A question for Airspy Frequency Scanner plug-in users...

[LloydCarol]

Hi everyone,

I am running an Airspy R2 with the frequency manager and frequency scanner plug-ins. I have the Airspy connected to a discone antenna mounted outside.

The antenna works great for with a Uniden 396. I routinely hear aircraft over 200 miles away with the scanner, but the Airspy range is a less than half of that and maybe quite a bit less than half.

Is that normal? Is there anything I can do to improve the how well the Airspy 'hears'?

Many thanks from Dallas!

-LC

 

[TDR-94]

I've had the same experience. In comparison to my IC-R20, the Airspy R2 and SDR# plugins just don't have the same performance, when it comes to weaker signals and noise in the airbands and I've tried all the methods for getting the best SNR. Some claim to have measured the Airspy R2 to have very good sensitivity.

 

[thewraith2008]

Is there anything I can do to improve the how well the Airspy 'hears'?

I'll state the obvious just in case it was over looked.
Did you adjust the Gain slider in SDR# for the Airspy? (approx. 13-16)

 

[LloydCarol]

First off wraith, thanks for all of the work you've put into the plug-in. It's amazing!

To answer the question about gain, I typically have it set at 19. That level seems to work best for me anyway.

TDR - I think I've read about a similar situations to yours and I'm a little concerned!

 

[TDR-94]

First off wraith, thanks for all of the work you've put into the plug-in. It's amazing!

To answer the question about gain, I typically have it set at 19. That level seems to work best for me anyway.

TDR - I think I've read about a similar situations to yours and I'm a little concerned!

Yeah, there have been others that have compared the performance to their current scanners and have noticed a difference.

I compared it with my ICOM IC-R20, using the same antennas and external mini circuits filters for both and even had the IC-R20's squelch level set to 6 out of 10 and the same signals that were received crystal clear with the IC-R20, many times were either never received at all or were so full of noise/static that they were much less intelligible with the Airspy R2. And this was just using VFO mode on both, held on a single frequency with the SDR# squelch level set to just above the noise level.

While "scanning" the Airspy R2 would get many more hits because of the way it quickly searches whole chunks of bandwidth, it has no competition there and was the biggest reason for me wanting to utilize it, but still would have the same issues with completely missed signals or increased noise/static.

 

[ab3a]

Do you use an FM band Notch filter? Without it, if you're close to any FM radio stations it may saturate the front end of your R2 with the gain set that high.

 

[kb5udf]

I've used both the airspy mini and airspy R1, but not R2. Based on experience with these two devices if a gain of 19 is working optimally for you, it seems like something amiss. On my receivers, gain that high causes massive aliasing due to signal overload. It makes me wonder if you have a connection problem, antenna problem, or deaf receiver.

JB

 

[TDR-94]

Yeah, I agree. Unless you are compensating for insertion loss without a preamp, a gain setting of 19 is pretty high. I never needed to go above 12-13, otherwise things start to get ugly.

As far as a FM band stop filter. I'm using a mini-circuits ZBSF-95+ and it didn't have any effect on that particular behavior with the Airspy R2. It did lower the noise floor a little though.

 

[LloydCarol]

Wow. Thanks for the input from everyone. I'm not certain about many of the terms but I think I can infer most of the meanings. Also, I'm newbie poster (but long-time lurker) so my posts get delayed, unfortunately. With that out of the way...

To answer ab3a, I don't use any type of filter, but I've wondered if that might be an issue. I do know I receive VHF comms on UHF frequencies. It seems like it's a double of the original (VHF freqx2). For example, if there is a civ of general aviation aircraft transmitting near me (as in almost overhead) on 124.000 mhz, I can pick him up on 248.000 mhz. Also, I ran the scanner plug-in earlier, and it stopped on a frequency that sounded like either an FM radio transmission or and advert from TV. I also heard Morse code in the Mil Air range. I've never that before.

Could I have some setting positioned wrong? Is this a computer issue?

Can these SDRs burnout out due to too much RF energy? Here's why I ask: I've been able in the past to scan the entire mil air spectrum in about 3 seconds. That stopped today. Today it's closer to 14 seconds. As a test, I raised the top level to 98 and the bottom level up to 76 and the SDR was still getting hung up on frequencies without generating a sound - if that makes sense.

 

[kb5udf]

Hearing 124 on 248 sounds like a 2nd harmonic. Likewise nothing unusual about hearing images of broadcast FM radio on the 118-136 and 220ish to 300ish mil aviation bands with an airspy; this definately worens if your gain is too high. If you are hearing morse code in mil air range, again you might be hearing a harmonic from a vhf repeater id'ing.

 

[LloydCarol]

Hey guys,

Thanks for your help. It was the gain setting after all. I picked up ground control at the navy base about 40 miles away this morning.