October 2026 - osmocom-sdr - lists.osmocom.org

[PATCH] rtl_tcp: keep serving after a client that disconnects at once
by Rodrigo Gressler 23 Oct '26

23 Oct '26

Hi, I hit this running rtl_tcp on Windows with an RTL-SDR Blog V4: a client that connects and drops right away (port probe, quick reconnect) leaves rtl_tcp accepting TCP connections but never sending the dongle header again until it is restarted. When the client goes away before rtlsdr_read_async() has started, the worker's rtlsdr_cancel_async() is a no-op, read_async then runs forever with do_exit set and the server never gets back to accept(). The attached patch: - rtlsdr_callback(): once do_exit is set, cancel from there and return - command_worker(): recv() == 0 (client closed) ends the session - tcp_worker(): a select() error ends the session; bytesleft/index only move when send() sent something It applies to master (v2.0.3) and builds without warnings. With it the server goes back to accept() after each such client; tested on the same setup. The same fix is in rtlsdrblog/rtl-sdr-blog PR #85. For transparency: I tracked this down and wrote the fix with help from an LLM. I reviewed the change, tested it and am happy to answer questions about it. Regards, Rodrigo Gressler

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Re: osmocom-sdr Digest, Vol 114, Issue 1
by Carl 23 Oct '26

23 Oct '26

Hi Oliver, SDR++ is one popular project that pulls from these binaries. The issue only came up just now because Blog V4L (Lite) support wasn't working after they updated to the latest build from the ftp. It must have been working back in 2023, because that's when Blog V4 support was added, and the binaries have picked up that change. So probably only 2-3 years that it has been failing. Regards, Carl On Sat, Oct 24, 2026 at 1:01 AM <osmocom-sdr-request(a)lists.osmocom.org> wrote: > Send osmocom-sdr mailing list submissions to > osmocom-sdr(a)lists.osmocom.org > > To subscribe or unsubscribe via email, send a message with subject or > body 'help' to > osmocom-sdr-request(a)lists.osmocom.org > > You can reach the person managing the list at > osmocom-sdr-owner(a)lists.osmocom.org > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of osmocom-sdr digest..." > > Today's Topics: > > 1. Osmocom Windows binaries not built on up to date code? > (Carl Laufer) > 2. Re: Osmocom Windows binaries not built on up to date code? > (Oliver Smith) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Fri, 23 Oct 2026 18:19:05 +1300 > From: Carl Laufer <admin(a)rtl-sdr.com> > Subject: Osmocom Windows binaries not built on up to date code? > To: osmocom-sdr(a)lists.osmocom.org > Message-ID: > < > CAP8SZq1LJkOkuvRNdycOdce3-3L1sExHv-PWBnjc5ByqHRfXOw(a)mail.gmail.com> > Content-Type: multipart/alternative; > boundary="000000000000b6b60a065e7b204c" > > Hi, > > I've just been testing out the latest Windows builds at > https://ftp.osmocom.org/binaries/windows/rtl-sdr/, but they do not seem to > be up to date. > > I tested the latest October 18 2026 zip file, and found that rtl_test does > not detect the RTL-SDR Blog V4L. > > But if I compile from source from the Osmocom rtl-sdr GitHub, I get working > V4L support for Windows and Linux, so the source is working fine. > > So it seems that the automatic builds are not working correctly and are > using old code to build librtlsdr.dll and possibly everything else? > > Regards, > Carl Laufer > RTL-SDR.com <http://rtl-sdr.com/> & krakenrf.com >

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Osmocom Windows binaries not built on up to date code?
by Carl Laufer 23 Oct '26

23 Oct '26

Hi, I've just been testing out the latest Windows builds at https://ftp.osmocom.org/binaries/windows/rtl-sdr/, but they do not seem to be up to date. I tested the latest October 18 2026 zip file, and found that rtl_test does not detect the RTL-SDR Blog V4L. But if I compile from source from the Osmocom rtl-sdr GitHub, I get working V4L support for Windows and Linux, so the source is working fine. So it seems that the automatic builds are not working correctly and are using old code to build librtlsdr.dll and possibly everything else? Regards, Carl Laufer RTL-SDR.com <http://rtl-sdr.com/> & krakenrf.com

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(Very Minor) Correction to Gain Values in librtlsdr.c
by Gary Schafer 03 Oct '26

03 Oct '26

I've been trying to understand how the RTL-SDR drivers adjust gain values for R82xx/R860 chips based on user input. I saw that a user input is set to one of 29 possible values using the "nearest_gain" function in "convenience.c". These values are listed in "librtlsdr.c" in the "r82xx_gains", with the last two gain values being 480 and 496. As I was going through the code, I looked up the gain values for the LNA and mixers in "tuner_r82xx.c", and then created a spreadsheet to understand the method of how these are used together to set the overall gain. The method is to add gain to the LNA and mixer in alternating fashion (LNA-mixer-LNA-mixer), as listed in the function "r82xx_set_gain", using the gain values for each amp listed in "tuner_r82xx.c". And I think that there's a value missing in "r82xx_gains". According to my spreadsheet, there should also be a value of 483 between these last, two values. That means the last three values of this array would be "..., 480, 483, 496]". Mind you, this is a minor 0.3 dB of gain. This is also my OCD kicking in. I'm not a programmer, so I don't know if I'm understanding this correctly. If I am, I don't know if the correction is to just add this value to the array. Regards, Gary

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