SDR Questions

[joeuser]

Is it possible to use UniTracker & DSD+ at the same time with SDR#? If so, how? Seems like SDR# pipes audio out to cable 1 & once you tell DSD+ or UniTracker to look for audio there, the other can't access it - since its in use already... I swore you had to get both of these running for listening to APCO25 & you could do it with one dongle... I can get one or the other working with SDR# - just not both, like I think? I need. I'm running WinXP (32) & onboard sound (not a discrete card)

 

[joeuser]

Well I gave up on this & just went with a second dongle to make life easier.

 

[RonnieUSA]

Man Did I mess up big time, I have deleted, and installed, and reinstalled, all because I messed with my PPM.
I was following some directions in other thread, and started fiddling with mine, and got it to where I couldn't hear anything.
Well I got it fixed, my adapters PPM is 38, I'll not mess with that again.

Now will that be the same for other programs?
SD-Radio, HDSDR.

 

[br0adband]

Well, the ppm is per stick/device so, since that setting needs to be adjusted for any SDR application to make proper use of the stick/device (if it can't tune the exact frequency +/- a ppm or two, and I mean 1-2 ppm off the exact frequency) you're never going to hear anything. I have two sticks, one is 57 ppm and one is 50 ppm - doesn't matter which software I choose to use, I know going in that I'll have to adjust them (not the stick which isn't possible of course) so they match what the stick/device is capable of.

So yeah, you'll have to do the same with every program.

 

[joeuser]

The real fun begins when the temperature changes & it begins to drift around!

 

[RonnieUSA]

Well, the ppm is per stick/device so, since that setting needs to be adjusted for any SDR application to make proper use of the stick/device (if it can't tune the exact frequency +/- a ppm or two, and I mean 1-2 ppm off the exact frequency) you're never going to hear anything. I have two sticks, one is 57 ppm and one is 50 ppm - doesn't matter which software I choose to use, I know going in that I'll have to adjust them (not the stick which isn't possible of course) so they match what the stick/device is capable of.

So yeah, you'll have to do the same with every program.

That's good to hear.

The real fun begins when the temperature changes & it begins to drift around!

I don't have much change here in my apartment during the Winter so far, Summer will be the fun part.

 

[br0adband]

Once one of these sticks is "warmed up" they don't typically show a lot of drift, but they do exhibit it pretty severely till they reach their operating temps - and I say that meaning the RTL-based sticks which are the overwhelming favorites based on sheer numbers; more expensive SDR hardware will be "higher quality" and most likely have TXCO-based tuners meaning temperature controlled oscillators in the circuit. Mine at 57 and 50 ppm hardly ever change and I rarely need to alter it anywhere between 115 and 940 MHz - if it's on frequency at 124.950 it'll be on frequency at 935.1125 just the same in my experience, for example.

Some people seem to have sticks that really do jump all over the place constantly, even after they're warmed up, which is a bit odd but I guess it happens (guess I got lucky with the two sticks I got from NooElec, they're "rock solid" once they're at operating temps).

Airspy from the author of SDR# will probably be my next major investment in SDR hardware based on the specs and the expected pricing, and it's TXCO-based as well but that's not really a big concern to me. The 10 MHz bandwidth should be awesome to play with but even with all that I still won't be able to monitor my biggest system here in my area which has way too many frequencies to capture at one time at this point on my old laptop. Should be fun, however.

 

[RonnieUSA]

Once one of these sticks is "warmed up" they don't typically show a lot of drift, but they do exhibit it pretty severely till they reach their operating temps - and I say that meaning the RTL-based sticks which are the overwhelming favorites based on sheer numbers; more expensive SDR hardware will be "higher quality" and most likely have TXCO-based tuners meaning temperature controlled oscillators in the circuit. Mine at 57 and 50 ppm hardly ever change and I rarely need to alter it anywhere between 115 and 940 MHz - if it's on frequency at 124.950 it'll be on frequency at 935.1125 just the same in my experience, for example.

Some people seem to have sticks that really do jump all over the place constantly, even after they're warmed up, which is a bit odd but I guess it happens (guess I got lucky with the two sticks I got from NooElec, they're "rock solid" once they're at operating temps).

Airspy from the author of SDR# will probably be my next major investment in SDR hardware based on the specs and the expected pricing, and it's TXCO-based as well but that's not really a big concern to me. The 10 MHz bandwidth should be awesome to play with but even with all that I still won't be able to monitor my biggest system here in my area which has way too many frequencies to capture at one time at this point on my old laptop. Should be fun, however.

Mine is on 24/7, so I guess it's warmed up.

 

[joeuser]

Mine are on all the time also but near a drafty window & a vent... It can be challenging!

 

[RonnieUSA]

Just an other question.
P25 sounds just as good as my scanner, but I'm having problems with a NXDN4800 system, it could be because how close I am to the repeater. ( 600 to 800 yards )
Sometimes it very clear, and sometimes choppy, is there anything in SDRSharp I can do about it?

I think, I found the problem, it was the antenna I was using, at least I hope it fixed the problem.

 

[br0adband]

All I can suggest - since most of the sticks we're using are susceptible to severe distortion and front-end overload with very strong signals - is decrease the gain considerably when you're monitoring that system. It only takes a few seconds to open the Configure menu and alter the RF gain down, and obviously for such a powerful signal there's zero need for RTL AGC or Tuner AGC (I stopped using either of those a long time ago). I have a few signals in the 460 MHz range that even with the RF gain set to 3.7 dB it'll still peak the spectrum at -10 dB because I'm like 4 blocks from the transmitter LoS, I can see the actual antenna from my balcony.

Let's just say the RF gain on my SDR apps gets altered quite frequently.

The other aspect with NXDN traffic - depending on the way they are set up, of course - is that they can be tough to nail down in terms of the exact frequency because of them being capable of that offset operation: every NXDN system here in my area that I've been able to snag recently is offset. The FCC license will show the primary frequencies but they end up transmitting either -3.125 kHz or + 3.125 kHz off that frequency, sometimes both at the same time. Can be either 2.5 kHz, 3.125 kHz, 6.25 kHz, or even 7.5 kHz off depending on the frequency bands, so if you note that you almost get them but not quite, the system you're trying to monitor could be offset on the transmitting side of things.

That picture you posted shows the peak being just slightly off the tuned frequency, might consider checking your ppm up or down 1 notch to get it centered on the peak - it might help, it might not, but in my experience with NXDN more so than any other of the digital protocols, it's extremely sensitive to the ppm and can result in horrid decodes if it's off by even just 1 ppm.

Might consider altering the FFT range too considering your noise floor seems to be at the "standard" of about -60 dB on average - anything below that level is basically not going to be seen (maybe on the waterfall I suppose but even so it won't show a signal peak on the spectrum) and you're making SDR# use more CPU power than necessary aka operate inefficiently by showing "nothing" on the spectrum all the way down to -130 dB.

Just my advice, of course...

 

[RonnieUSA]

All I can suggest - since most of the sticks we're using are susceptible to severe distortion and front-end overload with very strong signals - is decrease the gain considerably when you're monitoring that system. It only takes a few seconds to open the Configure menu and alter the RF gain down, and obviously for such a powerful signal there's zero need for RTL AGC or Tuner AGC (I stopped using either of those a long time ago). I have a few signals in the 460 MHz range that even with the RF gain set to 3.7 dB it'll still peak the spectrum at -10 dB because I'm like 4 blocks from the transmitter LoS, I can see the actual antenna from my balcony.

Let's just say the RF gain on my SDR apps gets altered quite frequently.

The other aspect with NXDN traffic - depending on the way they are set up, of course - is that they can be tough to nail down in terms of the exact frequency because of them being capable of that offset operation: every NXDN system here in my area that I've been able to snag recently is offset. The FCC license will show the primary frequencies but they end up transmitting either -3.125 kHz or + 3.125 kHz off that frequency, sometimes both at the same time. Can be either 2.5 kHz, 3.125 kHz, 6.25 kHz, or even 7.5 kHz off depending on the frequency bands, so if you note that you almost get them but not quite, the system you're trying to monitor could be offset on the transmitting side of things.

That picture you posted shows the peak being just slightly off the tuned frequency, might consider checking your ppm up or down 1 notch to get it centered on the peak - it might help, it might not, but in my experience with NXDN more so than any other of the digital protocols, it's extremely sensitive to the ppm and can result in horrid decodes if it's off by even just 1 ppm.

Might consider altering the FFT range too considering your noise floor seems to be at the "standard" of about -60 dB on average - anything below that level is basically not going to be seen (maybe on the waterfall I suppose but even so it won't show a signal peak on the spectrum) and you're making SDR# use more CPU power than necessary aka operate inefficiently by showing "nothing" on the spectrum all the way down to -130 dB.

Just my advice, of course...

I think I may have it now, I like all of the tips I get, most help me.

 

[br0adband]

Looks good, but as always it's up to you how to run things - I'd say use -60 dB as the "floor" for the spectrum so you can see those signals that are just peaked above that level, that way it's a relatively good match for the noise floor of the hardware itself.

Been spending a lot of time with SDR-Radio myself the past week or so, it's pretty awesome overall but I do still use SDR# for digital decoding work; as noted in that other thread, I haven't had much success using SDR-Radio to feed DSD+, the decoding is constantly full of errors no matter what I do. Same hardware, same antennas, same Windows audio system settings, only the apps are different and yet SDR# provides a vastly cleaner signal to DSD+ for that purpose.

I might just scrap everything and start clean at some point, getting a bit cluttered up I suppose.

 

[joeuser]

Looks good, but as always it's up to you how to run things - I'd say use -60 dB as the "floor" for the spectrum so you can see those signals that are just peaked above that level, that way it's a relatively good match for the noise floor of the hardware itself.

Been spending a lot of time with SDR-Radio myself the past week or so, it's pretty awesome overall but I do still use SDR# for digital decoding work; as noted in that other thread, I haven't had much success using SDR-Radio to feed DSD+, the decoding is constantly full of errors no matter what I do. Same hardware, same antennas, same Windows audio system settings, only the apps are different and yet SDR# provides a vastly cleaner signal to DSD+ for that purpose.

I might just scrap everything and start clean at some point, getting a bit cluttered up I suppose.

Did you try the dsdtune?

 

[br0adband]

Not worth going through all that considering SDR# + DSD+ works perfectly in my situation. I use both SDR# and SDR-Radio these days because each has its strengths and weaknesses. I doubt there will ever be a perfect SDR program (too many variables involved) so I/we just make the best of what we're lucky to have in the first place, especially considering these programs are free of cost and pretty amazing for what they're capable of.

 

[joeuser]

Not worth going through all that considering SDR# + DSD+ works perfectly in my situation. I use both SDR# and SDR-Radio these days because each has its strengths and weaknesses. I doubt there will ever be a perfect SDR program (too many variables involved) so I/we just make the best of what we're lucky to have in the first place, especially considering these programs are free of cost and pretty amazing for what they're capable of.

I used it myself. Recorded 45 secs of feed... Ran it thru dsdtune - got my settings/switches. However, afterwards, I got all sorts of errors. So I went back to *just* using the -f1 switch (that's all we have out here is the P25) & I got no errors. So it didn't help me, but I didn't really need any I guess.

 

[BM82557]

I use both SDR# and SDR-Radio these days because each has its strengths and weaknesses.

One thing I've noticed is that SDR-Radio is happier with more memory. SDR# and DSD+ run fine with 4Gig but SDR-Radio and DSD+ don't. I just use a spare flashdrive in readyboost mode to increase memory when using SDR-Radio with DSD+.

 

[joeuser]

One thing I've noticed is that SDR-Radio is happier with more memory. SDR# and DSD+ run fine with 4Gig but SDR-Radio and DSD+ don't. I just use a spare flashdrive in readyboost mode to increase memory when using SDR-Radio with DSD+.

PowerSDR, cuSDR, HDsdr, & SDR-RADIO (among others) seem very taxing to systems - compared to SDR#. However, if you really want eye candy & performance...Studio1 is reported to be the way to go. It is not freeware though. Its just shy of 220$ though, lol. Kind of defeats the whole radio on the cheap concept.

 

[RonnieUSA]

Just a couple more questions, and I should be OK.
In the Pic's I'm posting, what are the suggested settings?
I'm having no problems decoding.

 

[RonnieUSA]

In my 2 months using these adapters, I couldn't under stand why 1 day it all sounds good, and the next I had to choose one the other to listen to.
I think I found the problem, the City PD has a frequency of 460.58750, but when I load it into the Scanner plugin, and when they are talking it looked off center, so I started playing, and used the VFO to tune down to 460.58700, and it's in the center, and now I don't have to choose, all it sounding good.

Now I'm happy.