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  #21 (permalink)  
Old 02-12-2018, 4:05 PM
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So what's the consensus on this issue? Has it been fixed yet or did anyone find a workaround?

I was thinking of buying an HF+.
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  #22 (permalink)  
Old 02-13-2018, 8:41 PM
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Okay I had to follow up on this. I did some reading around and I found an article where an individual was having intermod problems with his HF+. He claims that a firmware update helped fix the problem so for those of you who are having this issue I would try to upgrade your firmware.

On the airspy hf+ page there is a link at the bottom to download the firmware update. Revision code is R1.1

I might just buy one now if this solves that problem.
  #23 (permalink)  
Old 02-14-2018, 4:48 AM
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I'm amazed that you found any complaints left at all as they have generally been removed, at least, most have. Many of the regulars have stopped posting too. Youseff now vets every post in the "official" group.io and simply rejects posts likely to result in reduced sales.

There was a firmware upgrade to improve the overloading issue but that was pulled. Another has appeared. Whereas it helps, it doesn't fix the hardware issues. Only a hardware mod will improve VLF (at the possible risk of static killing it) which may affect sensitivity further up, and only by using external filters can you prevent TETRA etc from running amok over VHF air.

It's not the radio that was advertised and that many hundreds, bought.
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  #24 (permalink)  
Old 02-14-2018, 1:05 PM
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Yeah I think a lot of the issues are originating from the gain control being locked in an algorithm. I have a very strong intermittent UHF telemetry signal literally two blocks from where I live and i'm a bit worried it would overload the VHF side of the hf+.

I've floated the idea of just putting the hf+ into service for hf monitoring but I'm not sure yet.
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Old 02-14-2018, 3:00 PM
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It's TETRA at around 400MHz that is stomping all over VHF with the HF+.

My remaining HF+ doesn't get used at all now. Tiny bandwidth, no bias-t, generally crap. I had two but fortunately flogged one while there was still a demand. You could wait for one to come up on ebay, a few have already. At least you should get your money back, unlike me.
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  #26 (permalink)  
Old 02-15-2018, 12:29 PM
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Yeah i see what you mean. I'm wondering how my low noise amp on the antenna would work with the agc on the hf+. The run is about 45 feet of LMR240 and there's an lna at the discone to overcome the loss, if I can't power the amp that's no good i'll have loss in the cable. I feel like the boost from the lna wouldn't play well with the agc on the hf+ though.

I guess I could always rip out the LMR240 and install 600 back to my office then ditch the lna..

Are you by chance using any kind of low noise amp at your antenna for the vhf side?
  #27 (permalink)  
Old 02-15-2018, 3:31 PM
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I have preamps but they are only use for testing, and never left inline. I use LMR400 class Messi and Paoloni - proper solid copper cored stuff, not that copper-clad aluminium that even Times Microwave use nowadays to keep the production costs down.

IMO, the HF+ seems like an experiment, not a proper tool. Most of what people want, is missing, and substituted with a promise of dynamic range, as if 12bit and a gain control isn't already good in most cases. I wrote some months ago that it seems like a niche within a niche. The low noise is probably partly a function of heavy decimation anyway, hence the 600k bandwidth. The lack of manual gain control is nothing but a demo of arrogance too. The whole thing hangs on the quality of the AGC, which clearly didn't work well at all.

With all of the above, the part that really got on my nerves is the year of blagging, to then have some of those claims removed from the website, as soon as hundreds of buyers had already paid.

Frankly, Youssef Touil should have all further claims verified by Snopes.
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  #28 (permalink)  
Old 02-16-2018, 5:00 AM
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Instead try the RSP1A online via Simon Brown's V3 beta software.

It's amazing.

I have logged many new broadcast stations.
On 11kHz, 315kHz, 337kHz and at night many between 1.7 and 2.0MHz

Never even knew these stations existed!
  #29 (permalink)  
Old 02-16-2018, 6:31 AM
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Try with the MW filter enabled. You may find that they are images. There is only military, experimental and natural radio at VLF. At round 300KhZ are navaids. At night, LF can become awash with very strong signals. They seems to leak in everywhere.
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Old 02-16-2018, 7:15 AM
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Impossible. How can they "leak in" with a 14bit SDR?
Even at day time.

They must be real signals.
  #31 (permalink)  
Old 02-16-2018, 10:51 AM
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The bit depth is referring to its dynamic range - of its ability to simultaneously process both weak and strong signals. These cheap SDRs are really hybrid receivers.There is still analogue hardware in there. They may be "digital" but only at the point of when the signal is digitised within the ADC - the analogue to digital converter. Before that point, they are normal receivers with local oscillator, capacitors, coils and resistors for filters, attenuators, matching etc. More expensive hardware - Winradio G31 for example, use DDC, which brings the digital processing much closer to the antenna input. My G33DDC samples 50Mhz and is always visible on the screen. Even the DDCs though have to use local oscillators to get higher frequencies.
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Last edited by Flatliner; 02-16-2018 at 10:56 AM..
  #32 (permalink)  
Old 02-16-2018, 11:23 AM
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No, I don't believe that.
The RSPA1A brochure says:

Excellent dynamic range for challenging reception conditions
Low levels of spurious responses
11 high-selectivity, built in front-end preselection filters
Software selectable AM/FM and DAB broadcast band notch filters

How could it ever be that weaker signals pop up in what you say is the navaids band, at day-time?

It must be broadcast in some other part of the world.
  #33 (permalink)  
Old 02-16-2018, 12:43 PM
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Quote:
Originally Posted by SigmaDelta View Post
Impossible. How can they "leak in" with a 14bit SDR?
Every SDR has an analog signal that is getting digitized. Eliminating images and stray signals is the responsibility of the analog circuitry that creates the signal to be digitized. You can't hook an antenna directly to an ADC. Even if the RF signal falls below the ADC's sampling rate, you still need at a minimum a preamplifier to boost the RF signal to the voltage range of the ADC's input. For higher frequencies, you need a local oscillator, mixer, etc. If that analog circuitry is not designed properly, stray signals and images can be introduced into the analog signal presented to the ADC. If that happens, the ADC cannot remove them, no matter how fast it samples, or how many bits it generates per sample.
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  #34 (permalink)  
Old 02-16-2018, 2:58 PM
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Quote:
Originally Posted by SigmaDelta View Post
No, I don't believe that.
The RSPA1A brochure says:

• Excellent dynamic range for challenging reception conditions
• Low levels of spurious responses
• 11 high-selectivity, built in front-end preselection filters
• Software selectable AM/FM and DAB broadcast band notch filters

How could it ever be that weaker signals pop up in what you say is the navaids band, at day-time?

It must be broadcast in some other part of the world.
You don't believe what?

Excellent Doesn't mean "perfect".

"Low level" doesn't mean "non-existent".

You may need to use filters, and that's clear by the spec that you've quoted, certainly by those with a modicum of radio knowledge.

You're lucky though. Things could have been worse had you have bought an Airspy HF+. Imagine how disappointed you would have felt had you have believed what you had read, there.

Here's what it said on its brochure up until January (after many hundreds of units had been sold, produced and delivered)

"No external band aid filters are required like the lower end HF receivers"

Wow, that's sounds definitive - no filters at all! And only 200? I'll buy one! In fact, I'll buy two!

Though by February, that claim vanished. WTF??

Now, if you scroll down 6 or 7 screens of further claims and irrelevance, such as where to download Gqrx… no, keep looking, there, right at the bottom, under the new section called “Product Limitations”, it now states “it will require some filtering”.

Yep, right at the bottom. Yet the removed claims were originally right at the top, in the first block of text. It's reminiscent of a Daily Mail apology.

So, by admission, it does need external band aid filters. And yes it does. So, by their own words, this makes Airspy HF+ a lower end HF receiver after all.
.
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Last edited by Flatliner; 02-16-2018 at 3:08 PM..
  #35 (permalink)  
Old 02-16-2018, 3:12 PM
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Quote:
Originally Posted by c_snyder View Post
Yeah i see what you mean. I'm wondering how my low noise amp on the antenna would work with the agc on the hf+. The run is about 45 feet of LMR240 and there's an lna at the discone to overcome the loss, if I can't power the amp that's no good i'll have loss in the cable. I feel like the boost from the lna wouldn't play well with the agc on the hf+ though.

I guess I could always rip out the LMR240 and install 600 back to my office then ditch the lna..

Are you by chance using any kind of low noise amp at your antenna for the vhf side?
I've just installed yet more firmware for the HF+. He put some AGC settings in, available from sdrsharp but they do nothing to help. In fact, now the HF+ suffers from AGC pumping. It's even worse. Jees...

The picture is with an external MW filter. Look at the mess without it

Well, if a picture says a thousand words, then this is a novel of the magnitude that Tostoy would have been proud of.

In this you have:

Very weak and eventually no valid signals under 50kHz. So much for "9kHz to...".
Horible AGC pumping
MW stations flooding LF

This is with latest 1641 sdrsharp and R1.2 firmware. It's actually now even worse than when I got it.
.
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Last edited by Flatliner; 02-16-2018 at 3:32 PM..
  #36 (permalink)  
Old 02-16-2018, 3:43 PM
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That's strange.
With the HF+ I don't see any of the broadcast stations on 11kHz, 315kHz, 337kHz, nor in the 160m ham band.
Is the HF+ less sensitive on these frequencies?
  #37 (permalink)  
Old 02-16-2018, 8:54 PM
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That's interesting. I see they have released another R1.3 update today. I think it adds an att feature and some other fixes.

What is your noise floor level average at 768k bandwidth?
  #38 (permalink)  
Old 02-18-2018, 5:57 AM
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Quote:
Originally Posted by c_snyder View Post
That's interesting. I see they have released another R1.3 update today. I think it adds an att feature and some other fixes.

What is your noise floor level average at 768k bandwidth?
Without a signal, at -100 to -105dBFS on HF according to sdrsharp, which a bit meaningless. I've have yet to put in a calibrated signal to test where that noise floor really is.

I loaded 1.3 and it enabled another option though I don't see much improvement, maybe a little but not much. I can make things worse now though!
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Last edited by Flatliner; 02-18-2018 at 6:03 AM..
  #39 (permalink)  
Old 02-18-2018, 5:59 AM
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Quote:
Originally Posted by SigmaDelta View Post
That's strange.
With the HF+ I don't see any of the broadcast stations on 11kHz, 315kHz, 337kHz, nor in the 160m ham band.
Is the HF+ less sensitive on these frequencies?
As you can see in the photo, I do. It will depend on how strong those stations are at your location.
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  #40 (permalink)  
Old 02-18-2018, 10:17 AM
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I don't see anything in the photo.
What HW? What antenna? What pre-amp? What version?
Anyone can overload any HW and post a meaningless waterfall detail.
Your posts read like a continuous one-brand rant without any technical information.
Or is it just me?
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