LINRAD VIDEOS

LINRAD VIDEOS
(Mar 15 2016)

This is my video channel on YouTube The videos you can find there are listed according to cathegories below. The most recent videos may be unlisted.

Installation on different platforms.

Use the linrad installers [linrad-installers-windows7] For linrad-04.00 and later.
Windows XP [linrad-install-windows-xp] How to install the Linrad executable.
Linux X11 [linrad-install-linux-x11]How to install Linrad from source using the latest (unstable?) version from the Linrad repository.
Linux in terminal mode with svgalib. [linrad-install-svgalib]How to install Linrad from source using a released version.
Linux in terminal mode with fbdev. [flinrad]How to install Linrad from source using the latest (unstable?) version from the Linrad repository.
Windows XP [linrad-install-win-repo]How to install Linrad from source using the latest (unstable?) version from the Linrad repository.
Linux Fedora 20 [linrad-libs-fedora20]How to install libraries for different hardware.
Linux Ubuntu 10.04 [linrad-install-x11oss]How to install 4Front OSS. An alternative sound system.
Linux Suse 13.1 [linrad-install-suse]How to install Linrad.
[afedri-usb-interface]How to use the USB interfac of Afedri SDR.
[xp64libusb]About using Zadig to install USB drivers under Windows.
[airspyUSB]About Airspy. 10 MHz is very fast on USB 2...
[GainModes]Gain modes in Linrad explained.
Libraries under Linux [install32on64] This video shows how to copy 32 bit Linux libraries to 64 bit Linux installations.

Setup and calibration.

[softrock-setup-and-cal]Softrock with a function generator. Installation and setup in Linux.
[softrock cal2]Softrock with a proper pulse generator. Description of a proper pulse generator. Use it to evaluate performance of the calibration using the function generator. Calibrate with the proper pulse generator.
[linrad-linux-install-cal-iqplus]IQ+ with a proper pulse generator. Installation, setup and calibration under Linux.
[linrad-windows-install-cal-iqplus]IQ+ with a multi-pulse generator. Installation, setup and calibration under Windows XP.
[win calibrate wse]The WSE converters. Installation, setup and calibration under Windows XP.
[win-rtl-install-cal]The rtlsdr USB dongle. Installation, setup and calibration under Windows XP.
SDR-IP. [win-sdrip-setup-cal]Installation, setup and calibration under Windows 7.
Maya 44 Here the problem with the Maya 44 soundcard is demonstrated. Linrad versions up to 04-07 can not be calibrated.
Maya 44 is here compared to a Delta 44.
Delta44vsMaya44blanker With linrad-04.08 and later tha Maya 44 can be properly calibrated, but there is some ambiguity in the system. Sometimes the hardware starts with a different time delay between channels.
iqpluswse Here an IQ+ is compared to a wse converter chain.

Setup and tests at large bandwidths. (Relative to the CPU used.)

bladeRF. [linux bladerf install]Installation from the repo under Debian wheezy. In February 2014 10 MHz bandwidth was possible which is demonstrated by the reception of cellular phones on 950 MHz.
bladeRF. [bladerf fm]Installation from the repository and setup under Linux, Fedora 17. This video shows the reception of the entire FM band 88-108 MHz and recording on the hard disk at a bandwidth of 25 MHz.
bladeRF [bladerf-460to465mhz]Setup under Windows 7 to receive 460 to 465 MHz with a 5 MHz filter and 8 MHz sampling rate. There are image spurs and overtone spurs, but with appropriate oversampling there would be no alias spurs. Performance is limited by reciprocal mixing, the images can be removed by calibrating Linrad.
Wideband FM 88-108 MHz on a slow computer using an RTL-SDR dongle. [rtlsdr-pentium4]The WFM mode in Linrad is not optimized for CPU efficiency, but nevertheless it is good enough to be useful on a Pentium 4 computer.
Using rtl-sdr on a slow computer with flinrad. [pentium3 flinrad] This video shows performance on a 650 MHz Pentium 3. Today that is an obsolete computer, but there are low end low cost ARM computers with similar or better performance.
Many USB dongles. [multi-rtl] This video shows a Compaq 6510b running with 4 rtlsdr USB dongles at 2 MHz. It also shows a desktop computer running 8 rtlsdr dongles at 2.4 MHz plus a PCIe-9842 at 200 MHz.
Frequency calibration for recorded files. [recording-cal] This video shows how to set parameters to correct frequency errors in recorded files.

Getting the best CPU performance from your system.

Effects of setting CPU affinity. [cpu-affinity] This video demonstrates that the improvement is small and explains why the routine for setting CPU affinities for heavily loaded threads is disabled in Linrad.
Here Linrad is run with a bandwidth of 100 MHz under several different operating systems. [pcie9842-200mhz] It is quite clear that performance differs significantly between the operating systems.
Hyperthreading. [hyperthreading] It is not a good idea to use hyperthreading to get twice as many CPU cores that sometimes have 50% of normal CPU power.
OS differences. [os-differences] Operating systems differ under high CPU load.
Win 7 peculiarities. [Winypeculiarity] Reducing CPU load may sometimes cause problems because the operating system decides it is OK to reduce the clock frequency for some CPU core(s) while that is not acceptable. (Or maybe there is some other problem.)
High speed recording and playback. [SDR record and playback at 25 and 40 MHz bandwidth] A BladeRF with a B200 transverter is used to record and play back the entire FM band.
Pentium IV with 2.5 MHz bandwidth [Airspy One on Pentium IV]Here SDRsharp and Linrad are used with an Airspy One. The Pentium IV is a very slow computer for processing a bandwidth of 2.5 MHz.
Linrad on Windows 10. [Windows 10 will never forget any mistake. (as far as I know.)]

Interference fighting on longwave and mediumwave.

Sensors Part 1. [sensors-part1]The first video in a series of four. It is about elimination of conducted interference on HF.
Sensors Part 2. [sensors-part2]The second video in a series of four. It is about elimination of conducted interference on HF.
Sensors Part 3. [sensors-part3]The third video in a series of four. It is about elimination of conducted interference on HF.
Sensors Part 4. [sensors-part4]The last video in a series of four. It is about elimination of conducted interference on HF.
PLT interference??? [plt1] This video shows impulse noise removal in Linrad. It is a challenge to DX listeners and radio amateurs to provide wideband recordings with worse problems that could be used to make a better video than this one.

Tests and comparisons of different SDR hardware.

Here several SDRs are compared in the 88-108 MHz broadcast band. [many-fm]ELAD FDM-S1, Mirics MSi3101 (MSi001+MSi2500), rtlsdr with R820T as well as with E4000 in original Osmocom mode as well as in Linrad sensitivity mode. FunCube Pro plus and PCIe-9842 with a converter. The general conclusion is that the cheap dongles are reasonably good and that it will be a good idea to have some different types. In situations where one dongle fails another might be OK. None of them is perfect...
PCIe-9842. [pcie9842] Here the high dynamic range of a PCIe-9842 is demonstrated. The card samples 14 bit at 200 MHz.
Direct A/D input on the bladeRF. [bladerfj61]A bladeRF can sample two channels with 12 bits at 40 MHz. This video compares it to a PCIe-9842 that samples 14 bits at 200 MHz corresponding to about 15.2 bits at 40 MHz. The bladeRF is used on the J61 connector directly into the A/D converters. A simple check of saturation vs noise floor shows that the bladeRF is very good, but real life tests show something else. There is a huge problem with digital feedback.
rtlsdr dongles compared with SDR# and Linrad. [donglecmp2] USE HD QUALITY (720p) and "Full screen." Linrad is pixel oriented! The tuner chips E4000, R820T and FC0013 differ a little in sensitivity and significantly in spurious responses. The linearity mode in Linrad shows some advantage over the original Osmocom mode due to a different gain distribution.
rtlsdr dongles compared with SDR#. [donglecmp] USE HD QUALITY (720p) and "Full screen." Linrad is pixel oriented!
Work bench for comparisons of USB dongles [MVI0017] Setup for the blocking and IM3 comparison below.
Compare dongles [donglecmp3] Dynamic range of rtlsdr dongles compared with Linrad. The above setup was used. USE HD QUALITY (720p) and "Full screen." Linrad is pixel oriented!
Sensitivity mode [e400 sensitivity mode]The sensitivity mode for the E4000 tuner. USE HD QUALITY (720p) and "Full screen." Linrad is pixel oriented! This mode requires an external filter, but it provides better performance in the close range by having a lower noise floor.
Linearity of AD converters. [ADCintermod] Here two units that sample at a high speed are compared. The Perseus SDR and the Adlink PCIe-9842 digitizer. Performance differs significantly!!
ANAN-100D [anan100d-dac] Sideband noise measured directly on the DAC when transmitting with the ANAN 100 D.
Compare tuners [SDRcompareTunersWide] SDRs that use tuners, rtlsdr, BladeRF, Airspy, SDRplay and others are not designed for a very large dynamic range within the range of their IF filters. As a consequence these SDRs have a mediocre performance as wideband receivers where we have both strong and weak signals within the passband.
Compare tuners. [SDRcompareTunersNarrow] Here tuners are compared for usage when the interfering signal is within the visible passband. For example 144 MHz with a suitable filter between the antenna and the tuner.
Compare tuners. [SDR on 88-108 FM part1]Compare tuners for usage on the FM band. Part 1, blocking and reciprocal mixing.
Compare tuners. [SDR on 88-108 FM part2] Compare tuners for usage on the FM band. Part 2, intermodulation at low signal levels.
Compare tuners. [SDR on 88-108 FM part3] Compare tuners for usage on the FM band. Part 3, intermodulation at normal signal levels.
The IF filter in R820T. [R820T with IF filtering] Here it is demonstrated that setting a narrow IF filter can improve the performance of rtlsdr dongles as FM receivers by 30 dB and more.
Testing the Softrock Ensemble RXTX. Here it is demonstrated that the input transformer does not isolate for RF voltages on the screen of the antenna cable. A capacitor will fix the problem.
Noise blanking in Linrad and Perseus.

The transmit side of Linrad

Tx setup. [Setup in SSB mode] The principles of the speech processor.
Speech processing. [Setup in SSB mode] Speech processing on voice signals.
Speech processing. [IC706 with the Linrad speech processor.] Here it is demonstrated how adding a speech processor can reduce splatter and increase the average transmitted power for a better readability at low signal levels.
Soundcard timing. [4Front OSS vs ALSA] Linrad allows both OSS and ALSA. Here Ubuntu 15.04 is used to compare the sound systems. Provided that Pulseaudio is disabled ALSA and 4Front OSS are both good.
First test of Softrock Ensemble RXTX as a transceiver in QSK
The Softrock Tx in "medium power mode"
The Softrock Tx in "QRP mode"
Screening a Softrock against electric fields.
The Softrock in Tx mode with different soundcards.
The Softrock Tx in high power mode.

Use Linrad as a test instrument.

S-meter calibration. [amplitude-calibration] Here the S-meter is calibrated with a rtlsdr dongle using the information that the typical noise figure for a dongle with the E4000 tuner is 8 dB.
Blocking dynamic range (BDR). [pcie9842-dynrange] A single very strong signal will degrade performance due to an increased noise floor on other frequencies. This video show how to measure BDR for a Linrad system.
How to measure signal to noise ratio. [measure-signal-to-noise] This video shows how to measure (S+N)/N on a weak signal by use of Linrad.
Here Linrad is used to measure reciprocal mixing in a Perseus receiver.

How to use Linrad processing functions.

Recorded files under Linux X11 [linrad-wav-x11]Download files from the internet and play in Linrad. This example shows a little about medium wave AM and how to use notches and synchronous AM detection.
Receiving spectral broadened CW [eme10ghz]This video is about receiving Morse coded signals on 10 GHz when doppler spread is significant.
Use of recordings. [long mw recording] An overnight recording of the entire medium wave spectrum is made here. It is demonstrated how Linrad can draw a waterfall from the entire recording in a fairly short time and how to select interesting time intervals to repeat over and over again when looking for specific things.
MAP65 with rtlsdr. [map65 with linrad and rtlsdr] Here it is demonstrated how Linrad can use an rtlsdr dongle to sample at 1536 kHz, downsample to 96 kHz and send the signal for decoding in MAP65.
utwente. [Linrad over the Internet] Here Linrad is used together with VAC to process signals received over the Internet.
Panadapter. [IC706 + rtlsdr] Here an rtlsdr dongle is used as a panadapter on a IC706MKIIG.
Sensitive waterfall. [Extreme sensitivity with rtlsdr.] Here Linrad is set up to produce waterfall graphs with high sensitivity for extremely weak signals.
Sensitive waterfall. [Extreme sensitivity with rtlsdr.] Here it is demonstrated on a Pentium IV how to set parameters that allow extreme sensitivity with a low CPU load.
Coherent processing on non-directional beacons. [Dig 6 dB deeper into the noise.]In a first stage coherent processing is used to improve S/N by 3 dB by using both sidebands of an A2 modulated NDB. In a second stage another 3 dB is gained by coherent processing of the 400 Hz modulation tone.
Coherent processing on non-directional beacons. [Dig 20 dB deeper into the noise.] By use of everything we know about NDBs we can gain about 20 dB compared to listening on one sideband with an optimum CW filter. This video explains how to do it - but someone would have to write some relatively trivial software to use this in full.
Netafedri with two coherent RF channels.