Hi Bodo et al,

I guess this email is a long-delayed-echo, internet style? ;)

I assume this was re-posted because there is some interest, so I will provide a brief update of where all of this ended up for me.

The original email was from April 2006 as you see. By June of 2006 I was routinely running 4 instances of Linrad simultaneously on one computer. This is possible using either Linux or Windows; I generally use Windows for this purpose for non-Linrad-related reasons.

My purpose for this was/is to monitor constantly the 50/144/222/432 MHz bands during a contest. This arrangement has worked great for that.

My initial configuration, in use for a bit more than a year, used 2 Delta-44's hooked to various combinations of the 28 MHz SoftRocks, TimeMachines setup for 28 MHz, and homebrew 28 MHz front ends. Each 28 MHz receiver was connected to a different transverter, covering the 50,144,222,and 432 MHz bands.

I found that the Softrocks didn't handle well the large number of very strong signals on 50 and 144 MHz that are present during a contest.

So for the past few months my configuration has been:
SDR-14 for 50 MHz
SDR-IQ for 144 MHz
Softrocks for 222 and 432 MHz
and this has worked well.

I had to reduce the bandwidth a bit on the SDR-14 and SDR-IQ to keep them from locking up when run simultaneously, but I still have more than 90 kHz bandwidth. The SDR-IQ needs to be started before the SDR-14 or the SDR-IQ won't be recognized by Linrad.

I used this setup for the ARRL September VHF contest just ended, and it worked very well.

I have it setup so that if I see a potentially interesting signal on any of the 4 Linrad bandscopes, I just click on it and the audio of course goes to my headphones. If the signal is one I want to work, I type 'q' and the 28 MHz frequency corresponding to that station is sent by Linrad over my network to my FT1000MP which is on another computer so I can quickly work the station, and then go back to doing what I was doing on whatever band I was on before I noticed the potentially interesting signal on the Linrad bandscope.

I have another instance of Linrad running using the WSE hardware on another computer that is used for the main band/receiver bandscope. It uses a homebrew transverter to convert the 28 MHz signal from my transverters for 50 MHz thru 10 GHz to 144 MHz so I can feed the signal into the WSE hardware. That instance of Linrad uses another SDR-IQ as input.

The Softrock 28 MHz


was out of production very quickly, but there is talk of bringing back a 28 MHz version, possibly now Tx/Rx!


In addition to less than ideal strong-signal-handling capability, the original 28 MHz softrock was insensitive; see for example:
and I have to run a 28 MHz preamp before mine.

I will be mentioning all of this in the talk I will be giving at Microwave Update on "A VHF and Up Operator's Discussion of Useful DSP Software and Hardware".


Hope that helps, and hope to see some of you at Microwave Update! There will be a lot of other people giving excellent talks:



Roger Rehr

Quoting Bodo Heyl <[EMAIL PROTECTED]>:

----- Original Message -----
From: "w3sz" <[EMAIL PROTECTED]>
To: "Linrad mailinglist" <linrad@antennspecialisten.se>
Sent: Saturday, April 22, 2006 2:45 AM
Subject: [linrad] multiple instances of Linrad

Hi, All,

The SoftRock v7s are so cheap I am starting to come up with all sorts of uses for them in conjunction with Linrad.

One thing I had mentioned to Leif in the past was running multiple instances of Linrad so that one could watch simultaneously the 'bandscopes' of each of the lower VHF bands at all times during a contest. Now that X Windows and MSWindows versions of Linrad are available, it is easy to display two or more Linrad windows on the screen at the same time.

With a Soft Rock dedicated to each of 50, 144, 222, and 432 MHz one would have things covered pretty well in terms of constant monitoring of the lower bands during a contest [or just looking for openings on each of the bands simultaneously at other non-contest times].

My thought is to have one computer and monitor dedictated to being this 'full time monitor' using 2 delta44's as inputs [each Delta44 could handle 2 SoftRock cards and therefore 2 bands], and the onboard sound for output, and constant simultaneous displays of the Linrad bandscopes for each of these 4 bands on the screen.

With the appropriate selection of parameters [and the fact that for MONITORING you don't even need to be clicked on a signal most of the time] one should be able to run 4 instances of Linrad and not overtax the cpu.

As I type this I am running two instances of Linrad with the Delta44 sending a different [I/Q] input to each and thus I am monitoring two different receive chains displayed in two different Linrad-for-Windows-Windows. Even when listening to both signals with 96000 Hz sampling the CPU is happy and I am not getting glitches [Windows XP, P4, 3.2 GHz, Linrad-02.6a].

So running 4 instances of Linrad at once with parameters chosen to minimize cpu overhead should be no problem.

I put a screen grab of the two copies of Linrad running at the same time, much as they would be displayed in this application, for your amusement at:


The only glitch that I forsee would be if two Delta44 cards installed at the same time are not handled properly by the OS. But mAudio's site says you can have up to 4 installed at the same time. If that is true, and if you had the cpu power...I will leave the math to you ;)

I can't wait to get those SoftRocks!  Its almost like free radio ;)

Maybe I had too much caffeine today at work.  Have a great weekend all, and


Roger Rehr

Roger Rehr

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