Running latest SDR# with latest DSD+ Fastlane

Discussion of SDR's and their use in the Scan New England listening area.
Post Reply
User avatar
Posts: 194
Joined: 29 Mar 2012 15:06
Location: Burlington, MA

Running latest SDR# with latest DSD+ Fastlane

Post by bfrederi »

I have been happily running a three year old version of SDR# with a year-old version of DSD+ Fastlane. Having recently retired, I used my newfound free time this week to upgrade both packages to the latest available versions.

This has been a mostly positive experience--I love the UI and feature upgrades in both. But I had to deal with one curve ball that had me knocking my head against the wall for a day and a half.

In fact, the first draft of this post was going to be a request for help from anybody who had encountered the same problem. Fortunately, just before hitting Send I tried one last thing and found a workaround, and am now writing this as a heads-up to anybody else who might risk stepping on this particular landmine.

PROBLEM: The latest version of SDR# downloaded from (v1.0.0.1732) may not play nice with the latest version of DSD+ Fastlane (v2.235), at least for decoding a P25 Control Channel. (This was the first thing I tried. I never even got to trying DMR or anything else.)

SYMPTOMS: Basically, DSD+ looks like it's starting to work and then acts, well...stupid. In the Event Log Window, it recognizes the system as P25 but displays an incorrect NAC and no system information. The Source Audio window shows a solid signal, and the DSD+ scrolling window shows a stream of P25p1 Sync messages, but nothing appears in the Channel activity window.

SOLUTION: Make sure that you download the basic "Windows SDR Software Package" from Do NOT download the "Community Package with Plugins". There is something about the way this package is configured that prevents DSD+ from handling SDR# P25 CC output.

AGGRAVATING VARIABLES: The official support forums on RR are filled with red herrings and misdirected advice. I ended up never posting there, and just read the existing discussions, which tended to all say the following:

1. You're still using SDR# with DSD+ Fastlane via Virtual Audio Cables? Don't! Use FMP instead!

[I don't WANT to use FMP. I want to use SDR#. My goal is not to trunk track a specific system using DSD+ and its built-in (and primitive) FMP tuners. I can do that with my 436HP. What I want to do is explore using SDR#, and analyze found signals with DSD+.]

2. DSD+ has deprecated Virtual Audio Cable support! Use TCP instead! (Along with "Use FMP instead of SDR#!")

[DSD+ Fastlane is perfectly capable of handling VaCs. Just use the nifty new menu system in the Event Log window and click Control > Passive Digital Monitor. I also saw one post that claimed that Fastlane no longer decodes P25 Control Channels (?!) Um, yes it does.]

3. The DSD+ Plugin in SDR# {doesn't work with Fastlane | doesn't work at all | is possessed by evil spirits}.

[I have no interest in the plug-in. I'm using conventional SDR # > Virtual Cable > DSD+. The fact that the plug-in is problematic is irrelevant to my issue.]

Anyhow, if you are running older versions of these packages and want to upgrade to the latest, I hope downloading the smaller basic package helps avoid some frustration.

Of course, there's still plenty of the usual SDR frustration to navigate through, even without the above. If you've gone through this once or twice in the past, you'll figure these out pretty quickly. (But if you are installing SDR#/DSD+ for the first time, you may find yourself fantasizing a swan dive off the Tobin Bridge.) Some of these can include:

1. Running install-rtlsdr.bat to install the zadig USB driver. (The Community Plugin Package did not alert me to do this. The basic package did.)

2. Source section in the SDR# UI: Selecting the correct Source: -- typically either RTL-SDR (USB) or Airspy. Then selecting the correct Device and ensuring that RF gain is not set to 0 in the Settings dialog.

3. Radio section: Ensuring that NFM is set.

4. Audio section: Ensuring that Output is set to the input Virtual Audio Cable.

5. Audio section: Ensuring that Filter Audio is disabled.

6. And in DSD+ Fastlane don't forget to enable Passive Digital Monitor as described above. (I didn't even notice the new menu UI when I first installed Fastlane!)

Some of the out-of-box defaults which require these changes baffle me. Hope this info helps anybody else undertaking this kind of upgrade.
Bruce, KA1FGY
Burlington, MA

Post Reply