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Airspy SDR by SDR# author

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KC1UA

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So far I'm optimistic. As advertised it is pretty much image free. I would like to have complete control over the FFT size, as it is now I'm restricted to certain bandwidths. I like to look at the entirety of the UHF-T band; it seems that I can only use 2.5 MHz or 5 MHz sizes with the decimation settings.

Gain settings will take some getting used to. For now I have IF Gain at 5 and mixer and LNA gains set to auto.

I did notice a NOAA weather signal in the UHF range; I need to revisit this to find out where.

I'll play with it more over the weekend but I'm starting a move of the entire setup to another room, so not sure how much I'll be able to.
 

mancow

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EDIT:
I see what you mean about decimation. I think that's just what it does. It divides it down by that factor of that figure.
 
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KC1UA

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Poor choice of words on my part, yes, 10 MHz is not a problem, and divided by the decimation offers different bandwidths but not ALL of them; I'd like to be able to have a 3 MHz FFT for the T bands as I mentioned. I know using SDR# with the HackRF you could manually type in the MSPS and overcome the limits of the drop down choices but it doesn't appear I can do that here. Yet, anyway. Simon Brown will have his soon and soon after that SDR-Console will be usable with it as well. I use both programs for various different purposes so it'll be nice to have both available.

I'm seeing my local 162.550 MHz NOAA Weather Radio broadcast at 152.250 and also at 463.7625. It's not a perfect world and thus far, although my use has been limited, those are the only two anomalies I've encountered yet. My noise floor is at -80 and I'm using my highest tower-mounted antenna, a Comet GP-15.

Even in my two biggest problem areas, which are around 152 MHz due to a nasty dirty paging transmitter, and 450-455 due to many super-strong DMR and NXDN control channels, are image free and are definitely better than my hackRF and bladeRF.
 

prog

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Poor choice of words on my part, yes, 10 MHz is not a problem, and divided by the decimation offers different bandwidths but not ALL of them; I'd like to be able to have a 3 MHz FFT for the T bands as I mentioned. I know using SDR# with the HackRF you could manually type in the MSPS and overcome the limits of the drop down choices but it doesn't appear I can do that here. Yet, anyway. Simon Brown will have his soon and soon after that SDR-Console will be usable with it as well. I use both programs for various different purposes so it'll be nice to have both available.

I'm seeing my local 162.550 MHz NOAA Weather Radio broadcast at 152.250 and also at 463.7625. It's not a perfect world and thus far, although my use has been limited, those are the only two anomalies I've encountered yet. My noise floor is at -80 and I'm using my highest tower-mounted antenna, a Comet GP-15.

Even in my two biggest problem areas, which are around 152 MHz due to a nasty dirty paging transmitter, and 450-455 due to many super-strong DMR and NXDN control channels, are image free and are definitely better than my hackRF and bladeRF.
Hi,

Can you describe your setup? W9RAN had some problems with NOAA broadcasts mixed up to the UHF band because of a leaky switch and bad gain settings. It turned out one of his many rigs was leaking the LO signal and it was mixed with the legit signals coming from the antenna. The result of the mixing is obviously very weak, but leaving the gain to "auto" might just amplify it when no legit signal is present. The AGC can pull up anything out there.

Concerning the sample rates, not all configurations are possible without compromising the quality of the signal. Airspy has virtually no restrictions in the hardware to output any sample rate to the sub Hz precision, just like the HackRF since they use the same clock chip; but as you can see in HackRF, this creates a lot of spurs and birdies which is not acceptable for me. The software decimation offers that same flexibility while adding more bit resolution. You end up with 10MHz, 5MHz, 2.5MHz, 1.25MHz, 625kHz and 312.5kHz spans with gradually higher dynamic range up to 100dB.

Can you try connecting Airspy directly to the antenna?
 

KC1UA

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Sorry for the response delay. I just moved all of my equipment from one room to another in the house so I hadn't had much time to try out the new Airspy until last evening. I have not gone back to observe whether those signals remain. I'll provide an update when possible.

Understood on the sample rates.

When you say "can you try connecting Airspy directly to the antenna" I'm not sure I understand what you mean; it is connected to any number of external antennas via a patch panel on my rack. If you're referring to the included antenna I haven't even taken it out of its sleeve to be honest.

I will say thus far I am very impressed with the performance of this device, both signal wise and even more importantly to me image/alias wise. Of the three SDR's I own (Airspy, HackRF, BladeRF) it is the clear and absolute winner in that category.
 

prog

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I meant connecting via an antenna switch can inject some signals that may look like images. But I'm happy with the results you got. Thank you for the feedback! You may want to try Vasili's fast scanner at http://rtl-sdr.ru?
 

rrbum

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From reading what you AirSpy owners have posted it sounds like it is well worth the money and is a good performer.
I am no expert by any stretch of the imagination. I picked up an airspy because I enjoy what the DVB dongles can do and recognized what the designer intended to do with the tuner chip. I looked at it as a dongle on steroids, and wanted in. I knew that the dongles were slapped together and used the cheapest of components, and if they worked so well than something designed especially for SDR using quality components would be for me. The airspy is set up to do so much more than I can even comprehend, but I only want to simply search and receive signals.
The performance has been terrific. It is nice to sniff around without so many images and a nice smooth noise floor.
I have found the sensitivity to be very good, the selectivity good when the proper bandwidth is set. The ability to adjust for gain and other parameters allows much flexibility in dialing any given signal.
I truly feel this is only the beginning of what can be done with SDR depending on where the skilled software writers take things and I think the airspy will be not only capable but affordable.
It is also good to know that the designer is here now on the forums.

Although I am not familiar with all of the options for receivers I would recommend airspy to anyone who wants to go a step beyond the DVB dongle for a more quality experience. Some have questioned the cost, I don't know the profit margin on each unit but if development continues and improvements/upgrades keep coming with software than I do not mind putting a little coin in the pockets of those that brought the airspy. :)
 

mancow

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I meant connecting via an antenna switch can inject some signals that may look like images. But I'm happy with the results you got. Thank you for the feedback! You may want to try Vasili's fast scanner at RTL-SDR
The fast scanner is amazing.

It's like what I envisioned years ago when dreaming of what the ultimate receiver could do.
 
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From reading what you AirSpy owners have posted it sounds like it is well worth the money and is a good performer.
I'm waiting for mine to be replaced, at 450MHz it is far less sensitive than a stock $10 TV tuner with an R820T chip, I wouldn't call it deaf but its not sensitive, it required 0.822uV for 12dB sinad at 451MHz. It also exhibits weird spikes every 300kHz in 2.5MSPS mode, Youssef has decided from the images I sent him it must be faulty.

Of the USB stick type receivers the best performer on sensitivity is the Funcube Pro+, however it does overload quite easily and only has 192kHz bandwidth, it does also cover HF though.

I am still hoping the Airspy might be what I was expecting, I am waiting for a new board to be sent to me, it certainly seems that quality control is not a strong point with these units.
 

prog

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I'm waiting for mine to be replaced, at 450MHz it is far less sensitive than a stock $10 TV tuner with an R820T chip, I wouldn't call it deaf but its not sensitive, it required 0.822uV for 12dB sinad at 451MHz. It also exhibits weird spikes every 300kHz in 2.5MSPS mode, Youssef has decided from the images I sent him it must be faulty.

Of the USB stick type receivers the best performer on sensitivity is the Funcube Pro+, however it does overload quite easily and only has 192kHz bandwidth, it does also cover HF though.

I am still hoping the Airspy might be what I was expecting, I am waiting for a new board to be sent to me, it certainly seems that quality control is not a strong point with these units.
We use automated RF tests every few MHz by injecting signals and measuring the SNR and checking for the images. It happens in all electronics productions to get cold solder joints. They may pass the test but deteriorate just after. As of today, we had only two cases. out of 500; I'd say that's a rather good ratio.
Btw, I just received my box of spies from Hong Kong so you should get your replacement board either during the week or next monday.
 
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High performance SDR choices

I am no expert by any stretch of the imagination. I picked up an airspy because I enjoy what the DVB dongles can do and recognized what the designer intended to do with the tuner chip. I looked at it as a dongle on steroids, and wanted in. I knew that the dongles were slapped together and used the cheapest of components, and if they worked so well than something designed especially for SDR using quality components would be for me. The airspy is set up to do so much more than I can even comprehend, but I only want to simply search and receive signals.
The performance has been terrific. It is nice to sniff around without so many images and a nice smooth noise floor.
I have found the sensitivity to be very good, the selectivity good when the proper bandwidth is set. The ability to adjust for gain and other parameters allows much flexibility in dialing any given signal.
I truly feel this is only the beginning of what can be done with SDR depending on where the skilled software writers take things and I think the airspy will be not only capable but affordable.
It is also good to know that the designer is here now on the forums.

Although I am not familiar with all of the options for receivers I would recommend airspy to anyone who wants to go a step beyond the DVB dongle for a more quality experience. Some have questioned the cost, I don't know the profit margin on each unit but if development continues and improvements/upgrades keep coming with software than I do not mind putting a little coin in the pockets of those that brought the airspy. :)
As well as the devices mentioned in this thread, there is also the SDRplay RSP at $149 where we see reviews like this:

"...for LW-SW reception I use a home-made pa0rdt-Mini-Whip antenna (50kHz-30MHz) in combination with a home-made tunable preamplifier.
For FM – 2m I use a modified telescope antenna. I also have RTL-SDR sticks with up converter and an old Kenwood R1000
receiver. For SDR I use both, HDSDR and SDR# software.
The first thing I noticed is that the SDRplay RSP works well below the specified low frequency limit of 100kHz. For example, the time
signal at 77,5 kHz is well received. The lower limit in frequency for practical use seems at approx. 50kHz.
That was a good start. However, the extremely high sensitivity really knocked me off my feet: Stations which are noisy on the R1000 (so
far my unbeatable workhorse) are crisp and clear in the RSP, thanks to the innovative LNA concept. Furthermore, I could receive week
stations even in between strong signals – of course somewhat noisy. But in the R1000 they are completely buried within the noise and
you would not have guessed that there is something. That also holds for FM and 2m: the RTL-SDRs are much, much worse, even when
using an external LNA.
The next positive impression was on frequency accuracy and stability. The displayed absolute frequency appears accurate within less
than 100Hz for my RSP. Besides accuracy, frequency stability is the key– otherwise any fixed ppm-corrections are useless. For my RSP I
could detect no frequency drift e.g. within a few hours of receiving SSB/CW or when tuning in the next day. In complete contrast to all the
RTL-SDR sticks I have tested – they drift like hell.
Another positive observation is the low heat generation of the RSP (– no comparison to the RTL-SDR sticks). Maybe this also contributes
to the good frequency stability of the RSP.
What is left to say: Congratulations to the SDRplay engineers who have developed this superb piece of SDR hardware! It is worth every
penny.“ , June 19th 2015

more candid reviews are on https://www.facebook.com/groups/sdrplay
 
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