SDR Maximum Overdrive

Status
Not open for further replies.

br0adband

Member
Joined
Apr 8, 2005
Messages
1,567
Location
Springfield MO
hi , Could you please explain how to do mulitple vfo's and multiple audio connections, I have set up the vfo's
but haven't a clue as how to set up multiple dsd+ with the vfos, this ones got me confused.

thanks
Paul

You have to use virtual audio cables to make that possible and assign the audio output of each VFO (set from their respective Audio menus) to one of the virtual audio cables. So for example you had 3 VFOs, and 3 virtual cables - you'd assign the first VFO to output to virtual audio cable 1, then the second to 2, third to 3, etc. Once the source audio for each VFO is piped to a virtual audio cable, then you'd start up DSD+ and attach or assign it to use virtual audio cable 1 (by using the command line switches to do so), then fire up a second copy and assign it to virtual audio cable 2, and then finally the last DSD+ copy to virtual audio cable 3.

Gets complicated fast but once you do this stuff a few times, it just becomes habit pretty fast and then you're not even thinking about it anymore as it becomes easier.

And of course it bears repeating: this multi-VFO functionality just from one RTL stick or SDR tuner only works when the frequencies you want to monitor are all inside the visible spectrum aka the bandwidth the device is capable of. RTL sticks based on the R820T tuner - the majority of them - have roughly 2.4 MHz of spectrum (aka the sampling rate) available whereas the better devices (bladeRF, HackRF, USRP, etc) are capable of very wide bandwidth of 10 MHz or more. The upcoming Airpsy - from the author of SDR# - uses the R820T tuner as well but a vastly improved controller chip that provides 10 MHz of spectrum as well as 12 bit capability as well (should help with dynamic range and noise considerably).
 

BM82557

Member
Joined
Aug 28, 2006
Messages
4,972
Location
Berkeley Co WV
The trick to doing so in SDR-Radio, and this is per Simon, is to set the mode to FM-W with a bandwidth of 12.5 KHz. I've tried it and it works like a champ.


Thanks for the info. Maybe he'll add it to the V2 user manual or the website. It would probably make things easier for a lot of people.
 

pdeveau2010

Member
Joined
May 8, 2011
Messages
80
Location
Tewksbury,MA
vac settings

hi, got everything to work, wasn't as hard as I thought, 1 more question, could you tell me your settings for VAC, I was using VB Cable and was working really well, but now using VAC and the decodes seem less strong.

thanks
Paul
 

galaxie67w

Member
Joined
Nov 28, 2009
Messages
34
Location
Seagrove, NC
Great thread guys... this is the stuff that gets me fired up about radio!

I'm using original VAC and I have 8 devices in play. Seems to work well. For VAC channels bound for DSD/DSD+, I think the most important setting is samplerate 48000hz.

I am monitoring the NC VIPER P25 (Motorola Type II Smartzone OmniLink) system using 2 RTLs and a tapped scanner for the control channel. At first I was using a single RTL with multiple VFOs to track multiple conversations, but alas the LCNs spanned 851-856Mhz on the tower I was interested in. So quite frequently VFO A would be 851.xxxx Mhz and VFO B on 856.xxxx Mhz, which on the RTL is too wide to catch both simultaneously. (Some towers in my area are NOT too wide for the RTL, and they work great up to 6 VFOs/DSD+!

That's why I'm so excited about the Airspy. A 10Mhz span would be great!

My setup feeds my stereo live audio feed http://www.broadcastify.com/manage/feed/6746
RTL #1 = left audio channel
RTL#2 = right audio channel
I've even made a program to bring the alpha tags from Unitrunker and feed them to scannercast. Check it out!

73
KJ4SPG
 
Status
Not open for further replies.
Top