Multiple critical bugs in qt-dab 6.10's SoapySDR device handler prevent proper operation with UHD-based devices (LibreSDR/USRP B210).

[Supermagnum]

Environment

• OS: Ubuntu 24.04
• qt-dab version: 6.10
• Device: LibreSDR B210mini (UHD-compatible)
• SoapySDR: 0.8.1
• UHD: 4.6.0 / 4.9.0

Bugs Found

Bug 1: Sample Rate Selection Failure

File: sources/devices/soapy/soapy-handler.cpp
Line: 155-157
Severity: Critical

The findDesiredRange() function fails to find 2.048 MHz in the B210's supported sample rate ranges, causing "no suitable samplerate found" error.

Root Cause:

• B210 returns continuous rate ranges, not discrete values
• findDesiredRange() checks if 2048000 is within range min/max but the function logic has issues
• Falls back to 2.285714 MHz (16/7 MHz) which is incompatible with DAB

Current Code:

int resultRate = findDesiredRange (sampleRange, length);
if (resultRate < 0) 
   throw (device_exception ("no suitable samplerate found"));

Workaround Applied:

int resultRate = 2048000;  // Force exact DAB sample rate

Proper Fix Needed:

• Improve findDesiredRange() to handle continuous ranges properly
• Or allow manual sample rate override in GUI
• Add debug output showing available ranges

---

Bug 2: Audio Device Selected Instead of SDR

File: sources/devices/soapy/soapy-handler.cpp
Lines: 50-63
Severity: Critical

Device enumeration loop breaks after first device found, which is often an audio device, not the SDR.

Current Code:

for (size_t i = 0; i < length; i++) {
   // ... enumerate device ...
   if (QString (results [i]. keys [j]) == "driver") {
      deviceString = results [i]. vals [j];
      deviceNameLabel -> setText (deviceString);
   }
   // ...
   break;  // BUG: Always takes first device!
}

Workaround Applied:

for (size_t i = 0; i < length; i++) {
   // ... get driver name into currentDriver ...
   if (currentDriver == "audio") {
      fprintf (stderr, "Skipping audio device\n");
      continue;  // Skip audio, find real SDR
   }
   deviceString = currentDriver;
   // ...
   break;
}

Proper Fix Needed:

• Present device selection dialog to user
• Save selected device in config
• Allow device preference order in settings

---

Bug 3: isFileInput() Returns True

File: sources/devices/soapy/soapy-handler.cpp
Line: 231
Severity: Critical

The isFileInput() function incorrectly returns true, telling qt-dab this is a file reader, not a live SDR device. This disables:

• Channel scanning
• Channel selection dropdown
• Live tuning
• All real-time DAB features

Current Code:

bool soapyHandler::isFileInput() {
    return true;  // BUG: Should be false for SDR!
}

Fix Applied:

bool soapyHandler::isFileInput() {
    return false;
}

Impact: Without this fix, the SoapySDR handler is completely non-functional for live reception.

---

Bug 4: Missing C++ Standard Headers

File: sources/protection/protection.cpp
Severity: Moderate (compilation error)

Missing #include <cstdio> causes compilation failure with modern compilers.

Fix: Add #include <cstdio> after existing includes.

---

Bug 5: C++20/Qwt 6.1.4 Incompatibility

File: qt-dab-6.10.pro
Line: 13
Severity: Moderate (compilation error)

Template destructor syntax in Qwt 6.1.4 incompatible with C++20 standard.

Current: CONFIG += c++20
Fix: CONFIG += c++17

---

Bug 6: UHD Handler Compilation Errors

File: sources/devices/uhd/uhd-handler.cpp
Severity: Major (if UHD enabled)

Multiple issues:

• Includes wrong header: virtual-input.h should be device-handler.h
• Typo: std:atomic should be std::atomic
• Typo: ~uhdInput should be ~uhdHandler

Workaround: Disable UHD handler, use SoapySDR instead (which supports UHD devices).

---

Reproduction Steps

1. Install qt-dab 6.10 on Ubuntu 24.04
2. Connect LibreSDR B210 or USRP B210
3. Enable SoapySDR support in compilation
4. Attempt to run qt-dab with SoapySDR device
5. Observe: "no suitable samplerate found" error
6. Fix sample rate issue
7. Observe: Audio device selected instead of SDR
8. Fix device selection
9. Observe: GUI opens but channel selector disabled (isFileInput bug)

Expected Behavior

• SoapySDR/UHD devices should work out-of-the-box
• Should select correct SDR device automatically
• Should support 2.048 MHz sample rate for DAB
• Should allow live channel scanning and tuning

Actual Behavior

• Three critical bugs prevent any operation
• Requires source code modifications to work
• No live reception possible without fixes

Suggested Long-term Fixes

1. Device Selection Dialog: Add proper device chooser for SoapySDR
2. Sample Rate Handling: Improve range detection or add manual override
3. Code Review: Audit all device handlers for similar issues
4. Testing: Test with actual SoapySDR/UHD hardware before release
5. Documentation: Note known issues with specific device types

Current Status After Fixes

Device initializes correctly with 2.048 MHz sample rate at 32.768 MHz master clock, but still no DAB signal reception. Further investigation needed for:

• Antenna configuration (TX/RX vs RX2 selection)
• Frequency offset/calibration
• Signal strength/gain settings
• TPEG data extraction configuration

Files Modified for Workaround

1. qt-dab-6.10.pro - Changed C++20 to C++17
2. sources/protection/protection.cpp - Added cstdio include
3. sources/devices/soapy/soapy-handler.cpp - All three critical fixes
4. sources/devices/soapy/soapy-converter.cpp - Added dab-constants.h include

PS: This might be relevant:
https://forums.linuxmint.com/viewtopic.php?p=2730350#p2730350

[JvanKatwijk]

Thanks I'll have a look Be aware that some devices - e.g. Airspy and pluto, but most likely others as well - do not support 2048000 as selectable samplerate, soone way or another a samplerate within a reasonable distance should be found such that a simple converter can be applied. Wrt issue 2, the position of the break was not very handly. I did not know that other devices than SDR devices could be detected, No problem with having isFileInput return false. I do not have (access to) an UHD device, very long time someone added the code, and it is marked as "unreliable" I test soapy with sdrplay and pluto best jan Op za 7 feb 2026 om 15:27 schreef Supermagnum ***@***.***>:

…

*Supermagnum* created an issue (JvanKatwijk/qt-dab#386) <#386> Environment - *OS*: Ubuntu 24.04 - *qt-dab version*: 6.10 - *Device*: LibreSDR B210mini (UHD-compatible) - *SoapySDR*: 0.8.1 - *UHD*: 4.6.0 / 4.9.0 Bugs Found Bug 1: Sample Rate Selection Failure *File*: sources/devices/soapy/soapy-handler.cpp *Line*: 155-157 *Severity*: Critical The findDesiredRange() function fails to find 2.048 MHz in the B210's supported sample rate ranges, causing "no suitable samplerate found" error. *Root Cause*: - B210 returns continuous rate ranges, not discrete values - findDesiredRange() checks if 2048000 is within range min/max but the function logic has issues - Falls back to 2.285714 MHz (16/7 MHz) which is incompatible with DAB *Current Code*: int resultRate = findDesiredRange (sampleRange, length);if (resultRate < 0) throw (device_exception ("no suitable samplerate found")); *Workaround Applied*: int resultRate = 2048000; // Force exact DAB sample rate *Proper Fix Needed*: - Improve findDesiredRange() to handle continuous ranges properly - Or allow manual sample rate override in GUI - Add debug output showing available ranges ------------------------------ Bug 2: Audio Device Selected Instead of SDR *File*: sources/devices/soapy/soapy-handler.cpp *Lines*: 50-63 *Severity*: Critical Device enumeration loop breaks after first device found, which is often an audio device, not the SDR. *Current Code*: for (size_t i = 0; i < length; i++) { // ... enumerate device ... if (QString (results [i]. keys [j]) == "driver") { deviceString = results [i]. vals [j]; deviceNameLabel -> setText (deviceString); } // ... break; // BUG: Always takes first device! } *Workaround Applied*: for (size_t i = 0; i < length; i++) { // ... get driver name into currentDriver ... if (currentDriver == "audio") { fprintf (stderr, "Skipping audio device\n"); continue; // Skip audio, find real SDR } deviceString = currentDriver; // ... break; } *Proper Fix Needed*: - Present device selection dialog to user - Save selected device in config - Allow device preference order in settings ------------------------------ Bug 3: isFileInput() Returns True *File*: sources/devices/soapy/soapy-handler.cpp *Line*: 231 *Severity*: Critical The isFileInput() function incorrectly returns true, telling qt-dab this is a file reader, not a live SDR device. This disables: - Channel scanning - Channel selection dropdown - Live tuning - All real-time DAB features *Current Code*: bool soapyHandler::isFileInput() { return true; // BUG: Should be false for SDR! } *Fix Applied*: bool soapyHandler::isFileInput() { return false; } *Impact*: Without this fix, the SoapySDR handler is completely non-functional for live reception. ------------------------------ Bug 4: Missing C++ Standard Headers *File*: sources/protection/protection.cpp *Severity*: Moderate (compilation error) Missing #include <cstdio> causes compilation failure with modern compilers. *Fix*: Add #include <cstdio> after existing includes. ------------------------------ Bug 5: C++20/Qwt 6.1.4 Incompatibility *File*: qt-dab-6.10.pro *Line*: 13 *Severity*: Moderate (compilation error) Template destructor syntax in Qwt 6.1.4 incompatible with C++20 standard. *Current*: CONFIG += c++20 *Fix*: CONFIG += c++17 ------------------------------ Bug 6: UHD Handler Compilation Errors *File*: sources/devices/uhd/uhd-handler.cpp *Severity*: Major (if UHD enabled) Multiple issues: - Includes wrong header: virtual-input.h should be device-handler.h - Typo: std:atomic should be std::atomic - Typo: ~uhdInput should be ~uhdHandler *Workaround*: Disable UHD handler, use SoapySDR instead (which supports UHD devices). ------------------------------ Reproduction Steps 1. Install qt-dab 6.10 on Ubuntu 24.04 2. Connect LibreSDR B210 or USRP B210 3. Enable SoapySDR support in compilation 4. Attempt to run qt-dab with SoapySDR device 5. Observe: "no suitable samplerate found" error 6. Fix sample rate issue 7. Observe: Audio device selected instead of SDR 8. Fix device selection 9. Observe: GUI opens but channel selector disabled (isFileInput bug) Expected Behavior - SoapySDR/UHD devices should work out-of-the-box - Should select correct SDR device automatically - Should support 2.048 MHz sample rate for DAB - Should allow live channel scanning and tuning Actual Behavior - Three critical bugs prevent any operation - Requires source code modifications to work - No live reception possible without fixes Suggested Long-term Fixes 1. *Device Selection Dialog*: Add proper device chooser for SoapySDR 2. *Sample Rate Handling*: Improve range detection or add manual override 3. *Code Review*: Audit all device handlers for similar issues 4. *Testing*: Test with actual SoapySDR/UHD hardware before release 5. *Documentation*: Note known issues with specific device types Current Status After Fixes Device initializes correctly with 2.048 MHz sample rate at 32.768 MHz master clock, but still no DAB signal reception. Further investigation needed for: - Antenna configuration (TX/RX vs RX2 selection) - Frequency offset/calibration - Signal strength/gain settings - TPEG data extraction configuration Files Modified for Workaround 1. qt-dab-6.10.pro - Changed C++20 to C++17 2. sources/protection/protection.cpp - Added cstdio include 3. sources/devices/soapy/soapy-handler.cpp - All three critical fixes 4. sources/devices/soapy/soapy-converter.cpp - Added dab-constants.h include PS: This might be relevant: https://forums.linuxmint.com/viewtopic.php?p=2730350#p2730350 — Reply to this email directly, view it on GitHub <#386>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACCPHQCGRMVAB5LEJYPMIUL4KXY3NAVCNFSM6AAAAACUKOLBPKVHI2DSMVQWIX3LMV43ASLTON2WKOZTHEYTAMZZGIZDGNY> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

-- Jan van Katwijk

[Supermagnum]

I was able to get one of the commands to work by patching the file to use uhd directly. I hereby suggest a -uhd toggle that uses UHD directly , and -samplerate 2048000 .

[JvanKatwijk]

Trying to address some issues, but not clear what the soapy UHD driver returns on the samplerate request In order to be abfle to add a quick fix, it would be helpful to know what the exact name is that the software sees when getting an UHD (compatible) device I was looking into the soapy library for UHD in order to find out what (type of) values were returned uhd::meta_range_t get_rate_range(const int dir, const size_t chan) { #ifdef SOAPY_SDR_API_HAS_GET_SAMPLE_RATE_RANGE return rangeListToMetaRange(_device->getSampleRateRange(dir, chan)); #else return numberListToMetaRange(_device->listSampleRates(dir, chan)); #endif } I added a device selector that is called whenever there is more than a single soapy compaitible device selected, and checked that with rtlsdr sticks hackrf and sdrplay best jan Op za 7 feb 2026 om 15:27 schreef Supermagnum ***@***.***>:

…

*Supermagnum* created an issue (JvanKatwijk/qt-dab#386) <#386> Environment - *OS*: Ubuntu 24.04 - *qt-dab version*: 6.10 - *Device*: LibreSDR B210mini (UHD-compatible) - *SoapySDR*: 0.8.1 - *UHD*: 4.6.0 / 4.9.0 Bugs Found Bug 1: Sample Rate Selection Failure *File*: sources/devices/soapy/soapy-handler.cpp *Line*: 155-157 *Severity*: Critical The findDesiredRange() function fails to find 2.048 MHz in the B210's supported sample rate ranges, causing "no suitable samplerate found" error. *Root Cause*: - B210 returns continuous rate ranges, not discrete values - findDesiredRange() checks if 2048000 is within range min/max but the function logic has issues - Falls back to 2.285714 MHz (16/7 MHz) which is incompatible with DAB *Current Code*: int resultRate = findDesiredRange (sampleRange, length);if (resultRate < 0) throw (device_exception ("no suitable samplerate found")); *Workaround Applied*: int resultRate = 2048000; // Force exact DAB sample rate *Proper Fix Needed*: - Improve findDesiredRange() to handle continuous ranges properly - Or allow manual sample rate override in GUI - Add debug output showing available ranges ------------------------------ Bug 2: Audio Device Selected Instead of SDR *File*: sources/devices/soapy/soapy-handler.cpp *Lines*: 50-63 *Severity*: Critical Device enumeration loop breaks after first device found, which is often an audio device, not the SDR. *Current Code*: for (size_t i = 0; i < length; i++) { // ... enumerate device ... if (QString (results [i]. keys [j]) == "driver") { deviceString = results [i]. vals [j]; deviceNameLabel -> setText (deviceString); } // ... break; // BUG: Always takes first device! } *Workaround Applied*: for (size_t i = 0; i < length; i++) { // ... get driver name into currentDriver ... if (currentDriver == "audio") { fprintf (stderr, "Skipping audio device\n"); continue; // Skip audio, find real SDR } deviceString = currentDriver; // ... break; } *Proper Fix Needed*: - Present device selection dialog to user - Save selected device in config - Allow device preference order in settings ------------------------------ Bug 3: isFileInput() Returns True *File*: sources/devices/soapy/soapy-handler.cpp *Line*: 231 *Severity*: Critical The isFileInput() function incorrectly returns true, telling qt-dab this is a file reader, not a live SDR device. This disables: - Channel scanning - Channel selection dropdown - Live tuning - All real-time DAB features *Current Code*: bool soapyHandler::isFileInput() { return true; // BUG: Should be false for SDR! } *Fix Applied*: bool soapyHandler::isFileInput() { return false; } *Impact*: Without this fix, the SoapySDR handler is completely non-functional for live reception. ------------------------------ Bug 4: Missing C++ Standard Headers *File*: sources/protection/protection.cpp *Severity*: Moderate (compilation error) Missing #include <cstdio> causes compilation failure with modern compilers. *Fix*: Add #include <cstdio> after existing includes. ------------------------------ Bug 5: C++20/Qwt 6.1.4 Incompatibility *File*: qt-dab-6.10.pro *Line*: 13 *Severity*: Moderate (compilation error) Template destructor syntax in Qwt 6.1.4 incompatible with C++20 standard. *Current*: CONFIG += c++20 *Fix*: CONFIG += c++17 ------------------------------ Bug 6: UHD Handler Compilation Errors *File*: sources/devices/uhd/uhd-handler.cpp *Severity*: Major (if UHD enabled) Multiple issues: - Includes wrong header: virtual-input.h should be device-handler.h - Typo: std:atomic should be std::atomic - Typo: ~uhdInput should be ~uhdHandler *Workaround*: Disable UHD handler, use SoapySDR instead (which supports UHD devices). ------------------------------ Reproduction Steps 1. Install qt-dab 6.10 on Ubuntu 24.04 2. Connect LibreSDR B210 or USRP B210 3. Enable SoapySDR support in compilation 4. Attempt to run qt-dab with SoapySDR device 5. Observe: "no suitable samplerate found" error 6. Fix sample rate issue 7. Observe: Audio device selected instead of SDR 8. Fix device selection 9. Observe: GUI opens but channel selector disabled (isFileInput bug) Expected Behavior - SoapySDR/UHD devices should work out-of-the-box - Should select correct SDR device automatically - Should support 2.048 MHz sample rate for DAB - Should allow live channel scanning and tuning Actual Behavior - Three critical bugs prevent any operation - Requires source code modifications to work - No live reception possible without fixes Suggested Long-term Fixes 1. *Device Selection Dialog*: Add proper device chooser for SoapySDR 2. *Sample Rate Handling*: Improve range detection or add manual override 3. *Code Review*: Audit all device handlers for similar issues 4. *Testing*: Test with actual SoapySDR/UHD hardware before release 5. *Documentation*: Note known issues with specific device types Current Status After Fixes Device initializes correctly with 2.048 MHz sample rate at 32.768 MHz master clock, but still no DAB signal reception. Further investigation needed for: - Antenna configuration (TX/RX vs RX2 selection) - Frequency offset/calibration - Signal strength/gain settings - TPEG data extraction configuration Files Modified for Workaround 1. qt-dab-6.10.pro - Changed C++20 to C++17 2. sources/protection/protection.cpp - Added cstdio include 3. sources/devices/soapy/soapy-handler.cpp - All three critical fixes 4. sources/devices/soapy/soapy-converter.cpp - Added dab-constants.h include PS: This might be relevant: https://forums.linuxmint.com/viewtopic.php?p=2730350#p2730350 — Reply to this email directly, view it on GitHub <#386>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACCPHQCGRMVAB5LEJYPMIUL4KXY3NAVCNFSM6AAAAACUKOLBPKVHI2DSMVQWIX3LMV43ASLTON2WKOZTHEYTAMZZGIZDGNY> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

-- Jan van Katwijk

[Supermagnum]

I've tested this with a USRP B210 (LibreSDR_B210mini) running:

• UHD 4.9.0.0
• GNU Radio 3.10.9.2
• gr-osmosdr 0.2.0.0

Sample Rate Test Results:

When requesting 2.048 MHz (DAB sample rate) via native UHD:

Requested: 2048000 Hz → Actual: 2047999.9991024241 Hz
Master clock: 32.768 MHz (automatically selected)

Key findings:

1. Native UHD returns virtually exact sample rates - only 0.0009 Hz off (0.00004% error)
2. Master clock auto-adjusts to 32.768 MHz for DAB (optimal for 2.048 MHz sample rate)
3. The tiny floating-point discrepancy is negligible for DAB decoding

gr-osmosdr Issue:

I encountered RuntimeError: list contains invalid format! when using gr-osmosdr with this setup. The issue is not related to sample rate accuracy, but rather a bug in gr-osmosdr 0.2.0.0's stream argument formatting when interfacing with UHD.

Workaround: Bypass gr-osmosdr and use native UHD directly:

from gnuradio import uhd
src = uhd.usrp_source(
    "",  # or "type=b200"
    uhd.stream_args(
        cpu_format="fc32",
        channels=[0],
    ),
)
src.set_samp_rate(2048000)

This avoids the gr-osmosdr compatibility issue entirely while maintaining accurate sample rates.

Also, this is what UHD sees:
python3 << 'EOF'
from gnuradio import uhd

Create a USRP source

src = uhd.usrp_source(
"",
uhd.stream_args(
cpu_format="fc32",
channels=[0],
),
)

Request different sample rates and see what we actually get

test_rates = [2048000, 2000000, 2500000, 1000000, 32768000]

print("Testing sample rate requests and responses:\n")
for requested_rate in test_rates:
src.set_samp_rate(requested_rate)
actual_rate = src.get_samp_rate()
print(f"Requested: {requested_rate:>10} Hz -> Actual: {actual_rate:>10} Hz -> Match: {requested_rate == actual_rate}")

Check the master clock rate

print(f"\nMaster clock rate: {src.get_clock_rate(0)} Hz")

Get valid sample rate range

print("\nValid sample rate range:")
print(f" Start: {src.get_samp_rates().start()} Hz")
print(f" Stop: {src.get_samp_rates().stop()} Hz")
print(f" Step: {src.get_samp_rates().step()} Hz")
EOF
[INFO] [UHD] linux; GNU C++ version 13.3.0; Boost_108300; UHD_4.9.0.0+ds1-1~noble2
[INFO] [B200] Detected Device: B210
[INFO] [B200] Operating over USB 3.
[INFO] [B200] Initialize CODEC control...
[INFO] [B200] Initialize Radio control...
[INFO] [B200] Performing register loopback test...
[INFO] [B200] Register loopback test passed
[INFO] [B200] Performing register loopback test...
[INFO] [B200] Register loopback test passed
[INFO] [B200] Setting master clock rate selection to 'automatic'.
[INFO] [B200] Asking for clock rate 16.000000 MHz...
[INFO] [B200] Actually got clock rate 16.000000 MHz.
Testing sample rate requests and responses:

[INFO] [B200] Asking for clock rate 32.768000 MHz...
[INFO] [B200] Actually got clock rate 32.768000 MHz.
Requested: 2048000 Hz -> Actual: 2047999.9991024241 Hz -> Match: False
[INFO] [B200] Asking for clock rate 32.000000 MHz...
[INFO] [B200] Actually got clock rate 32.000000 MHz.
Requested: 2000000 Hz -> Actual: 2000000.0 Hz -> Match: True
[INFO] [B200] Asking for clock rate 40.000000 MHz...
[INFO] [B200] Actually got clock rate 40.000000 MHz.
Requested: 2500000 Hz -> Actual: 2500000.0 Hz -> Match: True
[INFO] [B200] Asking for clock rate 32.000000 MHz...
[INFO] [B200] Actually got clock rate 32.000000 MHz.
[WARNING] [CORES] The requested decimation is odd; the user should expect CIC rolloff.
Select an even decimation to ensure that a halfband filter is enabled.
13 = (32 MHz)/(2.5 MHz)

Requested: 1000000 Hz -> Actual: 1000000.0 Hz -> Match: True
[INFO] [B200] Asking for clock rate 32.768000 MHz...
[INFO] [B200] Actually got clock rate 32.768000 MHz.
[WARNING] [CORES] The requested decimation is odd; the user should expect CIC rolloff.
Select an even decimation to ensure that a halfband filter is enabled.
33 = (32.768 MHz)/(1 MHz)

Requested: 32768000 Hz -> Actual: 32767999.985638786 Hz -> Match: False

Master clock rate: 32767999.985638786 Hz

Valid sample rate range:
Start: 63999.999971950754 Hz
Stop: 32767999.985638786 Hz
Step: 503.9370076531559 Hz

I hope it helps !

[JvanKatwijk]

Thanks, I uploaded a version where - in the soapy interface module - an explcit test is done on the "uhd" and "UHD" , and - if found - samplerate is set to 2048000 Op zo 8 feb 2026 om 13:19 schreef Supermagnum ***@***.***>:

…

*Supermagnum* left a comment (JvanKatwijk/qt-dab#386) <#386 (comment)> I've tested this with a USRP B210 (LibreSDR_B210mini) running: - UHD 4.9.0.0 - GNU Radio 3.10.9.2 - gr-osmosdr 0.2.0.0 Sample Rate Test Results: When requesting 2.048 MHz (DAB sample rate) via native UHD: Requested: 2048000 Hz → Actual: 2047999.9991024241 Hz Master clock: 32.768 MHz (automatically selected) *Key findings:* 1. *Native UHD returns virtually exact sample rates* - only 0.0009 Hz off (0.00004% error) 2. *Master clock auto-adjusts* to 32.768 MHz for DAB (optimal for 2.048 MHz sample rate) 3. *The tiny floating-point discrepancy is negligible* for DAB decoding gr-osmosdr Issue: I encountered RuntimeError: list contains invalid format! when using gr-osmosdr with this setup. The issue is *not* related to sample rate accuracy, but rather a bug in gr-osmosdr 0.2.0.0's stream argument formatting when interfacing with UHD. *Workaround:* Bypass gr-osmosdr and use native UHD directly: from gnuradio import uhdsrc = uhd.usrp_source( "", # or "type=b200" uhd.stream_args( cpu_format="fc32", channels=[0], ), )src.set_samp_rate(2048000) This avoids the gr-osmosdr compatibility issue entirely while maintaining accurate sample rates. Also, this is what UHD sees: python3 << 'EOF' from gnuradio import uhd Create a USRP source src = uhd.usrp_source( "", uhd.stream_args( cpu_format="fc32", channels=[0], ), ) Request different sample rates and see what we actually get test_rates = [2048000, 2000000, 2500000, 1000000, 32768000] print("Testing sample rate requests and responses:\n") for requested_rate in test_rates: src.set_samp_rate(requested_rate) actual_rate = src.get_samp_rate() print(f"Requested: {requested_rate:>10} Hz -> Actual: {actual_rate:>10} Hz -> Match: {requested_rate == actual_rate}") Check the master clock rate print(f"\nMaster clock rate: {src.get_clock_rate(0)} Hz") Get valid sample rate range print("\nValid sample rate range:") print(f" Start: {src.get_samp_rates().start()} Hz") print(f" Stop: {src.get_samp_rates().stop()} Hz") print(f" Step: {src.get_samp_rates().step()} Hz") EOF [INFO] [UHD] linux; GNU C++ version 13.3.0; Boost_108300; UHD_4.9.0.0+ds1-1~noble2 [INFO] [B200] Detected Device: B210 [INFO] [B200] Operating over USB 3. [INFO] [B200] Initialize CODEC control... [INFO] [B200] Initialize Radio control... [INFO] [B200] Performing register loopback test... [INFO] [B200] Register loopback test passed [INFO] [B200] Performing register loopback test... [INFO] [B200] Register loopback test passed [INFO] [B200] Setting master clock rate selection to 'automatic'. [INFO] [B200] Asking for clock rate 16.000000 MHz... [INFO] [B200] Actually got clock rate 16.000000 MHz. Testing sample rate requests and responses: [INFO] [B200] Asking for clock rate 32.768000 MHz... [INFO] [B200] Actually got clock rate 32.768000 MHz. Requested: 2048000 Hz -> Actual: 2047999.9991024241 Hz -> Match: False [INFO] [B200] Asking for clock rate 32.000000 MHz... [INFO] [B200] Actually got clock rate 32.000000 MHz. Requested: 2000000 Hz -> Actual: 2000000.0 Hz -> Match: True [INFO] [B200] Asking for clock rate 40.000000 MHz... [INFO] [B200] Actually got clock rate 40.000000 MHz. Requested: 2500000 Hz -> Actual: 2500000.0 Hz -> Match: True [INFO] [B200] Asking for clock rate 32.000000 MHz... [INFO] [B200] Actually got clock rate 32.000000 MHz. [WARNING] [CORES] The requested decimation is odd; the user should expect CIC rolloff. Select an even decimation to ensure that a halfband filter is enabled. 13 = (32 MHz)/(2.5 MHz) Requested: 1000000 Hz -> Actual: 1000000.0 Hz -> Match: True [INFO] [B200] Asking for clock rate 32.768000 MHz... [INFO] [B200] Actually got clock rate 32.768000 MHz. [WARNING] [CORES] The requested decimation is odd; the user should expect CIC rolloff. Select an even decimation to ensure that a halfband filter is enabled. 33 = (32.768 MHz)/(1 MHz) Requested: 32768000 Hz -> Actual: 32767999.985638786 Hz -> Match: False Master clock rate: 32767999.985638786 Hz Valid sample rate range: Start: 63999.999971950754 Hz Stop: 32767999.985638786 Hz Step: 503.9370076531559 Hz I hope it helps ! — Reply to this email directly, view it on GitHub <#386 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACCPHQBRL3VDMVMNNMKG5BT4K4SURAVCNFSM6AAAAACUKOLBPKVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTQNRXGA4DGNBQGU> . You are receiving this because you commented.Message ID: ***@***.***>

-- Jan van Katwijk

[Supermagnum]

That refuses to compile:
In file included from /usr/include/x86_64-linux-gnu/qt5/QtCore/qglobal.h:1305,
from /usr/include/x86_64-linux-gnu/qt5/QtCore/qcoreapplication.h:43,
from /usr/include/x86_64-linux-gnu/qt5/QtCore/QCoreApplication:1,
from sources/main/radio.cpp:23:
/usr/include/x86_64-linux-gnu/qt5/QtCore/qflags.h:123:80: note: declared here
123 | QT_DEPRECATED_X("Use default constructor instead") Q_DECL_CONSTEXPR inline QFlags(Zero) noexcept : i(0) {}
| ^~~~~~
cc1plus: all warnings being treated as errors
make: *** [Makefile:2481: main.o] Error 1
cc1plus: all warnings being treated as errors
make: *** [Makefile:2583: display-widget.o] Error 1
cc1plus: all warnings being treated as errors
make: *** [Makefile:2562: radio.o] Error 1

Fixed it with removing the werror flag,

also:
The uhd-handler.cpp file has many issues. It's badly out of date with the rest of the qt-dab codebase.

[Supermagnum]

I had to do this to get gr-dab working with native UHD (bypassing the broken gr-osmosdr):
Fixes Applied to gr-dab for Native UHD Support

1. Fixed /usr/local/lib/python3.12/dist-packages/gnuradio/dab/app/receive_dabplus.py
   Changed:

Import: import osmosdr → from gnuradio import uhd
Source creation from osmosdr to UHD:

python# OLD (osmosdr):
osmosdr_source_0 = osmosdr.source( args="numchan=" + str(1) + " " + '' )
osmosdr_source_0.set_sample_rate(samp_rate)
osmosdr_source_0.set_center_freq(frequency, 0)
osmosdr_source_0.set_freq_corr(0, 0)
osmosdr_source_0.set_dc_offset_mode(0, 0)
osmosdr_source_0.set_iq_balance_mode(0, 0)
osmosdr_source_0.set_gain_mode(False, 0)
osmosdr_source_0.set_gain(rf_gain, 0)
osmosdr_source_0.set_if_gain(if_gain, 0)
osmosdr_source_0.set_bb_gain(bb_gain, 0)
osmosdr_source_0.set_antenna('RX2', 0)
osmosdr_source_0.set_bandwidth(2000000, 0)
src = osmosdr_source_0

NEW (native UHD):

uhd_usrp_source_0 = uhd.usrp_source(
"",
uhd.stream_args(
cpu_format="fc32",
channels=[0],
),
)
uhd_usrp_source_0.set_samp_rate(samp_rate)
uhd_usrp_source_0.set_center_freq(frequency, 0)
uhd_usrp_source_0.set_gain(rf_gain, 0)
uhd_usrp_source_0.set_antenna('RX2', 0)
uhd_usrp_source_0.set_bandwidth(2000000, 0)
src = uhd_usrp_source_0
2. Fixed /usr/local/lib/python3.12/dist-packages/gnuradio/dab/osmo_or_zmq_source.py
Changed:

Import: import osmosdr → from gnuradio import uhd
Added: #include
Source creation:

python# OLD (osmosdr):
self.osmosdr_source_0 = osmosdr.source( args="numchan=" + str(1) + " " + '' )
self.osmosdr_source_0.set_sample_rate(samp_rate)
self.osmosdr_source_0.set_center_freq(frequency, 0)
self.osmosdr_source_0.set_freq_corr(0, 0)
self.osmosdr_source_0.set_dc_offset_mode(0, 0)
self.osmosdr_source_0.set_iq_balance_mode(0, 0)
self.osmosdr_source_0.set_gain_mode(False, 0)
self.osmosdr_source_0.set_gain(rf_gain, 0)
self.osmosdr_source_0.set_if_gain(if_gain, 0)
self.osmosdr_source_0.set_bb_gain(bb_gain, 0)
self.osmosdr_source_0.set_antenna('', 0)
self.osmosdr_source_0.set_bandwidth(2000000, 0)
self.src = self.osmosdr_source_0

NEW (native UHD):

self.uhd_usrp_source_0 = uhd.usrp_source(
"",
uhd.stream_args(
cpu_format="fc32",
channels=[0],
),
)
self.uhd_usrp_source_0.set_samp_rate(samp_rate)
self.uhd_usrp_source_0.set_center_freq(frequency, 0)
self.uhd_usrp_source_0.set_gain(rf_gain, 0)
self.uhd_usrp_source_0.set_antenna('RX2', 0)
self.uhd_usrp_source_0.set_bandwidth(2000000, 0)
self.src = self.uhd_usrp_source_0

Updated setter methods to replace osmosdr references:

python# Setters changed from:
self.osmosdr_source_0.set_center_freq(val, 0)
self.osmosdr_source_0.set_gain(val, 0)
self.osmosdr_source_0.set_if_gain(val, 0) # osmosdr-specific
self.osmosdr_source_0.set_bb_gain(val, 0) # osmosdr-specific

To:

self.uhd_usrp_source_0.set_center_freq(val, 0)
self.uhd_usrp_source_0.set_gain(val, 0)
pass # UHD does not support separate IF gain
pass # UHD does not support separate BB gain

[JvanKatwijk]

I am compiling on Fedora with relatively new versions of Qt-DAB and gcc. It might help to connent out the first kine in the unix section, the one that reads QMAKE_CXXFLAGS += -pedantic -Wextra -Wcast-align -Winit-self -Wlogical-op -Wmissing-declarations -Woverloaded-virtual -Wredundant-decls -Wstrict-null-sentinel -Wundef -Werror -Wno-unused I am trying to comply - as much as possible - to the C++ standard, and having this line "in" helps detecting incompatibilities Op ma 9 feb 2026 om 09:43 schreef Supermagnum ***@***.***>:

…

*Supermagnum* left a comment (JvanKatwijk/qt-dab#386) <#386 (comment)> That refuses to compile: In file included from /usr/include/x86_64-linux-gnu/qt5/QtCore/qglobal.h:1305, from /usr/include/x86_64-linux-gnu/qt5/QtCore/qcoreapplication.h:43, from /usr/include/x86_64-linux-gnu/qt5/QtCore/QCoreApplication:1, from sources/main/radio.cpp:23: /usr/include/x86_64-linux-gnu/qt5/QtCore/qflags.h:123:80: note: declared here 123 | QT_DEPRECATED_X("Use default constructor instead") Q_DECL_CONSTEXPR inline QFlags(Zero) noexcept : i(0) {} | ^~~~~~ cc1plus: all warnings being treated as errors make: *** [Makefile:2481: main.o] Error 1 cc1plus: all warnings being treated as errors make: *** [Makefile:2583: display-widget.o] Error 1 cc1plus: all warnings being treated as errors make: *** [Makefile:2562: radio.o] Error 1 — Reply to this email directly, view it on GitHub <#386 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACCPHQDTQJJECN4DQBC2A234LBCCFAVCNFSM6AAAAACUKOLBPKVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTQNZQGE3TQNZXGA> . You are receiving this because you commented.Message ID: ***@***.***>

-- Jan van Katwijk

[Supermagnum]

It

debug.txt

compiles and runs now, but there are no signals,- no activity in the spectrum analyzer, scanning cannot find any services.
I know that it is not a hardware issue.

[JvanKatwijk]

try this file https://www.dropbox.com/scl/fi/ffg8xdth2lowxojhfw5vk/Generic-RTL2832U-OEM-11D-Wed-Oct-16-2024-00-49-23.uff?rlkey=uq5u3g2of69n3hbs9aa6k9fth&dl=0 Op ma 9 feb 2026 om 18:36 schreef Supermagnum ***@***.***>:

…

*Supermagnum* left a comment (JvanKatwijk/qt-dab#386) <#386 (comment)> It debug.txt <https://github.com/user-attachments/files/25189158/debug.txt> compiles and runs now, but there are no signals,- no activity in the spectrum analyzer, scanning cannot find any services. I know that it is not a hardware issue. — Reply to this email directly, view it on GitHub <#386 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACCPHQGP4KEXE3FRXUD24AD4LDATVAVCNFSM6AAAAACUKOLBPKVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTQNZSHA3DKNJRGY> . You are receiving this because you commented.Message ID: ***@***.***>

-- Jan van Katwijk

[JvanKatwijk]

I am not familiar with Gnu radio. I sent the link to the file such that you can check whether or not the problem is in the "core" Qt-DAB or in the input handling. Op di 10 feb 2026 om 10:48 schreef Supermagnum ***@***.***>:

…

*Supermagnum* left a comment (JvanKatwijk/qt-dab#386) <#386 (comment)> Please look at: https://github.com/Supermagnum/gr-dab I can create a PR if you want to. — Reply to this email directly, view it on GitHub <#386 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACCPHQAQPEGNP736TXEWOMD4LGSQJAVCNFSM6AAAAACUKOLBPKVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTQNZWGUZTAMRYG4> . You are receiving this because you commented.Message ID: ***@***.***>

-- Jan van Katwijk

[JvanKatwijk]

are you referring to running with a file and fixed some bugs? then, where is your repo Op di 10 feb 2026 om 11:10 schreef Supermagnum ***@***.***>:

…

*Supermagnum* left a comment (JvanKatwijk/qt-dab#386) <#386 (comment)> I tried it, and it worked fine I also fixed some bugs , those changes are in my repo. — Reply to this email directly, view it on GitHub <#386 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACCPHQGXMSGAXJU5ZSJWSG34LGVBPAVCNFSM6AAAAACUKOLBPKVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTQNZWGY2DGNJTGA> . You are receiving this because you commented.Message ID: ***@***.***>

-- Jan van Katwijk

[JvanKatwijk]

Looking at the spec for UHD soapy, I noticed that the driver there was called b200, wold that be b210 in your case? Op di 10 feb 2026 om 11:20 schreef jan van katwijk ***@***.***>:

…

are you referring to running with a file and fixed some bugs? then, where is your repo Op di 10 feb 2026 om 11:10 schreef Supermagnum ***@***.***>: > *Supermagnum* left a comment (JvanKatwijk/qt-dab#386) > <#386 (comment)> > > I tried it, and it worked fine > I also fixed some bugs , those changes are in my repo. > > — > Reply to this email directly, view it on GitHub > <#386 (comment)>, > or unsubscribe > <https://github.com/notifications/unsubscribe-auth/ACCPHQGXMSGAXJU5ZSJWSG34LGVBPAVCNFSM6AAAAACUKOLBPKVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTQNZWGY2DGNJTGA> > . > You are receiving this because you commented.Message ID: > ***@***.***> > -- Jan van Katwijk

-- Jan van Katwijk

[JvanKatwijk]

OK, but the original question was whether or not your uhd could be handled with the soapy software for Qt-DAB Op di 10 feb 2026 om 12:53 schreef Supermagnum ***@***.***>:

…

*Supermagnum* left a comment (JvanKatwijk/qt-dab#386) <#386 (comment)> are you referring to running with a file and fixed some bugs? then, where is your repo Op di 10 feb 2026 om 11:10 schreef Supermagnum *@*.***>: … <#m_5085808410245112911_> Right here: https://github.com/Supermagnum/gr-dab — Reply to this email directly, view it on GitHub <#386 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACCPHQF6DVLHJ3Q3GKDQYU34LHBEBAVCNFSM6AAAAACUKOLBPKVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTQNZXGEZTINRYGY> . You are receiving this because you commented.Message ID: ***@***.***>

-- Jan van Katwijk

[Supermagnum]

A attempt at fixing your code, -
https://github.com/Supermagnum/qt-dab-performance-fixes
https://github.com/Supermagnum/qt-dab-performance-fixes?tab=readme-ov-file#recent-performance-fixes-and-hardware-verification