my last comment above.

I tried running some more test with the LMS\_GetGaindB call. Similar results.

**Python Code (configured for TX):**

```
#! /usr/bin/python3

import cyLimeLib

cyLimeLib.open()
cyLimeLib.init()

cyLimeLib.disable_all_channels()
cyLimeLib.set_center_frequency(2000e6)
cyLimeLib.set_lpf_bandwidth(20e6)

print("LPF Band", cyLimeLib.get_lpf_bandwidth())
print("Centre Freq", cyLimeLib.get_center_frequency())

print("Setting new normalised GAIN to 1, status: ", cyLimeLib.set_normalized_gain(1))
print("Printing Current Normalised GAIN: ", cyLimeLib.get_normalized_gain())
print("Printing Current GAINdB value: ", cyLimeLib.get_gaindB())
print("Setting new GAINdB to 70, status: ", cyLimeLib.set_gaindB(70))
print("Printing Current GAINdB value: ", cyLimeLib.get_gaindB())

cyLimeLib.close()

```

**Output**

```
Reference clock 40.00 MHz
Filter calibrated. Filter order-4th, filter bandwidth set to 20 MHz.Real pole 1st order filter set to 2.5 MHz. Preemphasis filter not active
TX LPF configured
LPF Band 20000000.0
Centre Freq 2000000000.0
Setting new normalised GAIN to 1, status: 0
Printing Current Normalised GAIN: 0.8421052631578947
Printing Current GAINdB value: 64
Setting new GAINdB to 70, status: 0
Printing Current GAINdB value: 64
```

---

<div class="post-metadata">

**Author:** ![andrewback](https://avatars.discourse-cdn.com/v4/letter/a/22d042/32.png) [@andrewback](https://discourse.myriadrf.org/u/andrewback)\
**Post date:** [14 August 2020 10:30 UTC](https://discourse.myriadrf.org/t/max-gain-limesdr-mini/6079/9 "2020-08-14T10:30:19Z")

</div>

@Garmus could you take a look, please.

---

<div class="post-metadata">

**Author:** ![BlackF](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/blackf/32/3251_2.png) [@BlackF](https://discourse.myriadrf.org/u/BlackF)\
**Post date:** [22 August 2020 20:37 UTC](https://discourse.myriadrf.org/t/max-gain-limesdr-mini/6079/10 "2020-08-22T20:37:41Z")

</div>

Just to assist with the investigation, I added some extra logging to the following functions and recompiled master

-\> LMS7002M::SetTRFPAD\_dB  
-\> LMS7002M::GetTRFPAD\_dB  
-\> LMS7002M::SetTBBIAMP\_dB  
-\> LMS7002M::GetTBBIAMP\_dB

As followed :

**LMS7002M::SetTRFPAD\_dB**

```
int LMS7002M::SetTRFPAD_dB(const float_type value)
{
    const double pmax = 52;
    int loss_int = (pmax-value)+0.5;

    //different scaling realm
    if (loss_int > 10) loss_int = (loss_int+10)/2;

    //clip
    if (loss_int > 31) loss_int = 31;
    if (loss_int < 0) loss_int = 0;

    int ret = 0;
    ret |= this->Modify_SPI_Reg_bits(LMS7param(LOSS_LIN_TXPAD_TRF), loss_int);
    ret |= this->Modify_SPI_Reg_bits(LMS7param(LOSS_MAIN_TXPAD_TRF), loss_int);

    Log(LOG_INFO, "SetTRFPAD_dB: loss_int: %i", loss_int);

    return ret;
}

```

**LMS7002M::GetTRFPAD\_dB**

```
float_type LMS7002M::GetTRFPAD_dB(void)
{
    const double pmax = 52;
    auto loss_int = this->Get_SPI_Reg_bits(LMS7param(LOSS_LIN_TXPAD_TRF));
    Log(LOG_INFO, "GetTRFPAD_dB: loss_int: %g return: %g return2: %g", loss_int, pmax-10-2*(loss_int-10), pmax-loss_int);
    if (loss_int > 10) return pmax-10-2*(loss_int-10);
    return pmax-loss_int;
}

```

**LMS7002M::SetTBBIAMP\_dB**

```
int LMS7002M::SetTBBIAMP_dB(const float_type gain)
{
    int ind = this->GetActiveChannelIndex()%2;
    if (opt_gain_tbb[ind] <= 0)
    {
        if (CalibrateTxGain(0,nullptr)!=0) //set optimal BB gain
            return -1;
        if (std::fabs(gain) < 0.2) // optimal gain = ~0dB
            return 0;
    }

    int g_iamp = (float_type)opt_gain_tbb[ind]*pow(10.0,gain/20.0)+0.4;
    Log(LOG_INFO, "SetTBBIAMP_dB: g_iamp: %i opt_gain_tbb[ind]: %g gain: %g", g_iamp, opt_gain_tbb[ind],gain);
    int modify_return = Modify_SPI_Reg_bits(LMS7param(CG_IAMP_TBB),g_iamp > 63 ? 63 : g_iamp<1 ? 1 :g_iamp , true);
    Log(LOG_INFO, "SetTBBIAMP_dB: Modify_SPI_Reg_bits: %i", modify_return);

    return 0;
}

```

**LMS7002M::GetTBBIAMP\_dB**

```
float_type LMS7002M::GetTBBIAMP_dB(void)
{
    int g_current = Get_SPI_Reg_bits(LMS7param(CG_IAMP_TBB),true);
    int ind = this->GetActiveChannelIndex()%2;

    if (opt_gain_tbb[ind] <= 0)
    {
        if (CalibrateTxGain(0,nullptr)!=0)
            return 0.0;
        Modify_SPI_Reg_bits(LMS7param(CG_IAMP_TBB),g_current, true); //restore
    }
    Log(LOG_INFO, "GetTBBIAMP_dB: g_current: %g", (float_type)g_current);
    Log(LOG_INFO, "GetTBBIAMP_dB: opt_gain_tbb: %g", (float_type)opt_gain_tbb[ind]);
    Log(LOG_INFO, "GetTBBIAMP_dB: return: %g", 20.0*log10((float_type)g_current / (float_type) opt_gain_tbb[ind]));

    return 20.0*log10((float_type)g_current / (float_type) opt_gain_tbb[ind]);
}

```

**When I run set\_normalized\_gain(0) I get:**

```
SetTRFPAD_dB: loss_int: 31
GetTRFPAD_dB: loss_int: 0 return: 21 return2: 0
SetTBBIAMP_dB: g_iamp: 16 opt_gain_tbb[ind]: -12 gain: 63
SetTBBIAMP_dB: Modify_SPI_Reg_bits: 0

```

**When I run get\_normalized\_gain() I get:**

```
GetTRFPAD_dB: loss_int: 0 return: 21 return2: 0
GetTBBIAMP_dB: g_current: 16
GetTBBIAMP_dB: opt_gain_tbb: 63
GetTBBIAMP_dB: return: -11.9044

```

**When I run set\_normalized\_gain(1) I get:**

```
SetTRFPAD_dB: loss_int: 0
GetTRFPAD_dB: loss_int: 62 return: 52 return2: 62
SetTBBIAMP_dB: g_iamp: 251 opt_gain_tbb[ind]: 12 gain: 63
SetTBBIAMP_dB: Modify_SPI_Reg_bits: 0

```

**When I run get\_normalized\_gain() I get:**

```
GetTRFPAD_dB: loss_int: 62 return: 52 return2: 62
GetTBBIAMP_dB: g_current: 63
GetTBBIAMP_dB: opt_gain_tbb: 63
GetTBBIAMP_dB: return: 0

```

I tried emulating the same test with SoapySDR but Soapy seems to work as expected.

**Soapy python code:**

```
print("Setting TX gain to maximum 64")
sdr.setGain(SOAPY_SDR_TX,0, 64);
print("Gain after ", sdr.getGain(SOAPY_SDR_TX,0))
print("PAD: ", sdr.getGain(SOAPY_SDR_TX,0, "PAD"))
print("IAMP: ", sdr.getGain(SOAPY_SDR_TX,0, "IAMP"))

```

**Output:**

```
Setting TX gain to maximum 64
[INFO] SetTRFPAD_dB: loss_int: 0
[INFO] GetTRFPAD_dB: loss_int: 62 return: 52 return2: 62
[INFO] SetTBBIAMP_dB: g_iamp: 8 opt_gain_tbb[ind]: 12 gain: 2
[INFO] SetTBBIAMP_dB: Modify_SPI_Reg_bits: 0
[INFO] GetTRFPAD_dB: loss_int: 62 return: 52 return2: 62
[INFO] GetTBBIAMP_dB: g_current: 8
[INFO] GetTBBIAMP_dB: opt_gain_tbb: 2
[INFO] GetTBBIAMP_dB: return: 12.0412
[INFO] GetTRFPAD_dB: loss_int: 62 return: 52 return2: 62
[INFO] GetTBBIAMP_dB: g_current: 8
[INFO] GetTBBIAMP_dB: opt_gain_tbb: 2
[INFO] GetTBBIAMP_dB: return: 12.0412
Gain after 64.04119982655925
[INFO] GetTRFPAD_dB: loss_int: 62 return: 52 return2: 62
PAD: 52.0
[INFO] GetTBBIAMP_dB: g_current: 8
[INFO] GetTBBIAMP_dB: opt_gain_tbb: 2
[INFO] GetTBBIAMP_dB: return: 12.0412
IAMP: 12.041199826559248

```

I get a correct value of 12 for IAMP

Hope this helps even a bit

---

<div class="post-metadata">

**Author:** ![BlackF](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/blackf/32/3251_2.png) [@BlackF](https://discourse.myriadrf.org/u/BlackF)\
**Post date:** [23 August 2020 00:40 UTC](https://discourse.myriadrf.org/t/max-gain-limesdr-mini/6079/11 "2020-08-23T00:40:52Z")

</div>

The discrepancy between the native library and SoapySDR seems to happen in **LMS7002M::CalibrateTxGain**

In the native library the value of “opt\_gain\_tbb[ind]” is 63 while in soapy is 2. This seems to come from the while(GetRSSI() \< 0x7FFF) loop.

I don’t think I can go any deeper than that

_ **Edit:** _  
FOUND THE ISSUE!!!  
I was forgetting to call **LMS\_EnableChannel** after the initialisation and it looks like this is messing the TX calibration. After I did, I get a correct value of 1 !

---

<div class="post-metadata">

**Author:** ![yt7pwr](https://avatars.discourse-cdn.com/v4/letter/y/ecd19e/32.png) [@yt7pwr](https://discourse.myriadrf.org/u/yt7pwr)\
**Post date:** [24 August 2020 10:42 UTC](https://discourse.myriadrf.org/t/max-gain-limesdr-mini/6079/12 "2020-08-24T10:42:02Z")

</div>

Problem was solved before latest release. I was experiment with timeout value in receive callback function and I forgot about it. Exotic problems started with 20.01 but after I return to default value of 1000mS everything return back to normal.  
p.s. not sure am I first to use LimeSDR for EME but yesturday managed to make two way contact with RX1AS on Moonrise (distance was about 1700km).  
My setup:

- radio: LimeSDR-USB, RX1\_L unmodifed input, TX0\_1 output
- antena: 11el 3WL YU7EF design, rotated by Azimuth only
- LNA: PGA103+ 0.7dB NF
- PA: first stage RA30H1317M1 (30W module), final stage SSPA BLF578 (about 500W output)
- software: LimeSDR# x64 + LimeSuite 20.07 + MSHV 2.42

LimeSDR worked all day without problem.